Increase delay time on older model FX96

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culturejam
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Post by culturejam »

I picked one of these up relatively cheap. I knew that the version I bought had only 220ms of delay time, and that's just pathetic! :lol:

So I googled for the schematic and found it hosted at the DIYstomp site:
https://www.diystompboxes.com/pedals/sc ... 6schem.pdf

And there was also a thread there about increasing delay time:
https://www.diystompboxes.com/smfforum/ ... ic=22010.0

I tried the suggestion from ExpAnonColin, which was to increase the value of C19. Most of the components are SMD, but luckily C19 is a plain-jane ceramic cap. It is stock at 25pf. I raised it to 220pf, and now the max delay time is about 1000ms. Of course, at the longest settings, you get some "Dalecks" type sounds in the repeats, but it actually sounds cool. Great for ambient, noise-rock stuff. :thumbsup

There are two version of the FX96. The later one has an internal trimmer to adjust delay time. The early one (pictured below) does not, and that's why I swapped the cap. I've shown which cap with an arrow, and also you can read the silkscreen easily (C19).

You can either remove C19 and replace it (the better way), or you can add a cap in parallel to increase the value. It's at 25pf stock, so I'd suggest 100pf, 150pf, or 200pf to add in parallel. The more capacitance, the more delay time...but also the more noise you get at the longer settings. And there is a something of an upward limit no matter how much capacitance there is (probably about 1200ms). Probably 100pf is all you need, but I went a little over just in case. :mrgreen:


Guts overview:
DODFX96_timemod_01.jpg

Guts detail (C19):
DODFX96_timemod_02.jpg
DODFX96_timemod_02.jpg (69.67 KiB) Viewed 919 times

Old version looks like this:
DODFX96.jpg

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EdJ
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Post by EdJ »

Hi,
great info!
I have the same delay and want to change the cap but,looking at your pictures,there is a resistor across the delay pot that doesn`t exist in mine.Did you put it there?

Thanks,Ed

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EdJ
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Post by EdJ »

I expirimented a bit and settled with a 100p.Higher introduced a nasty squeel and lower didn`t do much.
Still in the dark what that resistor(1K) is for.I put one directly on 1 and 3 of the pot but didn`t hear any difference.
There is a humm in the pedal that i don`t like though(the humm was there before i changed caps).
Is it normal for this pedal to humm?

Thanks in advance,Ed

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Post by EdJ »

Sorry;resistor is 100K.

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billmag
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Post by billmag »

I performed the C19 mod posted by culturejam and it works perfectly to increase the delay time! I used a 100pf as suggested in a newer model of the FX-96 pedal....the one without the 'tape loop design' on the box. Mine did have the mini trim pot on the inside but I did not mess with in conjunction with the C19 mod. The only side effect that was noticed when the delay time was increased (from 12 o'clock position onwards) was a "ring modulated" sound on the initial attack. Could be annoying to some but then again, a possible additional effect for creativity. The good news is that this can be dialed out with a lowered delay time. Hope this info helps other modders interested.... :D

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