Hi-Fi+ Issue No 64 Spring 2009.
Review by Alan Sircom
Break for the Border: The Puresound A30 with Border Patrol Power Supply
Click here to view the full review in Adobe PDF format
Hi-Fi Choice Spring 2006
Review by Jason Kennedy
The Border Patrol Control Unit pre-amplifier
Copper bottom! Border Patrol has finally finished its preamplifier, has it been worth the wait?
Though you’d not guess it from the website Border Patrol now operates from Maryland on the East coast of the United States, this continental shift seems to have had a subtle but distinct effect on the preamplifier or Control Unit as it’s known. The first and rather discreetly marketed BP Control Unit was nowhere near as heavy or sharp edged as its successor which is a more serious beast all round. To be fair the first BP preamp we had was more of a prototype than a manufactured product but that didn’t stop it working well and being professionally finished. Yet it didn’t have the sharp edged, thick aluminium facia or front panel on/off switch of this ‘shiny’ new beast, nor did it offer the option of a valve phono stage or all copper chassis construction.
When this Control Unit was launched it was offered in CU1 and CU2 varieties, the former being encased in aluminium and featuring some reduction in component quality for a 30 per cent cost saving. As things turned out the market was far more interested in the full monty CU2 so the more affordable variant has been dropped from the range. We asked BP proprietor Gary Dews what the advantages of the 2mm copper plate chassis are and he explained that it produces a richer sound than aluminium which is grainy, bleached and wispy by comparison. Possible reasons for this are the lower ferrous content of copper, ie it’s less magnetic, aluminium is not very magnetic but slide a magnet down an ally sheet and a copper sheet and you’ll note it moves more quickly down the copper one. The copper chassis is also twice the weight of the aluminium and this makes it harder to resonate, it’s also more ductile (malleable) which is said to be a benefit.
Compared to its predecessor the new Control Unit uses the same negative feedback free circuit but has higher quality components such as Blackgate power supply caps and Hovland Musicaps for signal coupling. The CU’s USP is the use of choke input filtering (CIF) for the heater supply, this is combined with a CIF high voltage supply using an EZ80 valve for rectification, as found in the original CU, which produces better regulation, lower noise floor and greater impunity to RF entering the signal path.
BP chose a single 5687 double triode valve signal amplification and used it in anode follower configuration because of the simplicity that this route offers. The price for this simplicity is a limited ability to drive interconnect cable and BP recommends keeping this link below three metres. It’s a technique that also works rather better with low sensitivity power amps such as those in the BP range, more sensitive designs will tend to give too much overall gain which can exaggerate microphonic tendencies in the valves.
The moving magnet phono stage adds £700 to the cost of the CU and as with the line stage is fully hardwired, it is a two stage design using an ECC83 and a 6922 double triode. At present there are no plans to offer a step-up transformer which would make this stage work with MC cartridges but these are made by other companies should you want to take the serious vinyl route.
The Control Unit has five line level inputs in standard guise or four plus phono with that stage onboard, there is a pair of output sockets and a tape out. Front panel controls are minimal and remote control is unfortunately not an option – this is a hardcore product after all.
There is a tendency to think of valve equipment as being slightly rose tinted, smooth and a little soft, this prejudice is not entirely surprising because there have been plenty of tube powered amplifiers made that fit that picture. However there have been almost as many which do not and Border Patrol’s creations tend to be in this latter camp, so much so that some in the ‘romance of valves’ camp describe the kit as being rather too hi-fi. We are of the opinion that whatever technology you use to create an audio component the end result is what counts, if it is resolute in all the right areas and it draws you into the music then it does what is intended. Valve romance is very nice, charming in fact but it is a coloration or distortion and thus diverts us from the goal of high fidelity.
The Control Unit is indeed pretty neutral by valve standards, compare it with a passive pot however and you’ll notice that high frequencies are slightly rolled off and the midrange is a little more obvious, while next to a Bryston BP25 preamp the CU’s bass is a little soft edged. On the credit side there is plenty to make up for these limitations at the frequency extremes, the midrange is transparent and vivid and the sense of timing right on the money.
The bass while not as crunchy as trannies will deliver is not short on weight or depth and it scores very highly on articulation, tonal resolve is a clear strength of tube amps and this is no exception. The electric bass on Neil Ardley’s Kaleidoscope of Rainbows is positively lush in its vibrancy and each note has a solidity that makes for a convincing sense of presence in the room.
Higher up the tonal scale things get even more entertaining, this is where you get a sense of transparency and resolve that will win over even the most hard hearted audiophile. It’s where music’s power to communicate is at its strongest, and this preamp makes the most of it without going overboard, thus Gillian Welch is as heart rending as one can bare thanks to a balance that’s relaxed but puts the edges right where they should be. The voice is beautifully warm but the guitars still have plenty of zing. This is the nub of the Border Patrol, its ability to get to the heart of the music without forgoing the strength of the elements that make it up, its fluid but also well separated.
We used an old Audio Innovations Series 1000 step-up transformer to bring a vdH Condor cartridge’s output up to a level that the BP’s phono stage could deal with to see how it fared. An experiment that revealed just how dynamic vinyl can be in the right company, the power of Ardley’s ‘prog orchestra’ delivering substantial dynamic energy and plenty of harmonic detail. The degree to which the BP unearths the organic, three dimensional aspects of an LP is particularly engaging, the term ‘chewy’ seeming wholly appropriate when trying to describe the sound of a well recorded double bass. Of course when terms like that start to turn up in the notes you know that an element of charm has taken over and you are having far too much fun to be observing results in an impartial manner!
There you go, even the toughest among us are not immune to the beguiling qualities of a fine valve amplier, and that’s in the context of hard nosed transistor power amplification. With one of BP’s single ended triodes as well analytical assessment would be nigh on impossible, still they are ‘hi-fi’ so maybe decorum could be maintained. Either way it’s hard to turn the music off.
Excellent transparency and dynamics combined with good focus and low noise, nice solid construction, lovely phono stage.
Needs short (max 3m) interconnect to a low sensitivity power amp for best results, no remote option, MC cartridges will need a step-up.
Conclusion This substantial and nicely built preamplifier delivers all the positive qualities of tubes while maintaining a degree of neutrality that is rare for the breed, if you want to get the heart of the music without losing its head this is a powerful tool.
Key features: Size (HxWxD): 12x45x35cm Weight: 12kg Solid copper plate chassis Five line inputs Optional phono stage.
Hi-Fi+ Awards issue 2004
Review by Jason Kennedy
The Border Patrol S20 SE power amp
BorderPatrol S20 Power Amplifier- Hi-Fi + Review. The full review in Adobe PDF Format
Hi-Fi Choice Collection Edition 2004
Review by Jason Kennedy
The Border Patrol S20 power amplifier and Control Unit pre-amplifier.
Border Patrol seems like a reasonable enough name for a valve amp manufacturer these days, but twelve years ago when the name was used for a rather unusual green valve power amp (with PX4 output tubes if memory serves) made by then Audio Innovations employee Guy Sergeant it was a source of some amusement. It was also dubbed the Big Ten, another humorous reference to the fact that it produced nine watts but one which back fired when Guy’s employers heard about it, whence the name reverted to BT for big trouble!
What became of the green amp is lost in the mists of audiophile time, which while slower than real time is no easier to keep track of, but the name has lived on thanks to the efforts of one time Audio Innovations retailer Gary Dews who used to run the southern arm of the small but passionate Definitive Audio retail collective.
Gary made his first Border Patrol in 1993 but the brand didn’t come of age and until the first silk screened models in ‘97. Since then BP has produced a number of variations on the power amp theme as well as some of the meatiest external power supplies in the valve kingdom. The latter re-introduced the notion of valve rectified choke input filtering to the hi-fi world and go some way to explaining why Border Patrol amps tend not to sound like traditional valve amps in as much as they do bass with no little conviction.
