DEMO Tape Delay mkII (with Envelope Controlled Modulation and Tails Time)

This post contains an audio or video demo
Aleph Null

Aleph Null

Member
This is my most recent design. I posted about it on the Mad Bean forum a week or two ago, but @jessenator says all the cool kids hang out over here, so I though I'd post here as well.



The enclosure is Aqua Vein from stompboxparts.com. It's beautiful, but difficult to photograph. I used the same cheeky graphics from the original version.



I'm starting to get my PCB layout conventions figured out and I think it shows in this build.



Version 2 implements a slow-opening mosfet switch which allows a “tails time” to be set before the delay signal is turned off. This maintains the tails bypass while eliminating the added noise you'd get from the PT2399 output being connected all the time. Additionally, the input and output sections were streamlined and filtering was increased slightly. The modulation section was revamped to allow for a much greater range and to eliminate the need for a switch. It is essentially the same technology I implemented in the Special Sauce and Trogodyte Reverb. It uses the CCO voltage to control Q1, which is set up as a current sink (a variable resistor).

Here's a demo:


If any one is interested in a PCB, just PM me; I'll be putting in an order for another upcoming project soon, so I can order more of these then.
 

Attachments

  • IMG_1535.JPG
    IMG_1535.JPG
    663.9 KB · Views: 0
Last edited:
thanks for sharing this!

Aleph Null said:
Version 2 implements a slow-opening mosfet switch which allows a “tails time” to be set before the delay signal is turned off. This maintains the tails bypass while eliminating the added noise you'd get from the PT2399 output begin connected all the time.
Click to expand...

I have a Mk1 tape delay board I haven't built yet, and I'm curious about this segment...
1748995156945.png
if one was not pleased with PT2399 output noise in bypass, and/or wanted to include that nifty controllable backing off with the tails, could this segment (perhaps on a piece of vero) potentially be inserted at R12/pin 3 mix pot?

1748995270026.png
 
You are a great your pedal sounds amazing! I did think the only way to add modulation to the pt2399 was with an external LFO wow!! if I try this with a regular delay with pt2399 will it work?
 
owlexifry said:
thanks for sharing this!



I have a Mk1 tape delay board I haven't built yet, and I'm curious about this segment...
View attachment 96666
if one was not pleased with PT2399 output noise in bypass, and/or wanted to include that nifty controllable backing off with the tails, could this segment (perhaps on a piece of vero) potentially be inserted at R12/pin 3 mix pot?

View attachment 96667
Click to expand...

That should work. And you're right; the intersections of R12 and lugs 3 of the Mix and Repeats knob is the best place to connect it. You'd want to connect pad 1 and 2 from the PCB to lug 1 and 2 of the bypass switch as normal, but leave 5 and 6 disconnected. You'd connect lugs 4, 5 and 6 of the bypass switch as shown in the circuit snippet above.

I didn't mention it in my original post, but you can change the max and minimum "tails" time with C14 and RV6. Increasing either will increase the maximum time. Increasing C14 will also slightly increase the "on" time, but probably not so much so that you'd notice. The default values give about 12 seconds of tails. Bumping C14 up to 100uF will give you closer to 30 seconds. 47uF and a 500k pot is five or six seconds, which might be enough for most use cases.

ivandelado said:
You are a great your pedal sounds amazing! I did think the only way to add modulation to the pt2399 was with an external LFO wow!! if I try this with a regular delay with pt2399 will it work?
Click to expand...

Thanks! It'll depend on the design, but most PT2399 delays don't do much with pin 8, so it probably won't break anything. I haven't tried this with tap temp delays, but I could see it potentially causing a problem there. My implementation actually evolved out of Dead Astronauts discovery, which is detailed here. That's even simpler to implement, though less flexible.
 
Aleph Null said:
That should work. And you're right; the intersections of R12 and lugs 3 of the Mix and Repeats knob is the best place to connect it. You'd want to connect pad 1 and 2 from the PCB to lug 1 and 2 of the bypass switch as normal, but leave 5 and 6 disconnected. You'd connect lugs 4, 5 and 6 of the bypass switch as shown in the circuit snippet above.
Click to expand...
wicked! appreciate the reply/confirmation 🤙

looks like i can get it down to 7x4 - should fit!
1749088859765.png
 
Wow, this sounds great. I feel like I am late the party here, but you designed this circuit? And it's based on a tape delay sound like the Echoplex?
 
joelorigo said:
Wow, this sounds great. I feel like I am late the party here, but you designed this circuit? And it's based on a tape delay sound like the Echoplex?
Click to expand...

The circuit isn't actually supposed to sound like a tape delay. I was just making a cheeky pun with the pedal art. It's designed to let the natural LoFi sound of the PT2399 come through—basically, it has all the fidelity of Scotch tape.

This is an original design, but I did pull inspiration from my forebears: the Noise control is lifted almost straight from John Patton's Hamlet Delay; the modulation is an evolution/refinement of Dead Austronaut's "after chorus" discovery as noted above. The Tails functionality is all my own idea (but there's nothing new about using a mosfet as a switch).

p_wats said:
Oh this is very cool. Arg. Don't want to build ANOTHER delay, but can I resist?
Click to expand...

Do your other delays have envelope-controlled modulation, a tone control, and adjustable tails length? :D What's $10 between friends?
 
Last edited:
Aleph Null said:
The circuit isn't actually supposed to sound like a tape delay. I was just making a cheeky pun with the pedal art. It's designed to let the natural LoFi sound of the PT2399 come through—basically, it has all the fidelity of Scotch tape.

This is an original design, but I did pull inspiration from my forebears: the Noise control is lifted almost straight from John Patton's Hamlet Delay; the modulation is an evolution/refinement of Dead Austronaut's "after chorus" discovery as noted above. The Tails functionality is all my own idea (but there's nothing new about using a mosfet as a switch).



Do your other delays have envelope-controlled modulation, a tone control, and adjustable tales length? :D What's $10 between friends?
Click to expand...
Your demo had already convinced me, but now I'm extra convinced. Ha
 
Feral Feline said:
What a way to make an ENTRANCE!

Welcome to the PPCB forum, @Aleph Null !








Hmmm I forgot to hit "Post Reply" again, this should've been out the same day as the OP.

I'm up for buying a Tape Delay PCB or two.
Click to expand...


Thank you all for welcoming me so enthusiastically!

I have a few more designs in my Cave of Wonders™ that I want to share, but I want to make sure I have stock before I post more build reports.
 
You must log in or register to reply here.
Back
Top