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commsysman
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New Coupling Capacitors for Superior Sound!

The word is out among audio engineers, but is a little slow getting to the average audiophile; the quality of the capacitors in the output stage of your preamp or the input stage of your amplifier is one of the major determining factors of the sound quality.
I have done four upgrades to my amplifier input stage over 20 years; from high quality electrolytics to MIT Multicaps (much better) to TRT Infinicaps (better yet) to TRT Dynamicaps (absolutely superb).
For those who might think this is a "tweak" like wood blocks or magic crystals, it is most assuredly not! The results of these upgrades are clearly audible; not all that subtle; clearly audible to even my always skeptical wife ("how can those little things make such a big difference in the way it sounds...?").
This same progression has been followed by Audio Research in the output stage of their preamps; MIT Multcaps in the early 1990s, Infincaps later, and most recently the superb Dynamicaps. They have certainly also made power supply upgrades, introduced the new 6H30 tube, and other upgrades, but the output coupling capacitors are a major, not a minor factor in the sound. They could put in cheap caps for less than $1 each, but instead they choose to spend $10 or more per capacitor BECAUSE IT MAKES SUCH A HUGE DIFFERENCE In THE SOUND OF THE FINISHED PRODUCT!.
As another example, I recently upgraded an AR LS2-B preamp from its original 1993 MIT Multicaps to the new Dynamicaps.
The resultant sonic improvement was startling; drastically improved dynamics, bass definition, and sonic purity. It now sounds closer to the LS-16 Mark II than the way it sounded before, for a cost of $150 and a couple of hours work (I used 8 1 microfarad caps; since this is a balanced output unit there are 4 output caps and each location required 2 caps in parallel).
Spending the $150 for this upgrade is an incredibly cost-efficient way to get a major sonic improvement; comparable to spending $3000 or more to trade up to a new unit. The Dynamicaps are a revolutionary design; they are so good that the improvement they offer is breathtaking; by far the best sonic improvement of any upgrade I have ever done.
If you check around on the web, you will find several other places where others besides myself have been lavish in their praise of the Dynamicaps. Parts connexion and Michael Percy are two sources for them; I'm sure there are others.
Spread the word and let all ears be most pleased...!

absolutepitch
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Re: New Coupling Capacitors for Superior Sound!

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.

Elk
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Re: New Coupling Capacitors for Superior Sound!

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!

Monty
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Re: New Coupling Capacitors for Superior Sound!

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...?

CECE
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Re: New Coupling Capacitors for Superior Sound!

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?

Editor
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Re: New Coupling Capacitors for Superior Sound!


Quote:
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.


Quote:
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

CECE
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Re: New Coupling Capacitors for Superior Sound!

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.

absolutepitch
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Re: New Coupling Capacitors for Superior Sound!

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.

cyclebrain
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Re: New Coupling Capacitors for Superior Sound!

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

cyclebrain
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Re: New Coupling Capacitors for Superior Sound!

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

absolutepitch
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Re: New Coupling Capacitors for Superior Sound!

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.

Lamont Sanford
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Re: New Coupling Capacitors for Superior Sound!


Quote:
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.

absolutepitch
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Re: New Coupling Capacitors for Superior Sound!

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.

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