[Turing]

i'm not using any jacks right now, just clips.

 

[Turing]

Quote:

Originally Posted by Pars Hmmm, 10mA sounds reasonable I think for an OPA2132. Do you have an LED in yet? I would suspect not. Does your meter have a mA range? Also, try measuring V+ and V- with the opamp out, but phones plugged in (check the output DC offset BEFORE you plug phones in... output L to ground, output R to ground... anything over 20mV or so DO NOT plug the phones in unless they are expendable!). If the DC offset is OK, do your V+ and V- behave the same without the opamp in? Did you use the stock PS component values of 4.7K resistors and 220uf caps? Increasing the cap size to 470uf may help some.

Forgot to answer this one.

I do have an LED hooked up (with the standard 10K resistor).

I get the desired 4.3/-4.3 split with the opamp out and the headphones in.

To summarize:
I get the desired split except for when the opamp is in, and the headphone ground is hooked up, then it goes 8.0/-0.5.

Could a bad opamp cause this problem?

BTW: I am using the stock resistors and caps

 

[Turing]

bump

 

[tangent]

It may be time to rebuild the amp.

 

[Turing]

i did that once already

tested all the parts (except the opamp) seperately and then put it back together again.

have you ever heard of a bad opamp causing the poor voltage split?

 

[tangent]

Quote:

have you ever heard of a bad opamp causing the poor voltage split?

It's certainly possible.

 

[bpribadi]

Mine has hiss also, very little though, and not noticed when music in on, only when my cd player stop (but on), or during the silent when changing tracks. I built without the R5 as well, and set the gain to 1+4.7 = 5.7

Probably I will reduce the gain, eventhough I doubt that 5.7 is consider high gain to cause noise.

When the input unplug, The inputs grounded, so no hiss at all.

I use LM1117T-ADJ for voltage regulator, set the output at around 7.18 volts, and split it. Since it is a low dropout voltage regulator, I still can use the 9 V battery.

I'm still looking the way to remove the noise completely.

 

[Kenny12]

hm.. i can't see a ground out or in?

 

[tangent]

Quote:

When the input unplug, The inputs grounded, so no hiss at all.

Not true. I suppose you mean the input is "grounded" through R2, but that's not truly grounded, not the way you'd do it if you were trying to test for input-stage noise.

The truth is, your source is noisy. End of story.

Quote:

I'm still looking the way to remove the noise completely.

Get a better source.

 

[Pars]

Quote:

Originally Posted by Kenny12 hm.. i can't see a ground out or in?

That's a damn good observation Kenny... you must have the input and output grounds referenced (as in connected) to your virtual ground down the center of the board.

 

[Kenny12]

Quote:

Originally Posted by Pars That's a damn good observation Kenny... you must have the input and output grounds referenced (as in connected) to your virtual ground down the center of the board.

actualy i was looking to see where he put ground because i wasn't sure if my ground was correct

 

[Turing]

I'm attaching my ground clips to the leads coming off the resistors below the opamp. I think that's right.

 

[Pars]

If you are using the CMoy layout from Tangent's excellent tutorial, anywhere down the two center strips of the board is virtual ground (the strips that are copper connected and jumpered to each other and run under the opamp).

 

[bpribadi]

Quote:

Originally Posted by Kenny12 hm.. i can't see a ground out or in?

I use an input socket that has another pin that will be shorted to the left and/or right input when the jack is unplug. So I connected those pins to the ground, so when the jack is unplug, the input connected to the ground.

The ground I mentioned here is audio ground, not the battery negative terminal.