A quick look around the BP website will reveal that there are numerous ways to use the popular 300B triode output tubes that feature on this and most other BP designs. There are pure single ended designs with one output tube per channel and so called push pull versions with two output tubes per channel which are technically, but not necessarily sonically, superior to the parallel single ended arrangement found on the S20. Paralleled output tubes amplify the whole signal for one channel, the effect being a slightly greater than doubling of the usual 7.5 watts offered by 300B valves. There are pros and cons to each configuration but in purist terms the hierarchy goes: single ended, parallel single ended, push pull. One reason not to build a single ended amp is that the output transformers have to be considerably larger than the equivalent push-pull– those aren’t mains transformers at the back of the S20 – because there is a continuous DC flow through the transformer which therefore needs a much larger magnetic core and an air gap to prevent saturation. Border Patrol designs all of its own transformers to ensure that results are not compromised by this critical stage in the chain.
The S20 is a fully hard wired, all triode, class A design. It uses an input driver valve that has high gain, low impedance and high transconductance. The latter in simple terms indicates sensitivity and used to be referred to as the ‘goodness factor’, greater sensitivity being A Good Thing in almost all high fidelity components. The other good thing you need in any amp is a decent power supply, the S20 being dual mono all the way back to the mains socket, has two very hefty supplies feeding the requisite voltages to the amplifier via meaty multipin connectors. Quite conveniently both supplies and the amp itself are powered up with a single switch, less conveniently this switch is located behind one of the supplies, and as this baby runs very warm indeed, you won’t feel inclined to leave it on all the time unless the central heating has packed up.
You get a choice of output valve with all BP’s. This sample came with TJ Full Music mesh-plate 300Bs, but both less and more expensive options are available, assuming that is, that Western Electric resolve the supply problems for its legendary 300Bs.
The matching pre-amp, or Control Unit as BP dubs it, is actually a prototype and full production units are expected in September and will bear an LED to indicate power on. It uses a 5687
triode valve in anode follower configuration with no negative feedback, the circuitry being fully hardwired as in the S20. The power supply also mirrors the power amp in being valve rectified with choke input filtering. A 24 position step attenuator is used to control volume and is combined with a five input selector for the line inputs on the back, these are joined by tape- and two pre- outs.
Performance We used the Border Patrol combo with Living Voice Avatar OBX-R speakers, a combination that works well because of the decent sensitivity of the speakers and a similar approach to sound reproduction, by which we mean that both brands value dynamics and timbral resolve more than other high fidelity virtues. If you can get these two things right everything else seems to fall into place, timing for instance, is very good – this is a nimble or agile amplifier that keeps up with everything you throw at it. It reminds you of why Quicksilver was such a good name for a valve amp brand. What you get alongside the speed is rather unvalve-like bass power. Those two power supplies are damn ‘stiff’ as they say in the trade, and allow the essentially low power output devices to deliver some serious grunt.
Because this is SET grunt it reveals all the colour and shape of bass notes in a tuneful and dynamic fashion. The majority of SET’s sound distinctly lame compared to the Border Patrol; this is a triode amp for those reared on transistor bass. Stick on some Outkast and you’ll know all about the instrumentation, recording and processing of the sounds used to produce the bass, the low synth bass on the track Love Hater being a good example.
Another atypical aspect of this amp is its response. Valves are famous for having a glorious midband and a tendency to emphasise this above all else. The S20 while phenomenally transparent in the mid-band has a remarkably flat response. You don’t miss out of the frequency extremes with it This is a wide band amplifier!
The midband is proper SET stuff though, voices are superb and you can hear all the words all of the time. This is a fluid and revealing amp that combines a delicacy that lets you hear micro dynamics clearly with an ability to swing real energy when it’s required. At the end of the day 18 watts is still 18 watts and you don’t get the power that a similarly priced transistor design can offer, but the way tracks like Deep Purple’s Never Before pump with energy and colour is extremely beguiling, and even if you push the level hard, the way it clips is actually rather nice with material like this. When a tranny amp clips the distortion produced is pretty offensive whereas a valve design on the other hand can actually sound quite good. That’s why many electric guitar players still prefer valves in their amps.
The Border Patrols are also very strong when it comes to producing three dimensional notes in a soundstage that is as deep as they come, the sampled and treated sounds on Fourtet’s Rounds are positively solid yet never static. The way that Kieren Hebden uses reverb and declining level to slowly pull the music away from the listener as track 1 fades out is extremely well put with the BP’s. This quality also applies to the recreation of acoustic space. This is not one of those blowsy valve amps that makes everything enormous, it’s a precisely focussed device, but when something comes along with height information such as a track from Bugge Wesseltoft’s Filming where there is the twitter of birds sitting way above the groove creation of the band, all is clear. What’s more the resolution of small sounds is so good that you can precisely identify what the sources for all those sounds are – sparrows methinks.
The track Clear Spot from Captain Beefheart’s album of the same name has gorgeous ‘phat’ bass lines, colour, life and energy with no apparent shortage of grunt in the BP’s capable hands. It’s a lovely meaty sound which majors on grin factor, Don van Vliet’s elastic blues works a treat with this level of attention to timing and energy. Technically speaking, single-ended valve amps are meant to produce lots of second order harmonic distortion, but if this is distortion – bring it on.
The Border Patrol amps are impressively well built, attention to detail is high and you get the impression that valves aside they would give more than a lifetime’s service. This combined with their glorious energy, drive and resolve makes them superb value and a sure fire way to get to the heart of your music collection.
Hi-Fi+ Issue No 25 August/September 2003.
Review by Roy Gregory
The Border Patrol P20
Way back in Issue 8, I reviewed the Border Patrol SE300B-WE amplifier, and was duly impressed, despite my skepticism when it comes to most things single-ended. Here was the first single-ended triode amplifier I'd heard that had authority at both frequency extremes and wasn't swamped in syrupy warmth and second harmonic distortion. In fact, the SE300B was pretty much as far from traditional valve sound as it's possible to be, whilst still retaining the dynamic virtues of thermionic amplification.
It timed, it had tremendous dynamic integrity, it had superb clarity and organisation, it had eight Watts a side.
Okay, so they were seriously impressive Watts, but unless you believe the "valve Watts are different to solid-state Watts" line of BS, eight Watts is still only eight Watts. And that seriously limits the available range of usable loudspeakers.
Since the departure of. the Border Patrol I've also discovered the Lamm ML2 mono-blocks, single-ended amps with a little over twice the power and around six times the price tag! Very nice they are too - as they damn well should be. They too have authority, dynamics, timing, clarity and organisation. They too sound nothing like the majority of single-ended amps. Which led me to the following suspicion. If the only single-ended triodes that I like don't actually sound like single-ended amps at all, then perhaps I just don't like what most people seem to like about single-ended amplifiers. Then along came The Soul (a single-ended Tetrode/hybrid amplifier of all things) and it simply underlined my conclusion. Fabulous amplifier absolutely none of the traditional SE virtues at all - except for linearity, but most SET's have such a pathetic power delivery into bandwidth that that's an irrelevance for them anyway.
Which begs the question, why saddle yourself with the flea-power output of the average SET if you don't even like what it does to the signal? I couldn't agree more. The only good SET is a properly engineered one, and those are rarer than the fabled fertilizer from the wooden horse that rocks. What people like about SET's actually seems to be the soft sound of inadequate power supplies combined with lashings of even order harmonic distortion, rather than any intrinsic benefit from the circuit topology or output device. All very cuddly I'm sure, but I guess that when push comes to shove, I'm just a push-pull kind of guy. Which brings me rather neatly to the Border Patrol P20, a 300B amp that meets all my criteria and has recently arrived for review. Quelle surprise!
