Doug Self Preamp from Linear Audio #5

[tomi2251]

i go trough the scematic and look over my psb cant find any fault.
i took some pictures.
if someone has any ideas what i can do i would be happy.
ps its the left channal that is low volume, i turn the balance all the way to left to get equal signal...but i cant use tone controll because off the whining noise.

[tomi2251]

Dropbox - preamp - Simplify your life

[jwilhelm]

Does it make any difference if you flip the tone bypass switch?

[Freecrowder]

Dont want to intrude on trouble shooting issues but this is the right place to post. Maybe I can help on TS also. Finally got around to putting into proper case. If anyone needs FPD files that work I can supply. I offboarded volume pot and changed lettering from Carls files. Kind of a throwback to the 1U pres from the 80's and 90's

[Freecrowder]

Kind of small for any detail. let me know if anyone wants to see more detail.

[Freecrowder]

Tommi,
BTW did you build up your own ribbon cables? I had the most issues with cabling getting PIN for PIN matchup and the selector switch with the ribbon connector header pin 1 pinout. Look that over carefully took me 2-3 times to get everything just right.

[tomi2251]

Hi
Yes its difference when i move The tone contrll, The biggest difference its The treble range its start to feed... Like feedback from a mic to loudspeaker.
I buy standard ribbon cable ready with contacts

[Freecrowder]

So are you saying that with the tone control switch in it has feedback and when it is out it doesn't?? Important to completely understand the symptoms

[tomi2251]

Yes IF I turn it off or turn down to lowest on The treble scale its get less and disapear.
But with out tone contrll its sounds good
Just That The left channal its half The output

[jwilhelm]

To try to narrow down where the issue is, remove A4 and see if the volume is louder with the tone control switch in bypass. Do the same with A3 removed.