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Aquaboy v2: Feedback control range / pot behavior

Started by Strategy, July 12, 2020, 03:58:34 AM

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Strategy

A family member has been using the Aquaboy V2 I built (with double delay time add on) and sent it back recently for tune up and a couple of minor repairs.
As I'm wrapping it up I thought I should double check the feedback control. Short slapback delays are only available up to about 8 o'clock and then anywhere beyond that is pretty intense, runaway style delays. It's been a long time since I worked on this.
- Is one of the trimmers a feedback maximum? I don't recall it having a feedback internal trim like T1 in the Aquaboy Deluxe, but maybe I'm overlooking or just can't tell from the docs.
- Do I get a more commonsensical sweep by maybe switching to an Audio taper pot?
- Or is the stock feedback just designed to go from zero to "jam section of Live at Pompeii" wild in a very slight knob turn?
thanks,
Strategy

danfrank

#1
By version 2, I assume you mean the aquaboy deluxe with the 2 MN3005 ICs?
Take a look at the first attached picture, this is what your AB has for a resistor (R30 22k) for feedback between the two sections of the compander. You want to change this resistor out for a 10k (R39) resistor and a 50k trimmer in series with the resistor. Take a look at picture 2.
To adjust, set the feedback knob to maximum and then adjust the 50k trimmer to where you want it. This is the way (including the new ABDX) most analog delays set the range of the feedback control.

Strategy

Hi, actually this is not Aquaboy Deluxe, it's from before that: plain Aquaboy, second version. Someone produced a 2x BBD kludge board that I added. I can't find the docs online anymore...I'll try and post a link here but will have to dig them off an old hard drive
Aquaboy Deluxe was the followup to this, I think its design evolved specifically from the double delay and LFO add-on's people had done with the vanilla v2 version.
Paging Mr Madbean?
Strategy

Bio77

The projects page has an archive section.  The build docs for the project you mention are there.  Looking it over, there wasn't a feedback trimmer on that version.  You could probably look at the releases after that one and figure out where the trimmer should be placed.  Or just socket that resistor and try different values that way.

https://www.madbeanpedals.com/projects/archives/index.html

Strategy

OK, I'll check it out. Also, I'm going to go back and see what potentiometer I used for Feedback. The sweep behavior strongly indicates Audio where a Linear curve really wants to be there. It's like...nothing nothing nothing FEEDBACK! Linear would make a ton more sense...I don't recall what I used; it could be this simple.
Strategy