I hope this is not redundant, but I posted a cap mod experience in the thread of 'why DBT is such a hot button', post # (6161). My experience is that everything matters. Some changes are so subtle, that it's not readily convincing until more mods are done. If I replace only one cap, the result may be very subtle to hear. If I replace all the caps in the signal path, the sound improves audibly. Replacing other caps too improves it less, but improves it in the same direction. I left circuits like the RIAA feedback alone, as it already has precision polystyerene or polypropylene caps.

My power amp has an electrolytic cap in the input signal path. I bypassed it (paralleled it) with a stack of mylar and polystyrene caps of decreasing value. It did improve the sound, but not much, probably because the rest of the amp is direct-coupled.

I also redid the internal wiring that carry the music signal with teflon insulated wire. For interconnects, I used teflon-insulated twisted pair (signal and ground) with the shield grounded only at one end.

Every little change improved the sound slightly. The sum total was surprisingly good.

The type and quality of caps *is* critical in amplification circuits.

Swapping out the caps in speaker crossovers also can improve the sound drastically.

As a separate issue, capacitors degrade with time. Simply replacing an old capacitor with a new one can also improve things.

Great reports, guys!

Some years back, Dick Olsher (I think it was DO?) spent quite a bit of time swapping out caps with Blackgates and wrote a piece about which ones seemed to offer improvements and which did not. As I recall, and I could be mistaken, he found that the lower value caps, which were also some of the least expensive, made the biggest difference.

Or was it Ken Kessler...?

all the parts in the ckt matter, but not the brand names, but their electrical and tempearature characteristics. Not just in audio ckts, how bout cell phones, GPS, and the stuff has to be tiny and physically robust. Why do audio ckts matter about the BRAND of capacitor, no one talks about the brand of capacitor in their tvs? No one cares about the brrand of their wall outlet when plugging in their tv or recharging their Garmin or cell phone. Just when you plug in a SACD player or TT. Is that normal?

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Why do audio ckts matter about the BRAND of capacitor?

It matters, Carl. 21 years ago, I performed blind tests at the UK Show comparing a series electrolytic with a polypropylene of the same nominal value. There did appear to be some identification of the capacitor type on some types of music. (See HFN/RR magazine, January 1986.)

Something you might be familiar with is that in the first two generations of Philips CD players, digital zero was arranged to be above analog zero so that the output coupling electrolytics were operated with a DC bias voltage to minimize any sound quality degradation from their less-than-ideal characteristics.

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No one talks about the brand of capacitor in their tvs...No one cares about the brrand of their wall outlet when plugging in their tv or recharging their Garmin or cell phone. Just when you plug in a SACD player or TT. Is that normal?

It is fair to point out that in those other products areas, ultimate sound quality is already compromised, so capacitor choice becomes irrelevant.

John Atkinson
Editor, Stereophile

No, but in reference to the best VIDEO images, pertaining to tv. Where video is the main ingredient. Do they ever converse about this brand or that brand of capacitor giving better video than that otehr brand. No reviews I have yet read, do.

Correction to my post. My amp is direct-coupled throughout the signal path. I remembered incorrectly in my previous post.

The large electrolytic connects between the base of the (pre)-driver transistor and the bases of the output transistors.

What differences can there be in capacitors? Capacitance, voltage and ESR. Am I missing something on this?

I say lets get rid of capacitors in the signal path and replace them with transformers.

Capacitors are usually thought of as capacitance, ESR, and some small inductance. I don't know if that is a complete model. A friend of mine says that this is too simple a model. I have not researched this to say one way or another.

My experience is from using the recommendations of other published audiophiles. I too was skeptical of any possible changes (you know, the capacitance, ESR and minor L effects that I learned in EE classes). I tried substituting or bypassing electrolytic capacitors with 'suitably' selected values of mylar or polystyrene caps, so to cover as large an audio frequency spectrum as practicable.

What I heard was much less interference of each instrument to another in an ensemble, from low volume to high volume levels. This was "unheard-of" prior to the changes.

The effect of these capacitor changes can be identified without question, but is subtle enough that if you're not familiar with how the system sounded before, one might miss it when listening after. The result is that the nuances of the performance comes through with better clarity than before - clearly identifiable. The change does not 'hit' you like a brick, but it dawns on you that something good has happened to the character of the music that comes out.

I've repeated this improvement in several pieces of gear, to date: pre-amp, amp, CD player, FM tuner. Each and every time, the direction of change is similar in effect in all those components.

I do not ascribe the improvement heard to a capacitor dielectric change as many accounts have. Several things have changed (solder, wire, position of the parts on the board, construction of the cap, leads on the cap, etc.). I merely state that the difference is there, and the sound is better from a musician's point of view, in my opinion. What causes this is not completely clear from a scientific or engineering point of view. I wish I had more time to investigate the physics behind the changes that caused me to hear the improvements that I heard.

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Some years back, Dick Olsher (I think it was DO?) spent quite a bit of time swapping out caps with Blackgates and wrote a piece about which ones seemed to offer improvements and which did not. As I recall, and I could be mistaken, he found that the lower value caps, which were also some of the least expensive, made the biggest difference.

I love it! I'm always belly-aching about people spending too much for sound. Sometimes I just feel like telling people you might as well went out on the front porch and set several hundred dollar bills on fire. But what the hell. It's not my money.

Quick post: the caps I used are from surplus electronic stores, typically cost about 10 cents each. I bring a small refrigerator magnet and verify that the leads are non-magnetic. I buy a bunch of each value and store them in one of those 30-drawer parts cabinets and use them as needed. I check each with a cap meter and match values in both channels, and close to original values.