The P20 is at once much the same and twice the amp that the SE300B is, at least physically speaking anyway. The main chassis uses the same profiled wooden surround and aluminium top plate that supports the same 300B output tubes, only in this case there are four of them arranged as push-pull pairs. There's also the obligatory choke filtered power supply, the product that established the Border Patrol name. Only once again there's two of them, one for each channel. In fact, you can buy the amp with a single supply (as the P21) and then upgrade it later, but it's not a simple plug-in upgrade and requires the unit to go back to the factory, so it's the finished article that we're considering here. And that's just the first of a bewildering array of options that I'll work my way through. The power supplies are each housed in a standard Border Patrol case, but are rather more complex than the more expensive of the two standard versions. Whereas the MB (M for maximum, the B I'll leave to your imagination) supply a single discrete voltage for the amplifier's HT, the supplies err... supplied with the P20 actually deliver five individual voltages each, two destined HT and one each for the negative bias and various heater supplies of each channel. That requires nine wires compared to the standard versions four.
Each supply is matched to it’s specific channel, correct connection ensured by the use of male and female mating collars on the two captive leads attached to the amp.
Each supply has a ground lift switch, a sensible move given the dual power leads required and the potential for earth loops.
One operational oddity of the amp is that, although one of the supplies acts as a master meaning there’s only one mains switch, the switch itself is located on the back of that supply making accessibility something of an issue if you prefer to power your equipment down. Unfortunately, there's physically no room to move the switch to the front panel and it would mean disturbing the preferred wiring layout, separating DC from AC. The other unusual feature is the volume control option. This consists of a chromed knob mounted centrally in the front of the amps plinth connected to a stepped attenuator. This allows direct connection of a single source, allowing users in this happy circumstance to dispense with the cost and complications of a line stage. Alternatively, the amp is available with a standard fixed input of a lower sensitivity intended for driving from a pre-amp. Twice the output tubes and the push-pull topology delivers slightly more than twice the power and that adds up to 20 Watts of class A grunt, which is far more familiar territory as far as I’m concerned. The amp arrived with a matched quartet of Western Electric 300Bs and an additional set of mesh-plate Gold Dragons, a cost and qualitative option that I'll get to later. Otherwise there's a CV4068 input valve supplying a Mullard E182CC driver which feeds the inter-stage phase splitter transformer. Using a transformer instead of a valve to split phase affords greater accuracy, time consistency and zero feedback.
Connections consist of a pair of RCA phono's for the input and decent 4mm binding posts with four and eight ohm output options.
One speaker that worked a treat with the SE300B was the resident Living Voice OBX-R, which was also on hand to try with the P20. But given the additional power available I was fascinated by the results with a wider range of partnering speakers. To that end I tried the Reference 3A DeCapo's (fairly sensible) the Alon Lotus Elites (sensible if we stretch our credibility a bit) and the KEF Reference 207s (not sensible at all). I ran the P20 mainly from The Vibe line-stage, but also direct from both the Wadia 861 and Groove and Vendetta Research phono-stages. Cabling was Nordost Valhalla throughout.
It's a while since I had the SE300B at home and aural memory is a notoriously fickle thing, but what sticks in the mind (apart from its almost astringent neutrality - if the Vatican made amps then this would be it: complete with in-built guilt as regards any flights of fancy or unwarranted addition) is the gusto with which it delivered every one of its eight Watts. There's a world of difference between sounding powerful and actually being powerful. Indeed, the effect is all too often the exact opposite of the fact, and the SE300B took this to extremes. It got there so fast with so much, that, whilst it never seemed to run out of steam (at least with a sensible load attached) you were frequently aware of the edge of the envelope and the precipice beyond. The P20 is a totally different kettle of fish. It has twice the power and its push-pull output stage brings a greater sense of focus and leading edge definition. The result is an amp that offers virtually all of the attributes of its single-ended sibling, but grafts on a sense of ease and poise combined with more emphatic dynamic contrasts. It's as if the music has been brought within its compass, and along with that comes a confidence in the placing and level of notes. There's more space around each note, in both dimensional and temporal terms, making each one easy to hear, along with relationship to the next. It simply makes life easier.
That handles the ease and poise: what about the emphatic dynamics? Well, at the same time that things become easier to hear, they happen faster too, so you have the slightly unusual situation that the music sounds slower in tempo but the amp is actually quicker. Think about it for a second and it all makes sense. If the notes start and stop quicker then you get longer (and more precise) spaces in between. The dynamic window is wider too and the increased sense of power and substance combine to create a showier, more immediately engaging and inviting sound. The musical performance becomes more dramatic, the playing more demonstrative.
Playing the Classic Records re-issue of the Cannonball Adderley classic Somethin' Else (Classic Records 200g/Blue Note 1595) the sound is big and stable, the bass really well grounded (it's those power supplies again). Autumn Leaves' opens with a beautifully measured limping walk of a bass-line, laid out in the piano's left band and shadowed by Sam Jones on bass. The P20 gets the rolling rhythmic gait just right, the slight slowing... then the speeding up, but never, ever dragging. The two instruments are distinctly separated, and that's down to tonal and textural definition on this mono disc. Miles' horn entry is unmistakable. The tone is spot on, the poise and spacing of the simple melody Nobody plays quite like Miles, and the contrast between his pure cool and the dirtier, fruitier bop-style of the Cannonball is what gives this quintet its special flavour, an evolution of the chemistry that fuelled his earlier outings with Charlie Parker. (No! Not that chemistry) It's the subtle nuances cal relationships that Patrol effortlessly reveals. But what makes it special is the energy it brings to the fun it has doing it. The clarity and stability that come from the firm bass foundation extend way up the range too. Art Blakey's stylish yet discrete cymbal work is one of the great pleasures to be had from Somethin' Else, and the P20 makes the most of his contribution, keeping it in the right lace and perfectly in proportion. Female vocals are similarly well served; gaining air and delicacy revelling in the musical space the amp allows them.
Play Breaking Silence (Analogue Productions APP 027) with Janis lan's fragile vocals caught in the dynamic spotlight of sudden shifts in level, and you'll see what 1 mean. The music gains drama from the contrast and emotional power as a result. And 1 know I've already talked about the bass at some length, but you really should hear the bass lines on this album. Hear them that is, in the sense of around, behind and beneath the notes. Tactile? I should co-co.
Whilst the P20 will drive a wider range of speakers than the smaller SE, to hear it at its best, you'll still want to play it with something reasonably efficient. Impressive with the KEF Reference 207s, it was downright spectacular with the Reference 3As and the latest Living Voice OBX-Rs. Here, the authority shape, pacing and tactile presence that the P20 brought to the nether regions of these physically modest speakers imbued them with a scale and sheer unflappable stability totally at odds with expectations. Tonal colour and separation were superb, with none of the qualitative sameness that collapses the individual character and texture of instruments (and performers). The P20 will never have the air and clarity the detail and transparency of the Hovland Radia. But then the cool American will never have the presence, energy and sheer musical gusto of the Border Patrol. What the P20 provides is the tonal sophistication and lack of colouration enjoyed by the SE300B, but coupled to a serious dose of authentic musical energy and improved focus and dynamic snap. Substituting the Mesh Plate Golden Dragons should bring added air, delicacy and fineness at the expense of some of the presence and sheer clout. I ran out of time to try the swap, but with meat to spare and based on past experience I feel that the P20 fitted with the Chinese valves offers a serious alternative to the Western Electrics, providing a different but qualitatively equal view of musical events. Cheaper too!
The P20 is a mightily impressive amplifier and one that explodes the triode myth. Once again, it proves that it's not what you use but how you use it that counts. Good engineering will win out. I've listened long and hard to the push-pull Border Patrol and still haven't got its full measure. And that's without the Mesh Plate option, which I've a sneaking suspicion I'll ultimately favour. Then of course there's the S20, the parallel single-ended version of the same beast. There's more, much more, to come...
