xcanv2 slight bias in one channel

[eightdigitword]

I have found a slight difference in amplitude in one channel. I feel that it is most noticeable in bass. It may be that all frequencies are slightly reduced in one channel. only that the bass stands out the most. 3 dB difference at most. just enough to get my attention.

I have fully modded my xcan v2 (2-3 months ago) courtesy of mikes kit. I have no doubt that something i have done is responsible for this small imbalance as the issue did not exist (as far as i noticed) prior to the upgrades.

what i've tried so far:

head phones on different amps + source with same material = no imbalance.

swap source supplying xcan = same imbalance in L channel

swap interconnects = same imbalance

swap interconnects L/R over into xcan = imbalance in same channel

valve swap L/R = imbalance in same channel

swap to different valves = same imbalance

Both gain resisters measure 46.7K (1% used)

headphones worn in reverse (check my ears) = same imbalance in headphone L channel

I'm sure its an obvious one, thought I'd post this before working my way through the likely components making a mess of all my immaculate work.

Thanks in advance to any suggestions or solutions.

[Deleted]

Do you have a digital meter ?
You could try feeding in a 100HZ test tone from a CD player or PC file.

[eightdigitword]

Jul 1, 2012 0:18:03 GMT @sandyk said:

Do you have a digital meter ?
You could try feeding in a 100HZ test tone from a CD player or PC file.

I'll hook it up to my laptop with a test tone and see where the imbalance is. I'll report back with what i find.

Cheers.

[eightdigitword]

got it!

I hooked up the amp to my laptop with a 1k test tone sine wave and traced through the circuit with my digital multimeter set to AC. I found that i had fitted one of the gain resistors in the wrong location. must have been in the excitement of getting the upgrades!

thanks to sandyk for the nudge! i was looking for the lazy fix of being told, this was much more enjoyable and satisfying in the end.

[Deleted]

Hi
I am pleased to see that you nailed the problem. I presume that this was my gain reduction mod that you were doing ?
Are you now able to use much more of the volume control rotation before maximum usable volume ?
Regards
Alex

[eightdigitword]

Jul 4, 2012 10:46:56 GMT @sandyk said:

Hi
I am pleased to see that you nailed the problem. I presume that this was my gain reduction mod that you were doing ?
Are you now able to use much more of the volume control rotation before maximum usable volume ?
Regards
Alex

nailed indeed, cheers Alex.

It is your gain mod yes. volume sits at 50% instead of 15%. much easier to find a suitable volume for listening now.

cheers.