Right Channel much lower than Left [solved]

[howzz1854]

HELP!.

first time solderer, and first amp, first everything. i followed the instruction extra carefully and took about 15 hours putting everything together. and now the right channel is much quieter than the left. i've plugged into my ipod to test to make sure it's not the DAC, or the cable, and it's neither. which leaves the question, where is the problem on the circuitry.  :'(

 

[Doc B]

Can you give us any voltage readings that are not within tolerance?

 

[howzz1854]

ok.. let me do another round of voltage read-out and post.

meanwhile, just for testing, i tried swapping the L/R input RCA, and the left ear still sounds much louder than the right ear. so is it safe to assume that it's not the input stage, but probably somewhere near the headphone output jack?

i'll go take the readings now.

 

[howzz1854]

ok. here are my voltage readouts.

Terminal    V
1              79.9
2              174.9
3              0
4              174.2
5              66.7
6              0
7              106.1
8                0
9                97
10              0
11              0
12              0
13              174.4
14              0
15              195.6
20              0
21              216.2

A1              66.7
A2              0
A4              0
A5              0
A6              79.3
A7              0
A9              0

B1              79.3
B2              173.9
B3              106
B4              66.5
B5              173.9
B6              96.8
B7              0
B8              0



#5, A1, and B4 seem lower than 15%.

 

[howzz1854]

ok... so i re-soldered #5, B4, and A1. now the three reading are within 15%. they were 67v before, now they're 76. exactly within 15%.

i replugged everything in, at first the left channel is still louder, but i found out that i have to turn the knob all the way up to the max for both channels to be equal, is this normal? or is something still wrong. it's like the lower the volume knob goes, the right channel becomes quieter and quieter until it disappears. please let me know if this is normal.

 

[howzz1854]

never mind, i measured those terminals again, and they're back down to 67v  :-\

don't know what to do. right now i can only listen to my music with the volume knob fully turned up to get both channels equal loudness.

 

[Strikkflypilot]

Have You, without power connected should be fine, measured resistance between inputs and outputs( left and right channels) on the volumepot in different positions, sounds like there could be a mismatch.

 

[Paul Birkeland]

This is most likely a cold solder joint in the amp.  I would reheat every joint in the amp to see if that evens things out.

The minor discrepancy in voltages is not responsible for channel imbalance.

-PB

 

[howzz1854]

This is most likely a cold solder joint in the amp.  I would reheat every joint in the amp to see if that evens things out.

The minor discrepancy in voltages is not responsible for channel imbalance.

-PB

Caucasian Blackplate, you're a genius!!!..

i am sure you all are, but that worked!!!... i resoldered almost every joint like you said, until my iron needed a break, that's when i told myself might as well plug it in and see if it works, and voila!.... now both channel even. thank you SO MUCH!...

 

[Paul Birkeland]

I'm glad you found the culprit!  You very likely will end up with a better sounding Crack also (on both channels).

-PB