Aune T1 - low gain

[hardisondan]

I bought an Aune T1 (Mk1) DAC a while ago and was very happy with. Then one day it just died. The headphone amp function still worked, but the USB DAC wasn't recognised any more, I tried different cables, different computers etc.. Anyway to cut a long story short, I returned it to China directly to Aune. They were good about fixing it and returned it. They mentioned they noticed I had an old chip and they replaced it with a new version. I'm not 100% sure what chip they were talking about. Anyway, I have it back and its working again.  BUT, now the gain is very low. Whether using RCA out (to my Crack), or via the headphone jack, you have to turn the volume up very high to get acceptable sound levels. I have the gain toggle switches set to maximum. It used to be MUCH louder. I really can't bring myself to send it back again.. the postage alone is starting to outweigh the cost of the unit.

So this leads to my question. I am tempted to open it up and have a look inside. I know this will void my warranty, but is there anything you gurus out there would look for that might cause the gain to be so low? In my simplistic mind, I'm thinking I could remove a resistor or something... is this wishful thinking??

Dan

[mcandmar]

Without a circuit diagram its going to be fun trying to decipher how it works.  I did a quick google search and found out it has a Tenor USB chip, PCM1793 DAC, an NE5532 opamp, and an OPA2134 opamp which is a bit odd.  It is a headphone amp, and a DAC so i would expect the 5532 is the output stage for the DAC, and the OPA2134 is the output stage for the headphone amp.  That does raise the question of what the tube doing?

It also looks like the gain switches only set the output level for the headphone output which makes sense, the line outs on the back of the unit should just be regular line out levels.  If your output volume is very low using either output there is something fundamentally wrong with the DAC section.  Personally i would contact Aune and see what they say before you do anything with it, especially since its just back from repair.

You could measure the RCA output with a multimeter. Download a 0db sine wave test file and see what its giving out, i would expect to see ~2vac.

[hardisondan]

Thanks. I might try the voltage check.

Regarding the tube, I am lead to believe it is used in the DAC, not the headphone amp circuit. At least that is what I've read.

Dan