Double Delay

[WelshWonder]

Hi all,

I'm thinking of my next project. What I want to do is build a double delay pedal. Here's a plan of what I've come up with;



My plan is to build it around the rebote 2.5 delay and to primarily run it off a 9v adapter as I doubt battery would last all that long. In addition I want to have two LED's that blink on the repeats of both delay phases so I can visually check the timing.

Firstly, I would like to ask if anybody would think this is a worthwhile project to build? Also, does anything stand out in my plan that may prove problematic?

[ulysses]

going for the brian may delay?

i think its already been done. there are cheap mass produced delays with a "brian may" or "queen" setting.

cheers
ulysses

[WelshWonder]

I Didn't have Brian May in mind with the project. I basically want to build a delay that will have a few creative options hence the double delay. I wanted the different outputs as options for different amps/fx chains etc and possibly build a signal mixer for my pedal board so I can mould my signal again. I just basically wanted to know if this is a good way of doing it and/or if there may be problems on the way...

I did come across the Digitech Brian May pedal but that's not what I am after, I am after my own sound and delay is a big part of it, hence a speacial delay box.

Thanks

[Antero]

Are you going to have some way to switch delays aside from the outputs?  Instinctively, if I was going for maximum flexibility, I'd want some way to choose 1/2/Mix/Bypass with switches.

[sfr]

I believe the rebote circuit already has a buffer in it (to feed the dry and delay lines0.  So if you were planning on just using the layout from tonepad and throwing two of those boards in a box, you can probably tap the clean signal off of one of those, and use it for your dry tap, and to feed the other delay, and save making a separate buffer.

I would also think about the option of being able to chain the delays, (series instead of parallel) that can be a fun sound as well.  I've certainly gotten some fun sounds chaining one rebote into another. 

[blanik]

i was plannig on trying it but with just 2 delays in series... one set for a slapback and the other for long delay, first one in mono second in stereo (dry/wet) but i guess playing with both setting can make pretty cool sounds...

R.

[WelshWonder]

Are you going to have some way to switch delays aside from the outputs?  Instinctively, if I was going for maximum flexibility, I'd want some way to choose 1/2/Mix/Bypass with switches.

I suppose this could be done but I had in mind using different output jacks for Delay 1, 2 and mix so they could go to different amps. Maybe I could design it so the mix output is switchable.

[WelshWonder]

I believe the rebote circuit already has a buffer in it (to feed the dry and delay lines0.  So if you were planning on just using the layout from tonepad and throwing two of those boards in a box, you can probably tap the clean signal off of one of those, and use it for your dry tap, and to feed the other delay, and save making a separate buffer.

Ah thanks for pointing that out, I haven't taken a good look at the circuit yet so I'll keep that in mind when I'm ready to go further into it.

I would also think about the option of being able to chain the delays, (series instead of parallel) that can be a fun sound as well.  I've certainly gotten some fun sounds chaining one rebote into another. 

I guess this could be switchable. The only thing I was thinking about this was maybe it would be too noisy?

[WelshWonder]

i was plannig on trying it but with just 2 delays in series... one set for a slapback and the other for long delay

That's exactly one of the ways how I want to use it. I think you can get some pretty good sounds with double delay.

[puretube]

fresh for Frankfurt:







(souped-down version of this Time Apparatus)

[Pushtone]

fresh for Frankfurt:

Cool, a fresh prototype from Messe and with a gut shot too!

I love the stacked boards! Nice use of header pins.
Do they conduct signals from one board to the other? Or are they structural?

Looking forward to your pics from Frankfurt. Coming soon?

Have a good show!

[WelshWonder]

Puretube,

That's some awsome sounding clips, simply wild. I love the auto whammy going on there, is that your own design or is there a design out there where we can all use?

[puretube]

it`s the PCBs from reply#28 in the other thread...

completely new (secret own) design...

yes they are connectors...

the modulated version gets a 3rd (control) PCB.


MusikMesse starts on wednesday - still gotta finish another box... 

[Auke Haarsma]

love the mystery around it! Very cool pics!

[WelshWonder]

OK, so back to my topic....

Does anyone see any problems in completing this project?

[slacker]

Can't see any problems, looks pretty cool. If I was doing it I'd add a option to have the delays in series as well as parallel.

[d95err]

In addition I want to have two LED's that blink on the repeats of both delay phases so I can visually check the timing.

That would be the difficult part. You'd have to somehow tap into the clock signal of each delay chip. I don't know if that's possible on a PT2399. It could be done if you use a different delay chip that uses a separate clock chip.

[WelshWonder]

In addition I want to have two LED's that blink on the repeats of both delay phases so I can visually check the timing.

That would be the difficult part. You'd have to somehow tap into the clock signal of each delay chip. I don't know if that's possible on a PT2399. It could be done if you use a different delay chip that uses a separate clock chip.

Actually, I found a cool topic on this site that will allow this function out of the PT2399, check it out --> http://www.diystompboxes.com/smfforum/index.php?topic=50185.0

[Mark Hammer]

Having two distinct delays on the same circuit board is apparently risky with respect to clock noise, especially with respect to heterodyning noise.  Each clock frequency may well be high enough that any suitable filtering will easily tame it without detracting from bandwidth.  Unfortunately, the sum and difference products (well, the difference, that is) may be substantially lower than the rolloff of the lowpass filters.

One way of getting around that is to use a single clock and clock frequency, and a combination of BBDs that can achieve multiple delay times.  So here is a suggestion, place an MN3007 ahead of an MN3011, and gang them to the same master clock.  The MN3007 (1024 stages) can produce a slapback delay of reasonable length and decent bandwidth.  The MN3011 has 3328 stages and 6 different taps (at 396, 662, 1194, 1726, 2790, and 3328 stages).  If you add 1024 stages to that, you get potential delays after 1420, 1686, 2218, 2750, 3814, and 4352 stages.  That latter one can potentially be around 400msec with decent bandwidth, which isn't too shabby at all.  If you install a pair of 6-position rotary switches, you can decide which tap (from 1 through 6) you want the first repeat and from which tap (2 through 7) you want the second repeat.  Hell, install three such switches, and you can also determine which tap you want to feed to the regeneration loop.

This arrangement will nail you slapback plus longer delay, reasonable maximum delay time, NO heterodying, ONE clock, and ridiculous flexibility of delay stagger.  The chips ain't cheap, but at around maybe $40-50 for all parts, that's actually a pretty decent return on investment if you can pull it off.  Certainly nothing like it on the market AKAIK......well, until Mr. Barmentloo gets back from Musikmesse.

[puretube]

with 2 serial delaylines @ 1 clock, you got 2 synchronized times of x-act half/double...
(without heterodyning at any frequency)

Mark: I`m not exhibiting myself this year, but bring some new design samples like every year for certain people. 

(wanted to show this off here, so 2 years from now no-one can claim it is based on s.th. posted here earlier...)