Tape Delay mkII

[Aleph Null]

 was always very happy with the sound of the original version and enjoyed the tails functionality; however, tails combined with the minimal filtering approach that this delay takes meant that there was always more noise from the PT2399 in bypass than I could tolerate.



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. 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.

Here's a demo:

I've got an extra PCB. If you're interested, just PM me. If there's enough interest I can do another run.

[NorthCoast]

Cool, always like reading about circuit development.

So you have it set up so that when it's in bypass, you're using the dry signal?

[Aleph Null]

So you have it set up so that when it's in bypass, you're using the dry signal?

Yes: when in bypass the dry signal still hits the input and output buffers. R8 helps to reduce popping when the effect is engaged.

The delay signal is bled to ground through the mosfet, which is acting as a switch. When the effect is engaged, there's no voltage at the gate, so the delay signal sees a resistance to ground of 2 or 3 mega ohms through the drain to the source. When the effect is bypassed, voltage builds up at the gate, which allows current to flow from the drain out the source to ground. The resistance drops to tens of ohms. All that mess between switch 1B and the mosfet gate controls how fast the resistance changes and thus how quickly the Mix and Repeats get turned down. With Tails fully counterclockwise, it's basically instantaneous. Fully clockwise, it's about 12 seconds of tails time.

[jessenator]

Slick as always, man. Sounds and looks great!

[gordo]

Damn, another winner.  You have some of my fave demo's: great tone to begin with, no overplaying, nice and direct, and no banter.  Great looking and sounding pedal!!!

[jimilee]

.....no overplaying, nice and direct, and no banter.

Shots fired!!! that tails option is pretty sharp. Nicely executed.


Sent from my iPhone using Tapatalk

[Aleph Null]

Thanks, guys. Your kind words make it easier for me to trust my own instincts.

[peAk]

Let me know when you have extra boards to sell, I am definitely interested

[Aleph Null]

Let me know when you have extra boards to sell, I am definitely interested

I sent a DM. Reply here if you don't get it.

[peAk]

Just bumping this thread to show appreciation to Aleph Null for some really great designed effects. This one (Tape Delay) was a no-brainer, but I was unaware of some of his other effects .