Recently I purchased two external Power Supply Units (PSUs), one for each of my 2A3 push-pull triode monoblocks. They are BorderPatrol MB PSUs which work in general with low to low-medium powered (up to 50 W) tube amplifiers, with 300B/VV30B/2A3/6B4G/ EL84/EL34/6L6/5881 push-pull or single-ended amps, see:
These PSUs with tube rectification (most tube amps have solid state rectification) provide the HT supply (B+ rail), while the tube filaments are still powered by the internal power supply of the amps. The PSUs are massive, as you will see from images here (there is a rack where you see four of them below a BorderPatrol amp; the last picture on the page shows the inside of a PSU):
Below are my observations, all from Red Book CD, with for me startling revelations about this standard music medium of our time after incorporation of the PSUs into my system. What I hear most likely not just reflects a more proper operation of the tubes under optimal conditions (bass reproduction in particular), but to a large extent also the removal of electronic noise that previously was generated by the solid state power supply in my amps, see the white paper:
At first I was skeptical about how much benefit the BorderPatrol PSUs would actually bring. When I read all those reviews, accessible on the BorderPatrol website, they were writing about better bass, better rhythm & timing, better dynamics, better soundstage etc. Yet I thought my old Audio Innovations Second Audio triode monoblocks (2 x 15 W) already excelled in all these areas, after they had been heavily modified and brought up to date over the years by a trusted expert in both the audio pathway and the internal power supply. They certainly did not seem to suffer from early compression, lack of composure and over-blown, loose bass, items that are advertised on the BorderPatrol website to be remedied by the PSUs. I had little to complain, only I perceived some minor strain at peaks, no wonder given that I prefer to listen at high, realistic volume levels (while making sure by monitoring with an SPL meter that my ears are not unduly stressed beyond NIOSH recommendations for daily exposure; sometimes this is more of a limiting factor than my willingness to 'crank it up'). The PSUs were my only hope to get improvement in that area without having to revamp my entire system, so I decided to purchase them, one for each of my monoblocks at two grand each (for a stereo amp you may only need one).
After installation not every benefit of the PSUs was evident right away, since the units needed some break-in time. Yet one thing stood out from the start: unexpectedly, it was the bass. It is sensational, and it alone would have been worth the upgrade -- many solid state aficionados would give the world for that bass if they'd hear it, I am sure. I had previously found the bass already excellent with my amps, yet now the power and control on many rock albums seemed unreal, I just couldn't believe it. Also, in my favorite recording of Beethoven's Ninth some (deep) bass lines in the second movement, Scherzo, blew me away -- I hadn't even heard them before. Similarly, in Bruckner's Fourth Symphony I heard many beautiful bass lines that I had never consciously noticed before. And all this even though the deep bass was always served by my active subwoofer directly through the variable line output from my DAC -- bypassing the tube amps -- and at the same volume settings. Strangely enough, there is a clear effect of the deep bass now also having significantly more slam following the 'upper edge' of the bass notes from the improved mid and upper bass that comes from the amps, served by the new PSUs, through my main speakers. Interesting how acoustic perception works. -- I suppose the deep bass through the amps themselves would also now be better with the PSUs.
Rhythm & timing (previously a problem area for CD) had almost always seemed excellent since the introduction of the Berkeley Alpha DAC 2 into my system last summer, yet a few problem spots remained. The bass lines in Joe Walsh's powerful rocker "Rocky Mountain Way" had seemed slow and somehow limping. What a difference with the new PSUs! Now for the first time I can clearly distinguish bass guitar from drums, everything falls into place, and the rhythm becomes naturally intelligible. Also the bass lines on Miles Davis' "Bitches Brew" are much clearer and less murky; this is one of a number of recordings where I now am able to turn up the subwoofer considerably more than before, which enhances the effect of a more powerful bass even more.
