Design delay/reverb multiple PT2399

Grumble

Ok, so I'm designing/building a delay/reverb module with three PT2399
Here is a preview with a delay using one PT2399

My question:
If I place the three PT2399's in series (the output of the previous one is fed into input of the next one) do I have to feedback the output of each PT2399 to the input of the module, or to the input of the PT2399 where the output signal is coming from?
I can't imagine what the sound will be like if I do one or the other?

earo · Joined: Apr 19, 2011 Posts: 13 Location: haifa

If you connect each output to the next input you'll get longer delays.
If you 'return' each output to the first input you'll get mono multi tap.
You can probably wire up a switch to give you both options and/or use separate tap outputs.

Grumble · Posted: Tue Sep 13, 2016 11:50 pm Post subject:

http://www.youtube.com/watch?v=0QfSGQ9v3m0

I'm a bit further, this sound is made with all three PT2399's fed with the same sound, all three different delay times and the outputs tied together.
Now I'm building the mixers on this board.
When all is finished, I can set the feedback from all three channels to the mixer with the input signal, and the inputs can choose between the main input (mixed with the attenuated outputs of the three channels) and the previous channel (1st channel input to last channel)
The output will have a wet/dry mixer.

Grumble · Posted: Wed Sep 14, 2016 6:56 am Post subject:

Pff.... 5 Volt, 560 mA Shocked

Grumble · Posted: Sun Oct 09, 2016 10:47 am Post subject:

http://www.youtube.com/watch?v=YcEFz9QIfgA

First impression using three PT2399's in one module

ejr27233 · Joined: Feb 08, 2010 Posts: 52 Location: UK

Love the youtube demo.
Does it really draw that much current?.?!!!
Are you planning to publish a schematic?

Grumble · Posted: Mon Oct 10, 2016 1:15 pm Post subject:

Yes, I plan to publish the diagram, but I made some last minute changes.
This module is powered by 5 volt and
i checked with a usb charge check device and drew 560mA. But it was unfinished and I will measure again.

Grumble · Posted: Tue Oct 11, 2016 4:38 am Post subject:

The Diagram as I made it

Edit: There is also a small dc/dc converter module on the board for the -5volt to power the negative rail of the opamps on the right hand side.

Delay PT2399x3.JPG

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blue hell · Posted: Tue Oct 11, 2016 4:50 am Post subject:

Nice module!

Cfish · Joined: Feb 24, 2016 Posts: 477 Location: Indiana

Loved the YouTube video. You came a long way since the last video I caught.

My digital age teen boy thinks I am nuts playing with analog. He is an arduino fan, but just really getting in to it.

You are his new hero. He thought I was nuts when I kept telling him people use those to build synths.

Absolutely awesome Grumble. Thanks for sharing your schematic.

Grumble · Posted: Sun Oct 23, 2016 2:42 pm Post subject:

Playing with my delay/reverb module.
Have some modulation on the delay time.
It starts and ends with the dry signal. In between I play around with the various settings.

modulated_delay.wav

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modulated_delay.wav

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Cfish · Joined: Feb 24, 2016 Posts: 477 Location: Indiana

Sounds great grumble. Lot of versatility in sound.

Grumble · Posted: Mon Oct 24, 2016 9:49 pm Post subject:

Thank you, Chris Very Happy

hakonbraga · Joined: Feb 02, 2018 Posts: 1 Location: spain

Sounds great!
I'm curious why you are using a Arduino to control the CV?
Could you not just skip that and send it straight into pin 6 on the PT2399, with maybe a little more resistance?

Grumble · Posted: Fri Feb 02, 2018 2:31 pm Post subject:

I did it this way (using a digital potmeter) because in my knowledge the frequency is set by an impedance, not by a voltage.

AlanP · Posted: Fri Feb 02, 2018 11:24 pm Post subject:

To my understanding, the PT2399's time thing is current controlled.

Grumble · Posted: Sat Feb 03, 2018 12:31 am Post subject:

Well, datasheets all have a (variable) resistor to gnd coming from pin 6 to set the internal frequency of the PT2399 and tables that shows resistor versus frequency, so I figured that maybe the resistor is part of an R/C networg and that is why I went for a programmable resistor. But by doing that, the benifit is that the delay time is very well controlable by a pot or CV.
While my initial assumption might be wrong, it still worked out beautifully Very Happy

gabbagabi · Posted: Sat Feb 03, 2018 12:39 am Post subject:

somehow i totally missed out that thread sleeping

nice work dr. grumble!

what happend to the idea to dasychain the delays?
recently i saw a discussion about to chain them digitaly, which is a nice idea but not working cos u cant sync the internal osc of the pt2399.

cheers,
gabbagabi

edit: if not already known for a long time,something about delay-time-CV: http://www.sdiy.org/destrukto/vc-echo.html#pt2399

Grumble · Posted: Sat Feb 03, 2018 6:23 am Post subject:

If you look at the schematics I showed earlier (THIS one), you see 3 PT2399's, the top one receives input via opamp U9B or from the third PT2399 which has the longest reverb time, the 2nd PT2399 receives input from U9B or the input is grounded, the 3rd PT2399 receives input from U9B or from the output of the 2nd PT2399.
This way I can have three PT2399's in series.
Input -> PT2399-2 -> PT2399-3 -> PT2399-1 -> and all three outputs mixed together to the output of the module. Besides that also 3 outputs are provided for each PT2399.
tho this setup working, it is not is not working to my fullest content, so in time it will need some revision...