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Swapped out Q1 anyway and it wasn't that. Did C3 in the process too and it wasn't that either.
This one is about to go into the bin of unwanted PCB's. Unfortunately I had already drillesd the Pot holes in the enclosure before I soldered them to the daughter board so that I could make should they were lined up ok.  I'm sure I can find another 3 knob 1590A build to use the enclosure
Should have been a simple build ... I built one of the BYOC 1590A mini Muffs with 2N5088's a couple of years ago and it fired right up.
I was doing this one to see if I wanted to mod my actual Big Muff to the Creamy Dreamer and I had the Rabbit Hole board laying around ... seen lots of conflicting info on it online but I don't care for some of the other mods out there.   

Thanks but still nothing new...

Reflowed Q1 and inspected everything. Reflowed everything else around initial gain stage.  The legs on the ceramic caps are fine ... I had trimmed a little of the insulation coating before I installed ... hard to see in the photo but they are fine. I checked continuity with pads and bare spots on legs and nothing faulty.

The higher voltage at Q1 still not making sense to me when I get 4 volts at other transistors. 

[Should I go after Q1 ??]

Still scratching my head on this.

I'm not great at circuit analysis at all but hard to see how I can get 4.25 volts at R12 (going to collector on Q2) and 8.6 volts on R6 (going to Q1 collector) other than a simply Ohm's law thing and something downstream of R6 drawing twice as much current

I changed R6 and R4 in the process ... I know not likely a resistor goes bad (and I measured them all while I was populating board) but I was lifting a leg on each while pokong around and didn't want to risk heat damaging them with the desoldering.  Of course each measured fine when I got them off the board so I am still working on this.

Should I go after Q1 ?? or does anyone else have  any thoughts. I normally socket transistors but this build didn't have much headroom with the small enclosure and tight spacing so I couldn't bend them over. Soldered them pretty quickly and waited in between each leg so don't think I heat damaged them but you never know ...

 Ha thanks ! ... I have a 2016 board so was using that build document (catching up on some that I never build and have been sitting around).

In the meantime I measured the voltages on my actual big muff and they are similar.

I think I'm getting close to my problem.  I have roughly 4+ volts at collectors on Q2-Q4 but the collector on Q1 is over 8 volts and 3 of the emitters are measuring 0 volts.

guessing something around R6/C2/R4 not right.  Will poke around some more and check values in the morning. 

 Thanks jwin615

Unfortunately the build doc for this one has no voltages but I have my actual Big Muff apart and will check its voltages tonight.

Yes I was using a signal probe and getting no signal after C1 and just about 1/2 of the loudness going into C1 and coming out of R2.  When I probed my actual Big Muff I have signal all over the place (Q1-Q4, clipping diodes, etc.) so I know something is drastically wrong.

Will report back voltages if I find anything.

Thanks.
Ok reflowed joints with no change.
Just for yucks I pulled the downstream leg of R2 and signal volume increased when I touched the loose leg so not a bad R2 resistor. Re installed and pulled C1 as well and also signal now passed to C2 (and it measeured ok with my analyzer) so not a bad C1 either.  So seams like it is feeling downstream circuit as a large impedence.

Also double checked the pinnout on the 2N5088's I used from the ones I had left (same batch) and fine.

Going to check some back to back voltages based on the stock EHX Big Muff I have unless anyone else has some beter idea.  I am getting good 9v from the Power connections and thru D5 etc.   

Thanks for the reply. I used 2N5088 just like the stock build of this pedal so pinout should not be issue . I checked each of the 4 with my PEAK analyzer beforehand as well because I wanted to check Hfe of them and everything else with them was fine.
The big ceramic caps are 50n per build instructions too. I have used others from the batch I have for a Nom Nom phasor build with no issue.
Here is back of board     
https://www.dropbox.com/scl/fi/k1mt8q6p33kv78h0f2pbi/Photo-Sep-14-2024-5-58-25-PM.jpg?rlkey=mk0u2sr56mux56d76sjys59b4&dl=0

Thanks for any suggestions. 

 Hi-

Built a Rabbit Hole and having issue.  Built it to the Creamy Dreamer spec. in the build document so that is why you see some jumpers in the photo.
Anyway when effect engaged I get no sound.  When I probe it with my signal probe I get a considerable volume loss thru R2 (33k resistor) and then no sound coming out of C1 (110n cap).  No sound at base of Q1.
I checked my Actual Big Muff and the signal carries loud all thru the signal pass (iei no volume drop at R2 and signal on base of Q1 thru Q4).

Any thoughts ?

Yes I built 3 switching boards all with latching relays and they all did the same thing ... passed clean signal on initial power up and then when I switched to effect the 1st time it would never pass clean signal after that ...

Changed relay (and jumper) on one of the boards to non-latching and it works fine ... so I still have two that don't work and it is a royal pia to de-solder the 8 pin relay ...

 Not sure why my pictures don't upload now ...

Further update and last one by me on this thread ...

I replaced the latching relay with a non-latching relay on one of the boards along with swapping the jumpers to corresponding ones per build instructions and voila it works now as advertised !!

If I hadn't built 3 of these with 3 Panasonic Latching relays I bought from Mouser I may have suspected my original latching relay ...

My only conclusion from this whole exercise is that the circuit for the latching relays is NG *&*%$

Any one else building these go with the non-latching relays.

Here is a picture before I box it up again ...

[Priceless]

All out of things I could come up with to try ... and lack of suggestions from others ... so I finally brute forced this.  Ditched the VFE power supply/switching board and wired up a road rage to get the +9/-9 v.

Works great now 

3 VFE boards, components & shipping $40.00, Many hours of time and frustration $$$, roadrage board and components $7.50 ... pedal that finally works .... Priceless

I have some non-latching relays that I didn't use ... if I get bored maybe I'll try one of these on one of the 3 relay boards that won't switch to bypass ... or maybe I'll just stick to 3PDT from now on ... always was more of an analog guy 

I also noticed that in your build document you show the non-latching relay and single jumper ... I used the latching relay and 2 jumpers in my 3 builds.
Has anyone had success with the latching relay ?   

Update -

We've had a few rainy days here and this project has been on my bench for weeks so I went ahead and built the 2nd one I had.

1)Plugged in for 1st time and it was in Bypass mode ... clean guitar signal came thru fine.
2)Press switch and effect came on ... effect and all settings work fine
3)Press switch and no sound
4)Little switch on relay board was at "buffer" setting originally ... un powered pedal and switched to bypass but still can't get it to pass clean signal.

Seems like something latched in the bypass leg of the circuit and it won't unlatch.

Only difference with this build from my other was that I socketed the transistors on the relay board (J175 & BS170) and I used TL074 on effect board instead of TL034.(and I haven't hooked up indicator LED yet).   
 

OK thank-you.
I have a 2nd Effect board that I have populated with everything except the pots and switches. Reluctant to go further and get same result.
I used the original Softtouch board and tried the one for the above with the 1st effect board with same result.
I tried disconnecting the IN/Out from the Softtouch board and just going direct to the mini-mu thru my test rig (i.e. using its in/out jacks and bypass switch but still using Softtouch power supply).  Now I'm just getting loud hum so afraid I messed something up.
I'll hold off doing anything else.