While the PSUs were burning in, I decided after a while not to bother too much with that process. Instead, among other music, I enjoyed some new rock CDs by Frank Zappa (2012 remasterings), the music as well as the sound, especially the now improved, powerful bass. Yet after a good burn-in time of some 30-40 hours I decided to put on my audiophile hat again, and listened to some classical CDs the sound of which I intimately know (or rather, knew on my old system before the PSUs). My jaw dropped. What a timbral resolution, unbelievable from plain ole' Red Book CD! I had said the same already after the purchase of the Berkeley Alpha DAC 2, but the BorderPatrol PSUs double down on the revelations. I could not have been more wrong about not expecting dramatic improvements beyond removal of strain by these PSUs.
The first thing I noticed was the fundamentally different sound of brass instruments, as a group or solo. The sound has a more airy bloom, but with a twist. Mostly in audio it is either or, more air or more body, but now it is just more airy bloom added to the same body and tonal balance, quite a feat. Even bass tuba, while retaining that gutsy and dark body of sound, sounds more airy. And in fact, it all appears closer to live music. I do not hear that airy bloom from brass in all live situations, but very often, frequently enough to recognize what I hear from my system on many brass recordings as real and believable. I never thought that bloom could be extracted from CD. What is more, within that bloom there is far more resolution audible. Individual timbres within unison playing of a group of brass instruments stand out more, and it seems to me that this is not just because the colors are better resolved, but also because the individual vibrations of tone coming from the instruments are much better reproduced. Slight irregularities, even from brass playing by top ensembles, are much easier distinguished, lending additional life to the music. And though noticeable before, in a few brass unison passages at beginning and end of some tracks on John Coltrane's "Trane's Blues" it became far more obvious that while the players are all tremendously accomplished soloists, their unison playing is far from stellar (but perhaps it is supposed to sound more spontaneous, who knows). With solo trumpet playing, the onset of blowing into the mouthpiece (e.g., on staccato notes), subtle variations of blowing for each note and the slight transients of timbre between notes are resolved to an amazing degree. Overall, the micro-detail within brass sound is incredible, unimaginable to me from the standard 16/44 CD medium prior to the incorporation of the PSUs in my system. It simply appears much closer to the real thing.
While the increase in resolution of the sound of brass instruments is the most striking to me, everything shows dramatically increased resolution with the new PSUs. With the Berkeley DAC it was the first time that I had heard on CD that characteristic silky inner sheen from orchestral violins playing at low to middle volume, yet now strings sound even more silky than before. Those long-stretched notes in the first fortissimo outburst of the violin section in my recording of Bartok's Concerto for Orchestra had let me down previously, sounding too strident and like a brick wall. Now this rare problematic passage is neatly resolved into believable string sound as well. Separation of instruments even goes beyond the already impressive degree of improvements in separation prior to the PSU upgrade, allowed for by acoustic room treatment and the Berkeley DAC. It strongly resembles the clear aural separation of instruments that I have always admired in the concert hall, enabling that characteristically effortless listening into timbral, harmonic and polyphonic textures. In the first movement of Hindemith's Symphony in E Flat there is a striking transitional passage consisting of bass-rich beats. It was never clear which were the instruments involved, now it is easily obvious that it is a unison combination of bass drum, timpani and plucked strings.
Also depth of soundstage and spatial resolution have seen dramatic improvements. On some orchestral recordings I had heard an enormously deep soundstage before, giving me confidence that my system was capable of reproducing recorded depth, while on many others the soundstage was rather shallow. I blamed this on recording techniques. With the new PSUs, the situation has changed dramatically. Now, on one orchestral CD after another musicians are presented in different large acoustic spaces that each feel real. On many more of the orchestral CDs that I listened to there is good or even tremendous depth of soundstage. I had no clue that this much spatial information was hidden in those humble and often maligned silver discs. And the spatial bloom seems no artefact either. Bone dry, close-up and spatially quite flat recordings, like the recording by legendary engineer Rudy van Gelder of Eric Dolphy's jazz avantgarde classic "Out to Lunch!", otherwise excellent for its stunning clarity (the man has a deserved reputation), retain that character. Also, the spatial clues for orchestra appear correct. Most of the time trombones and percussion are projected way back in the soundstage where you would expect them with regular seating while other instruments are more upfront, and again, the space sounds different on each recording. CD as a 'dry' sounding medium? That is a thing of the past.
