[leftshoe]

I'm measuring 400mv from the ground to the output headphone jack on both channels with no source plugged in. The input channels on the op amp are both recieving around 35mv, so at least the 11 gain is working...
When I measure the voltage at the input jack, it get around 3 mv or less, so Something must be happening to the signal between there and the chip.
I'll post photos of the board if needed.

Powersupply is splitting the voltage correctly, so that isn't the problem. Op-amp is likewise recieving the correct voltage on its voltage pins. I think it may be that the cheap op amp chip I'm using may be buggered. I'm using a LM833n for now, I've already ordered one of the bur-brown chips, I should get it in a couple of days. I think I may be using the wrong sort of caps for the C2 from tangents layout, I had to get them from the local radio-shack type store(dick smith) here in Australia, so I think they might just be poor quality.

I've done a fair amount of soldering before, but I've never had a problem this annoying

 

[Kenny12]

posting a pic would help best, powersupply is outputting correct voltage?

and what caps did u use in the amp stage? u need to use some film caps which dse does sell

 

[leftshoe]

I'm using what the catalog calls "metallised polyester film" caps. they are small square and yellow. Its abit of a pain for me to get a camera with decent micro functionality atm, so I wont be able to post pics for a couple of days.
Power supply circuitry is recieving around 9.5v from the single 9volt battery, and splitting it roughly correctly into two 4.7~ rails.

I was originally having power supply problems, but cleaning the flux off of the board managed to fix that. I may have blown the op-amp during that stage though. I'll try one of those dirt cheap op-amps from dick smith (Tl-something?) tommorow to see if that fixes it. I think they need at least 15v or such, So I'll have to swith the wall wort based power for that.

Any help would be apreciated.

 

[Kenny12]

try a different opamp and make sure that u wired the correct polarity to the correct opamp legs

oh and did u try it with some cheap 1 dollar headphones to see if it actually works?

 

[leftshoe]

I was testing it with some cheap earbuds, until of course they broke from the 400mv running through them. Now I'm testing through some $30 spare altec lansing headphones I had laying about.
I'm sure I've got the the + and - voltage lines into the op-amp correct.

I also hear at popping noise when I turn the amp on, and then nothing. I've only tried it a couple of times, I'm pretty sure if I leave it connected for to long I'll ruin these headphones as well.

 

[Kenny12]

ok wait sorry with a 400mV DC output yes don't test anymore


i would be looking at replacing the opamps and checking your wireing

 

[leftshoe]

Anybody got any ideas for what might be wrong?

 

[leftshoe]

I've got a cheap op-amp that I'm going to try out in it today, any ideas what I should be looking for?

 

[The Monkey]

Is anything getting hot?

Pics would really help. Or scan it.

 

[leftshoe]

I did try scanning it, but I figured that blurry images wern't much use. Oh, and nothing is getting hot...

 

[skyskraper]

check the solder connections, ie: the ones to and from the board. the jumpers to make sure they're not bridging. the general connections to make sure they're not bridging and are formed nicely.

 

[leftshoe]

I just finished switching the op-amp, and it fixed it. Stupid op-amps. I would have thought is would be hard to ruin the old chip, since I only ran 9v through it. Oh well.
It sounds pretty bad, but I think thats because of the horrible chip I'm using for now. Should It still sound ok through a cheap op-amp?

 

[chuck94022]

There aren't that many points between the input jack and the chip. Seems it would be a simple 5 minute check through circuit to find the point where the level changes, and that would be a big hint.

 

[skyskraper]

yeah it should still sound palatable with a cheap op amp. depending on what you're using though, some won't like being fed low low voltages.

 

[leftshoe]

I'm going to drop the gain down to 5-ish and try running in on 15v soon. Hopefully that will fix the distortion.
Any body know what the best gain would be for grado headphones?