Hi-Fi Choice issue No 231 Summer2002
Review by Jason Kennedy
The Border Patrol P20
Border Patrol is not the sort of company to rush into hasty new product launches. In it's ten year history it has put two valve powered components in to production - the original Border Patrol single-ended (SE) power amplifier and the BP choke input filter power supply.
Realising that a nine-watt, single-ended amp is not perhaps for everyone, BP has branched out into the world of push-pull and produced the subtly named P20. This uses a pair of legendary 300B triode output valves per channel and delivers a block rockin' 20 watts. Compared to transistor amps this may not sound impressive, but anyone who's heard a decent tube amp knows that with a reasonably efficient pair of loudspeakers (90dB or more) 20 watts go a long way. In fact it's the first few watts that are most important with any amp, so it's quality rather than absolute quantity that counts. In this instance there are two substantial standalone BP power supplies - a three-choke input filter, valve rectified supply for each channel. This thing is dual mono all the way back to the twin mains plugs.
So why on earth do these watts cost over £300 per pair (this is a stereo amp)? Basically it comes down to quality of components, build and design, plus of course the fact that this amp is a bit like a Morgan car; hand built to order, though fortunately the waiting list is weeks rather than years. This design is no compromise from the ground up, the power supplies each weigh more than most £1000 amps and deliver the stiffest power in the valve universe. The amp uses Western Electric 300B's, a set of which usually costs £1,200 alone, though alternatives are available and this amp with Tesla tubes costs £1000 less. This example also features a Danish Audio Connect stepped attenuator or volume control (£250 extra), so single source users can use it without a pre-amp.
The effect of the BP P20 on a pair of JBL Ti2K speakers (HFC230) was quite extraordinary. The treble in particular was transformed from being rather too obvious to sparkling and the bass took on a tunefulness that had me jumping around. Good valve amps do a number of things that their transistor counterparts can only dream about.
'Good valve amps do number of things that their transistor counterparts can
only dream about such as their ability to handle dynamics and timbral resolution.'
These include dynamics - the ability to open up music that normally sounds compressed, and timbral resolution- pin pointing the tonal shading of an instrument or voice. Where valves usually conceded to transistors is in absolute power, bass solidity and high frequency phase linearity.
The reason why the P20 has such humongous power supplies is so that it can deliver as much bass muscle as a pair of 300B's is able to muster, and this pair can kick arse (as opposed to ass, which is a donkey-like pack animal as I'm sure you are aware). While the bass on offer is not quite as thunderous as you'll get from 200 transistor watts it has a precision and fluidity that few tranny designs can imitate. And it's got grunt, a point proved by Missy Elliott's funked up beats on
All N My Grill, which reveals a rare architectural quality.
Moving up the scale to the midland is always a pleasant experience with good tubes and this combination does not disappoint. It is positively holographic, the expression and presence of instruments and voices quite startling and totally engaging. The EST Plays Monk CD
can be a less than complete experience but when you get to hear the instruments and interplay this clearly, everything falls into place- you hear what Monk was saying and you appreciate EST's interpretation to the full. The tone colour delivery is second to none, and I found myself playing acoustic music I had just to hear what the various instruments and voices really sound like. The saxophone on Bugge Wesseltoft's
Yellow is the Colour, the drums on Abdullah Ibrahim's Ekaya and Fontella's Bass' voice on The Cinematic Orchestra's
Everyday. It all comes with such vivacity and realism that it's hard to get anything else done.
Of course it doesn't end with a acoustic sound sources , electric ones have plenty to offer as well, even heavy rock music like Tool and the raucous Jon Spencer Blues Explosion make their mark in no uncertain terms.
In the right company this amp delivers transparency, fluidity of timing and grunt like few others out there. It won't crunch bones, nor will it drive insensitive speakers but if it's the musical essence you're after it's a tough act to follow.
+ve Phenomenal transparency, fluidity and tonal resolution combine with real grunt and dynamics.
-ve Needs two mains leads(!). Won't drive inefficient speakers (<87dB/W) to the max.
Superb triode amplifier with bags of power and genuine resolution, one of the best musical appreciation devices available. EDITORS CHOICE
Hi-Fi+ Issue No 8 Nov/Dec 2000
Review by Roy Gregory
The Border Patrol 300B SE (WE)
Listen to some audio commentators and you could be forgiven for feeling that single-ended amplifiers are the truth, the light and the only way. Indeed, the quasi-religious fervour that this technology attracts brooks no dissent - bizarre when you consider that it was last current over sixty years ago. This topology and only this topology delivers sound so natural that it renders all else false, music so powerful that mere Watts become irrelevant. Are we to assume that the development of all intervening technology was just a string of gigantic mistakes? Apparently so.
In fact, so universal has this crusade become (they'll be burning old copies of Wireless World soon, swiftly followed by a few reviewers and editors) that the odd voice of moderation has risked being swept away by the flood. But, unfortunately our experiences with a number of highly regarded single-ended designs have left us cold. Yes, as far as it's fair to generalise, they are warm and snugly and they breath across the midrange, but their lack of grip at frequency extremes, and an almost generic incapability to time bass notes robs music of drama and its sense of performance.
So, are we anti single-ended? Far from it. We call it the way we hear it.
But we're not prepared to write off an entire technology on the basis of a few bad experiences. One of the big problems that has emerged in hi-fi in the last twenty years, in direct proportion to the influence of marketing on product development, is the concept of the ‘magic ingredient' and the label that goes with it. The first really obvious example of this was the
metal dome tweeter. First there was the SL6, then the 600; all those lovely diagrams with lasers and soon you couldn't sell a speaker without a metal dome. So much so that established speaker designs were hastily re-jigged to accept some new wonder tweeter and a ti designation. Next came bi-wiring, and since then there's been similar stupidity over everything from
chipsets in CD players to materials in cables. With the benefit of 20x20 hindsight how many of you would buy any speaker today just because it uses a metal dome tweeter?
In fact, there's something of a backlash now, with soft domes making a real comeback. The problem with single-ended amplifiers is that in too many cases it really is just a label. A lot of manufacturers are producing them because they feel that they have to, rather than because they believe in the technology. The simple fact is that there's no such thing as a universal panacea, and an amplifier, properly used, is either good, bad or somewhere in between. Just because it contains single-ended circuitry and direct heated triodes is no guarantee of quality. In hi-fi it's not what you use but how you use it that matters, and buyers forget that at their peril.
Which brings us to the Border Patrol 300B SE(WE), an excellent and distinctive amplifier that also happens to be single-ended. Originally intended to partner the huge and extremely efficient Living Voice Air Partners, single-ended circuitry was chosen as the most appropriate topology and back in 1991, this was probably the first use of single-ended 300Bs in the UK. It was the limitations at the frequency extremes of that original design that led to the development of the sophisticated external power supply a simplified version of which soon became popular as a modification for other valve amps. But it's the full on three stage supply that remains at the heart of this amp. Which explains why the Border Patrol is a two box design, the non magnetic, wood framed chassis being linked by a heavy umbilical to the large external power supply. The amplifier proper is sparsely populated, with just four valves and four transformers. The socketry is all mounted vertically on the back of the top-plate, arid whilst that may not make for the tidiest cable dressing, hook-up is an absolute doddle. I definitely approve. Inputs are phono sockets, whilst single sets of 4mm binding posts are provided for each channel, with separate taps for 4 and 8 ohm loads. The amplifier sits on large cones, so be careful dragging it around, although thankfully the external power supply keeps its weight nice and manageable (I wouldn't want to pick this up if it was all in one box).
The only complication with set-up involved earthing, so hum free operation may demand a little care, but your dealer should sort this out for you anyway. I ended up running the Border Patrol from a floating earth. Otherwise, operation was completely fuss free throughout the review period. Incidentally the WE in the amps designation refers to the Western Electric valves with which it arrived. A £500 option, I didn't hear the amp in standard trim, but independent observers reckon that they're worth the £250 a valve premium, so who am I to argue? Otherwise you get a pair of JJ 300Bs from Slovakia, built on ex-Tesla machinery which Border Patrol reckon represent the best of the rest.
And the Border Patrol doesn't just look different. As you've probably already guessed the sound isn't exactly run of the mill either. Taut, crisp and solid are not words that apply to the vast majority of single-ended triode amps, but that's exactly how the 300B SE(WE) sounds. Lovers of the lush, blowsy and indistinct character that so many single-ended advocates seem to like are to be sorely disappointed.
There are no rose tinted specs, slurred and rolled off frequency extremes or over stuffed harmonics here. In fact, for the first time in my experience (the SAP Anniversary excepted), I'm listening to an amplifier with the linearity and directness that are supposed to be single-ended's great virtues. Indeed, the Border Patrol might have dipped out on the syrupy sweetness part of the single-ended deal, but it delivers the “real sense of power” with consummate ease, another area in which most of its compatriots fail to live up to their billing. Instead of lush and overblown, the 300B SE (WE) is wonderfully (and correctly) rich. Instruments have a natural weight and colour, and voices, especially tenors, have tremendous authority and a real sense of substance. Bjoerling's tone and power were awesomely barrel chested
(Cavalleria Rusticatia RCA VIC6044), while Milanovs magical poise and control
(La Forza Del Destino RCA SER 4516/7/8/9) forced you to question just why she is so consistently overlooked when people discuss great sopranos. There is absolutely no doubt that this amp is outstandingly natural in tonal and harmonic terms, giving the performer, be it instrumental or vocal, a tangible presence in the room.
All of which is useless if the whole thing doesn't hang together, so often a single-ended Achilles heel. Thankfully the Border Patrol has plenty of grip
in the nether regions, and keeps things moving purposefully along. Take the high energy drive of 'Look Down, Look Down' (Martin Stephenson and the Daintees
Bout to Bolivia KWLP5); from the jaunty opening phrase to the layer on layer of guitar and drum rolls as the song builds to its climax, the amp never fails to step up a gear an never loses control. The chopped guitar is tactile and full of direction, the twinned bass and bass drum notes are easily separated. And the voice? I think the word is direct. Unmistakably Martin Stephenson, the singer is never drowned no matter how frantic the band, never submerged in the (beautifully separated) backing vocals; the lyrics never lose that connection straight to you. In fact, the whole thing is a musical tour de force, belying the modest power rating of the amp, an impression that’s reinforced by the complete change in the size, shape and acoustic character of the sound stage (riot to mention the drum sound) on the next track, 'Slow Lovin' ', a trick one more normally associates with the kind of muscle amps we reviewed in Issue 6.
Of course, with around the same number of Watts output as I have fingers, the Border Patrol's performance is going to depend to a critical degree on the speakers it's asked to drive. Much of my listening
was done with the Living Voice Avatars, a speaker which often appears with the 300B SE (WE) at shows and in dealers demonstration rooms. With its 94dB sensitivity and benign load it's an obvious match, although it’s far from either an automatic choice or the only option. I used the Audioplan Kontrast IIIis to good effect, as well as the Ars Acoustica Devas (89.5dB and on the 4 ohm tap'). Both were fine but the Devas did underline the point that there's a real difference between sounding powerful (which
the Border Patrol does) and actually being powerful (which it isn't). Regardless of all the fond beliefs to the contrary a Watt is a fixed unit, not a sliding scale.
Pre-amp wise I used both the SPI.5 and the Hovland, whose capacitors feature in both the amp and the Living Voice speakers. I also ran the pre-amps and source components from the excellent PS Audio Power Plant 300, with the expected sonic benefits.
Throughout the various changes the 300B SE (WE) proved remarkably unconcerned, simply letting each amps essential character straight through, be it the musical coherence of the 1.5, the clarity and colour of the Hovland or the rhythmic, tonal and information benefits of the PS Audio. Is that the same as saying that the Border Patrol has no character? No, but the character it has is musically unobstructive. Comparisons with the JA30 are fascinating. The Jadis can't match the phenomenal tonal and harmonic accuracy of the Border Patrol (which is what lets it separate the simultaneous bass notes and the various voices on the Daintee's track), but they do inject an extra element of snap and coherence to the overall sound. These are distinct trade-offs, defined by personal taste and musical repertoire, but what the 300B SE loses in terms of absolute focus and leading edge definition, it makes up for in terms of substance, and like the
JA30, it gets the musical energy in the right place. Both are superb musical performers, they simply tilt their emphasis in slightly different directions. Listen to either in isolation and you soon forget the shortcomings, which is another way of saying that they both put the musical event first. Ultimately the Jadis offer the more dramatic performance, but combine the Border Patrols sheer presence with its large and capacious sound stage, and the result is a performance which retains its musical directness and purpose without shoving them down your throat, ideal for long term musical enjoyment. I could happily live with either, which places the Border Patrol 300B SE (WE) in very select company indeed.
"eye of toad and leg of newt?"
There's nothing magical about the insides of the Border Patrol amp and supply, just meticulous engineering taken to a logical extreme.
The amplifier is by its very nature very simple; a 13D3 input valve is capacitor coupled to the E182CC which uses an inter stage transformer to drive the 300B output tube. But it is the attention to detail that sets the Border Patrol apart. The inter stage transformers are bi-filar wound, the coupling cap is a Hovland. The main HT caps are from Elna/Cerafine, and elsewhere you'll find a scattering of Black Gates and Os-cons. The bespoke output transformer uses a double bobbin and no less than 22 sections. With so few components each and every one can be critically assessed, as can be heard in the final results. There's no assumptions here.
And so to the power supply. The large aluminium case contains three separate valve rectified choke input filter supplies. A GZ37 is used to supply HT to the output stage, while two EZ80's provide HT to the input driver and negative bias to the output stage (the latter via the secondary winding of the inter-stage transformer). This shouldn't be confused with the after-market add-on Border Patrol PSU which is a single stage device supplying HT only. Despite its less sophisticated nature this is an extremely impressive device, available for £595, or in more powerful form £995. Having heard the difference this (relatively) simple device makes to the likes of Audio Innovations, Leak, Audio Note, Art Audio and Croft amplifiers, the impact of its much bigger brother on the performance of the 300B SE(WE) can be nothing less than fundamental. Is it this that separates the Border Patrol from the vast majority of single-ended designs? Without a doubt it's the major influence.
Check this link for personal reviews by BorderPatrol SE300B
Hi-Fi Choice Issue No 186 January1999
Review by Jason Kennedy
BorderPatrol SE300B power amplifier
BREAK FOR THE BORDER - Jason Kennedy reckons the new
Border Patrol tube amp proves that you can get welly out of a 300B.
Novices to the valve amp scene may not be aware that all tubes were not created equal, and that the 300B triode power tube had a legendary reputation that seemed way beyond the potential of an audio component. That was until this '30s tube returned to production a few years back- the Chinese started making them first; then the Russians and finally Western Electric, the American company whose original tubes had created the legend, re-joined the game.
In the meantime there have been more than a few amplifiers created that use the 300B and its meagre seven and a half Watt output, most of them single- ended designs like the Border Patrol where one tube drives one channel. This is the least powerful yet also least compromised way of operating a triode tube.
