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Did I use the right input Capacitors? - Page 2

post #16 of 20
6/29/10 at 12:45pm
Thread Starter 
Quote:
Originally Posted by Avro_Arrow View Post

Yes, .1 uF is too small.

The cap I gave you the link to is 1 uF.

The cap will only have a few volts across it

but these film caps only come in higher

voltage ratings. A 1 uF @ 10 volt electrolytic

would be small, but it probably would not

sound very good.

 

Thanks my bad, I was reading it as 0.1uF . The Nichicon MUSE ES 270 actually works out cheaper for me, would it be a good choice.

 

My first CMOY was 0.1@50v and didn't sound to good, I am running out of protoboards and want to get this one spot on. 

 

The article I read (given in link above) recommends 0.47uF, do you think 1uF is better suited?

 

Also just for future reference do these input caps have to be bi-polar as music is AC or am I way off the mark..

 

Thanks, I am learning a lot here. 

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post #17 of 20
6/29/10 at 12:45pm

Here is a lower voltage version.

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post #18 of 20
6/29/10 at 12:54pm

A larger value than is needed almost never hurts.

 

I linked to the wrong cap earlier, I should have

linked to this 1uF cap

 

A polarized cap is usually used where there is a constant

DC offset like in the output of an amp. Polarized caps

don't sound very good if there is no DC to bias them.

These film caps are all non-polar.

 

Here is a good design article you might be interested in.

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post #19 of 20
6/29/10 at 1:31pm
Thread Starter 

Thanks for all your help, I'll make the trek down to RS-c tomorrow and pick up those caps, If i change R3 2k what will the effect be, from what I read it will lower the gain, is gain not the amount the signal is amplified by? Will the end Maxium volume without distorting be lower if I increase the resistance or R2?

 

Cheers,


Edited by dobby156 - 6/29/10 at 1:33pm
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post #20 of 20
7/1/10 at 2:16pm

http://en.wikipedia.org/wiki/RC_time_constant

 

That's the math behind how to exactly select the size of your capacitor in an RC circuit, but Avro_Arrow is right about the larger capacitor you select the lower in frequency it works down to.

 

If you can get away with it, use a mica capacitor. They sound awesome, where "awesome" means they don't change the sound much at all. However, they get really expensive (like $30+ each) and hard to find in the 0.1uF+ range. Ceramic and other non-polarized film capacitors are almost as good as micas, are much cheaper, easier to find, and have AC performance almost as good as micas. Both micas and ceramics have significantly better AC performance and usually a much lower ESR than aluminum polarized electrolytics, which generally sound like ass when placed directly in the signal path. Sometimes you don't have a choice - for example, you would need at least a 3900uF capacitor in your signal path to protect a 4 ohm load from DC and have it work all the way down to 20Hz with minimal distortion.

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