Hello,
My last build is an Hoof Reaper clone made with a musikding kit. Hoof Reaper is a 3-in-1 Tonebender, Octave up and a BIg Muff variant.
https://docs.pedalpcb.com/project/WarScythe.pdf
Everything sounds fine, all controls are working.
I only noticed one obvious issue : If i just use the Tonebender and if i activate the octave, there is a noticeable volume loss, between 5 or 10 db i think.
No volume loss with the Muff section when i activate the octave, this issue only happens with the Tonebender.
Instead of 2N1308 for Q4 & Q5, i have a pair of BC107A. But that's in the muff section.
The transistors in the tonebender are an MPSA18 and an unknown transistor, marked MП38A 9005. I guess it's an MP38A. The build doc calls for an AC176.
In my stash i have AC122, 90-99 hFe and AC125, 110-120. Or EFT83, 60-70 hFe.
I wonder if the volume loss with the octave could be related to the transistor substitution in the Tonebender section ?
Is MP38A a suitable sub for AC176 in this application ?
Edit : i am using this stompbox with a long signal chain. There are several other effects, including a compressor and a few buffered effects (MXR stereo chorus, GE-7, BD-2, etc.).
If i connect the Hoof Reaper in the first position, the volume loss from the octave's activation disappears, but the Tonebender on its own sounds very compressed on full chords. If i just play single notes it sounds normal, but there is a volume loss on full chords. I play with active double hambuckers Seymour Duncan pickups.
If i put back the Hoof Reaper after the compressor, a Meatball and a BD-2, all switched off, the Tonebender sounds ok on full chords, and the volume loss is back when i activate the octave... Isn't it strange ?
I wonder if there is something wrong with my build, or if this Tonebender and octave combo are just very sensitive to their location in the signal chain ?
Every observations and suggestions are welcome !
Here are a few pics in case someone can spot something wrong or suspicious :
(https://i.postimg.cc/R6WnBkx2/IMG-20241020-190519.jpg) (https://postimg.cc/R6WnBkx2)
(https://i.postimg.cc/mP4MHp7F/IMG-20241020-190707.jpg) (https://postimg.cc/mP4MHp7F)
(https://i.postimg.cc/hfTThRQB/IMG-20241020-190737.jpg) (https://postimg.cc/hfTThRQB)
(https://i.postimg.cc/jCGysS5c/IMG-20241020-190756.jpg) (https://postimg.cc/jCGysS5c)
(https://i.postimg.cc/jDhfQ6h3/IMG-20241020-190829.jpg) (https://postimg.cc/jDhfQ6h3)
(https://i.postimg.cc/bGNt6GCy/IMG-20241020-190846.jpg) (https://postimg.cc/bGNt6GCy)
Voltage readings are coming...
DC 9V+ = 9.47 V
ToneBender :
Q1 MPSA18
E= 184.4 mV
B= 0.8 V
C= 3.6 V
Q2 MP38A
E= 100 mV
B= 171 mV
C= 7.76 V
(https://i.postimg.cc/8JGPyxPh/Screenshot-2024-10-20-at-19-40-58-Pedal-PCB-Build-Guide-War-Scythe-pdf.png) (https://postimg.cc/8JGPyxPh)
Octave
Q7 2N5089
E= 1.4 V
B= 1.9 V
C= 5.19 V
Q8 2N3906
E= 5.83 V
B= 5.19 V
C= 3.3 V
Q9 2N5089
E= 3.7 V
B= 4.32 V
C= 9.23 V
(https://i.postimg.cc/s1D3vYBD/Screenshot-2024-10-20-at-19-48-06-Pedal-PCB-Build-Guide-War-Scythe-pdf.png) (https://postimg.cc/s1D3vYBD)