MichaelW
Well-known member
- Build Rating
So last week I built the Seabed Delay (Mad Professor Deep Blue Delay).
Absolutely love it, it's the best sounding PT2399 delay I've built yet. Very analog sounding and voiced extremely well. I see why it's so popular with a lot of people.
I made a comment in my build report that the only thing that could make it better would be if it had some modulation.
@swyse DM'd me and told me about a hack he had done to get modulation from a PT2399 without having to add an LFO circuit.
It was discovered by Rob from DeadAstronautFX kinda by accident. Here's the thread on DIYStomboxes for those interested.
He discovered that if you jumper pins 6 & 8 on the PT2399 with a 1m resistor you could access the chorus affect of the chip on the repeats of a delay.
So of course I had to mess with my build and test it. I found that with a 1m resistor I could definitely get modulation on the repeats but the repeats died off after about 3 or 4 repeats. Following the advice on the thread I tried tacking on 470n cap to the resistor in series and was able to get the repeats working properly with the feedback control on the board.
So then I got to thinking....hmmm...what if instead of a 1m resistor I used a 1m pot instead, so that's what I tried next and found that I could get some different types of modulation on the repeats from a vibrato to chorusey effect. I tried a bunch of different ways to hone in on where the modulation was happening on the sweep by using 100k, 250k, 500k pots with 910kr, 760kr and 510kr resistors respectively but oddly enough trying to narrow the sweep of the variable resistor gave me less effect than just using a 1meg pot. Then I tried an A1M, C1M, and B1M to see which taper worked the best and wound up using the linear pot.
So instead of trying to hack up my original build I ordered a second board and used a 125B this time to give me a little more room to add a toggle switch to turn the modulation on and off and I turned it into a 4 knob delay pedal with a dedicated pot for tuning in what type of modulation I wanted.
I have to say it works GREAT! It's not as "in your face" as an LFO but it's a really cool hack that extends the capability of an already great delay pedal.
Thank you @swyse ! Great hack!
Here's prepping the drilling, I moved the Feedback pot to off board wiring and located the new modulation pot as a 4 knob pattern.
I put the toggle switch at the top.
I would have liked to have hid the wires going to the toggle under the board but wasn't too confident that I'd have a robust connection soldering onto the nib of the DIP socket for the PT2399 on the back of the board. So instead I rigged up a couple of soldering points with buss wire on the DIP socket itself making sure that it wouldn't ground out against the adjacent pin.
All wired up gut shot. I probably could have done this in a 1590B but the toggle would have been pretty tight. Glad I didn't try
Finished pedal. The cream knob is the modulation knob. Helps me keep things straight heh.
I recorded a demo showing how it sounds. Interestingly it seems the modulation is triggered by signal strength, making it a dynamic thing. The harder you pick the more modulation affect you get. At the end of the video I show some extreme examples of this. Super stoked about how this sounds and it's already part of my rig running as part of my dual delay setup.
Absolutely love it, it's the best sounding PT2399 delay I've built yet. Very analog sounding and voiced extremely well. I see why it's so popular with a lot of people.
I made a comment in my build report that the only thing that could make it better would be if it had some modulation.
@swyse DM'd me and told me about a hack he had done to get modulation from a PT2399 without having to add an LFO circuit.
It was discovered by Rob from DeadAstronautFX kinda by accident. Here's the thread on DIYStomboxes for those interested.
He discovered that if you jumper pins 6 & 8 on the PT2399 with a 1m resistor you could access the chorus affect of the chip on the repeats of a delay.
So of course I had to mess with my build and test it. I found that with a 1m resistor I could definitely get modulation on the repeats but the repeats died off after about 3 or 4 repeats. Following the advice on the thread I tried tacking on 470n cap to the resistor in series and was able to get the repeats working properly with the feedback control on the board.
So then I got to thinking....hmmm...what if instead of a 1m resistor I used a 1m pot instead, so that's what I tried next and found that I could get some different types of modulation on the repeats from a vibrato to chorusey effect. I tried a bunch of different ways to hone in on where the modulation was happening on the sweep by using 100k, 250k, 500k pots with 910kr, 760kr and 510kr resistors respectively but oddly enough trying to narrow the sweep of the variable resistor gave me less effect than just using a 1meg pot. Then I tried an A1M, C1M, and B1M to see which taper worked the best and wound up using the linear pot.
So instead of trying to hack up my original build I ordered a second board and used a 125B this time to give me a little more room to add a toggle switch to turn the modulation on and off and I turned it into a 4 knob delay pedal with a dedicated pot for tuning in what type of modulation I wanted.
I have to say it works GREAT! It's not as "in your face" as an LFO but it's a really cool hack that extends the capability of an already great delay pedal.
Thank you @swyse ! Great hack!
Here's prepping the drilling, I moved the Feedback pot to off board wiring and located the new modulation pot as a 4 knob pattern.
I put the toggle switch at the top.
I would have liked to have hid the wires going to the toggle under the board but wasn't too confident that I'd have a robust connection soldering onto the nib of the DIP socket for the PT2399 on the back of the board. So instead I rigged up a couple of soldering points with buss wire on the DIP socket itself making sure that it wouldn't ground out against the adjacent pin.
All wired up gut shot. I probably could have done this in a 1590B but the toggle would have been pretty tight. Glad I didn't try
Finished pedal. The cream knob is the modulation knob. Helps me keep things straight heh.
I recorded a demo showing how it sounds. Interestingly it seems the modulation is triggered by signal strength, making it a dynamic thing. The harder you pick the more modulation affect you get. At the end of the video I show some extreme examples of this. Super stoked about how this sounds and it's already part of my rig running as part of my dual delay setup.
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