: Steve Marsh
Financial interests: click here
Analog Source: Nottingham Analogue Mentor turntable with 10” Anna tonearm, Benz LP-S moving coil cartridge
Digital Source: CAL Audio Alpha transport, CAL Audio Delta DAC, plus proprietary impedance matching device between transport and DAC (not a commercial product at this time)
Preamp: Doshi Alaap Purist Mk. II
Power Amp: Tron 211 SET amp with upgraded exotic-core interstage transformers (General Electric 211 power tubes, Western Electric 417A input tubes, RCA black plate 5U4GB rectifiers)
Speakers: Bastanis Prometheus Mk. II with Chrystal drivers and Gemini tweeters
Interconnect cables: Audio Magic The Natural (pre to amp), Bastanis (transport to DAC), Decware Silver Reference (DAC to pre), long Radio Shack interconnects from pre to subwoofer plate amps (flush-mounted into subwoofer cabinets)
Power cords: Bastanis Epilog II on Tron amp, industrial-sourced power cord on Doshi preamp, Nordost Frey 2 (on loan), Dynamic Design AE15 Spirit on DAC
Speaker cables: Audio Magic The Natural
Equipment rack: Adona 6-shelf
Power line conditioning: Triangle Art RA-6 power conditioner, Nordost Qv2 AC line harmonizers [on loan]
Sundry accessories: High End Novum PMR Premium Resonator, set of four Stein Harmonizers with Stein Magic Stones, Synergistic Research FEQ, Audio Magic Room Correction Bells, Audio Prism Ground Control, three Bybee Quantum Signal Purifiers, Isoclean Fuses, VPI 16.5 record cleaning machine
Room size: 22’ long x 17’ wide x 10’ high, with eaves on front and back walls
Review component retail pricing: $8’995; $11’995 for EXD; $16’495 with EXD + EXS, ElectroHarmonix 300B included (other 300B available for surcharge)

After hearing such great sound in the Border Patrol electronics room at RMAF year after year, I put Gary Dews’ SE300B amp(s) on my reviewer's most-wanted list. With the recent moving of my main system into my large upstairs listening space where my 100dB sensitivity Bastanis Prometheus Mk. II reside, the time was right. Since Gary already had individual reviews of each of the three levels of his 300B amps, he suggested that I review all three versions in order to point out what moving up the line will get you. Potential buyers should know that Gary supports his customers with an upgrade path up the line. The three levels of the single-ended (non-parallel output tube) designs are as follows:
1. Standard SE 300B amp with outboard tube power supply
2. EXD 300B amp with same outboard tube power supply
3. EXD 300B amp with EXS tube power supply

Gary can convert the standard 300B amp to the EXD version and also takes the standard power supply on trade toward the EXS power supply. Gary’s middle name might as well be choke input. He has championed the external, tube-rectified choke-input power supply as a key ingredient to getting the full performance potential from the 300B tube (and tube amps in general for that matter). It has become clear from his show demos and prior reviews that he has succeeded mightily in dispensing with any prior notions that the 300B inherently sounds syrupy with rolled-off highs and weak bass. Fuhgeddaboutit!

To kick things off, Gary shipped me the standard SE 300B amp as well as the EXD version with a pair of ElectroHarmonix (EH) 300B and a pair of EH Gold (gold-plated grids) 300B. The owner’s manual was delivered via emailed pdf. I prefer this over any hard copy version and think that in this day and age, it makes a lot of sense to distribute manuals this way. This one was very well written and had excellent diagrams. Things were off to a good start. The amps have a handcrafted appearance with a basic wood frame to which the top plate bolts with steel L-brackets underneath. The bottom plate attaches with six screws. The appearance could be likened to some of the boutique amps produced by James Burgess or Steve Berger of April Sound. The difference is that Border Patrol have a standardized line of products with a more professional market presence. Also, the outboard tube power supply sets the Border Patrol amps apart from most of these.

The amplifier circuit topology starts with a Russian (Reflektor or Sovtek) 6C45pi input/driver tube. The 6C45pi seems to see increasing usage in SET amps with interstage transformers as the supplies of the Western Electric 417A and some other such good vintage tubes have dwindled. In fact, Graham Tricker of Tron has switched from the WE 417A used in my 15-year old version of his 211 SET amp to the 6C45pi in his newer version called the Telstar. Today’s 6C45pi drives a 1:1 bifilar interstage transformer coupled to a single 300B per channel. This interstage transformer is rated for 25 watts so comfortably overrated for the 8wpc produced by the amp. Gary informed me that the amp does have some headroom of up to about 12 or 13 watts for short music peaks, with the 300B tube going into positive grid overload providing extra power.