Dimension P - New PT2399 Chorus

[Mark Hammer]

If a person wanted to do TZF using a PT2399, my gut tells me that heterodyned clock noise might be less of an issue if the fixed delay were done with a BBD and the swept one done with the PT2399.  The clocks of the BBD and PT2399 are likely to be in such different regions that any sums or differences would be inaudible, in comparison to a pair of counter-swept PT2399s where the clock frequencies could get awful close sometimes.  Just a hunch.

[Thomeeque]

As your LFO swings only cca 1V_PP around 4.5V and as you filter DC part from LFO signals out, you can IMO safely use 5V source as a reference voltage for U1b inverter.

D'oh! Should have thought of that. Thanks for the tip.

 You're welcome! You could actually replace R10+R11 divider by single resistor (with value of parallel combination of R10 and R11 ~ 24k) hooked to 5V as well (it would introduce some slight asymmetry of LFO wave, but it's not symmetrical as it is now as well, probably due to passive integrator used).

Here's a clip with some subtler settings:
http://sites.google.com/site/distorque/home/projects/sound-clips/dpdemo2.mp3
Light chorus - Distorted - Gilmourish. Again, I have a chord then a lick for each setting.

 Thanks, quite nice (I'd prefer slower sweep yet probably, but that's just note)!

I'll get a sample of the TZF soon. But, as I keep telling you guys, it doesn't sound that good!  

 I'm not that much into TZF, I was just curious how it sounds with symmetrical delay times and if there won't be some heterodinning added (you are cheating the output clock noise filtering a lot )

 Cheers, T.

[CynicalMan]

If a person wanted to do TZF using a PT2399, my gut tells me that heterodyned clock noise might be less of an issue if the fixed delay were done with a BBD and the swept one done with the PT2399.  The clocks of the BBD and PT2399 are likely to be in such different regions that any sums or differences would be inaudible, in comparison to a pair of counter-swept PT2399s where the clock frequencies could get awful close sometimes.  Just a hunch.

That would solve the heterodyning problem, but I'm still not sure if regeneration would work well with the PT2399's 30ms latency. I could be wrong, I don't know much about flangers.

You're welcome! You could actually replace R10+R11 divider by single resistor (with value of parallel combination of R10 and R11 ~ 24k) hooked to 5V as well (it would introduce some slight asymmetry of LFO wave, but it's not symmetrical as it is now as well, probably due to passive integrator used).

I'm not as sure about that change, but I'll try it out and see if it's worth saving a part.

I'm not that much into TZF, I was just curious how it sounds with symmetrical delay times and if there won't be some heterodinning added (you are cheating the output clock noise filtering a lot )

 Cheers, T.

A bit I suppose.    I still have the 4.7n cap on the end that should reduce the clock noise by 70ish dB, but, if one wanted TZF, more filtering might get rid of the heterodyne noise.


I'm currently putting together a v1.1 schematic with a few tweaks and improvements, so stay tuned for that.

[alparent]

Any layout for this one?
If not I'll make one.......just didn't want to re-invent the wheel!

[CynicalMan]

As far as I know, no. You might want to wait a day or two, though, for the updates that I'm working on. A layout would be much appreciated. I'm a slow builder, and I probably won't do this one until next year, which means that I won't be making a layout right away.

[Ben N]

That's lovely--not quite as lush and multi-dimensional as a DC-2, but definitely close enough for government work. The lack of LFO annoyingness makes me wonder how a vibrato setting might sound.

[Gordo]

I like the fact that at lower settings it sounds a bit more like a doubler than chorus/flange.  I gotta try this one.  I've drawn up an as yet unverified board if anyone is interested.  CynicalMan I'll hold off till I have your blessing?

[CynicalMan]

Go ahead, post whatever you want. I'm just saying that I'm going to be changing a few things soon, so you might want to hold off on making a layout. But if you already have one, post away.

[Gordo]

I'll wait...I'm not overly thrilled with my layout anyway...

[Tacoboy]

Okay, some work to do this weekend. I have some unemployed PT2399's...

[CynicalMan]

Here's the updated version:
(click for a bigger image)


No big changes. I used Thomeeque's suggestion and got rid of U1b's voltage divider. I also got rid of the cap to ground after the Depth pot, and I increased the value of the Speed control for more range.


I've also drawn up versions with mods and in stereo:

Dimension P Modded Schematic

The modded version has two added switches. The Dry switch selects whether the dry signal is mixed in or not. The Voice switch chooses between 1 and 2 voices. Between these two switches, you can get vibrato, normal 1-voice chorus, 2-voice chorus, or light flanging.

