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Re: Building a chip amp
Posted: Tue Mar 20, 2012 1:33 pm
by DaveF
Great work Fran. Very impressive.
I've got an old Myryad MA120 power amp that I havent used in many years. No idea if it works anymore. You're welcome to take it and rip it apart. Should have a good power supply and it has a lovely case.
Re: Building a chip amp
Posted: Tue Mar 20, 2012 4:54 pm
by Fran
Thanks Dave - yes indeed I would be interested.
It might be interesting some time to try the chip amp with the kharmas too - although its not a class D amp like Kharma's own....
Fran
Re: Building a chip amp
Posted: Tue Mar 20, 2012 5:24 pm
by DaveF
Fran wrote:Thanks Dave - yes indeed I would be interested.
It might be interesting some time to try the chip amp with the kharmas too - although its not a class D amp like Kharma's own....
Fran
Sure thing. Let me know whenever it suits you once you got the amp built.
Re: Building a chip amp
Posted: Tue Mar 20, 2012 11:07 pm
by Rocker
Fair play to you FRAN. Lovely work, can't wait to hear it.
Re: Building a chip amp
Posted: Tue Mar 20, 2012 11:20 pm
by cybot
Another year, another project :) Well done Fran.....
Re: Building a chip amp
Posted: Sun Mar 25, 2012 1:35 pm
by Fran
Final pics....
Not much has changed in the internals from the last pics, but I used a stepped DACT type attenuator instead of the Alps blue velvet shown in the earlier pics. I added bigger capacitors in the power supply as well, and lastly, I changed the resistors that set the overall gain of the amp to LDRs. These last ones are worth a mention. They are light dependant resistors - in other words, resistors whose resistance changes depending on the amount of light to fall on them. The particular ones I have used (and the ones that are used by all in audio around the world) are from a company called Silonex, and are actually a package of the resistor, plus an LED. So the idea is that the amount of power you put through the LED creates a certain amount of brightness, and therefore a certain resistance. If you can do that accurately, then the resistance is dead on accurate. Anyway, it turns out that these resistors seem to have a kind of magical sound quality. Example: I had used audiophile kiwame resistors in this position. Well regarded ones.... but when I added in the LDRs I got a better, more defined, cleaner presentation.
Anyway, I think she's kinda finished now. I might go back sometime and do another one with 2 chips per channel paralleled which is meant to give a higher power output, but its not something I feel the need to go for right away.
Excuse the fingerprints on the fascia: I thought I had them all off!
Fran
Re: Building a chip amp
Posted: Sun Mar 25, 2012 1:40 pm
by Ivor
It's lovely. Looking forward to hearing it sometime.
Re: Building a chip amp
Posted: Sun Mar 25, 2012 6:53 pm
by cybot
Beautiful......
Re: Building a chip amp
Posted: Sun Mar 25, 2012 8:06 pm
by fergus
Excellent work as usual Fran!
Re: Building a chip amp
Posted: Sun Mar 25, 2012 8:16 pm
by DaveF
very impressive Fran. Lovely neat finish too.