Best caps for signal passing

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While placing capacitors in the signal path should be avoided if at all possible, I got the following advice from "Picking Capacitors" by Walter G. Jung and Richard Marsh (Do a search on Google and you can find this very revealing article about capacitors and how they relate to audio). Anyway,

"Up to values of about 10,000 pF, polystyrene is the best all around choice, as it has reasonable size and is readily available in many sizes, with tight tolerances available. Above 10,000 pF, and up to 0.1 u F, it still can be used but is much harder to obtain. Above, 0.1- u F polypropylene (or metalized polypropylene) is the dielectric of choice, as it has nearly the same relative qualities of DF and DA as polystyrene. Tight tolerances are available (but will be special order), and you can get capacitors up to 10 u F or more. Teflon may well be the best dielectric of all for audio, but is produced in limited volume and is generally not practical. Parylene is an excellent dielectric also, but limited in electrical size ( 1 uF or less) and not widely available. Polycarbonate is perhaps the next best all-around choice behind these and is generally available in a wide range of values. Polyester types are the most widely available for all the films and are already widely used in many audio circuits. There is no doubt that this is due to the generally low cost of these capacitors, but convenience and low cost should not be primary selection criteria to a critical audiophile. Polyester capacitors can be readily heard in good systems, with defects similar to those described for tantalum but, of course, reduced in magnitude. In our opinion, polyester capacitors should be very carefully applied in an audiophile's system, and any system using them in the signal path may potentially benefit by the substitution of (equal value, voltage and tolerance) polypropylenes or polycarbonates. We have done this ourselves on different items of equipment, tube and transistor, with always the same result—a stunning upgrade in sound quality. Further, we have observed others do similar things, either completely independently or at our direction, with the same type of results."

Hope this helps.
 
Christer said:


And even more than that (which means even deeper into your wallet).

Really? Where? I'm only acquainted with the selection at PartsExpress and Madisound. Not that I need such things as my crossover of choice is electronic, but it's nice to keep up with available parts.

<Geezer>
I remember the ARRL book telling me that a farad was an almost impossibly large unit of capacitance that nobody could have a use for. My, how times have changed.
</Geezer>
 
Just as an FYI, Jung's article is a bit out of date. These days you can get polypropylene caps up to 200 uF, so long as you dig deep in your wallet.

Good to know. I am kinda a newb at DIY electronics. Where do most people go for their capacitor needs? I do not have a deep (or a deeper) wallet, as I assume most DIYers do not, and I can't find any good deals on capacitors. In any case it seems from reading many threads on this forum that DIY audio becomes somewhat of an addiction at some point and spending nearly needless amounts of money on parts becomes almost common hat. Call me crazy, but I think thats exactly where I am heading, which is ok with me, I love this stuff .:nod:
 
DSP_Geek said:


Really? Where? I'm only acquainted with the selection at PartsExpress and Madisound. Not that I need such things as my crossover of choice is electronic, but it's nice to keep up with available parts.


Maybe I gave you false expectations, but at least SCR makes them up to 330 uF. I suspected they might make even higher values which were just not available at "my" supplier, but checking the datasheets, 330 uF seems to be the biggest they make. Still, they may have other series, and there might be other manufacturers, perhaps.
 
I have a quick side question and it kinda fits in with this post, but don't let it divert the attention of the original question. I am new to most of this, and I see many designs for SS power amps having two power supply decoupling caps, one being something like a 0.1uF non-polarized and one being something like a 10uF polarized.

First, can I get polarized film type capacitors (non electrolytics) to use here? If so what do I search for?

Maybe I am getting electrolytics and polarized caps mixed up. I know electrolytics are often made as polarized also, so when I see a cap with a + on one side in a schematic does this mean I should be using any polarized cap (not necessarily electrolytic) or does it mean to use an electrolytic?

Maybe I am all backwards on this, perhaps someone can explain.

Thanks, Ron
 
Any polarized cap you see will most likely be electrolytic or tantalum. Most electrolytics are polarized, but some are not / are bipolar. Yes you can get film and other caps to replace these, but they will likely be larger physically. Film caps and the like are not polarized, it is perfectly fine to replace a polar cap with a non polar cap. The converse is not always true. The symbol means that if you are using a polar cap, it must be oriented correctly.
 
AndrewT said:
Hi,
let's have some opinions on using motor start film caps in audio.

How comparable are metalised polopropylene suppression caps to audio polypropylene caps?

I believe you mean 'motor run' caps, which are generally metalised polypropolenes, as 'motor start' caps are generally specialized electrolytics.

My very limited exprience with motor run caps, in powerconditioning applications, was that comparing GE, ASC, Ducati, Arcotronics,.... to conventional axial metalized polypropolene AC caps is that I preferred the conventional axials. But my comment only applies to this specific application, and many dearly love motor runs for HV tube supplies.
 
In the past few years I've been doing some cap evaluation for a diy loudspeaker project. Richard Marsh has an arrangement with Rel-Cap, and apparently wholesales specialized audio caps to a few dealers. I use Michael Percy at http://www.percyaudio.com/. Sound Connexions is another dealer I've used, in Canada. That is a very extensive line, and in general, sigh, you get what you pay for.

For the very large value polypropes we used
http://www.northcreekmusic.com/CrossoverComponents.html
Some of these were designed to be different sounding depending on direction (darned if I know how he did that), and I did not care for either. However, 2 units in anti-parallel gave a very neutral sound. (Memory falters, but I think that was the Zens, and not the Crescendos; the owner of North Creek is approachable and very helpful.)

Capacitor differences include anti-microphonic measures, lead material and fastening method, and the ever vital color.

Other things being equal, in increasing order of quality and cost, metallized polyprop, alum foil/polyprop, tin foil/polyprop, and tin foil/polystyrene. I've not tried teflon, as in crossover value sizes it is too expensive. (And only two of the polystyrenes). Higher voltage units tend to sound better than the same type in a lower voltage.

I have a little experience with the Nichicon Muses, and I tend to more or less automatically use the Panasonic FC series (HF, Hi temp) for supply. The Black Gates, which I have never used have an excellent reputation, but I've heard that production has been discontinued.

We found that about 40 hours of break in as a rule of thumb is needed to properly evaluate. Very tedious. Without the breakin, our listening results were pretty erratic.

Edit: P.S. I forgot to mention that the multi-terminated types tend to sound better than the single termination types. Multi-Cap, and many stacked foil box types are among the many models available. Whether the difference is the lower inductance, better connection method, or many connections more or less in parallel I cannot say.

And by all means stay away from iron/steel leads. They are welded, which is quick and reliable to manufacture, but steel does not sound good.
 
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