hi guys, happy new year to all.... 8)
been tinkering with a standard pt2399 delay on breadboard just for fun again.....poking and tweaking here and there, as you do..
and found a great little easy peasey mod for ''after chorus'' (chorus on the delays)
adding a 1M from pin 6 to pin 8 on the pt2399 creates a warble, but just enough to chorus the delayed signal..
heres a clip ...first without the 1M, then with the 1M.
just thought it was interesting enough to share...a nice easy mod for any pt2399 delay...which we probably all have..
add a switch to it, for optional spaceyness... 8)
https://www.dropbox.com/s/ikyz8lnfq4jgnzr/pt2399chorusmod1.wav?dl=0
it can get pretty crazy as you change values to lower ones...so if you like totally warped noise stuff make it a pot :)
i hooked up a meter to the 1M (pin6/8) and without playing it sits at around 1.65v
when playing it dives down to around .20v then creeps steadily up to the idle at 1.65v again...
which creates the warble as it is connected to the delay time pin 6. so why not use it...
anyway have fun. rob. 8) 8) 8)
Ooh nice discovery!
Quotejust 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
A man who hates delay.... :icon_eek:
Thats a first for me....i love delays n verbs...spacey man. :icon_mrgreen:
8)
Really cool, Rob. I've got one PT2399 delay boxed up, three in the works. Gotta give this a go. Cheers!
Awesome, Rob! I'm going to play with this with some of the upcoming projects I've been planning. Just might be the ticket for something I'm spec'ing out right now!
sounds great.
yeah give it a go guys, i put lfo's on my delays for the chorusy effect,
but i was looking at how to wobble it without all the extra circuitry...it works.
if you have a ready made pt2399 delay just tack a 1M on pin 6-8
let me know if its not just a fluke.. 8)
Lovely. Instant Andy Summers!
Thanks so much for that. I need to see if there's room for another toggle on mine.
I usually use separate LFO's as well, but sometimes I do stuff that is very space constrained, so this seems like a great thing to try. I also want to play with bypassing the 1M resistor with a cap to see if there is any additional weirdness that can happen! Too bad I have to wait until I'm home from work to get the breadboards out... :icon_evil:
Quote from: deadastronaut on January 04, 2022, 10:20:34 AM
A man who hates delay.... :icon_eek:
Thats a first for me....i love delays n verbs...spacey man. :icon_mrgreen:
8)
ow, reverb is totally fine because it is continuous, not instantaneous. i really don't know why i cant stand playing with a delay on, i just dont like the feel and response. only really short slapback is acceptable when im playing blues.
another idea: envelope dependent impedance between those pins, instead of the 1M resistor. i guess a Jfet would do the job if the right one or several ones in series are used and the amplitude of the envelope isn't too big.
cheers
Yeah i hear ya....with blues etc..
Mind you a slow delay just buried withn the reverb level is quite nice for slow bluesy stuff.....anyway ...
Yes the "wobble" is kind of envelope detecting already, as it sits at 1.65v when idle, then goes to around .20v
When actually playing /hitting..thrn recovers to 1.65v again...but i get ya, it could be explored further, but im cheap and lazy..and like
To keep it simple, just like me :icon_mrgreen:
update, brian/ripthorn hit on it...nice one. 8)
use a 470n and 820k in series from pin 6 to 8.
without the cap the long repeats got a bit stuttery....
with the cap, nice long repeats and lush chorus...sorted.
have fun. 8) 8) 8)
Nice! Thanks for saving me the effort :). I started soldering up a development board for this last night (and to allow for some other investigations for a new project), but wasn't able to finish. So I will use this as a starting point, for sure! I think a three way SPDT toggle could be cool, to give a very subtle flavor, a more extreme flavor, and nothing.
As a side note, I had an ES56033-based delay on breadboard already and tried this trick. It doesn't work for that chip, but I am not surprised. You can't get delay time modulation with it like you can with a PT2399 due to what I believe to be internal compensation between the two Fadj pins (pins 2 and 3). Oh well, it was worth a try, and now we know...And knowing is half the battle.
Just finished trying out the mod, but didn't see your note about the series cap until now. I would get the modulation for a moment, and then it would disappear. Conceivably, the added cap will block a presumed DC from getting in the way. Off to the green grocer now, and will try it when I get back.
grab me an apple ;D
weird how it disappeared...its been on my breadboard for 3 days now and works no probs,
but yeah add the cap... ;)
edit::: a clip with 470n-100k in series....like a spacegun ducking effect..
then back to 820k chorusy...so yeah on a switch...options. ( i tried using a 1m pot but it was better just as presets) 8)
https://www.dropbox.com/s/e54eg0cleqzb7jf/100kto820kdelaymod.wav?dl=0
Sounds cool! How does it respond with distorted tones? I would assume still nice. I'm totally designing this in to at least one of my upcoming projects :)
Havent tried with dirts yet....will do. 8)
Quote from: deadastronaut on January 05, 2022, 11:47:01 AM
grab me an apple ;D
I actually did and would gladly send it to you, but I'm not so sure it would be all that edible by the time it reaches you. :icon_mrgreen:
Quoteweird how it disappeared...its been on my breadboard for 3 days now and works no probs,
I guess it may be one of those depends-on-which-batch-o'-chips things.
