[frs224]

I built a Cmoy amplifier as my first DIY amplifier project recently, based on Tangent schematic.

After testing it, the output sound feels fading, wide and missing some of the sound, like some of the vocals and instrument cant be heard (not sure how to better describe it), but it doesnt sound noisy. Checking the amp on my PC using Realtek audio manager to basically test the left and right output, i found that both channel outputs sound both when testing right channel only, as well as left channel only.

Then i tried using only one the two input channel (right or left) and open the other, and found that the output sound is very clear as it should be, and weirdly clear sound can be heard from both right and left output.
I cant seem to find the source of the problem so i try to manipulate connections and i got these results:
- one of the input is opened -> got a clear sound on both output
- one of right or left output is opened -> the opened output makes no sound, the connected output make very little to no sound
- input ground is opened, then one of the right/left input is connected to ground -> clear sound on both output
- one of the right or left output is connected to ground -> clear sound on both output

Also i tried using both 9V and 18V as the power input, and it doesnt really make any change.
Does anyone know what could the problem be? Thanks for your help.

 

[tomb]

You've mis-wired it somewhere, most likely in the input connections or the headphone jack.

 

[frs224]

You've mis-wired it somewhere, most likely in the input connections or the headphone jack.

it seems so.
I tested the amp again today by connecting the output directly to my earphone (which has 4 pins, including microphone) without using the socket, and found that the the ground of why earphone is on the second ring insted of the sleeve, while before i was using 3 pin socket, which means that the output ground connected to the mic all this time.

I'm planning to replace the socket with the 4 pins one. What should i do with the microphone pin? should i leave it hanging or is it okay to ground it?

 

[tomb]

Stick with the 3-pin socket. Just make sure you wire it correctly this time - ground is the sleeve.