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Good capacitors for cmoy

post #1 of 5
Thread Starter 

I have already build cmoy with some cheap capacitors from local store.
Now i am willing to build one more but this time wiht metal film resistor and some quality c1 and c2 capacitor.
I have 2 question.
First , is it worthy to invest in capacitor that are costing 2-5 euro.
If i invest in expencive capacitor, would  i hear any sound difference.

If i should buy some expencive capacitors, can you recommend some capacitors.

Best caps in my local store are ULTRA LOW ESR elko Nipon Industrial Company, JAPAN, 220uF, 50V, 105°C, 10x16mm, RM:5mm  for 0.5 euro.
Are they worth any

 

I am using opa2134pa.

 

tnx.

post #2 of 5

IMO- Yes  you should buy quality caps. The ones you suggested sound good with low  ESR and metal film resistors. I always use good spec components. like -polypropylene-polystyrene - and various quality resistors.Others in the sound science  will disagree and say--"they all sound the same" not as far as I and John Lindsay Hood/Cyril Bateman[ capacitor design engineer] and others  and many here who use them too     in the high quality amps they build .  There again I am a subjective along with 80% of the people here..I also have used the same family of chips in the past that you are using. You should not be disappointed with the reproduction.


Edited by duncan1 - 10/6/13 at 6:46am
post #3 of 5

OK, I will present a slightly different point of view, but one which IMO chimes with those of Bateman and Hood. We're specifically talking electrolytic caps here. I don't think anyone in the 'Sound Science' forum will disagree that electrolytics do distort, however the remedy for this is not, IMO, to buy some of the exorbitantly priced caps advertised on sale.

 

1. You don't need 50V capacitors. A cmoy won't have greater than 18V rail-to rail so a 25V cap will be fine, if you're running 9V with a rail splitter, a 16V cap will do. Lower voltage caps are smaller and cheaper.

 

2. Look at the temperature/time rating of the cap. A 3000 hour / 105°C cap is better than a 2000 hour / 85°C cap, purely in terms of how long it will last, but remember that a cmoy should not be running hot, especially if you don't cram it into a tiny box..

 

3. Electrolytic caps do cause distortion, this is a measured and measurable effect, but the best way to avoid it is to use an oversize capacitor. So in your case you could use a 3000 hour / 105°C cap (or better hours), rated 16V if you're running 9V with a rail splitter, and use 2200uF instead of 220uF. Because of the lower voltage rating the cap may well be no bigger than the 220uF/50V. The result is a smaller AC voltage across the cap, and consequently smaller distortion. Once the distortion is reduced to levels comparable to that arising from other sources, there is nothing to be gained by spending money to reduce it.

 

4. With regard to distortion, you only need to concern yourself with caps used for signal coupling (DC blocking) in the signal path. If the cap is bypassing the battery or power supply (opamp power pins), you can be a lot less fussy about the make, and you don't need to make them oversize.

 

Buy caps with a respectable name, Panasonic, Nippon, Vishay, Rubycon, etc. not 'no-name' caps, but don't spend out for the expensive caps like Black Gate, marketed as 'audio' types. If it says 'audio' on it, it's almost certainly a ripoff.

 

Many people like to buy high-priced 'audio' caps, as is evidenced by the wide variety on sale, but most engineers and others who trust measured performance parameters feel it is better to save the money and spend it elsewhere.

 

w

post #4 of 5

Of the working voltage of electroyltic caps that Cyril tested he found the lowest distortion on the 35 V range. Remember his own designed and built "cutting edge"[at the time ] but still good at =0.00001 % dis ability to display - Capacitors help in a specially designed jig to test with DC current flowing through them just to make thing    not only more harder but more to the point testing under near working conditions. Cyril published a series of articles on EE spread over a year.Nobody disagreed with him. Including DS.  

post #5 of 5
Quote:
Originally Posted by duncan1 View Post
 

Capacitors help in a specially designed jig to test with DC current flowing through them just to make thing    not only more harder but more to the point testing under near working conditions.

 

Duncan

 

If you're going to repeat things that you've read, you really must stop blathering and report the content accurately. DC current doesn't flow in capacitors, as any fool knows. With stuff like this in your posts nobody knows what to trust in what you have written and what significance to attribute to it.

 

Now I haven't read what Cyril Bateman wrote, but I know that DS has, and what I wrote is largely based on what he wrote, and that comparatively recently, and he suggests using lower voltage rated caps, quote "I tested 100uF 16V and 100uF 6V3 capacitors, and both types gave exactly the same results as the 1000uF 25V part in figure 2.17, with useful reductions in CV product and can size."

 

He also says "From (the) data, it appears that the AC voltage across an electrolytic capacitor should be limited to below 80mVrms if you want to avoid distortion. I would emphasize that these are ordinary 85°C rated electrolytic capacitors, and in no sense special or premium rated types."

 

Quotes from "Small Signal Audio Design."

 

w

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