Quotebut yeah add the cap... ;)
edit::: a clip with 470n-100k in series....like a spacegun ducking effect..
then back to 820k chorusy...so yeah on a switch...options. ( i tried using a 1m pot but it was better just as presets) 8)
https://www.dropbox.com/s/e54eg0cleqzb7jf/100kto820kdelaymod.wav?dl=0
So, I just added the cap to a 1M pot, so as to dial in the sound. I didn't really get the chorussing until I dropped the resistance to 500k Sounds really nice, so thanks. But may require individually tailoring the pedal, rather than 470n/820k as a "boilerplate" solution.
Cheers for the apple... 8)
Yeah i figured it may be a batch dependent thing, glad you tried it..nice one.
And glad it wasnt a fluke...try the 100k space gun, ducking one too... 8)
Sick little devil that I am, now I'm curious to try it on ONE of the delay chips in the Equinox Reverb. :icon_twisted:
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....
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.
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. 8)
Thanks for the suggestion. Mine currently has the cap at pin 8. I'll try flipping it.
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 (https://www.dropbox.com/s/vkp7o61mfccy64y/SpareRoomWithPin6_8.mp3?dl=0)
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.
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.
Quote from: iainpunk on January 04, 2022, 10:08:00 AM
Quotejust 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.
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.
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.
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.... 8)
This sounds really cool to me. Is it doable/worth doing on your Abductor 2 delay? How would it be done (for dummies please :icon_biggrin:)?
Hi, no need on the abductor as is has built in lfo already ;)
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. 8)
Rob, I'm assuming it was a red LED? Sounds like it's worth playing some more!
hi. no it was a clear 3mm led...i,ll try standard red though in a bit...
edit: red dont work...
Fascinating! Thanks for keeping us updated.
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. :P
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 ;D
It was no hallucination and it´s here https://www.diystompboxes.com/smfforum/index.php?topic=88178.msg951618#msg951618 (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" ;)
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.. 8)
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.... 8)
Edit: yes ive been trying different diodes, leds etc....still tinkering, itll be on my breadboard for a while i think....
tried every permutation in the thread, but got zero chorusing.
it DID make the delay sound a bit thicker, but it also killed the runaway effect of the feedback.
also tried using a 470k fixed resistor and 500k and 1m pots with various caps, same thing. when i disturb the circuit,
it wiggles a little bit, or on really heavy attacks, but that's more like exceeding the power supply demands of the chip than
chorusing.
so, sorry, but for me? didn't work. tried it with three different chips. all reacted the same. :-\
I think it depends on the circuit.
I tried it on a circuit with a delay in series
with a reverb which are both in a feedback
loop. I got no chorusing either.
At very low resistance I got some cool
percussive repeats so I added it as a
sort of "Hard repeat" mode on a switch.
I need to try it on a simpler Rebote type
delay.
had a thought this morning. just curious, anyone tried using the pt2399 onboard op amps for an lfo?
rather than just the usual caps across 9/10...11/12
might be handy... 8)
Quote from: deadastronaut on March 10, 2022, 05:53:57 AM
had a thought this morning. just curious, anyone tried using the pt2399 onboard op amps for an lfo?
rather than just the usual caps across 9/10...11/12
might be handy... 8)
There's the One Chip Chorus: https://www.diystompboxes.com/smfforum/index.php?topic=92872.0
Also, I don't think this was mentioned in the thread so far, but if you put an LED from pin8 to ground (parallel to the 100n cap) you can sometimes get it to light up with repeats. Don't remember if there are any caveats with that. But combined with a photocell across the time pot it would make for some fun.
hi brian, cheers man, ill take a look, and try those suggestions....still on breadboard
just been too busy lately to get back on it.... :)
if i added an lfo to pins 9 10 11 12 it would kill the delay time repeats though wouldnt it?
Quote from: deadastronaut on March 10, 2022, 07:41:14 AM
hi brian, cheers man, ill take a look, and try those suggestions....still on breadboard
just been too busy lately to get back on it.... :)
if i added an lfo to pins 9 10 11 12 it would kill the delay time repeats though wouldnt it?
Yeah you'd have to add an external mixing stage to the delay output at pin12 then mix the repeats back to the input at pin1 in that case. I think that's the only way to free up LPF2 op-amp for an LFO? Maybe I could modify my Cave Dweller delay along those lines.
those opamps do shit inside, internal connections and stuff. the only free free oppie is 13 14. 15 16 as part of an osc might be interesting in that it also feeds stuff to the innards, whether youse likes it or not.
I was wrong about the LED thing on pin8. It will light up but it clips the delay badly.
