The design of the outboard power supply
is where a lot of the ingredients for Border Patrol’s high quality sound can be found. It is a robust aluminium box housing one power transformer, three chokes and three tube rectifiers. The rectifiers are a Mullard GZ37 for the B+ rail and two EZ80 for the input/driver tubes. The three choke filters are for the voltage supplied to the 300B output tube, the input/driver tube and lastly, the output tube bias. Gary told me that he found the choke filter even improves the sound when used in the bias circuit supply. Popping off the bottom cover of the amp chassis or the clamshell cover of the power supply reveals hard-wired circuitry with a clean layout and meticulous build quality. It certainly inspired confidence in the products and as it turned out, I did not experience the slightest hiccup during my rather extended time with the amps and their power supplies. I would imagine that these amps are very reliable in the long term too. Another reason behind Gary Dews’ success is that he can be found demonstrating his products every year at U.S. audio shows, mainly at Rocky Mountain Audio Fest and the Capital Audio Fest. He apparently does have a few dealers but most sales are direct from his Maryland location. He allows for a 14-day trial period with some flexibility. Also, global audiophiles can purchase these amps as the primary voltages are user changeable between 110, 120, 220, 230, 240 volts (the procedure to change between AC voltages is outlined in the owner’s manual). A different fuse rating (1.6 amps) is required for the higher voltage countries.


Setup of the amp was simple. The first order of business was to connect the umbilical cord from the main amp chassis to the external power supply, insert the supplied ElectroHarmonix 300B, turn on the amplifier via the rocker switch on the front of the power supply and set the bias of the 300B tubes to 0.7V. There is a hum cancellation screw on the bottom of the amp but after connecting interconnect and speaker cables, the amp was dead quiet through my 100dB speakers. If a ground hum is noticeable with an active preamp, a switch on the back of the power supply isolates the amp in the up position. It was already in this position so I flipped it down and there was still no hum but I left it back in the up position. For years, fans of lower power SET amps have searched for speakers of high sensitivity. The Border Patrol amps provide the owner with a bit more latitude. According to the owner’s manual, Gary’s robust designs will mate well with "loudspeakers of >94dB efficiency with an impedance characteristic that is relatively uniform and does not drop below 4 ohms. These are guideline parameters, not hard and fast rules as the SE 300B has been successfully used with loudspeakers as diverse as Quad Electrostatics, Snell Type A and Living Voice Tone Scout." With my Bastanis Prometheus Mk. II, frequencies below 100Hz are handled by a 12-inch sealed box woofer powered by a built-in plate amp. I am thus judging the bass performance of these amps solely above 100Hz. Throughout this review, I used the only other SET amp I had on hand for comparison purposes. My version is about 15 years old and at the time I believe retailed in the same neighbourhood as the current Border Patrol amps. However, the current Tron version is called the Telstar. A couple of years ago, its price was around $20’000. At last year’s RMAF, that had jumped to $40’000. I do not know the reasons behind this doubling but hope it is not part of the growing trend to court upper-class buyers.


To start things off, I played the last album I’d listened to with my Tron 211 SET amp: Sony Stitt and Paul Gonsalves, Salt and Pepper [Impulse SA-52]. The immediate impression was one of fully developed tone in every note just as I recalled from my listening experiences at RMAF shows. Gary resists calling his amps warm. To him it connotes a rolled-off sound akin to many vintage tube amps. However, if your definition of warm is a full-bodied sound rich with natural harmonics, then it definitely qualifies. If I had to summarize my initial impressions à les short descriptive bullets that were so fun to read in the back of a British audio magazine whose name I don’t recall, I would capitalize with these four words: tonal balance, tone density. The bass and mid bass from the SE 300B above 100Hz was firm and well balanced with the midrange and high frequencies. Keep in mind that many 300B SET amps often cannot provide enough bass even in the 100 - 300Hz region to support a truly neutral tonal balance. Substituting my Tron showed that the SE 300B was not the last word in authority and weight here but this was hardly a fair comparison on price. This is not really a matter of power since Graham Tricker, designer and builder of my Tron amp, runs the 211 tube conservatively at an only slightly more powerful 10wpc. However, a 211 properly implemented is a different kettle of fish from a 300B. It is known for its sheer authority throughout the frequency range while the 300B tube is classically known for its sublime midrange and overall musicality.

 
On Duke Ellington & John Coltrane [Philips 841 962 BY], the top-to-bottom tonal balance of the SE300B puts your ears at ease from the first few notes. On the cut "Big Nick", Coltrane’s sax was well projected out of the speaker to give a good sense of presence. The amp’s imaging qualities are not carved from stone in holographic fashion like some amps. Rather, the instrumental images fade into the soundstage gradually. Some would argue that the imaging presentation of the BP amp is more natural. My own listening preferences tend toward more defined image boundaries and a good sense of space between them. The macrodynamic performance of the BP amp is one of its crowning achievements. It is certainly well above average for a single-ended 300B amp. On The Ellington Suites [Pablo 2310-762], "Northern Lights" starts out with a powerful alternating burst of chords that includes what sounds to be the entire band playing at fortissimo. The standard version of the 300B amp held together quite well and portrayed this difficult section with perhaps only a slight amount of blurring of the different instruments. This only became evident as I stepped up to the higher level amps later in the review.