I have put together an equalizer from a schematic, using gyrators.
When I play through it, the sound is very weak and static-y, almost digital sounding. It fizzles away quickly in a distorted mess. If I bypass the EQ, the sound is back and massive. There is also a low end hum with the EQ in. The three frequency controls do have an effect on the output. They all contribute to their corresponding frequency ranges. The low pot accentuates the hum as well.
So far, I have swapped out all the transistors, re-soldered the inputs/outputs, replaces the input/output coupling capacitors, tested all the transistors (diode check), resistances all look good from measuring in circuit. I have combed over the schematic vs layout three times now.
I am running out of ideas other than starting from scratch. Any ideas?
When I play through it, the sound is very weak and static-y, almost digital sounding. It fizzles away quickly in a distorted mess. If I bypass the EQ, the sound is back and massive. There is also a low end hum with the EQ in. The three frequency controls do have an effect on the output. They all contribute to their corresponding frequency ranges. The low pot accentuates the hum as well.
So far, I have swapped out all the transistors, re-soldered the inputs/outputs, replaces the input/output coupling capacitors, tested all the transistors (diode check), resistances all look good from measuring in circuit. I have combed over the schematic vs layout three times now.
I am running out of ideas other than starting from scratch. Any ideas?