freestompboxes.org

I have another question: does the signal-phase stay the same when the mpsa18 is used inversely?
If so, then this could be the answer.

The signal-phase stay the same.

Albru80's layout have now been confirmed over at tagboardeffects. There is still the mystery diode, but as both the pictures shown in this post by modman, and the comments over at tagboardeffects show, diffused red 3mm have been used by EQD, and sounds good.

Here's a perf/pcb layout for this. Pots are board mounted, switches are off board. Best fit is going to be in a 1790NS like the original.

There are a couple of ideas for improving the scheme
1) The output buffer and booster must be interchanged, then in boost mode the output impedance will not change - so it is more logical
2) The input buffer is not to be disabled, but in the 3pdt button there are 2 pins connected between the sobo (bottom row, right and bottom pins, connect to the buffer, using the DPDT toggle switch)
This will enable the selection of a bypass, and in the operation mode of the overdrive we will always have a buffer at the input.
3) Volume potentiometer should be changed to A10K
4) Boost potentiometer should be replaced by A100K
this will give smoother adjustments

Got a comment on my Instagram from a guy who works for EQD who said "You have some discrete misses." So unless he's trolling (which I kinda doubt), we're close but not quiet there yet.

@ Storyboardist. It is an MPSA13 in the booster, not an MPSA18.

kmmoe wrote:@ Storyboardist. It is an MPSA13 in the booster, not an MPSA18.

Fixed

storyboardist wrote:Got a comment on my Instagram from a guy who works for EQD who said "You have some discrete misses." So unless he's trolling (which I kinda doubt), we're close but not quiet there yet.

I think the schematic posted is more or less in the right ball park so maybe it has something to do with the boost

I have gone through the whole schematic one more time, and I really can't find anything that does not add up. I have measured all the connections I can't see clearly, measured all the caps and resistors in the original pedal, and it all checks out. Just beware that the original pedal uses a B100K volume pot, not a A100K, if you want it correct.

What makes to me, nevertheless, taken aback the fact that the input buffer headroom is noticeably reduced when the transistor works in the inverse operation mode, the buffer output signal starts clipping at a input voltage of 250 Millivolts.
In the normal operation mode the output signal starts clipping at a input voltage of 2.6 Volts.

So it could be the twisted designers logic - without buffer is actually the "buffered" sound ?

Some people reported issues with Tagboard build, any news on a "more" verified schematic?

I built this from tagboard. Everything works but the boost. The boost volume goes to just under unity gain. Everything else seems to work well though

Nobody solved the booster issues of the Tagboard vero?
I will love to add it to my rig

V2

A couple changes in V2. Buffer Q C & E are reversed compared to the schematic floating around. The 1k R and .1 uF C order are reversed and the switch terminal (bypass path) is between them. Boost has a filter cap at the input. Everything else seems to match up at first glance so that's all for now, gotta watch fight night at MSG.

Thanks for tracing der Version 2.

Buffer Q C & E are reversed compared to the schematic floating around.

Maybe the reverse mode of Q in version 1 was indeed an error in board design.

Yeah could be, pretty odd. Seems like a pretty large mistake to make all the way to production. If it was a printing error it could easily be fixed by populating Q1 backwards.

Does Buggs PCB need to have that fix?