Tone Control for PT2399 Based Delay?

[chromesphere]

I was talking to a friend today whos into sound engineering and amongst his 'top 3 things to look for in a delay' was a tone control and it got me thinking.

Would it be difficult to add a tone control to a pt2399 based delay? i thought i would just shoot the idea out to see what you guys think (or if its already been done...or not possible...etc etc).  It would be pretty cool to be able to change the delay signal from light to dark!

Cheers,
Paul

[frequencycentral]

I use a Muff tonestack in the repeats loop, but configured to be flat in the mids.

[midwayfair]

I was talking to a friend today whos into sound engineering and amongst his 'top 3 things to look for in a delay' was a tone control and it got me thinking.

Would it be difficult to add a tone control to a pt2399 based delay? i thought i would just shoot the idea out to see what you guys think (or if its already been done...or not possible...etc etc).  It would be pretty cool to be able to change the delay signal from light to dark!

Cheers,
Paul

It's very easy, actually

Here's a couple different ways to do it:
Hamlet: https://docs.google.com/document/d/1P7uOYFRH6ZW5eGoquhAiMQMyUU76bod_gNKkiSlPNJM/edit
Varies the resistance at pin 13 only. [Shameless plug: there are still some boards available for this project in the emporium ...]

CultureJam's "Tweak Tone" (sold as the De Profundis by Grind Customs):
http://www.grindcustomsfx.com/forum/viewtopic.php?f=2&t=100
Varies the resistance at pins 12-14 to ground through a cap simultaneously.

Culture Jam also did one that turned the delay pot into a voltage divider, so that a single-gang pot made the repeats darker as you turned up the delay. I can't find the schematic for that, though. I thought that was a very cool idea.

[chromesphere]

Gotta remember to do this mod in my next pt2399.  I just think it would add alot of functionality to a delay / reverb pedal!  One of the best things i like about the sea urchin is its dark repearts.  Being able to control that (to some degree) would be really nice.
Next reverb / delay pedal im building is probably going to be deadastronauts reverb oh wait...thats a belton brick...pretty sure its possible with the belton as well, might ask this question in the reverb thread.
Edit: its already got one....damp control pays to look at the schematic before you start asking questions hey? lol
Thanks for the helpful responses as always guys!
Paul

[Mark Hammer]

There are two points to consider inserting tone adjustment: the final delay path, and the feedback loop.  Personally, I prefer the feedback loop, because it comes closer to mimicking the way that reflected sound behaves in the real world, as it changes over time.

A bit of treble cut in the feedback loop can result in the repeats becoming progressively darker, much as they do in the real world a minimally reflective surfaces eat up the high frequency energy.  One of the other nice things about progressive dulling of the feedback path is that ittends to "declutter" the repeats.  The greater HF/harmonic content of the dry signal and first repeat stand out more against the background of subsequent repeats, such that it doesn't sound like too much going on, even though you may have things set for a half dozen repeats.

Been doing that mod to analog and digital delays for 25 years now.  The trick is to identify a shallow rolloff point such thatthere is still a bit of treble left to shave off on subsequent repeats; the goal being to have something thatgets duller and duller, rather than reaching maximum dullness the first time out.

[chromesphere]

Good info Mark!  I would suspect the Belton Brick tone control would be in the final delay path which is unfortunate...

Paul