Dimension P Stereo Schematic

This version is untested, but it adds a switch that should select between Mono use (with the dry signal in Output B), and Stereo chorusing, with one voice and the dry signal going to each channel.

[CynicalMan]

I've set up a page with all of this info, so you can follow further developments here: http://sites.google.com/site/distorque/home/projects/dimension-p

Has anyone done a layout yet? If not, I can do one, but I'm not that good at designing nice layouts.

[alparent]

I've done one.......fits in my 125B.
Only 1 jumper.

I'm no layout wiz.....

Designed in Eagle...
Woudent mind having it reviewed and revised. (I like to have all my off-board connections on the same side, but this one as them on 2 sides. Not a big deal I know!)

Not confirmed/built yet.

I want to mod the 2 switches (voices and dry signal) with pots to blend rather then just in or out.

[roseblood11]

This is one of the most interesting projects that I found here over the last few years. Many thanks for sharing!!! 

Has anyone done a layout yet?

I think of doing a veroboard layout for a 1590BB enclosure.

What about a version that includes all the possibilities of the "modded" and the "stereo" version?
Can you post sound clips that demonstrate the mods?

regards, Immo

[CynicalMan]

I've done one.......fits in my 125B.
Only 1 jumper.

I'm no layout wiz.....

Designed in Eagle...
Woudent mind having it reviewed and revised. (I like to have all my off-board connections on the same side, but this one as them on 2 sides. Not a big deal I know!)

Not confirmed/built yet.

I want to mod the 2 switches (voices and dry signal) with pots to blend rather then just in or out.

I'm a jumper junkie.  I can't get rid of them. I can take a look at your layout, however.

You could probably do the pot thing, just replace the switches with pots wired as variable resistors. 100kA would be my recommendation, but I haven't tried that out. I'm not sure how useful the pots would be, but it's worth a try.

I think of doing a veroboard layout for a 1590BB enclosure.

What about a version that includes all the possibilities of the "modded" and the "stereo" version?
Can you post sound clips that demonstrate the mods?

regards, Immo

A vero layout would be great. I'm planning to build on vero, although I was going to try a 1590B.

I'm personally planning to build a modded stereo version with three switches. I just didn't put it up because I wanted to limit the number of schematics that I put up. The mods are pretty simple, and I figured people could mix and match at their leisure.

The first sound clip has the dry signal cut out at the very end. I can do clips of the other mods if you want, although that's the most unusual one.

[deadastronaut]

+1 on 1590b...

[CynicalMan]

Here's a clip of the mods:
http://sites.google.com/site/distorque/home/projects/sound-clips/dpmods.mp3

Two voices, dry on - One voice, dry on - Two voices, dry off - One voice, dry off

Normal - Light Chorus - Flanger - Vibrato

[roseblood11]

I'm personally planning to build a modded stereo version with three switches. I just didn't put it up because I wanted to limit the number of schematics that I put up. The mods are pretty simple, and I figured people could mix and match at their leisure.

But that would be the most interesting version. And when somebody posts a vero layout for it, it will be good to have the schematic...

Great soundclip, thanx! The mods sound really usefull.

[frequencycentral]

Just a couple of thoughts to ponder on multiple PT2399 designs:

- it would appear from recent reseach that pins 3 and 4 are connected internally by a low value resistor. If you look at the example circuits on the PT2399 datasheet, the delay pot is connected to digital ground. So maybe connect the anti lock up circuit should be referenced to pin 4 rather than to ground.

- it would further appear from recent reseach that the PT2399 dumps a load of hash into the 5v supply rail, so the 5v supply rail should not really be used as a convenient vref for other stuff (not that Alex has done this). So, as the PT2399 is dumping hash - would it not make sense in a multiple PT2399 delay to use a seperate 7805 for each PT2399, thus further isolating and reducing hash?

[Suicufnoc]

- it would appear from recent reseach that pins 3 and 4 are connected internally by a low value resistor. If you look at the example circuits on the PT2399 datasheet, the delay pot is connected to digital ground. So maybe connect the anti lock up circuit should be referenced to pin 4 rather than to ground.

Seems like I read somewhere that someone tried this on the Little Angel and had problems, but I may be wrong.

- it would further appear from recent reseach that the PT2399 dumps a load of hash into the 5v supply rail, so the 5v supply rail should not really be used as a convenient vref for other stuff (not that Alex has done this). So, as the PT2399 is dumping hash - would it not make sense in a multiple PT2399 delay to use a seperate 7805 for each PT2399, thus further isolating and reducing hash?

Maybe it would be enough to isolate each chip with say a 100 ohm resistor from the 7805 and its own filter cap?