Here is an old odd cat. This is an all discrete clean monophonic octave down effect made by Shin Ei back in the early 70s. Initially I though this was a Maestro OB-1 clone but the schematics revealed that's not the case.
See the notes below the layout for components that needs matching for best result. And I must admit the switching is a bit confusing but I think I got it right. Also worth mentiong is that reducing the horizontal cap right to Q11 will give a more aggressive and louder octave down signal.
It was sold under several brand names like Pax, Rands and Sekova. Colorsound also made their own version called Octivider but it had a quite few value changes so that one deserves an own post.
*Update 240120* Verified by JRuss with a small correction. Pinout of Q77 altered to match the schematic.
Excellent brother, thank you very much for your work, there is also a circuit of shin-ei, it would be excellent to see it afterwards, he waited for us to also give this
ReplyDeletehttps://www.tdpri.com/attachments/shin_ei_hurricane-jpg.565106/
Thanks for the schematic. Saved it in my schematic folder.
Delete(Is that a 4P4T rotary switch???)
if brother uses a 4p4t rotary switch for the selection of effects, this pedal is interesting, I think that one of the best wah of its time
DeleteNice! Thank you :)
ReplyDeleteI got this one working! There is an error in the layout: there should be a cut between the base of Q7 and the base of Q8. The collector of Q7 should instead connect to the base of Q8. I used a jumper wire. Took me forever to figure that out! It's a fun pedal now that it's pumping out those suboctaves. Thanks!
ReplyDelete