I did throw a new version of the Cave Dweller with Rob's modulation idea on the breadboard and it sounds pretty dang cool! I've got a few cap values to adjust then I'll put up a draft schematic for anyone who wants to give it a try.
The belton brick uses one pt2399 opamp for lfo related stuff. It can be made to work (using the pin 13 and 14 opamp s mentioned above), though I don't recommend using those opamps for mixing signals, as they don't have a lot of grain for gain, being run at 5v and all.
I ran out time to do any more on this for a few days, but here's what I came up with. I'm sure it could use tweaking. I recorded a quick sound sample to demonstrate the modulation with different pick attack. I neglected to cover really short delays with the modulation. This is a really nice discovery! Also, don't mean to take over the thread. This just fired up the old squishy brain this morning.
PS I just realized C12 is not on the breadboard. It should go to the input before R1, if used at all (it's not required).
You can also make MOD 1M and then use whatever value you want for R14 for added range.
There's a bit of underlying garbage in the delay so I'll work on dialing that out.
https://soundcloud.com/madbeanpedals/cavedweller2022-test
(https://www.madbeanpedals.com/misc/CD2022_d1.png)
This whole thing is awesome. 8)
Tried clicking your Soundcloud link Bean, but it says 'This track was not found' :(
yep same here.....
like the idea of the pot brian...nice. as the warble changes with long and shorter delays i found.
8)
Quote from: niektb on March 11, 2022, 05:24:53 AM
Tried clicking your Soundcloud link Bean, but it says 'This track was not found' :(
Huh, not sure why. Here's the link copy from soundcloud (I don't use it often so probably my error):
https://soundcloud.com/madbeanpedals/cavedweller2022-test?utm_source=clipboard&utm_medium=text&utm_campaign=social_sharing
Quote from: deadastronaut on March 11, 2022, 05:26:39 AM
yep same here.....
like the idea of the pot brian...nice. as the warble changes with long and shorter delays i found.
8)
I tried tying the MOD pot to ground to stop the modulation altogether at the min. setting. It works, but the repeats start to duck/distort a bit (I had the resistor and pot reversed so the resistor goes to ground in parallel with pin8). Maybe someone can think of a way to eliminate the switch.
What's D1 for? to raise the voltage a bit?
Quote from: niektb on March 12, 2022, 04:17:44 AM
What's D1 for? to raise the voltage a bit?
Yeah it kicks it up to around 5.5-5.6v. I started trying that out with some low parts count delays/choruses thinking it might offer a little extra headroom at the internal op-amps. It's never caused a failure so I tend to put in all PT2399. I' haven't tested to see it shortens the delay time. Maybe that's a benefit with chorus designs. One thing I want to try out is using an LM317 and see what happens at different supply voltages. Just never got around to it.
One other neat little trick is if you put a 22R 1/4W resistor on pin1 then temporarily toggle it to ground, the delay repeats drop pitch steadily as the current drains. It becomes non-operational after maybe ten seconds but springs back to life once you disconnect the resistor. So a momentary switch is a lot of fun.
Finally dickering around with a pair of Cavedwellers in series today (the first ones from 2012; I had a few populated boards sitting around). It is interesting enough as is, getting some of those "dotted eighth" skipping effects. But tack on the the 470N/470k pair between pins 6 and 8 on the first delay and...oh...my...goodness. So thick and rich. I just wanna move in and live there.
Excellent mark, full on lush spaceyness... 8) 8) 8)
Anyone try this in the deep blue delay? Looks like it should be about the same as the cave dweller...
I cant see why it shouldnt work in any usual pt2399 topology based delay really....
Tack it on and see... 8)
Quote from: deadastronaut on September 01, 2022, 02:44:22 AM
I cant see why it shouldnt work in any usual pt2399 topology based delay really....
Tack it on and see... 8)
I did and crack open mine and ran some wires out to a bread board. I'm not really noticing anything. It's connected on a strip after the 100n goes to ground would that matter? So here I'm connecting to pin 8 on that last hole in the strip.
(https://i.postimg.cc/dkfkYRG3/4-D001-C23-04-E0-46-D1-AA29-2-D71-D0-DD65-BD.png) (https://postimg.cc/dkfkYRG3)
Heres the schematic for the finished pedal. " ebe delay"
https://www.diystompboxes.com/smfforum/index.php?topic=129208.msg1247718#msg1247718
The mod is literally tacked on to an existing pin 6 and 8 setup.
With lower values i got a " ducking effect" just before the chorus effect settled in.....
I'll have to play with values after removing the pot and just running the 470n to the 470k I can hear it. It's subtle but def there. Oh your using a 1u and basically a 1.5M resistor.
Yeah thats values what i settled on...
Itll be ok with 470n too......down to taste really....
The amount of modulation is modest. What that means is that one doesn't notice it quite as much (if at all) on the shortest delays, but it becomes more apparent (for me at least) as delay time is increased.