[poli275]

Hi guys, I built a Cmoy recently and have one major issue. Circuit seems okay, checked voltage and current draw which all looks fine. Major issue is, I get very bad sound quality. After fiddling around for some time, I found that if I disconnect the ground wire of audio from the virtual ground, I get better sound, but turning the volume up will make the noises obvious. Any idea what would had possible went wrong? Thanks for any help or suggestions  
 
Btw I wired according to the schematic provided on tangensoft wbsite

 

[peranders]

Where have you the ground connected then? Opamp type? Supply voltage?

 

[poli275]

Hi, thanks for your reply. Pictures speak a thousand words, so I shall show you my board which is clearer than I explaining it
http://imgur.com/a/VpMXZ
 
T[size=small]he 6th strip from bottom up is virtual ground rail with a bridge to the strip where capacitors are. Ground from audio out is connected to that rail.[/size]
 
[size=small]The cmoy is Opamp type, DC supply of 9V from a single 9V battery.[/size]
 
[size=small]Thanks for your help.[/size]

 

[peranders]

Which opamp do you use? Can the opamp you have handle only 9 volts in supply voltage? Measured your ground? Do you have a connection between all ground points?

 

[poli275]

Hi Peraners, thanks for your reply. I have an OPA2132PA Opamp, the datasheet shows max tolerable 36V. I measured the positive and negative voltage against ground, they are all equal, is that what you meant? All ground points are connected together to the virtual ground rail.

 

[poli275]

I just found out that my left channel is not producing any sound, which causes the intense distortion to both channels on my earpiece. I will trace the signal along the path for any problem, in the mean time I could use more suggestions or possible solutions from everyone

 

[nikongod]

My suggestion would be to follow the steps in Tangent's troubleshooting guide and report back if that does not make the problem obvious.

 

[poli275]

OK sure, I will do the tests again tomorrow and come back again, thanks for all help provided. By the way, is it possible to have a damaged chip causing the left channel to be not functioning?

 

[nikongod]

Yes, it is possible that a damaged op amp would only have one channel working although not really likely. 

 

[poli275]

I built a new cmoy from a protoboard I received this morning, now I got a working cmoy! thanks for your help guys

 

[nikongod]

Did you ever figure out what you did wrong on the first one?

 

[poli275]

Hmm, I think the problem is that I soldered the 10k resistor before the 1k one on the I- pin. I only found the cmoy layout pdf file yesterday, was using the schematic only when I first soldered my first one and I'm not good in interpreting schematics.