PT2399 mods--- wampler faux tape echo modulation-- jack deville dark and mod

[claytushaywood]

I've seen some pt2399 delays coming out and I'm wondering if anyone has any information on how they're getting these sounds.  The wampler faux tape echo has a VERY cool modulation effect.  the modulation on the delay repeats actually speeds up and slows down according to playing and dynamics (i believe- might be random).  It sounds very, very cool IMO.

Also there's a pedal company I recently found out about called jack deville (check out his site- very cool, super clean layouts, amazing prices, and great sounding pedals... his board layouts are just beautiful works of art and architecture- also has some pedals with silent switching)- anyways he has a pt2399 with very dark repeats and a cool subtle modulation.

Just wondering if anyone knows anything about adding modulation to these delays?  Or maybe any other mods?  I got the overall level mod, and the runaway repeats... I found a mod for an fx loop to put effects on the repeats only... but whenever I put an effect in the loop, the volume jumps through the roof and causes all sorts of distoriton in the circuits...-

I applied the loop mod from the sea urchin thread in extra projects on this forum and checked out the diystompboxes thread here http://www.diystompboxes.com/smfforum/index.php?topic=71129.0

anyone know anything about this stuff?
Thanks

[midwayfair]

I think Jack posts here sometimes. He certainly does on TGP. You could ask - he might actually be willing to share.

Adding modulation is a fairly standard process. The Echobase has modulation, for instance. One of the Madbean members has added it to the Deep Blue Delay.

There's nothing particularly special about the way those two delays do their modulation, though they're both well made and designed. Most pt2399 delays sound like they have some modulation even when they don't, and when you have one with modulation there tends to be some warping that occurs when you move around the fret board while the chip catches up. At least, that's what's happened on the two I've build.

Skreddy's main innovation with his echo is that it'll oscillate without the volume getting out of control.

[madbean]

Yeah, Jack is a member here. He may have posted a little about the Dark Echo on FSB. I know the Wampler one has also been picked apart some---IIRC, there is a vactrol in parallel with the Delay pot which is keyed off dynamics, like you mentioned.

Also, midwayfair-- I don't know how Skreddy does his, but you can definitely clamp oscillation with a couple of back to back diodes to ground after the repeat pot in a delay. I did this with my old Rebote. I had a switch that simultaneous turned the repeats to max and kicked in two 1N4001 diodes which keeps the volume under control.

[culturejam]

I believe the Faux Tape Echo uses a very simple envelope detector made from an op amp with output clipping LEDs to ground. Pick hard, you get more light, and vice versa. Wampler's has a vactrol and also a discreet LED in parallel with the vactrol's internal LED. I believe this is because set up the way it is, just one LED by itself won't conduct (for some reason). You need them in parallel, thus the extra LED.

Allegedly. 


What's interesting about the Dark Echo (I just got one), is that the Sway pot inversely controls depth and speed. So on low depth, it's fast, and vice versa.

[midwayfair]

Yeah, Jack is a member here. He may have posted a little about the Dark Echo on FSB. I know the Wampler one has also been picked apart some---IIRC, there is a vactrol in parallel with the Delay pot which is keyed off dynamics, like you mentioned.

Also, midwayfair-- I don't know how Skreddy does his, but you can definitely clamp oscillation with a couple of back to back diodes to ground after the repeat pot in a delay. I did this with my old Rebote. I had a switch that simultaneous turned the repeats to max and kicked in two 1N4001 diodes which keeps the volume under control.

Thank you for that! I will try this with my next PT2399 build. Skreddy might have actually posted about it; heck he might have even made the schematic public himself on FSB, since he posts there. He credits someone on his site, I'm just too lazy to go look it up right now ...

Also, I completely forgot about the vactrol in his. So yeah, his modulation is kind of special.

[culturejam]

heck he might have even made the schematic public himself on FSB, since he posts there.

No sir. I do believe that the Echo (or Skrecho, as some call it) is one that he will not ever divulge. Too much of a cash cow, and it's actually a unique circuit (unlike the Muffs he sells).

[madbean]

From what I gathered he uses two mosfets as ground clippers at the delay output and an inductor as a double pole low pass filter after that.

[claytushaywood]

I was gonna say I dont really dig the runaway that most pt2399's I've played have... it's very bright and sterile.  None have ever seemed to have any low end content like an analog delay.  I was thinking a low pass filter would work, but I've never had one with enough low end content to begin with to approach the runaway of analog delay.

I actually never looked into the skreddy much and did not know you could get runaway without huge volume increase.  So he uses an inductor as low pass filter (to make it sound 'better' and more analog) and mosfets to ground off the feedback pot (to clamp volume)?  Skreddy's runaway sounds better than most pt2399's but it still doesnt have the low end content of analog delays I've heard.  Maybe I'm just thinking of one particular analog delay.

What about the effects loop?  I added an effects loop- I didnt have switching jacks so I just use a patch cable when I dont have effects in the loop- and it works fine like this, but when I put ANY effect in there (even ones I can shut off the volume completely on) the volume goes through the roof!  and distorts the delay circuit (and/or the circuit in the loop)... anyone have a solution to this?

I figured the wampler was using some sort of LED/LDR thing to respond to dynamics.  Anyone know where I can find out more about the implementation of the vactrol to control the modulation?  I'd have to see a good deal more of it at this point to even come close to implementing it myself

[bajaguy]

Brian's concept on the use of the vactrol is really cool. I'd love to implememnt this into another design and play with it, but it seems to be a very closely guarded secret on the forums. I'm all for a guy using a new and innovative approach to make a little money, but it sure can be frustrating to try to figure out how he skinned the cat

ANy chance someone with a good idea of how this is done could post a sample snippet just to explain the theory behind it?

Baja

[midwayfair]

Brian's concept on the use of the vactrol is really cool. I'd love to implememnt this into another design and play with it, but it seems to be a very closely guarded secret on the forums. I'm all for a guy using a new and innovative approach to make a little money, but it sure can be frustrating to try to figure out how he skinned the cat

ANy chance someone with a good idea of how this is done could post a sample snippet just to explain the theory behind it?

Baja

Look for an envelope circuit that uses an LED -- Dr. Quack/Nurse Quacky are good because they only need half an IC. Hook up an LDR to the sensitivity LED (that's the LED that doesn't go straight to ground). The sensitivity LED will light and flicker (some) with your guitar input. Mess around with how much it's allowed to change the LFO speed or depth (use a parallel resistor) in a PT2399 modulation circuit (or check out CJ's Neptune for another opportunity for creativity), and that's how you can use it to key off of the playing dynamics. There are some simpler ways to get the guitar signal to light an LED, but an IC envelope circuit will give you a lot more control.

Great, now I want to go build something like this.

[madbean]

I don't know how Wampler does it in his pedal, but implementing a dynamic envelope for the delay is pretty straight forward. I've actually done some work on this already. Gimmie a day or two to get together and I will post my results in the Extra Projects section.

[bajaguy]

Thanks guys! I've been biteen by the delay bug and have started messing around with different circuits, but Wampler's pedal is just flat out cool! If I wasn't so stuck in the DIY I'd buy one just to tear it apart an see how it ticks

Bob

[claytushaywood]

I don't know how Wampler does it in his pedal, but implementing a dynamic envelope for the delay is pretty straight forward. I've actually done some work on this already. Gimmie a day or two to get together and I will post my results in the Extra Projects section.

did you ever work on this?  I was also looking for info on how to implement a delays only fx loop on some of your delay projects and 1776's stuff-  I really like the idea of the delay repeats getting more and more effected by whatever is in the loop. Ive been looking around for information on this but have yet to find something that works!