Mini3 circuit question

Greetings head-fiers!

I've recently assembled a Mini3 amp (gain 2) to use with the LOD of my 6G ipod. I've built one canare interconnect so far and will probably make a silver one this weekend. The issue I'm running into is that at low listening volumes the right channel is slightly louder than the left. I've got a pair of Nuforce NE-7Ms that have 13.6 & 13.7 ohm impedance (right & left). I'm certain its not the LOD that's causing the imbalance as I've checked with other mini-to-mini cords from the ipod's headphone jack with the same result. The headphones and my car's stereo work fine as well. And yes, I know the Mini3 shouldn't be expected to run well at low levels.

My question is where to start replacing resistors (or capacitors??) on the board to balance out the sound. I'm not suggesting other rated values, just using others I didn't use after the matching process. I matched all resistors leaving at least 4 extras and usually to within about 0.2% of eachother.

When I slowly turn up the volume from nothing, the right channel becomes about as loud as a conversation in another room while the left is nearly silent. At normal levels, the focal point of the soundstage seems to be about 25-30 degrees to the right of the direction I'm facing (making up my own terminology here ). I hope this is an easy fix, but I will understand if using these iems is unreasonable...

Thanks for any help you can give!

Eric

PS: Thank you Ti for such a wonderful DIY project. Expect more business from me soon

well yes. The volume difference is a fixed amount and becomes unnoticeable at high levels, but these levels are unbearable to listen to for more than a minute.

Interesting... I assume I can check this with my DMM? I'll have a look tomorrow.

Other thoughts?

That's what I was thinking, but then more than one person on here said that such an adapter causes distortion. If I go ahead and build one, what impedance should I aim for? 32? Also, would a 1/8 W resistor be enough?

I really appreciate the advice guys!

UPDATE

So I had a look at the ALPS potentiometer just now and took some measurements. Do these look normal? According to the graphs, Anything after 70 degrees of rotation is pretty good. The green and yellow highlighted data represent the levels I was listening to with yellow being my limit for extended listening.





BTW, these position numbers are only visual estimates

I played around with the numbers a bit and determined that a resistance of 9 ohms added to the right channel would tighten up the channel agreement.

Here's some graphs, just for fun:






So before I add resistance to both channels, I'll try to add just the 9 ohms to the right and see (hear) how that works. Thanks for the help guys. I'll post back here with results.

AMB: Is there any way I can contain this correction within the amp's case? That would be amazingly convenient

You wouldn't make the gain for the left channel slightly higher (or right slightly lower)?