Bathtub Reverb Accu-Bell Effector Upgrade Project

S

SamuelG

Member
This is my project thread to invite comments / mockery *cough* shared laughter or any input readers might deem worth while :cool:
Here is my draft graphic of the Effector against the Reverb
2025-06 AB Effector.png .png.png
I have yet to label the three way switch at top left. It will be up-Reverb, mid-Delay, down-Chorus.
The labelled switch second top left, is the voicing switch similar to the Mod I built from TassiVicking's idea.
There will also be another momentary footswitch in the bottom left corner for the tap-tempo.

I have based the circuit from the ABE data-sheet example and borrowed ideas from the GT-Stasis Lead Build. Schematic attached.

Thoughts? Ideas for a better name?
 

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I would just try to wire the Effector module to the same place that the BTDR2 module was connected to, and hope I don't see any magic smoke.
I would change the L7805 to a L7806 and use that for powering the ABE, just connect the In, out1+, out2+, +6V and ground at the terminals for the BTDR2 module.

I would hope that the circuit would be ok for an ABT since it works with the BTDR2 module, you could always run some tests first if you are worried.
I would not add any opamps if it really don't need any.

Place the Tap LED right above the tap switch or to the right of it, unless you want to see it when you tap the switch with your foot.

I might have to try this myself so I get another chorus pedal, one with tubes in it.
The Bath Tub Reverb PCB is the only one I haven't ordered because there is none in stock, all the rest I have or they are on the way right now.
 
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I had considered this.
In the end I decided to use this build as a learning experience. I’ve never used op amps before and am enjoying the learning. :)

I know it's expensive, but if I learn how to use the OPA2134 dual op-amp it'll open up more design possibilities for me.

My current inquiry is about signal inversion. I’m trying to find out if the differential output is in phase with the input. I don't have a dual input oscilloscope to make a direct test.

I'm playing with the idea (not entirely seriously) of integrating the tap LED in the UV design using basic 1mm light fibres (red dots).
2025-06 AB Effector 3.png
 
Well hells bells SamulG, you really screwed me over with this one, I can't stop thinking about what I could stick in there instead of the BTDR2.
I am really gonna have to do some measuring so I can determine what I can stick in there, I think the first triode stage has a voltage gain of 2.44 and the second triode has a voltage gain of 33.81 unloaded. (7.75dB and 30.58dB)
I guess anything could go in there, auto wah, octaver, analogue chorus...........
And first I have to wait for Nathan to come back from holidays and order some more BTR PCB's.
At least I have a smile on my face while I wait. :):)
Cheers
Mick
 
Are you familiar with the MN taper pots ? they are dual pots where both are at full output at 12 a'clock.
One track starts at 0% and goes to 100% at 12 a'clock and stays at 100% from 12'clock to 5 a'clock.
The other track starts at 100% and stays at 100% till 12 a'clock and then it drops to 0% at 5 a'clock.
They are really good to use as blend pots since you can have the wet signal at 0% at7 a'clock and then go to full output at 12 a'clock and then stay there till 5 a'clock.
Then you have the dry signal starting at 100% at 7 a'clock and stay at 100% till 12 a'clock and then drop to 0% at 5 a'clock.

When you use a normal pot you can never have both the wet and dry signal at 100% output at the same time, with the MN pots you can so they are great for blend or balance pots.

I wonder how that would go in a reverb module, I think I read somewhere you can get some nice effects that way.
I think it was a tremolo effect with just the wet signal, or something like that.

That is whats missing in your circuit, a way to mix the balance of the wet and dry signals, you don't always want them both at 100%.
 
Great call sir!
No I was not aware of these.
So… how much of a change would it be to swap the current mix pot with the MN taper pot? Perhaps a matter of changing the pin configuration? It could be relatively simple!! I’ll have to have a look next time I’ve got a moment…
The Vol pot will still set the over-all output… hmm… Now you’ve got me excited :)
I have a circuit board ready for print with my current set-up but I want to buy a twin trace oscilloscope and an ABE module to see if it inverts the signal before I order the test boards. I don’t want unintended doppler effects if I can avoid them…
I’m also thinking the plate reverb sound in the ABE might work better than the spring verb I currently have.
Thanks again sir!
 
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