*** The DIY Audio Thread ***

[Kanifee]

you need to remove the four caps in the middle of the board, once that is done you need to connect the + of each rca output to the R- and L- were the caps used to be so these become your signal output, you can still use the ground from the rca ouput as the ground and this will bypass the opamps circuitry

 

[gurusan]

ah! and that's where p4radox's pics come in handy. thanks guys!

 

[Kanifee]

 

[MikeHunt79]

4ohm drivers with 8ohm tweeters, not sure what you would work that as though im going to upgrade them soon but the hifi first

Tweeters use very little power so just treat them as if they are 4 ohm.

 

[gurusan]

erm guys help!

I removed the 4 caps and connected -L and -R to the RCA outputs but am getting 2.52V on each RCA out!

What have I done wrong?

 

[Katoom]

^ Same as mine, now it's to loud.

 

[gurusan]

ah it's because I needed output caps. Put some 3.3uF Philips MKC caps on and the DC is gone Sounds quite good too!

Just have to figure out how to fit these caps inside my tiny enclosure! argh

 

[Katoom]

Where did you put them, any pics?

 

[gurusan]

I put one each inline of -L and -R....I put mine next to the connector, my case is really cramped and "just" fit the caps in there. Going to buy some copper tape for EFI shielding because the DAC and RCA outputs are right next to the transformer :/

 

[Katoom]

Cheers mate. I've just been reading your post on the art of sound to.

 

[p4radox]

Good news and bad news.

The DAC is now fully modified, with a modified Cmoy output stage and it sounds bloody fantastic. The AMP10 is also finished, and works.

Unfortunately there's horrendous buzzing on the AMP 10 when no source is connected, and a bad background hiss when there is.

 

[Katoom]

Pics, pics, pics.

 

[p4radox]

At the moment my desk is a complete rat's nest of cables everywhere. I'll take some in a minute.

 

[gurusan]

Some problems here....I accidentally took off the solder pad -R so have no right channel. looking at the schematic I thought I could just tap from pin 19 of the CS4397 chip but this doesn't work for some reason.

Tapping from +R works but obviously the sound is out of phase. Is there any reason I shouldn't just take the signal from +R and +L? or is there somewhere else I can take the right channel signal from?

 

[gurusan]

Well I went ahead and connected the outs to +R and +L and all seems ok. Got everything stuffed into the case with some ventilation. Casework is much harder than I thought! Couldn't get things to line up properly and I got fed up after awhile... now its good enough for me, even though the rear of the case is a bit rough, lol.

 

[Kanifee]

looks good, you find most of the time the case work is the hardest part but yet still looks pretty good to me

 

[MikeHunt79]

^Nice. Using R+ and L+ is fine. Are you getting any 50Hz hum from yours?

I've actually found different sources give different amounts of hum so I think it's a ground loop.

Hopefully optical should eliminate the hum...

 

[gurusan]

I'm not getting any noise and i have the DAC board literally within 2 or 3 cm of the transformer, and line out cables run right next to the power board and transformer. I am using optical input from my mobo btw.

I think I am going to get some copper shielding tape and make some shielding just for good measure though. A roll of it is only 3 quid so I might as well.

 

[MikeHunt79]

Nice, I've ordered an optical cable now so hopefully I should have this sorted.

 

[gurusan]

Yeah good luck with the optical cable

....1 other thing. I see people talking about 96kHz and 192kHz sampling but which files are sampled that much?

I thought CD audio was 44.1kHz....I was watching an episode of The Shield last night and the sample rate was 48kHz though.

Confusion :/