Scott bernardi PT2399 VC delay

[sneakthief]

re. rebote: stick a vactrol between the 50k delay time pot and the 1k resistor that goes to pin 6 of the ic. do the same between the repetition pot and the 33k resistor and bob's your uncle.

this will expedite the process:
http://bridechamber.com/VC_Res_PCB.html

[Sebo]

Yes, that will be easy. I was thinking using transistor like the circuit posted in this thread.

[brother303]

Hi guys,

thanks for reply.

The vactrol-idea sounds good! I think I´ll give it a try.

What type of vactrols should be used? Same as on Thomas White 292 lowpass-gate?

Cheers
Greg

[sneakthief]

I suggest something fast like a vtl5c3/2.

[brother303]

Hi,

[inlifeindeath]

Just got done perf boarding this circuit from Scott's original schem. Used a vtl5c1 and it works great! Thanks for the circuit Scott!

[inlifeindeath]

video here:
http://www.youtube.com/watch?v=W17-Z0nMmx4

[JE]

Hello there,

I built the Delay by using 221’s Layout. But the problem is, that there won’t be any Feedback, and the Delay time is very limited.
All I get is a single, short repeat.

Sound Sample:
http://dl.dropbox.com/u/37021051/delay%20sample.mp3

I checked every Resistor, found one where i soldered a 27k instead of 2.7k and fixed that.
The Wiring should be okay, too.

I replaced the Free Resistor by a 10k Trimmer and can slightly change the length of the Delay. The 100k Trimmer is used for setting the CV input, right?

If I connect the Mix Pot like it used to be in the old Layout I get some kind of Lo-Fi Feedback, which won’t stop. But the Feedback Poti still has no effect!

Any Ideas what’s wrong? As far as I understood several people where able to build it from 221’s Layout, So there shouldn’t be any Faults in the Schematic / Layout!?

And does any one here has the Old Layout/Schematic from Scott Bernardi? Because his website went offline, and i can't find it anywhere.


Hope for fixing this soon (It's part of a Yusynth Modular, and only two Modules are missing...)!

Thanks,
JE

[Sebo]

Hi:
Check that the BC560 is OK at the right top of the PCB (and notice that isn't a BC550 like the other one).
Also check that the LM3080 is OK (if you have another one swap it).

[Dave Kendall]

Wilkommen!

The .pdf of the schematic is attached, and here's the text from the site;

[Sebo]

Just note that the schematic posted before uses a vactrol and isn't the one that matches the PCB posted at the begining of the thread.
If you look at middle of page 2 of this thread you will find the corresponding schematic posted by 211.

[Dave Kendall]

Thanks for the clarification Sebo.

cheers,
Dave
(in archival mode today )

[Paradigm X]

Intersting thread. cant etch myself but good to read.

[JE]

Okay this week I spend some time with testing again, but i didn't find any faults. The BC560C is alright. Maybe the CA3080E is broken, but since it's very expensive i don't think that I'm going to buy another one.
It sounds like only the High Frequencies are affected by the Feedback!

This is the last module of a modular synth and maybe i just put a 1U Digital Delay inside and use the spare 1U for something else ... But before this i'll do a final testing session.

Greetings,
JE

[Sebo]

Try bypassing the VCA portion of the feedback path. Just use a pot to control the feedback directly (no CV). Just to see if the 3080 is the problem.
To do it get the signal at the Delayed Output, wire it to one extreme lug of a pot (50K - 100K), wire the other extreme lug to ground, and wire the middle lug to the second audio input of the filter.
If feedback works OK, you have to check everything in the feedback path again.

[Paradigm X]

nvm sorry

[Sebo]

[Paradigm X]

im sorry i got really confused

[JE]

Thank you Sebo!
I think I will have time to try this and to read through the schematic again next week. Than I will report about the Progress.

[Sebo]

Paradigm X:
It's OK, you don't need to delete the link, is a useful schematic to have as a reference.

JE:
Your welcome. Hope you find the problem.