*** The DIY Audio Thread ***

Thanks for your help, but i think I'll wait till i can see some pics of yours;).

If i bypass the output, i will have 2 wires, L- and R-, where does the other wire come from? I have 3 going to the RCA's at the moment.
 
Do you mean the 3 wire output from the DAC board? The black wire is ground, it can still go to the middle pin of the 3 wire output.
 
I'm also planning on using this chinese DAC, if you do want to use your own output stage, then you can skip the rail splitter and just use the rails from the PSU board.
 
p4radox said:
This is my project log if it's any use:
http://forums.overclockers.co.uk/showthread.php?t=17860076&page=3&highlight=cmoy

This is my circuit as it ended up:

http://img242.imageshack.us/img242/5852/design1mj7.png

The two black electrolytic caps you can see in the photo are simply in parallel across the battery input, to give better "big hit" response. Not sure if they made any difference really.

edit: the large blue caps are 0.1uF coupling caps to prevent DC offset reaching the op amp circuit. They allow the AC sound signal through though. :)
Click to expand...

thanks that helps immensely :D

aardvark said:
that looks interesting - do you have a parts list for this? where did you get them from?

thanks a lot.
Click to expand...

I got lucky and found a guy who had a bunch of spares left over from previous builds and put together a kit for me. Unfortunately, he has none left.

Here are the parts he included though:
Parts Info:
2x Nichicon 680uF 63V UPW electrolytics
2x Nichicon Muse ES 330uF 50V electrolytics
4x Wima MKP2 .22uF 100V film caps
all dale vishay 1% resistors
1x Shin Chin rocker switch
1x Eagle Plastics black aluminum volume knob
1x Kobiconn power jack
2x IRF510
2x Wakefield 1.5inch heatsink
2x heatsink mounting kit (Aavid high-temp, rigid polysulfide glass-filled shoulder washer, Bergquist adhesive-backed thermal pad (no grease required), nut, bolt, flat washer, locking washer)
1x Neutrik NYS 1/4 jack (I have mini jacks too if you prefer).
1x Alpha RV122F potentiometer
1x Cisco 34-1977-03 power supply
2x ceramic gold plated sockets
2x 19j6 tube
1x red nickel plated Kobiconn RCA
1x white nickel plated Kobiconn RCA
**Heatsinks, volume knob, power switch, caps, etc can be seen here
Click to expand...


Here is the schematic, more info, and a gallery showing completed builds.

http://www.pmillett.com/starving.htm
 
Last edited:
I've been reading through this thread and amp building is something I'd like to take up as a hobby.

Thing is- I don't know a big deal about chips (I know the basics, but not capable of making one for an amp out of the blue).

Could someone perhaps point me in the right direction? I've done a bit of googling but to no avail.
 
Yes the cmoy is great. I have learned quite a bit in the last few days building mine.

Prepping myself for 2 different electronics class for my 2nd year of uni too :D Electronics for engineers and datalogging/control systems
 
Hey I know a few of you guys here are using the infamous chinese DAC. I was wondering if anyones tried having a separate output stage?

Also, I was wondering if the PSU would be up to powering 3 or 4 op-amps? Basically I'm trying to integrate a volume control and crossover within my DAC unit.
 
I'm using a CMoy-esque output stage. Infact it pretty much is a CMoy. It does work very well though, and sounds as good, if not better than the onboard stage (when using headphones at least...).

I'd like to try something else, but my funds are drying out!
 
Ahh, a CMoy-esque output stage does sound a good idea. Are you taking the sound from the differential outputs on the board (L- L+ R- R+) and also have you got some sort of volume control?

I have a 4 gang alps pot that I plan to use, I'm guessing it would be best to have the pot before the op-amp?
 
The output stage is a line driver, its not deisgned to power 32ohms headphones.

Depends what you want from it. Something like a zapfilter would work well, or maybe jisbos.
 
I originally toyed with the idea of removing the 4 smallish coupling caps and feeding the output stage via a 4 pole single throw rotary switch as a "source select". But I had trouble figuring out the diff amp circuit, and on inspection a simple non-inverting amplifier stage sounds better anyway. Also, the volume control gave me nightmares with impedance matching and some crazy non-linear volume adjustment. So now I've removed the output stage, replaced the crappy op amp anyway and fed it from "R-" and "L-".

I've got a 50k Alps dual gang pot between the DAC and the op amp input and it works fine.
 
Last edited:
I should add, the reason for my tinkering with the output stage is that I'm feeding the DAC into my Tripath amp via a switched headphone socket, so I needed a pre-amp/headphone amp but also a volume control. I don't have a 4 gang pot to deal with the differential DAC outputs.
 
Hi all, ive had a depressing weekend to say the least. Got my pre up and running first which was my only ray of sunshine, for any one that hasnt seen the pics on the page overleaf its a SOAP II. the bass it gave my system is unreal, really deep and tight and this is before i replace the crappy opamp ive used for testing it.
Now the depressing bit, i thought i would try my hand at some matrix board tinkerings, my plan was to construct both channals of a bridged lm3886 amp, ive never worked with matrix board or p2p wiring so it was a little confusing to start with but i got to grips with it, anyway to cut a long story short, i managed to blow two of my lm3886 chips and in my annoyance and stress blew another from the other sid, so to recap after a weekends hard work i have one out of 4 lm3886 ic's left and a very bitter taste of defeat in my mouth.
To cap it all off i found an lm4780 bridged stereo kit over at audio sector for little under £50. Needles to say the mood im in at the moment im contemplating scrapping my latest efforts and just buying the kit!
Maybe this type of construction just isnt for me :(
 
Ouch indeed, I know how you feel. I blew my Tripath chip a week ago after excessive fiddling and it was incredibly annoying.
 
You must log in or register to reply here.
Back
Top Bottom