Jon L of Enjoy The Music: ... when the copper foil version of the AmpOhm PIO's became available, I had to give it a good listen and compare to the other versions. After the obligatory burn-in period, I directly compared the copper version with the tin foil version, changing back-and-forth.
I would say the difference in character between copper and tin is larger than between tin and aluminum, yet all three versions share similar presentations, which is no doubt due to the exactly identical construction except for the foil material. All share a well-balanced clarity with great detail resolution, at least for PIO's, and above all, music is well-served. This does not make it any easier to describe precisely how the copper and tin sound different, but I do have a few observations.
With the copper, there is a little more attention-grabbing presence or copper-glow, mainly in the midrange, which can be described as slightly rounder yet with a fraction more detailing of the texture. Both female and male voices step forward half a step closer while the high and low frequencies remain similar to the tin foil version. This "mien," if you will, is mildly reminiscent of the Jensen copper PIO, yet the AmpOhm copper seems to have better clarity and extension at both ends of the spectrum.
Over the years I have evaluated countless audio capacitors to use in our products. When I started voicing our BellaMax preamp, I was looking for a capacitor that would provide me with refinement and detail with just the right amount of richness without being overly warm or rolled off. I was fortunate enough to be able to evaluate a few of the Ampohm capacitors in this product along with several other highly regarded capacitor manufacturers.
Needless to say, the Ampohm capacitors are now standard in our BellaMax preamp. Their Metalized Poly capacitors make up our power supply while the Paper in Oil - Tin Foil bypassed with some of the poly capacitors are used in the coupling position.
I am now trying the Ampohm capacitors in some of our other products and I can now confirm it won't be long before Ampohm capacitors find their way into a few more of our models.
Jon L of Enjoy The Music: ...it came to me as a pleasant surprise when the AmpOhm Tin Foil PIO directly replaced Mundorf SIO and seemed to be sounding at least as good! AmpOhm really seems to hit the right balance among PIO's. In some circuits, the wonderful Jensen copper PIO can sometimes sound a bit too refined and buttery for my tastes, but AmpOhm avoids that while still remaining smooth. What it has over Mundorf is higher density of tone and richness while not sounding syrupy or slow.
I still remember the first time I played Bach Cello Suites via AmpOhm. The cello sounded so magnificent I almost fell off my chair! Every detail, texture came through with power and vigor.
If you are looking to PIO's as sort of a filter to hide system faults by rounding, glossing-over, or rolling-off, these AmpOhm Tin Foil PIO capacitors are not the way to go because they are incredibly detailed and revealing of the signal chain.
My initial impression is that the paper in oil aluminum foil cap is very smooth - the impact of the by-pass on the midrange was excellent - very solid sounding. In fact I got the impression that the soundstage was much better.
Jon L. Enjoy the Music: What I wrote about the tin foil PIO pretty much can be re-written here without significant changes, which is a very good thing. Invariably, someone will STILL ask which one they should get for their amp XYZ. If I had to give an answer, for no good demonstrable reason, I might say go for the tin if your amp is already on the slightly smooth, round side and go for the aluminum if one's looking for a touch more forgiving sound...
The overall sound of AmpOhm paper-in-wax was even and pleasant, with no part of the spectrum jumping out and biting off your ears. This is a great capacitor for tweaking an overly-bright or analytical system to more forgiving side, allowing one to enjoy a larger portion of poorly-recorded albums. The flipside was that great recordings could not reach the heights that tweaked Teflon caps can achieve; there just seemed to be a finite limit on how much resolution and transparency was available. It’s not really fair to compare any cap’s resolution to teflons, but that’s how it goes around here.
Jon L. Enjoy the Music: Many people believe polyester capacitors are cheap and bad-sounding and tend to avoid anything that says "polyester"; however, most of this belief stems from bad experience with cheap polyester capacitors, not serious polyester film capacitors like the AmpOhm.
True film polypropylene capacitors tend to sound better than metallized polypropylene caps, and so do film polyester caps like AmpOhm compared to MKT caps. In my experience, cheap, small MKT caps tend to sound rough, bright, and forward, lacking true extension and refinement. Some of them do sound decent and maybe even "good", but they are not going to be mistaken for good teflons or PIO's anytime soon. So when I first inserted the AmpOhm polyester film cap after the burn-in apparatus and heard a brightish, thin sound, I said to myself, "Yup, that sounds like polyester." But following my usual protocol, I let the caps burn in more in the actual amp position for a long additional period.
When I came back to the rig, I could hardly believe what's happened to the sound. The sound gained an intense, clear, "juicy" quality that was irresistible, especially for female voices. Upper-midrange to midrange was translucent and illuminated with glowing floodlight with every detail present yet with no grit or grain. The tangible palpability was off the charts and perhaps one of the most "fun" times I've had with the human voice. The degree of presence was akin to the proverbial female singer closely singing into your ears.
This is very different from the polypropylene presentation, which does not highlight the midrange presence as much. The treble and bass of the AmpOhm polyester cap is probably in the same ballpark as good polypropylene film caps, but the midrange is definitely something special and unique. In addition, this is not a cap to be used lightly if you have weaknesses in digital front-end, interconnects, power conditioning, etc. The sheer amount of detail and presence in the midrange will not be kind to hard, forward source or components, which is very different from AmpOhm PIO caps, which tend to be more forgiving of such things while remaining musically revealing. At any rate, this capacitor has opened my eyes to polyester film capacitors, and I hope to try some others built to the same high standard in the future.