madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: danfrank on November 18, 2020, 07:55:25 PM

Title: Question on Aquaboy 2016
Post by: danfrank on November 18, 2020, 07:55:25 PM
Pin 12 of the compander... Shouldn't there be a resister there going to ground? Like a 20k or 33k?
Title: Re: Question on Aquaboy 2016
Post by: madbean on November 18, 2020, 08:01:29 PM
On the OG version of the DM-2, no. I think the later MN3205 versions did have a 20k on the inv in pin.
Title: Re: Question on Aquaboy 2016
Post by: Scruffie on November 18, 2020, 08:03:28 PM
The compander is self biasing but to an internal 1.8V reference. The additional resistor is to offset that and provide the most signal swing for the supply voltage.

Don't forget the pedal originally used a battery so optimum isn't always... optimum.
Title: Re: Question on Aquaboy 2016
Post by: danfrank on November 18, 2020, 08:24:31 PM
Whatever that means... Lol!
I need to brush up on compander ins and outs...
I was comparing the AQB2016 to the AQDX2019 and that is the one discrepancy between the two schematics.
My AQB sounds bad, I should have left it alone. But I am running it at 15volts so I'll try out a 33k at pin 12.
Thanks for the replies