2399 triple splashback delay

Ah washers, that’s a perfect idea! What about on the wiring side? The pcb has 5 points, for stereo jacks I think…? is that being summed down to mono? And which point is which?

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You are right, it is only mono, so only two pins are really used. You can see which ones on the tiny jacksocket pcb. But I think, you should not use this tiny pcb at all and just wire the 3.5mm sockets directly to the large pcb where the pin header usually goes.

The main PCB is about 175 mm high vs. around 110 mm available between Eurorack rails, so to get it in you’d have to rotate it to make a module either 175 mm wide (about 35 HP) or more than 175 mm deep. Either way making a new front panel would presumably be necessary, unless you could figure a way to extend its 100 mm width to 129 mm (and its length to exactly 35 HP if you care about gaps).

It all seems a bit much. You could just bang together a Kosmo case out of a few pieces of wood much more easily — you’d need a power supply, but you could do an FC Microbus for about $40. Then you’d be set up not only for this module but other Kosmo too.

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What did you find out about your low LED? Mine are low as well except when cranked. My second delay signal is hard to hear, might have to reflow some solder.

Didn’t figure it out yet, but I do plan to poke around some more.

I also need to investigate, but I can not decide on which scope I want to buy xD (see Looking for a cheap oscilloscope )

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thanks sebastian for posting the pic so I didn’t have to look it up . I got the washers from an auto supply place on EBay .

they are thin but being stainless steel they are pretty strong .

Okai, mine are fine now! I have reduced the 100k resistors R4 R5 and R6 with 2.2k and they light up very nicely now! The exact values depend the LED and preference, I would say. Probably it also helped that I reduced the input resistors on my Filter from 100k to 20k as described in the the Performance Filter thread and I have a louder signal in general now. Going to do the wet-only mod now that I have it open!


sorry I missed this , one pad is ground and there is another that you can see the traces on the pcb lead to it , so just two leads to solder

this is where to solder jumper wires to when using 3.5 mm jacks instead of 1/4 "

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So, I soldered 1K resistors in parallel with the 100Ks for the four LEDs. The time LED isn’t working at all, and I did test the LED separately. The other three are now in a good range. To match the bypass LED to them, I added an additional 900R in series. So, If I can just figure out why the time LED isn’t turning on, I’ll be set. Did the wet only mod as well.

hey, would this work as a guitar/bass pedal ? (most intrested for the bass pedal)

You would probably want something to boost the signal going in since synth signals are hotter, and then attenuate the signal coming out. Also it requires a ±12V power supply. If you can do the mods on a stripboard, feed it ±12V, and fit it all in a pedal enclosure, why not.

Maybe you could modify Ken Stone’s (synth-to-) Stomp Box Adapter:


Ahhh this is perfect, thanks!!

Has anyone tried to get the outputs from separate delay lines post-fader?

I’d love to do a mod with outputs of each delay line individually, and also mixing them to stereo with pan controls.

Anyone know what points would be the best place to get the delays?


The output comes from an inverting amplifier with gain 100/15

whose input comes off the third PT2399’s pin 15 through a 1k resistor and a 10uF capacitor

On the first two PT2399s that resistor and capacitor are not present

so the obvious thing to try would be to add them and from there go into three attenuator pots, then sum those with 15k resistors at the input to the final op amp. However, my guess is that would affect the signals from the first two PT2399s going into the next ones. Maybe add voltage followers to each of the three outputs or at least the first two before going into the low impedance summing amplifier.


i’ve got this built and working for the most part but the input is either very low or clipping. the delay seems to have similar issues where it’s either very quiet or feeding back like crazy. i’ve checked over the input amplifier section (U4A) carefully but i don’t what to do next. the on/bypass switch thunks pretty hard as well, not sure if this is normal or a sign of something bad. any help would be appreciated!


annoyingly. to save on component count I did not buffer the outputs of each of the delay outputs. however it doesn’t mean you cant experiment!

if I had put opamp buffers between each delay stage you could have tapped into each of the delays without any negligible effect, however at the same time! it may not effect it. depending what you plug it into. best bet is to wire a jack for output of delay 1 to pin 15 of the pt2399 chip. maybe via a 10uf capacitor, + on p[in 15 and minus going to the jack socket??? do the same to the second delay to get the output of that.

but Like I said I have no idea if this will effect the end of the output, it may very well not do!


hey! that doesn’t sound like normal operation. it shouldn’t be clipping however I have had a similar problem with one of mine before and it turned out to be a dry joint, which I cannot for the life of me remember what. I think it was one of the capacitors going to ground. C23,24,25 ground pin?

I suggest turning up the heat and going over it again. maybe wiggle some components and see if there is any movement on the other side of the board, this would signal a loose connection.

your very close!!! itll just be a tiny error I recon


Thanks! i think i’ve got it all sorted now. i didn’t see the note about C22 and with that removed it’s much more well behaved. seems like taking some care to limit the dynamic range at the input is also necessary. it’s working well now, no more clipping and no more thunking! i think i’ll look into a fine adjust for the delay time eventually.


Hey guys just built my delay and it worked! All but number 3 for reasons unknown

I set about reflowing and plugged back in to get a puff of smoke and then it went dead

Noticed I had shorted C4 legs to each other so I replaced it assuming it had burnt out but still doesnt work

Certainly never had such an exciting failure but now dont know what to do, what else am I likely to have damaged do you reckon?