Comparison with the Tron illustrated that the BP SE 300B amp sounds more rounded. The leading edges are not as tactile and distinct. This was most easily heard on instrumental solos, such as the incredible one by Sonny Rollins on the title cut of The Bridge [RCA APL1-0859]. This cut has proven to be an acid test for reviewing. For my money, it is among the most mind-blowing saxophone solos every recorded. In looking back at a 2010 review by Chris Redmond, he compared the DIY HiFi Supply Lux 91 mono amps (discontinued due to manufacturing cost obstacles) to the Border Patrol WE 300B amp and noted the same thing; "slightly blunted leading edges". In the soundstaging department, the BP amp produces a very wide stage in the front plane but not oe as deep and transparent as the Tron 211. Again keep in mind the difference in price and that some portion of this difference may lie in the basic sonic properties of the 211 versus 300B. However, my past experience with a very special pair of 300B monos (WE 417A input tube, interstage coupled, custom Tango transformers) hand-made by my departed friend Arthur Loesch would say otherwise. It had depth and transparency galore. I decided to switch tubes to the EH 300B Gold and see what that rendered. This tube gives a notably smoother presentation with creamy rich vocals. The vocals were excellent with the standard EH 300B tubes and slightly exceeded the Tron’s presentation.  I felt that the Gold version was a bit too soft. Less than stellar recordings benefited from this but it was just too polite in the final analysis.


When discussing various current production 300B with Gary one day, I asked if he had tried the Emission Labs.  He had years ago and did not care for it in his amps. Since one of the EH Gold tubes went bad (its base became loose to no work), Gary arranged for a pair of EML 300B tubes to be shipped. I replayed the last few Ellington cuts again. The introductory chords on Northern Lights were now more aggressive and the brass slightly forward. The EML had more authority but I preferred the less expensive ElectroHarmonix in the standard SE 300B amp. It was time to install the next level up, the Border Patrol 300B EXD version chassis, leaving the standard power supply in place. The EXD version has three areas of design improvements:
1.  The output and interstage transformers are cryogenically treated
2.  The top and bottom chassis plates are copper
3.  The power supply capacitors are bypassed with MusiCap film capacitors.


I also noted that the nuts on the 5-way speaker terminal binding posts on the EXD chassis are completely metal, not the plastic-capped version of the standard chassis. Otherwise I could see no differences. In another conversation with Gary, I asked about the transformers. Gary told me that his transformer bobbins are wound in the UK. Then he has them shipped to the US where he puts on the M6 steel laminations. For the EXD amp, the transformers are cryogenically treated by a company in Massachusetts. They bring them down to -170°C over the course of the first day, let them sit there for another day, then bring them up slowly on the third. They then give them two exposures to +100°C, slowly heating and cooling them to temper them. Gary’s experience with permalloy or amorphous cores is that they do not provide the inductance for proper bass. They can be very smooth in the midrange and highs but the bass is lacking. He feels this is true for either the interstage or output transformers.


With the EXD amp on my rack, I played the Neville Brothers Yellow Moon [A&M SP5240]. On "Wake Up", it sounded like the amp needed some wake up after the trip from Maryland. Aaron Neville’s voice was clean and clear but everything sounded closed in and lacking in dynamics. Also, the amp was bright and lacking in body and bass. Suspecting that the EXD version might not have received as much break-in, I put in a quick call to Gary and sure enough, he said that the standard version had many more burn-in hours than the EXD amp as he was listening to it for days whilst working on other things. The EXD version had very little time on it because he had to leave for the UK and wanted to get it out to me before he left. Gary recommended that I put about 100 hours on it and try again. I carefully logged the hours whilst letting it play in the background in another system. After 125 hours, I tried again and there was little improvement. Gary asked me to ship it back so he could take a look. When he got it back, he agreed with my assessment and proceeded to put another 100 or so hours on it and that did the trick. Buyers should take note of this and not jump to conclusions about the sound until it is fully broken in (apparently in excess of 200 hours). This break-in was not a subtle thing either.


Upon return of the EXD, I played the same Ellington cuts with the EML 300B and unlike the standard 300B amp, they did not sound aggressive. The soundstage opened up more with some improvement in the dimensionality toward the rear in particular. Another very notable improvement was in the reduction of electronic haze. In other words, there was a lowering of the noise floor. The bass drums at the beginning of "Apes and Peacocks" from the Ellington Suites album were more distinct and the drums could be heard more clearly as coming from the rear of the stage. Ellington’s piano riffing on the "Big Nick" cut was more intelligible. In fact, the entire musical message was easier to follow. There was more refinement and nuance. Coltrane’s masterful control over his saxophone was more clearly evident with the EXD amp. The EXD version is cleaner and more informative. Since I own a pair of the coveted vintage Western Electric 300B, it seemed like a good opportunity to try them in the EXD amp. I bought them as new-old stock many years ago and they still test like new and matched. They were the best sounding 300B valvesI had tried in my DIY HiFI Supply Lady Day Cherry Special amps as well as in the Loesch 300B SET amps mentioned before. Playing "Big Nick" again, the amp now sounded softer and, surprisingly, leaner. I was taken aback. In fact, Gary Dews stopped by to bring the EXS power supply. He heard the same thing. We were both very surprised. So, back in went the EML and all was well again.