is there a way to extend delay time?

[ronnes]

just bought a modtone delay pedal and its quite nice but i was wondering if there was some sort of possibility to extend the delay time? im no stranger to soldering so no problem there. i just want a little more delay time. the max delay time is 350ms, which is a bit on the low side...

if the resistance of the potmeter is lower would it make the delay time longer?

isnt it like that it works? if i put in a pot meter with lower resistance in example from 500k to 250k, what would happen then?

thanks!

[ronnes]

no one has a opinion on this?

[PaddyWagon]

Checking on their site they're not doing a straight bucket brigade analog so it's real hard to tell. Pretty cheap to drop a resistor across the pot to see what happens, or try a different pot after measuring the one that's in there.

The danger will be that if you do manage to slow it down at some point you'll start to hear the clock driving the analog part which is why all the original analog delays were pretty stingy with their maximum times.

http://en.wikipedia.org/wiki/Bucket-brigade_device

[ronnes]

Originally Posted by PaddyWagon

Checking on their site they're not doing a straight bucket brigade analog so it's real hard to tell. Pretty cheap to drop a resistor across the pot to see what happens, or try a different pot after measuring the one that's in there.

The danger will be that if you do manage to slow it down at some point you'll start to hear the clock driving the analog part which is why all the original analog delays were pretty stingy with their maximum times.

http://en.wikipedia.org/wiki/Bucket-brigade_device

ok thanks a lot!

i have absolutely no idea on stompboxes, but i figured maybe altering the resistance over the potmeter would increase or decrease the delay time. maybe its as simple as that? or maybe not. what is a typical potmeter in delay stompboxes or is there no typical value on the pot. can you give me some examples on how much i should try to increase in the resistance of the potmeter

by the way...i thought the modtone delay is really a digital delay that simulates analog delay?

[callaway]

If it were as simple as changing a resistor/pot value to increase delay time, they would have done it to begin with. There's a limit of how slow you can clock a BBD and still have acceptable signal fidelity after the recovery stage. At some point, you're going to start hearing the sampling clock.

[dalandan]

open her up and look for dipswitches, etc.

[ronnes]

just opened the pedal. i saw nothing that could resemble a switch inside...the value of the potmeters is: timeknob B20K, repeatknob B50K and the mix knob B100K...

how do i know its a bucket brigade device?

[callaway]

Originally Posted by ronnes

how do i know its a bucket brigade device?

Because they say it's an analog delay. It's obviously not a tape or magnetic platter delay, so it's gotta be BBD.

[ronnes]

Originally Posted by callaway

Because they say it's an analog delay. It's obviously not a tape or magnetic platter delay, so it's gotta be BBD.

ok, but what ive heard is that this delay pedal is really a digital delay that simulates analog delay as i said earlier in the thread..dont know if it matters tho...

[PaddyWagon]

Hmm, combining analog circuitry with a digital processor; that phrase means absolutely nothing as far as I can tell I may be wrong, and often am so take that with a grain of salt.

On the other hand the PT-2399 processor they're using has external control over the clock via resistors on pin 6. The application notes have a 20K pot paired with something between 10-50K in series (10K recommended).

You may increase the delay by using a bigger pot than what's there if I read this correctly, but at the risk of artifacts since 350ms is at the outer edge of their resistor=delay table in the application notes.

I am not an electronics lawyer, your mileage may vary, we're all grown ups here but if anyone asks I never said any of this.

[ronnes]

Originally Posted by PaddyWagon

Hmm, combining analog circuitry with a digital processor; that phrase means absolutely nothing as far as I can tell I may be wrong, and often am so take that with a grain of salt.

On the other hand the PT-2399 processor they're using has external control over the clock via resistors on pin 6. The application notes have a 20K pot paired with something between 10-50K in series (10K recommended).

You may increase the delay by using a bigger pot than what's there if I read this correctly, but at the risk of artifacts since 350ms is at the outer edge of their resistor=delay table in the application notes.

I am not an electronics lawyer, your mileage may vary, we're all grown ups here but if anyone asks I never said any of this.

ok so if i decide to give it a try would you say i should try something like 50K-100K potmeter or is that to much?

would i do any damage to the pedal by doing this?
would the pedal act as normal up to the point of 350ms and could act funny over that? i mean as long as it stays normal up the point it was before modding it, it really doesnt matter if it still sounds the same only with extra travel on the potmeter.

im so clueless on this sort of stuff but im very eager to learn tho...

[callaway]

Originally Posted by ronnes

ok, but what ive heard is that this delay pedal is really a digital delay that simulates analog delay as i said earlier in the thread..dont know if it matters tho...

Yeah, I nearly mentioned that there are several pedals masquerading as analog delay that are actually digital delay. If you posted a picture of the circuit board, we could tell you.

If it's really a digital delay, it's going to be limited to the memory size of the chip. I'm sure they would have maxed out its delay time, leaving only a little margin for tolerances, etc. Let's say it really had 600 ms available with the chip they used, well... why would they have not set it for a 600 ms max delay? No reason if it's just that simple to do.

So what I'm really trying to say is that I don't think there's anything useful you could do by trying to mess around with it. Now maybe if you wanted to change the coupling caps or buffer stages to change the tone, that could be feasible. But I just don't see anything positive happening in terms of delay time.

[callaway]

Okay, I just checked it out... maybe I should have paid more attention earlier in the thread.

Anyway, the delay pedal is a digital delay using a PT2399 delay chip. According to the device datasheet, the maximum recommended delay time is 342 ms. So I think there's your answer.

Now you may be able to lower the clock frequency, which would give you a whole new range on the delay time knob, but you'll start hearing artifacts similar to a low bit-rate mp3 file. This could be a cool effect though, just be aware that that's your option. If you lower the clock to low, then you'll start hearing the clock ticking, as someone already mentioned.

[ronnes]

so here comes the next question...is there possible to use another delay chip maybe? or does that come with more things to do than its worth? i dont expect it to be a easy drop in mod, but you guys seem to have a lot of knowledge about this so maybe its possible...

i could post a pic or two of the circuitry if that would help

[callaway]

I think it would be much easier to keep your existing stomp box intact and build yourself a new one from scratch if you're going to bother doing anything. This way you could even sell your current unit after building your own and probably come out even (or ahead) in cost.

[ronnes]

Originally Posted by callaway

I think it would be much easier to keep your existing stomp box intact and build yourself a new one from scratch if you're going to bother doing anything. This way you could even sell your current unit after building your own and probably come out even (or ahead) in cost.

hmm..maybe i would do so. what should it cost me to build an delay pedal? could you give me examples on some of the ones to choose from? and where to get?

[PaddyWagon]

http://www.buildyourownclone.com/analogdelay.html

It's not an easy project by any means and it can just barely be tuned without an oscilliscope if you cheat and tap into the signal and do it by ear; you will need a some skill at working in tight spaces and God help you if you screw the pooch and have to debug the circuit

If you build it yourself that's around $150.00 usd. BYOC has an approved builder who'll make you one but specials come and go so no idea what the price would be like: http://axeandyoushallreceive.com/store/page1.html

I've worked with their kits before, I don't work for them or build for anyone else, and the only reason I mention this particular one is that it really pushes the limits at having 4 bucket brigades to cover up to 1 second.

There's a video there so you can hear what it would sound like and he goes into the drawbacks too, which is good to know. Welcome to the analog world