What marks out the BorderPatrol SE 300B is the attention that its maker Gary Dews has paid to power supply design and the resulting neutrality of the amplifier. Virtually every single-ended amp I've encountered creates a slightly rose-tinted view of the music it reproduces, and often it's this euphony that turns regular music lovers into tube fetishists. It's a very appealing sound. However, very few SE's have the bandwidth, power and transparency of a good transistor design. Bass and treble extension is often compromised, the designer apparently blinded by the irresistible midrange. However, unless you listen to solely acoustic music the lack of bass grunt can be a significant shortcoming. By going to town on the power supply, however, the Border Patrol puts pay to the notion that SE's can't play bass. The secret lies in the hefty black box that accompanies the solid-wood framed BP chassis. This contains three separate choke input filter power supplies for the high voltage, negative bias and heaters. Which leaves only signal amplifying tubes on the main chassis.
This is not the BP's only USP -even rarer is the use of inter-stage driver transformers which are designed to enable large voltage swings with low distortion, and present a very low impedance to the output tubes. Having heard SE's with serious PSU's before I suspect that it's this latter aspect which gives the BP its surprising low frequency grunt.
"If I hadn't used this amp I would still be wondering
where the 300B tube got its reputation from."
I listened to the BP in two different systems and with Svetlana and WE 300B tubes, the latter adding £500 to the £3,995 price tag on the amp. For the most part it co-existed with a DNM 3C Twin pre-amp and B&W Nautilus 802 speakers, but also had a spin with JBL4312 Mkll's and the more sympathetic combination of an SJS Arcadia pre-amp and Living Voice Avatar speakers.
Having heard the BP a few times in the past I was not surprised by its nimbleness, speed, agility and grunt- quietly enthralled would be a more appropriate description. I was, however, shocked to hear that it could cope with the N802s. These fine speakers have proved more difficult to drive properly than most I have encountered, so to find an amp whose output is claimed to be nine Watts at best producing rockin' beats through them was quite a surprise. It couldn't reproduce the level that the 200 Watt Sirius achieved but it did a more convincing job than amps with five times its output.
But being an SE design, the BP isn't just about power, it's about the ability to reproduce music with its timbral and dynamic elements fully intact.
You tend to take good tone for granted with tubes but when it's created with so little coloration, as it is here, you can fully appreciate its beauty and richness. Instruments are created for their tonal character, yet so little audio equipment can reproduce this in its full glory. Trannie amps usually dry it up, while most tube amps add extra lushness. The 300B, when used with this much attention to detail, appears to add no colour of its own and combines the skill with lightening speed, removing any sense of electronic intervention. In some respects the lack of tube-type colorations make this an extremely difficult amplifier to get a handle on, the broad bandwidth means there's a lack of euphony. The BP has a more honest, bare-bones style that rewards improvements in source material to a far greater degree. It makes a lot of trannie amps sound thick and earth-bound with its superb transparency and fleetness of foot. It doesn't quite match good trannie bass but does a far better job than any other SE I've heard. What's more you get the purity of midrange and treble that such amps are renowned for, say goodbye to grain forever. Add to this superb high frequency extension and you've got some idea of its prodigious capabilities.
The Border Patrol review has been a long time coming. Gary's been building the amp since 1992, but it has been worth the wait. If I hadn't used this amp I would still be wondering where the 300B got its reputation from. One evening with this fine amplifier was enough to reinforce that reputation a thousand times.
VERDICT: SOUND * * * * * BUILD * * * * VALUE * * * * *
Uncommonly capable single- ended design with less colouration and more grunt than any of the alternatives- resolution guaranteed.
Hi-Fi Choice Issue No 174 January1998
PERSONAL MESSAGES by Paul Messenger
Border Patrol SE300B
When, like most ll-year-olds, I started listening to music seriously, hi-fi wasn't part of the vocabulary. By my late teens, however, I'd become aware of a world beyond the transistor radio, tape-recorder and record- player. I converted the (mono) Dansette to stereo operation, and found myself starting down the rocky road towards hi-fi nirvana.
My ambition wasn't too great at first, but some lucky second- hand purchases helped me assemble a pretty decent system over the next couple of years, and it wasn't long before the hi-fi bug had dug in its claws. The desire to blend business with pleasure was one of my principal reasons for joining the hi-fi industry in the mid '70s.
It wasn't long before I started dreaming of a truly great system, and the prospect of assembling it became all the more feasible when I moved from making speakers with Spendor, to working for one of the hi-fi magazines. Contacts were made, and there seemed a real chance of my dream becoming reality. Not just a great system, but The Best.
Some 20 years down the road, hi-fi has given me enormous pleasure and satisfaction. But two decades of accumulated experience has made it necessary to revise the ambition. Quite simply, there is no 'The Best'. It may be The Best for me- I'm not looking at changing anything right now- but it isn't perfect, and does involve compromises.
Back in the '70s I used Radford valve amps, but changed to Naim transistor electronics. I can still recall the trade-off involved, between the delicious midrange transparency of the valves, and the full-bandwidth slam of the solid-state devices. I took the transistor route back then, and have stuck with it ever since, but I do get the chance to try valve gear from time to time. (Briefly, I even grappled with the legendary Ongaku from Audio Note.)
Such experiences only serve to remind of a hi-fi dimension I normally do without, and never more obviously than during the few weeks I spent recently with a Border Patrol SE 300B power amp. The plan was to try for a completely feedback- free chain, but it's is taking a bit longer to organise than I expected. The single- ended triode power amp is only the third link in my electronics chain, yet swapping to it from my regular NAP I35 power amps still had much greater impact than I'd imagined.
Quantitatively it was much greater, but qualitatively it was similar to my earlier experiences. This, I presume, has to do with the steadily improving resolving power of my system. Inserting the Border Patrol brought forth a gush of enthusiasm for rich mid-band lucidity, which is the valve amp's stock in trade, and reaches its peak with a high-class single-ended design. Because it sounds so effortlessly natural and beautiful, basking seems more appropriate than nit picking; to take a critical stance seems churlish.
After days of tubular basking, I went back to my transistors. I missed the mid-band clarity; instead there was a congested quality, as though the system had picked up sinusitis. But there was a return to the full, wide-bandwidth sound I'd been missing, especially in deeper and much more authoritative bass. However, to say that one was 'better' than the other would be to miss the point entirely. It would be like saying oranges are 'better' than apples, coffee 'better' than tea, or The Prodigy 'better' than The Chemical Brothers. Any attempt to make the comparison is simply invalid.
A question of taste
Some suggest that a preference for valve or transistor amplification is likely to be related to one's musical preferences. There may be something in this, but I'm not convinced. The musical genres of The Prodigy and The CBs are not that far apart, yet there was no denying that Breathe (from The Prodigy's
Fat of The Land album) was a more involving experience with the Border Patrol in command, yet I had to return to the Naims to get the full tension and scale of it Doesn't Matter (from The CBs' Dig four Own Hole). Twist my arm and I'll admit that Breathe has a slightly more 'acoustic' quality to its instrumentation, but not one to warrant generalisations. In the final analysis it comes down to personal taste and preference.
Given the ghastly recording quality of many modem pop recordings, I sometimes find myself wondering whether 'listenability' might not be a more valid hi-fi criterion than sheer information-retrieval -at-all- costs. However, the fact that the best recordings carry on getting better as the system resolution increases would seem a good enough reason to carry on pursuing The Best- even though the concept is entirely mythical.
Hi-Fi+ Issue No 15 Jan/Feb 2002 Review by Roy Gregory
The Border Patrol Power Supplies
When it comes to buying hi-fi, most of us are forced to take the cost/ performance/value for money triangle into account. It applies when we buy our first system; we know what we’d like but we’re limited to what we can’t quite afford. It applies to our later upgrades. In fact, it applies with a vengeance to upgrades because as soon as we replace something in the system the question of depreciation raises its ugly head. Sure, we don’t think of it like that because to us the upgrade seems cheap: the cost of the new unit less what ever we get for what it’s replacing. It’s a bargain; at least that’s what we tell ourselves, our wife, girlfriend, partner and anybody else who’ll listen. Which is a nice way of deluding ourselves because the actual cost of the new unit is the purchase price plus whatever we’ve lost on the outgoing one. You’ve had the use of it, but don’t think you got it for free. Unless that is, you can upgrade without throwing out your original purchase.