On other recordings spatial depth is seductive as well. I have a CD of works for a capella choir by British contemporary composer Maxwell Davies that I had always admired not just for the music, but also for its natural timbres. Yet when I listened to it with the PSU upgrade, I was completely floored. For the very first time the choir was put into a real, enormously large acoustic space, and voices deliciously arose from there, far receded from my speakers, instead of sounding upfront as before. Also remarkable was a rather trivial aspect on that CD, but one that speaks volumes about the newly gained resolution and removal of noise. For the first time I heard the fade out/fade in of a very quiet and unobtrusive steady acoustic and/or microphone background between each of the tracks. There it was, so obvious that it was 'staring me in the face' as it were, but I had never consciously noticed it before! (And my amps had already been dead quiet before in terms of lack of hiss/noise in idle state.)
Timbral colors are improved as well, for example, John Coltrane's sax on "Trane's Blues" has never sounded so natural in tone. Finally, everything has more ease, the sound is naturally relaxed (remarkable from CD) and considerably more open. Climaxes show much less strain. There is also less 'whitening' of cymbal crashes above orchestra playing in triple forte. The lack of strain is precisely what had been my main goal with the purchase of the PSUs and I have not been disappointed. The only problem with this is that for some orchestral pieces and some rock I want to crank up the system even further, but my SPL meter says "no, you bad boy, not good for your ears". But obviously there is so much more that I got with the PSUs than lack of strain.
If the quality of a system can be assessed by its lack of coloration which allows all recordings to sound very different from one another, instead of painting them all with the same brush, then the insertion of the BorderPatrol PSUs into my system passes the test with flying colors. One CD after another, the sonic differences between the recordings are now greater than before. A lot of the differentiating spatial and timbral information appears to have been buried in the electronic noise previously coming from my amp.
I may spend serious money on better power conditioning for my system in the future because of my general concern with electronic noise, but no power conditioner will give you the benefits of these PSUs, and I am glad I acquired them. While there are conditioners (Shunyata) that mutually shield your electronic components from the noise generated by each one of them (e.g your amps from the noise emitted by your DAC and vice versa), rather than just shielding the system as a whole from external AC noise through the wall outlet, the BorderPatrol PSUs make sure not to generate the type of electronic noise that may be directly afflicting your loudspeakers. This noise is generated by the power supply within your amp and enters the signal pathway from there (the PSUs shield the HT (B+) circuit supplying the amp from external RF noise as well). Regarding all these amazing things that I heard from CD, electronic noise from an amp may of course not allow for hearing them to full extent from a vinyl collection or hi-rez digital files either.
I should emphasize that all these great improvements in spatial and timbral resolution would hardly be audible in my room without the implementation of ASC room treatment (6 tube traps, 11 sound panels) over the last two years. It was absolutely crucial as a foundation. Without it I would still have a flat and congested soundstage within which better components could not shine -- there was only a marginally audible difference between my 20 year old Wadia 12 DAC and the Berkeley DAC; after room treatment the differences in resolution were huge (while the Wadia DAC turned out to be still better than some other highly regarded modern DACs that I tested).
While the acquisition of the two PSUs was not entirely cheap in absolute monetary terms at two grand each (well, plus two Pangea AC-9 power chords feeding the PSUs for 80 bucks each from amazon.com), it was an incredible bargain relative to performance gain. The spectacular upgrade feels like a system upgrade of perhaps 15 grand or more. I would have been happy to have had this kind of upgrade in sound from a Shunyata Triton/Typhon combo including expensive power cables. Yet while I may still go for that option additionally in the future, I now know that without the BorderPatrol PSUs I could not have gotten to where I am because of electronic noise previously generated within my amp and directly entering the final signal pathway to the speakers.