How to Add Trails To a Boss DD-2/MIJ DD-3

[aviherman5]

Hi all,

Does anyone have any ideas for how to make a Boss DD-2/MIJ DD-3 have trails? Literally just have it continue the repeats after it is turned off and only make new repeats when turned back on like a traditional trails delay.

Thanks so much!

[ElectricDruid]

Have you got a schematic? That would help

[aviherman5]

Ah yes that would! So sorry I forgot!

[aviherman5]

Someone had said in this form (https://www.diystompboxes.com/smfforum/index.php?topic=79596.0) that taking the negative leg of C18 and feeding it 1/2V_cc from the R27 R19 junction (bottom left of the schematic) would do this, but I tried and just got no delayed signal at all.

[ElectricDruid]

Ok, so looking at this schematic linked from that thread you mentioned:

http://www.8bitsindgenug.net/boss_dd2.png

In general, to add trails to a delay, you cut the *input* to the delay rather than the *output*.

In this case for the DD2, we can see that Q8 cuts the output signal from delay (post expander) and prevents it from reaching the feedback control or the effect level control. The two switches 4a and 4b seem to stop signal going into the delay. How you get it to do one of those and not the other, I have no idea. It's too late here and my logic isn't working that great. But this is a DD2 schematic anyway, so we're not even sure we're looking at what you're looking at.

[aviherman5]

Got it!

I totally get the concept. What do you think about this schematic I found on this thread (https://www.diystompboxes.com/smfforum/index.php?topic=104072.0) for adding tails to any delay?



Thanks!

[aviherman5]

Hi all!

Just bumping this, any ideas? Thanks!!

[ElectricDruid]

Got it!

I totally get the concept. What do you think about this schematic I found on this thread (https://www.diystompboxes.com/smfforum/index.php?topic=104072.0) for adding tails to any delay?



Thanks!

Yep, looks like it would work. It's switching the input (by grounding one or the other) between a straight-through signal, and the delay, but leaving the outputs both connected, so when you switch to straight-through, any delays still in the pedal can carry on.

I take it you've had no luck finding a schematic that matches your pedal then?!