You’re going to need to borrow our hand truck” were the words that came out of my friendly mail-carrier’s mouth as she swung open the side door to let me collect the BorderPatrol SE300B. My old body usually doesn’t appreciate a sentence like this, but BorderPatrol packs almost ten pounds per watt into their entry-level two-box SE300B, so I got pretty excited.
Tube amps with ample iron are prized by many audiophiles, and the weight here is in the transformers, not fancy aluminum faceplates or extravagant chassis design. The SE300B is roughly the size of a turntable plinth, with wood around the edges. The review sample came with a light-maple trim and looked elegant but understated.
The main amplifier chassis has two output transformers as well as two interstage coupling transformers for the two driver tubes, along with two output tubes. Gary Dews of BorderPatrol has chosen 6C45pi driver tubes because it “has very high transconductance, low output impedance and exactly the right amount of gain to make it the perfect input/driver tube, provided it is used with an interstage transformer like in the SE300B.” From the amp’s name you’ve probably guessed that those 6C45pi tubes drive a pair of 300B tubes, providing 8 watts of power. The well-written owner’s manual recommends 300B tubes from Electro Harmonix, EML (but not their mesh-plate tubes), Takatsuki and Western Electric. The review amp was shipped with the premium Takatsuki tubes. I was puzzled by the caution about mesh-plates because they’re a favorite of mine. Dews’ explanation was that he runs the 300B tube at a level that would be the maximum for a mesh-plate but well within the range of a solid-plate version. Reliability and tube life would be issues with mesh-plates in his amps, so he suggests sticking with solid-plates, and it’s refreshing that his design allows the owner to get recommended performance with a such a wide range of power-tube options.
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