Morley JP10 circuit inquiry

[jmasciswannabe]

Building a Morley JP10 over the holiday and am a little bit baffled. I have it up and running but the drive and level controls are acting a bit odd, or better yet, I am not sure how they are supposed to act necessarily (no knob twiddling youtube vid.) Basically, I am building from this project:

https://griffineffects.com/byo-pcbs/dist-fuzz-od-pcb/jd10-emulator-pcb

With level all the way down I get bypass volume, as i increase it, the volume attenuates and then increases. The gain does the same thing, except does not do anything with the volume all the way down. I would note that I am using 250k log pots instead of 220k. Is N supposed to be Vref? IF so, I am getting 5v instead of 1/2 v+ which is 9.2v

Any input greatly appreciated!

[Rob Strand]

It sounds like the VREF bypass cap C21 isn't connecting.  That means VREF isn't being bypassed by the cap.  That would do some weird stuff.

Is N supposed to be Vref?

N = VREF   ; N = is a Boss convention.

IF so, I am getting 5v instead of 1/2 v+ which is 9.2v

Totally normal due to unequal Vref resistors - which is deliberate.


It would be helpful to check the DC voltages on the outputs of all the opamps.

[jmasciswannabe]

Awesome. I will check it out! In my previous research I found a sabrotone layout where you did the schematic a decade ago! Glad you are still at it. THANKS!

[Rob Strand]

In my previous research I found a sabrotone layout where you did the schematic a decade ago! Glad you are still at it. THANKS!

No problem. Many of those earlier schematics were collaborative works.  Without the help from others it would be very hard to capture all the fine details required to get an accurate schematic.