Review of Three High End Audiophile Capacitors

Audio Note Silver Foil/Mylar, VH Audio CuTF and Duelund/Coherent Audio CAST-PIO Cu


In the Audio Note Kits L3 pre-amp, sound signal passes through only one capacitor for each of the channels that is the coupling capacitor of the 5687 line board.  So it would be natural to assume the critical role that this capacitor plays in determining overall sound quality of this pre-amp.  For this reason, I decided to “go for broke” so to speak, when choosing this critical component.  Over the course of the past year or so, I tried Audio Note Silver Foil/Mylar, VH Audio CuTF and Duelund/Coherent Audio CAST-PIO Cu.  Following are my impressions of these three capacitor models listened through my system.  They are not the result of typical A/B comparison tests but my accumulated impressions through listing to each of them through an extended period of time. I  shall call this a “real world review” :) 

Audio Note Silver Foil / Mylar

I really like the sound of Audio Note UK products.  I used AN-Vx, AN-V, Lexus interconnects and Lexus speaker cables, AN-K Spe speakers, and OTO SE Phono integrated amp for an extended period of time.  That is how I ended up with my stereo system built around Audio Note Kits’ products and if it were not for AN Kits, I may not have gone into kit building and DIY audio.  I must say that the out of the box, kits’ do sound differently from the finished products but kits could be refined through parts upgrade etc. to sound similar to Audio Note UK finished products or even better to suite more to one’s liking. 

I always struggle trying to describe sound of an audio system in words.  It is something that I can recognize and differentiate when I hear it but very difficult to describe and explain.  As with many smaller HiFi equipment manufacturers, I think Audio Note UK does have its characteristic “house sound”.  What comes to my mind is the Confucius’ “Doctorine of the Mean” achieving exceptional balance and harmony of different attributes without any apparent excess.  This except for the price of course but Confucius apparently said that “the virtue embodied in the doctrine of the Mean is of the highest order.  But it has long been rare….”:).   L3 Pre with the Audio Note Silver was no exception.  It has wonderful mid-range, well put together sound overall, may not be as extended in either end of frequencies but very musical and pleasant to listen to.  Not the last work in resolution or details but it is much better in these attributed compared to AN-UK copper capacitors.  For example, listening to Tierny Sutton’s Blue In Green (female jazz vocal), vocal is bit forward with body but cymbals are polite and bass is not as weighty.


VH Audio V-Cap CuTF

Changing AN-Silver with V-Cap CuTF, I had immediately noticed more air, more details and weightier bass.  Initially, it may sound a bit metallic and bright but after a notoriously long break-in ( VH Audio indicates 400 hour break-in period), musicality comes back with more natural tone/texture to the sound.  It is the most transparent, neutral and detailed capacitor of the three and arguably most flat/extended in the frequency range, subjectively speaking.  It has excellent sense of speed, pace, rhythm and timing. It is a wonderful capacitor and I can understand that a lots of audiophiles are very happy with them, including me. 


But, as “a contented audiophile is an oxymoron; it's the ultimate bad attitude” ( ), I had to live up to the audiophile code of conduct and had to look for something that can be improved, right?  The only thing I wish I had bit more with the CuTF was natural warmth of voices and acoustic instruments.  I am nitpicking here but sometimes, CuTF had highlighted weaknesses of recording/mastering quality a bit too obviously that can be bit of a distraction.  


Duelund/Coherent Audio CAST-PIO Cu

Around November 2012, I noticed that the Parts Connexion had started to sell what it referred to as “special OEM priced” CAST PIO-Cu that are “up to 70% off” of regular retail prices.  I have read about Duelund’s VSF Black being perhaps the best of the best and new CAST PIOs even better.  Even with my “go for broke” attitude, their prices were way too expensive especially after investing into AN Silver and CuTF.  Furthermore, their shape and size are very awkward to say the least, especially for the CASTs, moon pie, can of soda or a roll of toilet paper depending on the value.  However, those “special OEM” versions seems to be much more competitively priced as far as high-end audiophile capacitor are concerned and they are made in manageable size and shape, though still bit and unconventional.  Since I had started to work on a new audio DIY project, I decided to take the opportunity and got a pair of 0.1 uF CAST PIO-Cu.  As usual, I procrastinated on this new project and at the same time I became bit too used to the wonderful sound of VH Audio CuTF.  So, I decided to give them a try in the L3 Pre-Amp. 

Immediately after the installation, those capacitors sounded a bit-off but never too harsh or too bright.  It had a strange tonal balance as if one has gone creative using an equalizer.  After a few days of breaking in, the sound truly blossomed.  What struck me first was the sound texture of music instruments.  I was listening to drum solo in the Tommy Flanagan’s “Overseas” CD and the tum tums sounded incredibly real.  I was able to clearly hear the resonating sound of the body of the string instruments, especially cellos and acoustic guitars.   Saxophones and trumpets sounded warm and brassy.  Human voices are very real with warmth and sounded holographic for those CD that are exceptionally well recorded.  Classical and many genre of Jazz recordings sounded closer to the way I am used to hearing them in live performances than I have ever heard from my system.  Highs are smooth and extended and lows are weighty, deep and tuneful.  Compared to CuTF, it may not be the as neutral, detailed or transparent.  Some of the resonance sound of the recording environment can be heard more clearly with the CuTF. 

As you may be clear by now, that I decided to stick to the CAST PIO Cu at least for now.  This is just based on my personal preference in the context of my system played in my room.  I am not saying one is better than the others but this one suited more to my taste. 



Both CuTF and CAST PIO Cu are highly recommended if your budget permits.  Both achieve a fine balance of high-fidelity and musicality.  CuTF may be tilted slightly towards high-fidelity while CAST PIO Cu emphasizes musicality a bit more.  Although they are very expensive as far as capacitors are concerned, I can argue that they may be one of the most cost effective upgrades available that could get you closer to audiophile nirvana.  It would depend on one’s equipment of course but in my case, the improvements I heard from those capacitors far exceeded improvements I heard of expensive NOS tubes or from changing cables.  For those who are tired of audiophile rat race and wishes to simply forget about tweaking and simply wants to indulge into music then Audio Note Silver/Mylar or even their Copper/Mylar capacitors at a fraction of the price may be the ticket. 



(June 6th 2013)


For Further Reading


Jeff's  Place :


Jimmy's Junkyard :


The Great Capacitor Shoot Out:


AV Front Line :


Humble Homemade HiFi: