Aquaboy after clean boost distortion / tweakable EQ values

[osprey]

Hi! 

I've read the most recent distortion related thread on the Aquaboy.  Here are some observations/questions. 

1) The only value of C10 that would eliminate the "ggggkkkk" described in the other thread under heavy string attack when running a clean boost was 47nF.  Any thoughts on this relative to how well the DM-2 handles heavy clean boosting on the front end?  PS -- I tried the Coolaudio compander as well as a vintage 570 I pulled out of a rack mount. 

2) Are there any well known values that can be tweaked to get some distortion out of the high end of the repeats?  From what I understand there's some transistor-driven filtering that goes on.  Can said filtering be tweaked through experimenting with certain component values? 

Thanks! 

[Boba7]

Are you running it at 15v?

In my build I used 220nf for C10 (standard).
It runs at 15v, and I changed R13 and R14 to 56k to get 7.5v at pin 7 of the SA571n.
It took quite a long time to bias it properly by ears and I used a Fatpants in front of it to bias it with a boosted signal. In the end I found the perfect spot, and it doesn't distort even with a huge signal.

Hope it helps.

My build report: http://www.madbeanpedals.com/forum/index.php?topic=25164.0

[osprey]

Thanks!  How do you easily get 15V?  My other project I've always used charge pumps for tailored voltage.  I wonder if I can use 18V from my pedal power supply somehow. 

[Boba7]

I used a Road rage pcb in mine with a charge pump and voltage regulator to get 15v out of 9v. If you plan to use a 18v power supply, you could just use a voltage regulator.

[osprey]

Thanks!  I found a wall wart hanging around that measure 14.6V.  So I replaced r14 and r15 with 33k and C10 is not 100nF.  It works great now under heavy boost.  Maybe a bit too clean now, lol.   

[osprey]

Hmmm...  Now that I tried backing off the 9V again I get a (naturally) dirtier repeat but no more issues with the "ggggkkk" distortion.  Is it a bad thing to run it at 9V after having made the R14 and R15 adjustments to 33k?  Is there a voltage to watch for on the compander pins to tell me if I'm running something unsustainably? 

[Boba7]

I read somewhere on the forum that it was best to get half the power supply value at pin 7 of the compander. I must have the link somewhere...