LW Dual PT2399 Delay

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rumblesan
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LW Dual PT2399 Delay

Post by rumblesan »

Hey all,

I spent a bit of time over the past few months designing a delay using two pt2399 chips and thought I'd share.

Inspired equally by the Serge WAD and the Strega, it does clean pretty well but also pushes into the usual 2399 wierdness.

Schematic is attached, and the full kicad project/BOM/gerbers/etc zipfile can be downloaded from this repository on Github
https://github.com/rumblesan/dual-pt2399-delay

Gerbers
panel and PCB
https://github.com/rumblesan/dual-pt239 ... s/tag/rev3

Features
Dual pt2399 delays
single input with gain control and mild overdrive when past about 1 oclock
switch to have delays in series or parallel
Delay goes from short as I think I could manage to well into clicks and squeels territory
CV control over delay time of each independently, with attenuverters
Join switch to have delay 1 CV/knob control affect delay 2 as well
Independent full wet outputs for each delay
independent mix levels for each delay and dry into main mix out, with additional overdrive on the delays when pushed past 1ish

Signal Flow
signalflow.png
Photos
dual-digi-rev2-front.jpg
dual-digi-rev2-side.jpg
dual-digi-rev2-boards.jpg
dual-digi-rev2-fixes.jpg
Audio Demos

Sound source for this is the variable output of a CGS348 oscillator, through the CGS364 VCA enveloped by a DUSG slope and then through a VCFS filter just to take a little bit of the high end off.

The delay sounds quite bright to me, but I deliberately didn't put in any more filtering that what seems standard in the PT2399 data sheet circuits. My logic is that if you want more filtering before/after/in the feedback loop, well... you can patch it up hah.

Single delay, about 50% feedback, not pushing any clipping, just turning the time knob through its full range
Single delay, about 50% feedback, not pushing any clipping, just turning the time knob through its full range
delay1-simple.mp3
(2.15 MiB) Not downloaded yet
Single delay with time modulation from a triangle LFO. playing with delay time, mod depth, mod speed and feedback.
Single delay with time modulation from a triangle LFO. playing with delay time, mod depth, mod speed and feedback.
delay1-modulated.mp3
(4.26 MiB) Not downloaded yet
both delays being used in series. no external modulation just tweaking time and feedback
both delays being used in series. no external modulation just tweaking time and feedback
dual-delay-series.mp3
(1.92 MiB) Not downloaded yet
both delays in series, but only the output of the second one in the final mix. idea is to allow for longer delay times before hitting too much noise
both delays in series, but only the output of the second one in the final mix. idea is to allow for longer delay times before hitting too much noise
series-delay2-out-only.mp3
(2.75 MiB) Not downloaded yet

It's probably not the best design people may have seen here, first time designing anything sizable from scratch and going through the itteration process. It's all THT, designed to have PCB mount directly to jacks/pots on the face panel and so has three boards.
Hopefully it's not awful though, and it's been a lot of fun to make and have in the rack.

Might see about doing a run of decent PCBs if there's enough interest, but wanted to share regardless.

Schematic
dual-digi-delay.pdf
(388.62 KiB) Downloaded 26 times
cheers
Last edited by rumblesan on Tue Jan 18, 2022 1:05 pm, edited 5 times in total.
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neutronarmy
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Re: LW Dual PT2399 Delay

Post by neutronarmy »

This looks like a really great design. Thanks for sharing your labor with the community!
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J3RK
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Re: LW Dual PT2399 Delay

Post by J3RK »

Nice!!!! I have 50 PT2399s, and still never got around to designing anything for them. Maybe I could build a couple of these.
Are you lemon? Does your head come to a nub?
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KSS
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Re: LW Dual PT2399 Delay

Post by KSS »

:tu:
kevin0
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Re: LW Dual PT2399 Delay

Post by kevin0 »

Looks great! Definitely interested in a pcb :)
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cygmu
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Re: LW Dual PT2399 Delay

Post by cygmu »

rumblesan wrote: Fri Jan 14, 2022 3:50 pm Might see about doing a run of decent PCBs if there's enough interest, but wanted to share regardless.
This is excellent to see. I'm looking forward to demos!

If my experience with the Scanner PCBs for Serge/LW format is anything to go by, there will be more interest in a production run than you may expect.
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rumblesan
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Re: LW Dual PT2399 Delay

Post by rumblesan »

well, thanks for the positive response all, glad to hear people are interested. have recorded a few audio demos that I'll attach to the original post in a moment. They don't cover the full range by any means, but I think they give a good idea how it sounds as a delay and some of the directions it can go.

I'm going to spend a bit of time tweaking it over the next few days as I think the knob ranges and levels could be a bit better, but I'll start looking into making it available.

If anybody is really interested in having a go ASAP I still have three of the prototype boards and panels available that I'd be happy to ship out to anybody willing to give me some feedback (is that a delay pun? I think that's a delay pun)
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hox3d
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Re: LW Dual PT2399 Delay

Post by hox3d »

Great work!

Would be curious to see some pictures of the back.
Will also be interested at some point, but I can only build so many at the time!

Always nice to see new LW modules.
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rumblesan
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Re: LW Dual PT2399 Delay

Post by rumblesan »

photos of boards and construction added.

I'm also thinking that the bit TO220 for the 5v delay chip power regulator is a bit overkill, but my calculations (which may be wrong, planning to ask in the DIY forum) had it running at around 60c which felt a bit hot for my liking, and also I happen to have a bunch of them so decided to run with it.
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rumblesan
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Re: LW Dual PT2399 Delay

Post by rumblesan »

Just moved the project into it's own github repository for less hassle in the future. Also updated the link to the gerbers as I realised I'd not updated them since fixing the rev2 bugs
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Re: LW Dual PT2399 Delay

Post by harpooneer »

rumblesan wrote: Sat Jan 15, 2022 9:48 am Just moved the project into it's own github repository for less hassle in the future. Also updated the link to the gerbers as I realised I'd not updated them since fixing the rev2 bugs
This looks killer! I've been putting off adding delay to my system so I think I'm going to take the plunge and order up some boards from JLC.

Just a note: the "PCB gerbers here" link in the first post appears to still give Rev.2, but I was able to get Rev.3 from the repo.
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rumblesan
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Re: LW Dual PT2399 Delay

Post by rumblesan »

ah cheers for the heads up, just updated the post to point to the new repo release.
I've got the rev3 PCBs on the way and once they're built and checked I'll get the ball rolling for distribution of some sort.

Let me know how you get on
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Re: LW Dual PT2399 Delay

Post by pat »

This looks great! I’d be interested in a pcb for sure.
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