[diablo9]

pics coming...

right channel no DC offset, left channel has 12mV DC offset. Is that normal?

The way I measure is to connect power, no source connected, measure the OG to OL and OG to OR using DC, mV option on DMM, is that correct way to measure DC offset?

 

[bigmike216]

Quote:

Originally Posted by diablo9 pics coming... right channel no DC offset, left channel has 12mV DC offset. Is that normal? The way I measure is to connect power, no source connected, measure the OG to OL and OG to OR using DC, mV option on DMM, is that correct way to measure DC offset?

Offset should be measured with a source conencted. Measuring with the inputs floating can cause wierd readings.

 

[diablo9]

OK I did it again, still the same result, 0mV and 12mV, is 12mV a normal value?

 

[Pars]

12mV is a bit high, but not really trouble. What opamp are you using? Does the amp sound OK? Check the board over really well visually (with magnification). Have you cleaned it (i.e. solder flux)?

 

[diablo9]

the AMP sounds OK on my cheapo earbud. haven't tried any AKG/Senn yet. I am afraid of blowing those babies.
Haven't cleaned the flux yet but everything else seems OK.
What DC offset should I reach before I can plug in my AKG501?

 

[tangent]

Quote:

Originally Posted by diablo9 left channel has 12mV DC offset. Is that normal?

Depends on the op-amp you're using, and the gain.

Quote:

measure the OG to OL and OG to OR using DC, mV option on DMM, is that correct way to measure DC offset?

Yes.

Quote:

What DC offset should I reach before I can plug in my AKG501?

For best sound, anything under 20mV. They'll tolerate more, but at some point you begin robbing them of dynamic range.

 

[diablo9]

post some pics

I hooked up AKG501, iPod, 320K MP3, but I am not impressed. I can't really tell the difference of MINT and the stock iPod headphone jack, is that normal?

 

[Teerawit]

Are you using the ipod's line out?

 

[diablo9]

yes, Sik Din