Ever wonder why Naim are so successful? Now you know. It’s all those add on boxes (as well as the fact that if you don’t want the box you’ve got, then somebody else will). Which of course is only any good if you own a Naim system – or a valve amp, because what a Supercap does for a Naim set up, a Border Patrol power supply will do for most of the thermionic alternatives. They even do it in a similar fashion, by grafting on a high quality regulated supply, but there, not surprisingly, the similarities end.
Don’t valve amps have high quality power supplies built in? Not like this they don’t, but to understand why that is we need to look at a couple of typical power supply topologies. In a valve rectified circuit of the type most commonly applied to current valve designs (see diagram below) the degree of regulation is defined by the size of the input capacitor and the size of that capacitor is limited by the low current capability of the valve rectifier. Consequently the regulation of the supply is poor. Why do we want good regulation? Because without it we get the fat ponderous bass, poor dynamics, flat compressed sound and inability to play anything but the simplest passages of music that characterises so many valve amplifiers.
The obvious alternative is to use solid-state regulation. Solid-state rectifiers can pass plenty of current so the input capacitor can be much bigger (just look at the size of the input capacitor in the circuit diagram below) and the regulation therefore better but solid-state recs are guilty of producing high frequency switching noise which adds metallic edginess to the sound and pollutes the noise floor of the amp robbing the sound of resolution and low level information. Solid state rectifiers are usually used with smoothing resistors, rather than smoothing chokes (check out the Audio Innovations supply) and this approach offers very little high frequency attenuation so any mains borne HF rubbish finds it way into the amplifier and further pollutes the sound. So either of the common approaches suffers from problems when it comes to supplying clean, well-regulated power.
But there is an alternative, the valve rectifier- choke regulated supply, and this is the approach that Border Patrol employ. BorderPatrol claim a valve rectifier used in a choke input filter topology gives an ideal combination of regulation, high frequency attenuation and lack of electronic noise. Back in Issue 8 I reviewed their 300B power amp, an unusual two box design, and basically, what we’re talking about here is the power supply section of that amp, but applied to other designs.
At first sight engineering a universal power supply for a whole host of different power amps might seem like an incredibly complex task, however, it’s considerably simplified by the inherent simplicity of valve circuits themselves. Each Border Patrol supply can produce a single regulated voltage either 300, 390 or 430V and applies it to the HT circuit of the amplifier. But given that the vast majority of the more commonly used valves run at between 300 and 430 volts, that means that they can be set to embrace any amp using EL34, 6L6, EL84, 300B or 2A3 output valves, amongst others. As many cheaper amplifiers, such as the Audio Innovations 800 that Gary loaned for listening purposes, employ a single HT supply, that means the whole amplifier benefits from the external regulation supplied by the Border Patrol. That leaves the unit’s own mains transformer with only the heaters to worry about. There are of course output valves that run at far higher voltages, such as the 845 and 211 triodes, and whilst it would be theoretically possible to build a choke regulated supply capable of delivering the thousand or so Volts that they demand, it would be monstrously expensive. Add to that the prospect of passing that kind of voltage down an umbilical and into the amp and it’s easy to understand why Gary is reluctant to follow that course.
So having established the operating context I guess I ought to describe the Border Patrol units in a little more detail. There are two outwardly identical models, the Standard at £595 and the MB (answers on a postcard please) at £995. The essential difference between the two is that the MB is capable of delivering 350mA of current to the Standard’s 250mA, necessitating a much larger transformer and choke, along with a noticeably heavier overall weight. Owners of the Standard model can have it upgraded to MB status for £450, on which more later. Going back to the general schematics that we used earlier, this is how the Border Patrol supplies cut into the circuit.
The first thing to notice is how the GZ37 rectifier valve feeds directly to the large choke which is then responsible for the regulation, making the valve’s current capability irrelevant to the question of quality. Basically, the bigger the choke the better the regulation it provides. Note also that the input capacitor is bypassed in the Audio Innovations. Being a push-pull amplifier the circuit topology actually provides a degree of self-cancellation of power supply ripple and thus requires less smoothing. The same isn’t true of single ended designs, as we shall see. The second thing is that the Border Patrol transformer works at a higher voltage than the original. Like many things that sound good, choke regulation isn’t the most energy efficient way of doing the job, which helps explain why you don’t find choke regulated supplies fitted as standard (except in the aforementioned Border Patrol amp and the Pure Music amps reviewed in Issue 12). They need big transformers, large chokes and big boxes to put them in. All of which are expensive. Add to that the fact that the chokes are prone to mechanical noise and create huge hum fields and it should be obvious that it’s far from straight-forward to get the best out of the technology, requiring considerable skill and patience to deliver the full potential.
In use the donor amp is fitted with a hard-wired umbilical which is connected via a substantial locking socket to the Border Patrol unit. As well as carrying the regulated HT back to the amp, this wire also carries voltage from the amp’s heater supply to the Border Patrol, where it operates the main power relay.
The benefit of this is two fold: it provides remote switch on for the supply meaning it can be tucked away, but more importantly it also makes it impossible for HT to reach the valves without heater voltage, thus avoiding potentially disastrous consequences.
Both Border Patrol units are finished in black painted casework with identical silver aluminium front panels. The effect is workmanlike rather than impressive, but then as I mentioned earlier, you’ll probably want to tuck them away anyway.
Gary supplied the power supplies along with the Audio Innovations 800 and Audio Note Meishu amps already described. These were fitted with rear panel switches so that they could be played as standard or connected to either of the Border Patrol supplies. At the same time he delivered the Canary Audio 608 integrated, reviewed elsewhere, with and without the MB power supply, so I won’t dwell on that here. However, it should be noted that the Border Patrol supplies are simply a blood transfusion for ageing valve amps. Whilst they’ll transform both vintage (Leak, Radford) and valve renaissance designs (Croft, Audio Innovations and Art Audio) they are equally at home with and just as applicable to brand new purchases, either when you buy them or as an upgrade.
We started listening with the AI 800, a fairly standard ultra-linear EL34 design, remembered chez Gregory mainly for its easy, open midrange rather than as an outstanding amp in its own right. The kind of product whose school report might have read “polite enough but really could do better”. And how! Adding the BP Standard PSU brought immediate gains in almost every aspect of performance: greater transparency, a blacker, quieter background, better separation, better focus and crisper, wider dynamics. The soundstage was clearer and much more coherent, the playing was tighter and the performance musically and rhythmically more coherent. Playing ‘The Thing You Love (Is killing You…) (Dolly Varden The Dumbest Magnets) the individual instruments and voices each took on a more separate and identifiable character: the guitar placed stage-right suddenly grows a body and harmonic complexity, the tambourine becomes a ring of distinct rattles rather than an irritating tizz. But the really important thing is that despite the increased colour and separation, musically speaking the band pulls in closer together. The chemistry in the performance, the players playing off of each other, the careful interweaving of the two voices becomes clearer and stronger. Diane Christiansen’s voice loses the edge and grain that characterised the performance of the standard amp. Now it was smooth and direct and communicative, singing straight to you.
Now this isn’t a subtle change in performance, or a musically trivial one. It isn’t cosmetic or a question of taste. It cuts right to the heart of the amp’s function and creates better, more credible music. Substitute the MB PSU in place of the standard model and you extend that tendency even further. The bass gains additional authority, you can hear the bottom of the bass drum and guitar now, rooting their notes with a proper foundation. More importantly, the sound grows in temporal sophistication. Now it’s the band that defines the pace and attack of the song, controlling events and their destiny.
