So, today I got my package from Fred_fred with Cmoy boards and some on/off clicky pots. I put this together this afternoon, happy to say it was only about 40 minutes of work, and it worked perfectly the first time through. A bit of confidence, and only a couple of small audio projects under my belt, seems to be helping immensely with this, its a great feeling to be able to tell you're improving, especially considering the amount of time I spend per day reading about audio electronics!
This specific amp is a gift for my father's birthday tomorrow and I'm stoked I managed to get the boards and parts before then! All I have to do tomorrow is find a nice enclosure for it and get some better quality connectors to replace then temporary ones I'm using.
Here's a picture of my handywork...
http://iforce.co.nz/i/2i1qty0k.vpa.jpg
What really blows me away about this little one compared to my stripboard cmoy (that I've been logging some serious hours of use on in the past week or so), is the low noise floor and overall sound quality improvement, while using the same supply and exact same opamp chip(Yeah, it's damn expensive here in nz for a decent audio opamp. I paid 13.95 for this single one in Jaycar! It really adds to the scariness factor when your rather expensive ic's might produce the magical $13.95 smoke that smells so sweet, with just one little wiring mistake... yeah right...
The only difference between this and my other Cmoy was choosing slightly higher quality/better choices of components. Instead of polyester greencaps, I used 474pF polypropylene rectangular ones (if someone could enlighten me as to what the correct name for these are, I'd be grateful) There's also a small low-ESR electrolytic that I added between the two rail splitter caps and ground, I'm not really sure what it even does, but I suspect it might have something to do with the improved sound quality, and who am I to question the markings on the board?!
Finally, I also managed to scrounge a couple of 1000uF 15v Sanyo electrolytics out of an old car amp, which according to everyone I talk to, should beat the crap out of "Suntan" caps in quality... the last one I built had 220uF caps in the place of these, and I can definitely hear an improvement in bass "boom" with the much higher rating.
My dc offset is only 0.6 on one channel, and 4.5 on the other. This is with an opa2134pa, would that be considered within spec/safe range?
peace ya'll!
chris