Designing a "Cascaded Delay" PCB

[ianmgull]

I like this idea
I'm going to build this... including about a square meter of room for the pots! well nine actually.

At first I had no idea what this was but after staring at the Rebote schematic for the past two days all I have to say is PLEASE build this, and post sound clips when you do!!

[sean k]

Thanks Bro, I'm gonna try real hard to build this. It's having spare time at the moment 'cause I'm never short of the will.

[ianmgull]

Thanks Bro, I'm gonna try real hard to build this. It's having spare time at the moment 'cause I'm never short of the will.

Somebody needs to, for science.


/s

[ppatchmods]

i found this on youtube: http://www.youtube.com/watch?v=HGGtgL91GG4

[ianmgull]

i found this on youtube: http://www.youtube.com/watch?v=HGGtgL91GG4

I saw this too, very very cool. Hopefully this layout will fit in a BB though.

update: I've started populating the board, waiting on some parts to arrive.

[sean k]

I've done the pcb and will etch it up soon... then save up for the 16 or so pots I'll need because I'm also doing the echo blender and I think I'll put the both in one box and have what might be called "Echo, Echo and Echo"
Notice those kinda dryed out bits, especially on the TL072, the sharpies go funny and that seems to be where I have the biggest problem when I'm etching. It's as if the sharpie dries too fast and doesn't stick as well as it could. Funny thing is that in scanning it it has become obvious where I have to rework it as under normal light its quite hard to notice a difference.

[Thomeeque]

I like this idea
I'm going to build this... including about a square meter of room for the pots! well nine actually.

Hi!

Two comments:

1) Mixing of dry and A and B signals as designed here strongly limits possibilities of the circuit - lets say you want to mix in ratio 100% / 30% / 10% (pretty usual situation, when you want just light touch of delay) or something experimental like 40% / 80% / 100% or zillion others - no way here. Instead of W/D MIX and A/B MIX pots I'd advice to implement very basic 3-pot mixer (e.g. Circuit 3 here), giving you full range of mixing possibilities (any combination of 0-100% of dry, 0-100% of A and 0-100% of B).

2) AR2 pot does not make much sense either, why not to send full A signal into the B delay line (for the best S/N ratio of the B line and full signal for feedback pots from the B line) and alter amount of B signal at the output of B line (solved by mixer mentioned above)?

T.

EDIT: You could probably feed B line directly from pin 12 of A line's delay chip ommitting one IMO redundant LPF in the way, plus you can ommit coupling 1uF capacitor either (both parts are on the same DC level).

EDIT2: If I'd build something like this (and I plan to do that once ), I'd use pre & de-emphasis on input/output buffers for better SNR (just "steal" these buffers, they'll fit nicely here ).

EDIT3 : Reconfiguring AR2 pot into DRY/A MIX pot for the B line input (for starters just rewire grounded node of AR2 pot from the ground to the output of input buffer) could be interesting! It would significantly expand range of possibilities here allowing to dial fluently from the parallel to the serial configuration of the delay lines!

[sean k]

FUnnily enough, I'd suggested to somebody else, doing the aquapuss, that going back through an extra stage of  comp/expand was a waste of time and here you have brought me up and my overlooking two stages of filtering between A and B.

I can see what you're saying about the sing of mixing nodes at all the output points befor the final section of the TLO72 and I will let that ferment but for the moment I'm thinking of the way that I use a delay and how I perform with it. I have the echobase and spend all my time on the speed and feedback knobs with almost all the rest being somewht redundant though by building this, above, I might be able to use the echobase more along the lines of its intended purpose... using the oscillator on the speed, so the mix pot is there for me to be mostly at the B end of the track but to occasinally drop it down to A and cut B with AR1... but I can see your point that AR1 doesn't serve much of a purpose and I can take the output of A from pin 12 straight to the 12k at the beginning of B.

A possible, maybe, for the A/B mix pot is to get a dual pot and be able to switch it from same phase to opposite phase but then again, if I'm losing AR2 then two mix pots on the outs wouldn't make much difference to the eventual pots layout on the deck.

As for edit 3 I'm not getting you at all as to how a pot on the end of A could possible allow signal at the beginning of A to find its way into B. Maybe if the two ends of the pots were accross A, input and output, which is basically like AR1 with FA1 except the wiper of FA1 would go to the input of B? something like that would allow the series/ parallel thing to happen. Maybe removing AR2 and connecting it to the ... actually I have to go and work now, I'll come back to this.

[Thomeeque]

As for edit 3 I'm not getting you at all as to how a pot on the end of A could possible allow signal at the beginning of A to find its way into B. Maybe if the two ends of the pots were accross A, input and output, which is basically like AR1 with FA1 except the wiper of FA1 would go to the input of B? something like that would allow the series/ parallel thing to happen. Maybe removing AR2 and connecting it to the ... actually I have to go and work now, I'll come back to this.

I meant basically something like this:



T.

[sean k]

Oh er, Mr T, that is very clever indeed, I like it alot!

Thanks very much for taking the time to work that up for me. Ya reckon 50k is going to be enough. I used 50k because the original feedback was 25k and I was paralleling them up so I'd change AR1 back to 25k and maybe the new AR2 would be better at 100k, or even more, as the effets of putting the original signal through 50k to pin 12 might not have enough resistance. Easy enough to try it though and if it ends up with a 250k, 500k pot that needs to be swung from one end to the other to be effective then even a switch would still acheive the same thing.

But I do really like the idea and can see how a mixer with two pots, well three to include the wet/dry, would be an advantage. Choice Bro!