Did I use the right input Capacitors?

I used 0.1uF capacitors in my Cmoy amp.

These: http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=622-4202

The amp works out, the sound is good but not perfect, and it distorts quite early, although can decent volume out of it.

I noticed Tangent used 100v polypropylene 0.1uF caps what are the advantages of this in comparison to the ones I used?

Also what effect does increasing the Capacitance (as suggested to 0.22uF) have (and why?).

Finally what is the realistic range to increase in. Is the restricting factor just physical size and cost?

Thanks 

Thank you for your reply, these are currently driving a set of cheap sennheiser HD215's @ 32ohms

but they will also have to handle beyerdynamics DT770 and Grado sr60. (If it is unrealistic to expect the amp to do that range, I will happily build a second if I know what should be modified)

the schematics I used are the ones given on Tangent Soft

http://tangentsoft.net/audio/cmoy-tutorial/

I have learnt a lot by doing this project, and am keen to know what the input capacitors are actually doing, and how capacitance effect the output, and what difference material makes.

Also beginners question: how do you measure input impedance? Is that the load on the source determined by the 10k Pot?

Thanks again.

100k ohms in that case.

thanks.

ok now this odd, I just powered it up, and there was a lot more noise and something it was was picking up the radio!!!

That you for your replies, and that links was excellent. I bought enough parts to give this a second shot.

However this time I am going to splash out (as cheaply as possible) on some audio level caps, so to clarify I should be looking at around 0.47uF (the source is MP3 players, computers... normal h/Phone outputs) and the headphone are fairly low impedance.

Do you know what the minimum voltage I should be considering is, I know it make little difference once the caps are over the value, but I am not sure what the value is to start with. By power source is 18v (2x9Vdc).

Are these good choices? I want a clean sound where possible.

Nichicon MUSE  NES-270 @ 0.47uF - 50v

http://www.hificollective.co.uk/components/nichicon_es.html

Blackgate Nx HiQ  @ 0.47uF - 50v

http://www.hificollective.co.uk/components/black_gate_n_type.html

Finally, does it matter if these are polarised?

Thanks, it is a great help.

anyone? it's a big help.

Thank you for your reply, it that case I'll for the lower end then, but after reading the article given above I was now under the impression that 0.1uF was too low? Any thought on this?

Finally what is the minimum voltage i should be looking at.

Thanks as always.

Quote:

Originally Posted by Avro_Arrow 

I think this is all you need...

 

 

Also that would actually cost more to me than the Nichicon MUSE  NES-270; if someone could confirm whether they are or are not a good choice than I am happy to go ahead and get them.

Thanks.