PT2399 DELAY simple 'after chorus'' mod...

[Mark Hammer]

Sick little devil that I am, now I'm curious to try it on ONE of the delay chips in the Equinox Reverb. 

[deadastronaut]

Yeah cool idea.....


Im going to bread up 2 current mirrored pt's  as in my dreamtime delay, instead of one then try the wobble, on both...

Might be interesting.,,see how lush and spacegun/ducking it can get....

[Ripthorn]

Mark, I'm actually doing this now on my Spare Room reverb. I just soldered up a board and will start testing it to see what it can do for reverb.

[deadastronaut]

just as a note:

i had the 470n cap from pin 6, then the 820k to pin 8.

i tried that reversed and had slightly different results, especially with the raygun/ducking.

but the chorus still worked ok..

so go with cap pin 6.   

[Mark Hammer]

Thanks for the suggestion.  Mine currently has the cap at pin 8.  I'll try flipping it.

[Ripthorn]

So here is a quick and dirty clip of the mod on my Spare Room reverb. It has the mod first (470n/1M) followed by mod disconnected. To me it seems that it mellows out the sound of the reverb a little bit, though it's a little hard to tell. Please don't mind the noise. My test box/power supply/work bench is a noisy area with all the things going on around there.

https://www.dropbox.com/s/vkp7o61mfccy64y/SpareRoomWithPin6_8.mp3?dl=0

[Mark Hammer]

Not hearing a big difference.  Although that might be because, like my Rebote, your chips also require a resistor lower than 1M for maximum effect.

[Ripthorn]

Good thought Mark. When I get a few more minutes to play with it, I'll try messing with resistance, perhaps with a B1M pot.

[slashandburn]

just thought it was interesting enough to share...a nice easy mod for any pt2399 delay...which we probably all have..

no, i don't

despite that, nice idea, if i ever choose to build a delay (despite hating the effect), ill put such a warble mod in!

cheers

Ah, how the turns have tabled! I remember not so long ago being chastised by yourself for not having much time for tremolo (for which I'm genuinely forever thankful, btw. I laughed, I cried, it changed my life).

Get a delay and run a tremolo just in front of it. I dont know how they work but the PT2399 echos are a lot of fun.  Most of them seem like much of a muchness and all based off the same schematic from my dimwitted point of view but the Keeley Magnetic Echo is probably the one that really opened my eyes to what could be achieved with that chip. From my own simpletons point of view it gets a bit digital sounding at longer delay times but I'd say don't let that put you off. If nothing else its definitely worthy of being the subject of a quick wank on a Sunday afternoon.

[Mark Hammer]

S, I think I still have to play with the resistor value a bit more.  As well, my build used a pair of 100nf filter caps instead of the 82nf units Francisco shows.  So, mine may be a little duller-sounding on the wet side than Rick's sample.

But what I find interesting is that it seems to make the circuit sound a little more reverb-like by the way the mod "smudges" the attack of each repeat.  It's a bit like the way one can draw with oil pastels, and rub the edges of a region to blend it.  The small bit of modulation seems to do that to the repeats...at least on mine.  And if I introduce hi-cut to the repeats, it's even more reverb-like.  Clearly NOT reverb, by any stretch; just a little more like reverb.

[Ripthorn]

Alright, I had a good debugging session. Turns out I recorded my clips with a board where the mixing resistor for the chip with the mod wasn't well soldered. Ooops. No wonder it doesn't sound any different.  Moving on.

I tried a 470n from pin 6 through a B1M pot to pin 8 on both chips in my Spare Room reverb (significantly modified Equinox II). It looks like the effect is dependent on delay time. The first chip that produces the shortest delay doesn't seem to really be impacted by it much. Perhaps it's because the resistor to ground is much smaller. On the second chip, the effect is a little more noticeable, but I certainly don't get into the ducking effect, but it gives a slight wobble. In my Spare Room, I already put an LFO on the second chip (disconnected for the purposes of experiments), so I don't think it buys anything in this context, but I certainly think it warrants more experimentation. Perhaps a different cap size and resistor value for the shorter delay times. I did take the pot to 0R on both chips, and for the shorter delay time, there isn't much of a noticeable difference that I can tell. I'll play some more and report back any findings.

[deadastronaut]

As luck would have it i have a built dreamtime delay with switchable lfo on , off....which saved me breading it all...

So tacked on wires to both chips 6/8 pins.

It uses 2 pt2399 current mirrored for accumulated delay time , so hooked up a 470n / 820k to both chips,

And yes it chorused ....but, had to be on both chips, and i had to drop the resistors to 560k too....

Yay....

[skyled]

This sounds really cool to me. Is it doable/worth doing on your Abductor 2 delay? How would it be done (for dummies please  )?

[deadastronaut]

Hi, no need on the abductor as is has built in lfo already 

[deadastronaut]

guys had another little tinker....

this time with a 470n then led - /+

and voila it works.  the 820k /1m worked, but had a kind of amplitude/envelope detect

which made it wobble harder when played harder....

the led. keeps it stable....nice. 

[Ripthorn]

Rob, I'm assuming it was a red LED? Sounds like it's worth playing some more!

[deadastronaut]

hi. no it was a clear 3mm led...i,ll try standard red though in a bit...

edit: red dont work...

[Ripthorn]

Fascinating! Thanks for keeping us updated.

[noisette]

Supernice development, sometimes this stuff happens, you add a resistor and a cap and things turn into a different color and you enter SECRET LEVEL. 
I had this once too with a 2399, when adding a diode and cap (from input to pin6? a basic envelope follower? I don´t
remember) and the echos turned into cascades of beauty
It was no hallucination and it´s here https://www.diystompboxes.com/smfforum/index.php?topic=88178.msg951618#msg951618
Maybe I need to try both of these mods with my Zeitgeist delays!

Thanks deadastronaut, again, for your inspiring "work"

[deadastronaut]

Excellent noisette,  good to see other explorers throwing bits on that you shouldnt ...or should..

Yeah its pretty cool....the good old humble pt2399 and its little secrets lol..


Now if only there was a new pt  type chip with at least 1 sec worth of memory....that went from 1ms to 1 sec

That would be fun....


Edit: yes ive been trying different diodes, leds etc....still tinkering, itll be on my breadboard for a while i think....