ADT-Automatic Double Tracker Simulator

Started by rockgardenlove, May 08, 2006, 07:32:46 PM

Previous topic - Next topic

Mark Hammer

Small Bear carries an 8-pin version of the MN3208 -

I *think*, but am not absolutely 100% certain, that the BL3208 has the same pin out as the MN3207, just twice as many stages.  Assuming they do have the same pinout, if one had a 3207-based chorus pedal (and there are loads of those at decent prices), subbing the on-board MN3207 with one of those 8-pin BL3208s would double your delay time, without having to change anything else like the filtering.  A chorus whose delay range went from 5-20msec would now go from 10-30msec.  One would likely need to adjust the depth control a bit though, because the same amount of clock modulation at longer delays will require Gravol for all users and listeners.  A simple fix is to simply stick a fixed resistor in series with the input lug of the depth pot.

So, two questions:  1) Who knows what bargain-basement chorus pedals are currently sold that use through-hole (no surface mount) MN3207 BBDs?  and 2) Is the BL3208 identical in pinout to an MN3207?

EDIT/UPDATE:  Did some digging and the BL3208 can successfully be plugged into the socket where an MN3207 used to be.  Pin for pin compatible.  I think we may have a winner here.


i got my rocktek(3205) ch01 pretty rockin by tweaking the d-time cap and adding a chorus/vibrato switch plus i added a fast /slow switch AND a trem switch (also makes the led go on and off ;D) PLUS i found a spot for a switch that changes the waveform of the chorus... kinda ramps up then starts over, ramps up again... sounds just like sci/fi startreck or Robalard... remember him? the alien who loved all kinds of candy bars? then tried some "earth fruit" and discovered it was yummy and not bad...
nothing says forever like a solid block of liquid nails!!!


I like Mark's question.  I need a chorus to base my project on :)


So there are no DIY chorus's!?  I'm suprised!

Mark Hammer

There are several over at Tonepad, but after clones of the CE-2 and Small Clone became available (not to forget the completely DIY Zombie from John Hollis), I suspect people ran out of interest in making others the way there is no end to the fascination for new fuzzes.  Unfortunately all 3 of those chorus units employ an MN3007 for which the 3207 (and 8-pin 3208) can not just plug in and work without modification.

What we need is a project for an MN3207-based chorus so that a BL3208 can be plugged in for ADT experiments.


If you can wait until August, this book promises to explain it all.  The authors were interviewed for the current TapeOp mag and they mention a big section of the book being dedicated to ADT.

This book has been promised for such a long time, I forgot about it. 
Help build our Wiki!

Ibanez CS9 chorus.  Does that look right?  I think that has the right chip.


Just a little bump so it won't pass over to the second page ;)

Will that CS-9 work?  Anyone know where I can get a PCB layout?


Mark Hammer

Yes, that will work.  never seen one myself, or a layout.


Hmm alright...

That would be horrible to perf...I think a layout is the only option.  I'd like to eliminate as much as possible though first.  I won't be needing stereo for the chorus, how might I take that out?  I also don't want any buffers, etc. 

I think I have a basic idea of what to do, I just want to verify.




I'm back!

I've been experimenting with LFO circuits to find which ones I want.  Simple op-amp ones are turning out the best...nothing too special going on with them.

I'm using a pretty fast LFO to change the speed on a slower one...sounds pretty cool indeed.  They're hooked up to a simple trem setup just now...haven't used them on a delay yet.

I think I'll base it off the PT80 delay. 

I'll be posting schematics and maybe some clips up here, if you're interested. 

More ideas/comments/facts/anything is welcome!  Post everything you know, it helps!


......somewhere in my magazine collection here, I read that effect was done by wrapping white cloth adhesive bandage tape around either the pinch roller or the capstan-if I remember correctly......I am looking for it today..............dr
Quoteexperience is what you get when you didn't get what you wanted