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Regardless of make, etc. if I had a choice of a specific value cap to use in a coupling position, say 4uf, and I had a choice between 100V and 200V where each would fall into the minimum voltage requirement, which should sound the best? In a nutshell, should the higher voltage have better sonics or are there other variables to consider? The reason I'm asking is in my preamp, the output cap uses a 100V poly cap( it is actually a cap designed for speaker cross-overs which usually require lower voltages so I was wondering if replacing the identical cap with a 200V coupling cap would make the preamp sound better.
Follow Ups:
Jim McShane, thanks for the link! I've been looking for that article for some time. Now it's sitting on my hard drive.
UncleStu, if you still have samples of the round and oval caps around, you may have an opportunity to objectify the differences you hear between the two. You could run signals from an audio generator through them and compare the results using a scope. If you have a dual trace scope, you could compare directly. By doing this at several frequencies and voltages over several samples, you may be able to see differences and hypothesize a correlation between deviation from ideal response and percieved sound. That could be a real benefit for our chosen insanity!
I have the original samples. I believe I did my evaluation of a pair of Dyna mkIV's with each channel set up with different caps, including values.
Only trouble is everything is packed away right now.
As I recall,the ovals sounded clearer, more detailed and extended on the top end. I may be wrong,but I seem to recall they wind all caps round and simply press the caps in order to achieve the oval configuration! The engineer was very surprised that I could disceran audible difference betwen the two configurations.
Stu
I once had Southern F-Dyne build a few thousand caps for me in mylar and polyprolylene. They were very kind and actually supplied some samples before we went into production. I had space limitations so they also made samples in round and oval configurations.It was an interesting learning experience. The ovals sounded better than the identical cap in a round configuration. I have no idea why. A more tightly wound cap sounded better than a cap with a slightly looser wind. We were looking for a replacement of a Sprague instrumentation cap which Sprague had just discontinued. We had a few left and the engineer at F-Dyne, a very pleasant man, told us that the cap used a bit thinner mylar than they would have normally used for the voltage rating, but it was wound extremely tightly. IIRC, he told us only one machine that they had could wind the caps to that particular tension.
All this probably tells you nothing useful, but a higher voltage rating probably means the thickness of the insulation will be greater and thus lower performance, most likely.
The thing here is that many factors enter in the sound of capacitors. I was told that it was more difficult to wind polypropylene because the material is not as stretchy as mylar, and thus more difficult to maintain tension and evenness. I later found out that you could make an oil wetted film cap where the film passes over a felt wetted pad before winding in order to capture that certain oil cap kind of performance. The manufacturers were not so keen on that as you had to be very careful when sealing the epoxy ends found on most film caps. The oil also made it more difficult to maintain the the tension as the film of oil moves.
There is a lot more to cap technology than sometimes meets the eye. There is a lot more than I know. To be honest, the more I asked, the more hesistant the staff was willing to tell me things. The engineer told me frankly that he did not know what to measure for in order to make a good sounding cap. And I believe to make his work and life easier, he was a bit reluctant to feed me too much. I don't blame him, though. I met the same reaction talking to the sales staff at Richardson electronics way back in the early 80's. That guy told me all his tubes which measured perfectly fine, seemed to be un wanted by the 'audiophile' users. He couldn't figure it out.
good luck, and let us know on your experimentation.
Stu
How about that....
You've revealed Russ57 and my best kept secret in capacitors.:-))) But, since F-Dyne (SEC) aren't a boutique name, nobody wants them.
We've been using them for many years.
Too bad John sold the company.
My rule of thumb for coupling caps, is to not go overboard in voltage ratings, due to increased inductance.
Regards,
Mitch
When I first approached F-Dyne, I knew they were a smaller company and I asked the VP if they had any experience building for the audiophile market. The answer was brief and succinct. " We build for Krell, Mark Levinson, and Conrad Johnson, to name a few. Is that good enough for you?"Talk about being shot down !..........
Considering I was a a very small potato in their overall market, they were very helpful and courteous. Of course, I have a few thousand caps left.Stu
I was going over the site, just getting into it really and stumbled upon this gents musings. Any way here are some thoughts on caps and why we think the way we do. The engineering explanation of ceramic vs mica caps is interesting as well as the bit about orange drops.
Also refer back to an article way back in Audio Magazine. I believe Marsh and Jung (or was it Curl?) were co authors and explained the nature of the plastic films and how they affected performance.
Many modern electrolytics are spin offs of 'Flash' cap technologies: small packages with high voltage and uF ratings, but I personally do not like them. IMHO, they perform like they were designed for in a camera flash, they discharge and then you have to wait for the cap to charge up again. They sound ok for the first dynamic passage and sort of muddy out after that.
I believe the teehnology uses an acid etched foil in order for the film to develop maximum surface area in a small package. Older caps and those in theoretical models employ parallel surfaces. I believe a lot of the sonic differences come about because of that. Older, very large computer grade electrolytics have superb bass and bottom end, the newer caps have a rising top end, probably because there are many little 'peaks' on the foil surfaces.
Just my experience. YMMV
Stu
The Audio piece was by Walt Jung and Dick Marsh. It was entitled "Picking Capacitors", and ran in February and March of 1980 in Audio magazine. Don't let the age of the article put you off - it's every bit as relevant today as it was then.Use the link below to go to Walt Jung's page, and scroll down until you find the articles - they're in .pdf format.
READ 'EM - twice or three times - and you'll come away much wiser...
Stu
Straight into me tiny brain that went! There's a Science side to caps, and then there's a Magick side.
Poinz
I have read that using a cap that is rated for a much higher voltage is not a good thing to do for electrolytics. Because if the operating voltage is not high enough the layer of aluminum oxide will not form properly on the plates.
At least one respected Japanese designer has previously stated that operating a cap near to its rating sounds best. The basic rule of thumb for a safety margin is to have the voltage rating at least 20% over the applied voltage.
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