I ordered a sub osc kit for my ‘78 2823 and I cannot get it to work properly. I’m certain everything is wired correctly. I get tones when I turn up the sub volume controls, but they are not sub octaves and when I mix in the main oscillators the volume dips when they got to the same volume, like they were out of phase. The kit I received says for Ody Mk1 and 2, even though I added the kit to my cart from the MK3 parts page. Are there two versions of this kit for the different versions? There’s not much to this circuit. Could I have a bad 4013?
There are two different versions of the kit, just to accommodate different output levels - so only resistor values are different. You’ll want to have the correct one so that the maximum volume of the subs is matching the maximum volume of the regular oscillators.
That said, it should not be causing the trouble you describe. There could be a faulty 4013 chip, and the best procedure will be for you to contact sales@syntaur.com to get a Return Authorization number. Once we can get the board back, we can test it here and take the next step in getting this resolved for you. I’m sorry for the trouble you are having!
Thank you for responding, Sam. that was helpful. I got the sub frequency issue sorted. As far as the volume mismatch I see from the schematics that the difference between the early and later models relevant to this issue are the 100k vs 680k mixing resistors for the VCOs. Would I be correct in assuming that if I were to change the 100K output resistors on the sub osc pcb to 680K will that likely improve the volume mismatch and ‘phase’ issue?
I give up on this thing. What a frustrating waste of time and money. Wish I hadn’t drilled holes for it.
I’m dismayed to hear this. We will be happy to test it if you return the board to us. I know that’s a fair bit of trouble to pull it out, but I’d rather get it sorted out and have you happy instead of frustrated! I’m sorry this has not been a good experience.