DOD250 + HM2 EQ combo help - Breadboard to Perfboard

[schoolhouse905]

Hey all,

I've been stumped on a circuit I've been working on for a while, and decided it was finally time to turn to smart people for help!

I've been trying to combine a DOD 250 with a Boss HM2 EQ. I have the circuit working fine on my breadboard, sounding cool and how I want it. I used the vero layout from Tagboard for the DOD250 section, and the schematic of the Swedish Chainsaw EQ from Dirtbox Layouts (I've included both of those layouts) to get the circuit working on the breadboard. It's essentially just sticking the HM2 EQ section after the 250 section, before the volume pot of the 250.

I then drew my own schematic following the working circuit on my breadboard (schematic also included), and then used that schematic to try and make a layout for perfboard. I think this is currently the 4th or 5th revision of the perf layout. With every failed build, I spend some time looking over the layouts finding some random errors.

However, I've spent a bunch of hours with this most recent layout and failed build trying to find any errors, but haven't had anything obvious jump out at me.

Is my perf layout correct and I just a bad build, or is there something I'm not catching in the layout?

Thanks so much for any help!

[PRR]

So what happens? Distortion? Squeal? Only plays foxtrots?

Are there any DC voltages in there?

Signal tracer?

[duck_arse]

one of your circuits shows a rail splitter biasing the opamp stages, the other shows a rail splitter providing a reference, but the opamps going to ground instead. first thing would be to draw the circuit, the complete circuit, and get that checked for errors, and then do the layout - yours shows the reference connected to one single point, and all other oppies are ground referenced.

oh. I see. well then, your circuit diagram is wrong, and all those opamps need connecting to the rail splitter/reference generator.

[schoolhouse905]

So what happens? Distortion? Squeal? Only plays foxtrots?

Are there any DC voltages in there?

Signal tracer?

There is no distortion and a lot of static and noise that is introduced when turning any of the eq pots all the way up.

I rechecked the voltages against the breadboarded version of it today and found some stuff going on with IC3.

So that'll be my starting point tomorrow.

Thanks for you help!

[schoolhouse905]

one of your circuits shows a rail splitter biasing the opamp stages, the other shows a rail splitter providing a reference, but the opamps going to ground instead. first thing would be to draw the circuit, the complete circuit, and get that checked for errors, and then do the layout - yours shows the reference connected to one single point, and all other oppies are ground referenced.

oh. I see. well then, your circuit diagram is wrong, and all those opamps need connecting to the rail splitter/reference generator.

Thanks for all your help! I'll redraw the circuit from scratch with all this in mind.

Thank you again!