Svart
Well-known member
ok finished wiring my dual 1176 box and decided to try it out.
no smoke, checked PSU voltages, all looking good! plugged the input and output in and then houston we have a..
PROBLEM..
Audio is VERY weak and very distorted. started poking around with the multimeter and most of the voltages are looking good.
next I pulled the FET, no change in the audio.
third I ran a lead from the wiper of the input pot to the input of the output pot to bypass everything and i get audio loud and clear(however the bass seems rolled off around 200hz or so..) so my problem is in the area after the preamp and before the output driver section. I have doublechecked just about every cap and resistor for value and they are all good.
so.. I decide to try the other board. SAME PROBLEM. hmm so i start looking again and see one thing that I am unsure of.
the PCB has BC107B written on it. the parts i am using are BC107. the schematic on Gyraf's site shows BC107 and so does the parts list. I've been through the datasheet and see nothing that would cause the BC107's not to work so I'm sure it's not that but what else could it be?
so here's the facts in a nutshell:
the audio seems to be lost after the FET but before the output stage
It doesn't matter if the FET is installed or not leading me to believe that the FET isn't bad nor is the GR section at fault.
any ideas?
I'm headed back down into the studio to test some more.
:thumb:
no smoke, checked PSU voltages, all looking good! plugged the input and output in and then houston we have a..
PROBLEM..
Audio is VERY weak and very distorted. started poking around with the multimeter and most of the voltages are looking good.
next I pulled the FET, no change in the audio.
third I ran a lead from the wiper of the input pot to the input of the output pot to bypass everything and i get audio loud and clear(however the bass seems rolled off around 200hz or so..) so my problem is in the area after the preamp and before the output driver section. I have doublechecked just about every cap and resistor for value and they are all good.
so.. I decide to try the other board. SAME PROBLEM. hmm so i start looking again and see one thing that I am unsure of.
the PCB has BC107B written on it. the parts i am using are BC107. the schematic on Gyraf's site shows BC107 and so does the parts list. I've been through the datasheet and see nothing that would cause the BC107's not to work so I'm sure it's not that but what else could it be?
so here's the facts in a nutshell:
the audio seems to be lost after the FET but before the output stage
It doesn't matter if the FET is installed or not leading me to believe that the FET isn't bad nor is the GR section at fault.
any ideas?
I'm headed back down into the studio to test some more.
:thumb: