Author Topic: A DIY foot tap controlled delay?  (Read 9742 times)

Benny C

A DIY foot tap controlled delay?
« on: October 07, 2004, 05:57:04 PM »
I'm thinkin this one is beyond the realms of DIY but here goes.

I'm a guitar repairman by trade. Effects come up in conversation now and again (I had some fun building the Omnidrive, the only effect I've so far found the time to build. Thank you Mr. Hollis and Mr. Keen it was fun. Don't worry though, I haven't been selling anybody elses designs as my own. Though I must say quite a lot of my customers would pay good money for custom built effects. I'm starting to ramble here....). Anyway, a number of customers have expressed an interest in tap controlled delay (for delay time that is, tapping foot along to the beat) pedals. As far as I'm aware there are one or two commercially available.

Now my own take on it is that this would probably be fairly difficult (if not downright absurd) to build. I'd imagine it would need to be digital with some awkward detection. My own thoughts were that it might be easier to have an analog delay with delay time controlled with a rocker pedal (I reckon I have the necessary mechanical skills and equipment to build one of those). However, this got shot down by complaints of "it'd be too awkward to tune to the correct delay on stage" and "the control would have to be too course to give sufficient range, making it too inaccurate to be useful". Though one did say that a rocker pedal to control feedback with lateral movement to control sweep would be nice.

In any case, it's a nice thought, and for the entrepreneurial a market. Feasible? Or perhaps my ignorance is a little over-evident. Cheers for taking the time.
Good with guitar tech questions, bad with guitar anorak questions.

The Tone God

A DIY foot tap controlled delay?
« Reply #1 on: October 07, 2004, 08:31:09 PM »
This has been talked about before. The general conclusion is that it can be done but you would need a microprocessor to do it properly. This is beyond the capacity of the average DIYer.

Andrew

ExpAnonColin

A DIY foot tap controlled delay?
« Reply #2 on: October 07, 2004, 09:08:33 PM »
It's possible but not easy.  There are PLENTY in-production of tap tempo delays out there:
Digitech Digidelay
Line 6 Echo Park
DLS Echotap
Line 6 DL4 (well, almost)
DOD DFX4 (I think that's the name, this one might be OOP)
Akai Headrush (The original is OOP, there is a new one released)

And there's more, too.

-Colin

R.G.

A DIY foot tap controlled delay?
« Reply #3 on: October 07, 2004, 11:20:09 PM »
BEGIN
(setup all the counters, registers and other junk to satisfy this particular
chip's operating environment; initialize registers, blink the lights, whatever
fire drills you want to do before getting down to work)
WHILE (power is on) DO
READ Switch()
IF (switch is different now)
    THEN
        GOSUB (debounce the switch)
        (calculate how long it's been since the last time the switch was
          pressed)
        IF (it's been a reasonable tap tempo time)
            THEN
                  DO
                      (calculate whether this interval satisfies making a new tap
                        interval based on the last few tap intervals
                  END
                  IF (it's a new tap interval according to the averaging criteria)
                         THEN GOSUB (write the new interval into whatever does
                                               the interval)
                         ELSE (just remember this interval because it may be the
                                   earlier ones of a valid average)
                  ENDIF
            ELSE
                   DO
                       (reset things for intervals were too long; this could be the
                        first switch make for a new interval determining set)
                   END  
        ENDIF
ENDIF
ENDWHILE
END
R.G.

Quick IQ Test: If anyone in a governmental position suspected that YOU had top-secret information on YOUR computer, how many minutes would you remain outside a jail cell?

Ed Rembold

A DIY foot tap controlled delay?
« Reply #4 on: October 08, 2004, 05:17:43 AM »
There are also production analog delays which feature expression pedal control of both repeats and delay time.
I'm thinking of one in particular......

Ed R.

Manolo Dudes

A DIY foot tap controlled delay?
« Reply #5 on: October 08, 2004, 05:37:59 AM »
Quote from: anonymousexperimentalist
...Line 6 DL4 (well, almost)...

Why "almost"?
a.k.a. "Calambres" in www.pisotones.com

mikeb

  • Guest
A DIY foot tap controlled delay?
« Reply #6 on: October 08, 2004, 07:00:47 AM »
Quote from: Ed Rembold
There are also production analog delays which feature expression pedal control of both repeats and delay time.
I'm thinking of one in particular......

Ed R.


Ahhh, yes, that one's a beaut...... ;) :)

Mike

Claus H

A DIY foot tap controlled delay?
« Reply #7 on: October 08, 2004, 07:27:43 PM »
Quote from: R.G

BEGIN
(setup all the counters, registers and other junk to satisfy this particular
chip's operating environment; initialize registers, blink the lights, whatever
fire drills you want to do before getting down to work)
WHILE (power is on) DO
READ Switch()
IF (switch is different now)
THEN
GOSUB (debounce the switch...
...
...


To control an analog delay with BBD's

Use an microprocessor to create the clock do a little math and..

Here you go Tap to delay time algorithm: :) :)

Tap'ed time/Delay time = 51.2ms (Short but just an example)

BBD stages = 1024

Clock: 0.5 * (1 / (0.0512 / 1024)) = 10kHz

Claus H
"Ya' know, these days kids seem to be getting younger and younger." — David Foster

vhollund

A DIY foot tap controlled delay?
« Reply #8 on: March 29, 2005, 08:22:06 PM »
Hello Claus, you here too!! :D

I have this Headrush that I use with a Skrydtstrup buffer in font , but just for the feeling , does anybody know how this pedal handles the signal when the effect is turned off?

Btw : I heard that some people found them noisy and opened to find a very messy stressed korean work, but I opened mine and it is very clean inside.

Claus H

A DIY foot tap controlled delay?
« Reply #9 on: March 29, 2005, 11:26:33 PM »
Quote from: vhollund
Hello Claus, you here too!! :D

I have this Headrush that I use with a Skrydtstrup buffer in font , but just for the feeling , does anybody know how this pedal handles the signal when the effect is turned off?

Btw : I heard that some people found them noisy and opened to find a very messy stressed korean work, but I opened mine and it is very clean inside.


Jep I am here... I have been trying to keep it a secret But I seen now the jig is up :) :)

Buffers and tap tempo stuff is still in pre production :) I got a new amp/guitar tech job and I am very busy like 45+ hours a week.. Hope to get some time to do a buffer run soon..

See you later

Claus H
"Ya' know, these days kids seem to be getting younger and younger." — David Foster

R.G.

A DIY foot tap controlled delay?
« Reply #10 on: March 30, 2005, 08:31:00 AM »
Quote
Tap'ed time/Delay time = 51.2ms (Short but just an example)
BBD stages = 1024
Clock: 0.5 * (1 / (0.0512 / 1024)) = 10kHz

Getting a 51.2ms delay between foot taps is faster than I can move, but I think the math may be a bit flawed.

The clock is going to be 20kHz, I think, even with a two phase clock, because two phase clocks are simultaneous out-of-phase waveforms, not half-speed waveforms.

A 10kHz clock will give you 102.4mS of delay, and require a signal limited to under 5khz to avoid aliasing.

I think that my pseudocode does the whole task, and the actual timing is subsumed in the pseudoinstruction
Quote
THEN GOSUB (write the new interval into whatever does
the interval)
R.G.

Quick IQ Test: If anyone in a governmental position suspected that YOU had top-secret information on YOUR computer, how many minutes would you remain outside a jail cell?

Claus H

A DIY foot tap controlled delay?
« Reply #11 on: March 30, 2005, 11:26:52 AM »
Quote from: R.G.
Quote
Tap'ed time/Delay time = 51.2ms (Short but just an example)
BBD stages = 1024
Clock: 0.5 * (1 / (0.0512 / 1024)) = 10kHz

Getting a 51.2ms delay between foot taps is faster than I can move, but I think the math may be a bit flawed.

The clock is going to be 20kHz, I think, even with a two phase clock, because two phase clocks are simultaneous out-of-phase waveforms, not half-speed waveforms.

A 10kHz clock will give you 102.4mS of delay, and require a signal limited to under 5khz to avoid aliasing.

I think that my pseudocode does the whole task, and the actual timing is subsumed in the pseudoinstruction
Quote
THEN GOSUB (write the new interval into whatever does
the interval)


I have to disagree with you.. But let's try it !! I got some 1024 delay lines laying around (or just use a chorus pedal ;) ) If you read the data sheet for a 1024 stage BBD line the max delay time is 51.2ms the min clock is 10Khz this fits nicely with the math :) The 51.2ms is way faster than anyone can move ther feet I completely understand "This delay time is only use as an example" (It also says so in the text ! ) I also understand that this does not do it as a pseudoinstruction set.. I just wanted to share the math with all you.. It took me some time to figure out how the data sheet's  delay time related to the clock.. Or might be completely off THEN GOTO END

Claus H
"Ya' know, these days kids seem to be getting younger and younger." — David Foster

Dirk_Hendrik

A DIY foot tap controlled delay?
« Reply #12 on: March 30, 2005, 12:07:12 PM »
Quote from: The Tone God
This has been talked about before. The general conclusion is that it can be done but you would need a microprocessor to do it properly. This is beyond the capacity of the average DIYer.

Andrew


For any average DIY-er with a little knowledge of uP's this is a faily sioimple thing to program. Info on programming is widely available. Check the sites of microchip (PIC's) or Atmel (AVR's, my favourite since the're more 8051 compatible). These guys work hard at making the step to uP circuits as low as possible in order to sell chips. And: those chips are cheap as well.
More stuff, less fear, less  hassle and less censoring? How 'bout it??. To discuss what YOU want to discuss instead of what others decide for you. It's possible...

But not at diystompboxes.com...... regrettably

The Tone God

A DIY foot tap controlled delay?
« Reply #13 on: March 30, 2005, 01:28:25 PM »
Boy this is a fairly old thread to be dug up.

Quote from: Dirk_Hendrik
For any average DIY-er with a little knowledge of uP's this is a faily sioimple thing to program.


A "DIY-er with a little knowledge of uP's" is not an "average DIY-er". Most DIYers here do not have a background in uC. Only a handful of people who visit do and yes for them I agree this is a simple thing.

For the record I already have done a uC based tap tempo. Been there, done that, got the prize. :)

Andrew

Claus H

A DIY foot tap controlled delay?
« Reply #14 on: April 06, 2005, 09:02:00 PM »
Proof that my math is right :)

http://factaee.elfak.ni.ac.yu/fu2k01/fu01.pdf

See Page 4 and 6 here 3 cascaded mn3005 (4096 stage) BBD's are used to make 256 ms of delay with a clock of 24khz this means they each produce 0.256 / 3 = 85 1/3 ms of delay

My math is

0.5 * (1 / ((0.256/3) / 4096)) = 24kHz  

No harm intended

Claus H
"Ya' know, these days kids seem to be getting younger and younger." — David Foster

Claus H

A DIY foot tap controlled delay?
« Reply #15 on: April 07, 2005, 04:31:21 PM »
Quote from: R.G.


Quote from: Claus H

Tap'ed time/Delay time = 51.2ms (Short but just an example)
BBD stages = 1024
Clock: 0.5 * (1 / (0.0512 / 1024)) = 10kHz  


Getting a 51.2ms delay between foot taps is faster than I can move, but I think the math may be a bit flawed.

The clock is going to be 20kHz, I think, even with a two phase clock, because two phase clocks are simultaneous out-of-phase waveforms, not half-speed waveforms.

A 10kHz clock will give you 102.4mS of delay, and require a signal limited to under 5khz to avoid aliasing.

I think that my pseudocode does the whole task, and the actual timing is subsumed in the pseudoinstruction
Quote:
THEN GOSUB (write the new interval into whatever does
the interval)



I did a little research to day I plugged in a Carl Martin Delayla and measured the clock at max delay time.. The Delayla contains 6 cascaded MN3007 (1024 stage) BBD's and it's maximum delay time is 500ms

0.5 * (1 / (0.5 / 6144)) = 6.144 kHz

My measurement of the clock at max delay time (500ms) was oddly enough 6.149 khz :) :) :) So my math is all right..

Well no reason to gloat :)

later

Claus H
"Ya' know, these days kids seem to be getting younger and younger." — David Foster

puretube

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« Reply #16 on: April 07, 2005, 05:40:23 PM »
nosy...