If I was impressed by the performance on the Innovations amp, it did nothing to prepare me for the transformation wrought on the Audio Note Meishu, a £3500 single-ended integrated running one 300B per channel. In stock form this amp could only be described as disappointing. The musical picture it paints is grey, flat and disjointed, with no separation to talk of and no dynamic discrimination. The overall effect is congested and messy, exacerbated by a splashy tendency and very poor control: All in all a bit of a sonic disaster area.
Adding the BP Standard PSU brought about a Cinderella makeover of the kind that day-time TV producers can only dream about. It was as if the milling herd of musical notes had been rounded up and sent off in a single direction. Now the music had a sense of unified energy and purpose. Individual instruments and voices were properly separate and took on something approaching their real colour. All of a sudden the rhythm and pace of the music hove into view like a ship out of the fog and we were off and running. Diane Christiansen’s acerbic delivery regained its sardonic twist, the musicians started to actually play together. In fact, it’s difficult to overstate the magnitude of this improvement. Any Meishu owners out there would be shocked to the core: the designer should seek a very, very dark room.
Once again the MB PSU extends the tendency, bringing authority and definition at the frequency extremes to the extent that you could even follow bass lines (an impossibility with the amp in standard trim). Don’t assume that because the description is rather glib this is any less important than what the Standard model achieves. It is actually even more fundamental, with the music gaining a solid foundation and temporal base. The end result is the ability to convince and transport the listener, which is what really good hi-fi is all about. There’s no law of diminishing returns here, but the good news is that if you’ve invested in the Standard supply you can always have it upgraded to MB status at a later date.
Why the BP supplies should have such a staggering effect on the Meishu is open to question. Gary believes that it reflects the fact that the inherent simplicity of single-ended designs allows you to hear the power supply that much more clearly: Certainly, the evidence of his own 300B amp (reviewed in Issue 10) supports that view. In the case of the Meishu they succeed in turning a very nasty, soggy mess into something very respectable indeed, averting the necessity for replacement, saving you from financial disaster and a stricken conscience. I mean, who are you going to sell it to?
The performance of the Border Patrol supplies is impressive indeed both with single-ended and push-pull designs. Because they add value to an existing unit their return on outlay is even higher, easily outperforming more conventional upgrades in monetary as well as sonic terms. Like all modifications they’ll invalidate the guarantee on the existing amplifier, something to consider if you are purchasing it brand new. However, in that case I’d talk to your dealer about taking that on. After all, it’s in his interest to make the sale. The only other consideration is that the modification should be undertaken by one of Border Patrol’s qualified dealers: HT is no place for enthusiastic DIY! With those two provisos dealt with I can’t recommend the Border Patrol power supplies highly enough. Well thought out and executed, they represent a perfect way of realising the hidden potential inherent in a literally thousands of systems out there. If you’re using a valve amp and you’re looking for an upgrade: if you’re using a valve amp and you’d like to hear what it can really do: if you’re using a valve amp and you’re just down right sceptical: give Border Patrol a call and arrange a demonstration. I’d be surprised if you’re only surprised: shocked is generally nearer the mark.
Given the loss to depreciation inherent in any upgrade, the notion of a universal add-on to improve the performance of basic valve circuits is appealing indeed. BorderPatrol have created a choke filtered unit that will replace the HT supply to a wide variety of circuits and output valves. The benefits have to be heard to be appreciated. The modification is straight forward and reversible, although to date no one has asked for it to be removed once they've heard the results. Cost effective engineering to extend the life and performance of existing amplifiers.
Roy Gregory Hi-Fi+ Jan 02 EDITORS CHOICE
Hi-Fi+ 2001 PRODUCT OF THE YEAR Awards Issue
Click these links for online audioasylum.com review's and comments by PSU owners.
Patrick J (UK)
Hi-Fi Choice Issue No 165 April 1997 Review by Jason Kennedy
Border Patrol Power Supply
Jason Kennedy brought his Jeep and night-vision glasses, but in fact this month's
Border Patrol is a stunning new power supply for amps of the valve'd variety.
You don't know it yet, but your valve amp sounds a mess! Strong-stuff, perhaps, but once you hear your amp with a Border Patrol supply in tow, I think you'll agree with me. The item in question is a valve-rectified, choke-input-filter power supply, which can be used to replace the HT (high tension) supply in virtually any tube power amp. To double the performance of anything from a Leak Stereo 20 to a megabucks single-ended design is a rare achievement, so at £595 I think the Border Patrol's a bargain.
The choke input filtering is where the BP differs from the onboard HT supplies in most amps. There are a few valve-rectified designs around, but they tend to be rather expensive; when it comes to choke-input-filtered there are only a few to choose from. Why so few units embodying an apparently effective solution? Because it's hard to make a choke filter that doesn't have severe transformer buzz. Gary Dews, Border Patrol's creator, has overcome that issue and the result is pretty spectacular.
In order for your amp to feel the Border Patrol effect, Gary or one of his dealers must solder into it a flying lead, which plugs into the back of the supply. This lead carries the HT supply, obviously, but also control signals for an ingenious relay attached to the amp's heater supply. This allows Border Patrol to turn itself on and off in tandem with your power amp, so you never need to touch the black box itself. This is an immensely convenient feature, but more importantly stops you from destroying the amp if you accidentally leave the HT on with the L.T. (low tension) heater supply off.
Gary demonstrated the Border Patrol with amps including the aforementioned Leak, an Audio Innovations Series 800, and my own Marantz 8B. Previously I've heard its effect on an Audio Innovations First Audio, not to mention the BP'ed units powering the Living Voice Air Scouts I wrote about in issue 163.
That Patrol Emotion
In every instance the Border Patrol effect was nothing short of a transformation. Bass solidified, imaging became significantly more three-dimensional and substantial, and the power-supplied amp made the regular version sound, quite literally, a mess. And don't forget this is with amps that are by no means shabby; these are units I have used extensively and found to be very effective. Now I couldn't tolerate them in their standard all-too-valvey guise.
Perhaps because I haven't lived with a tube amp for several years, I have become critical of the genre's shortcomings compared to transistors- particularly the soft bass and rather hazy, ill-defined imagery. Tubes still offer beautifully fluid mid-bands and fine dynamics, but I came to be dissatisfied in all but a small number of cases with the thermionic lack of grunt. The BP removes these limitations. Tube bass now has power and depth, high frequencies shine and sparkle with seamless definition, and the overall presentation is more dynamic.
For the purposes of his demo, Gary powered up an Audio Innovations L1 pre-amp and Series 800 power-amp with the BP supply already attached. It sounded pretty good after the tranny gear I had been listening to. Then he took off the supply and caused an alarming loss of definition across the band. Cymbals became fizzy and the structure of the music fell to pieces. With the Border Patrol back on the music regained its composure: instruments not only sounded more natural and realistic, but seemed much more musically coherent. In many respects it was like taking the good things about transistor amps and adding them to the natural strengths of valves- a remarkable blend.
Small is Beautiful
The Border Patrol effect, in the breadth of its applications, reminds me of Trichord's Clock 2 CD player modification, which also breathed new life into a wide variety of products. It's interesting how these little companies are devising enhancements that make the most of bigger players' designs, yet a big company often has limited room for manoeuvre because of self-inflicted corporate constraints or rigid commercial practice.
But neither the Clock 2 nor the Border Patrol would cost a great deal more if instigated at the manufacturing stage. For example Pioneer's new PD-S505 Precision CD player (to be reviewed next month) has a variation on the Clock theme on board, which with a variety of other mods adds 260 to the price of the standard machine.
So how many years will it be before a tube-enhanced brand incorporates one of Gary's supplies into a power amp? I suspect it may be only a matter of months when people hear what it can do.