Anyone know a reverse delay schematic exists?

[Yuan Han]

"what happens, when switching between 2 diff. delay-times
very fast, and with varying duty-cycle?"

So, lets say I play 2 notes on the guitar. During the first note, the delay is long (1sec). And I play the second note, maybe 0.3 seconds later, with the delay time at 0.3 seconds.

Tada, the 2 second note is "played" by the bbd at 0.6 seconds and the first note at 1second. reversed!

But this would result in warppy pitch shifting sound right ? like how you play on a delay changing the delay time. Hmm or does it depend on the how the delaytime/clockspeed vary, like if it is a slow descend, or a quick almost vertical one.

Han

[R.G.]

Lets be clear about terms: there are "attack delay" pedals that fake some parts of tape reversed notes, and there are real time reversed delays.

The faking pedals are moderately OK for giving the impression of tape reverse.

However, nothing can predict the future, and that is what a real tape reverse pedal would have to do to play back the end of a note first, using only the start of a note to work from.  It violates Causality, and if you can do that, you can have a lot more fun that playing guitar. So far, Mother Nature hasn't let anyone violate Causality.

No live play pedal can do a really time reversed delay - nature is causal, and doing real time reversed sound implies that you can see the future. There is nothing, for instance, that will give you "pre-echo" as in certain Led Zeppelin songs, other than taping it and printing the later stuff earlier on the tape for later playback.

Even DSP techniques cannot see the future, and so cannot do true tape reverse in a live situation.

What you *could* do is a better faking job. You could produce a pedal that would read in and store a snippet of real time, say about maybe four beats of a song, then play them out backwards, with the samples coming out Last In, First Out (LIFO) or time reversed. While the pedal is playing out the previous snippet, you could ignore the playback that's going on and play into the pedal the next snippet. This would require some real skill on your part as a player to pre-concoct the stuff you'd play to be time reversed in segments as you played so that the delay/LIFO pedal would reassemble the snippets into what got heard correctly. It would be a bear to design, and very difficult to play.

[puretube]

"what happens, when switching between 2 diff. delay-times
very fast, and with varying duty-cycle?"

So, lets say I play 2 notes on the guitar. During the first note, the delay is long (1sec). And I play the second note, maybe 0.3 seconds later, with the delay time at 0.3 seconds.

Tada, the 2 second note is "played" by the bbd at 0.6 seconds and the first note at 1second. reversed!
Han

close, but only a cigarillo -
your first note would -after having been read in with the purpose to stay in memory for a second- be accelerated after 0.3sec of time, and be spit out at triple pitch, before the second note (at normal pitch) would become audible; and: the notes themselves would still sound "forward".
You almost described the analog pitch-shifter (whammy).

Things become different, however, if you play the first note "A" into a first
delayline set for 1 second, and after that first note (let`s assume it is 0.1s long) is finished (and "hanging round" in the memory, waiting for about 0.9s to appear at the output),
you play the second note "B"(again 0.1s duration)immediately after "A" into a second delay line, which is set for 0.3s of delay:
the pitches stay unaltered, but the notes appear at the output (assumed you listen to both delaylines simultaneously) indeed in reversed order!

Still, the individual notes themselves however will "feel" sounding forward...

R.G.: don`t be afraid I wanna predict the future  
just wanna sample parts of the presence
(let no one hear it for a short while),
and then audibly play timeslices of that "presence"
back a short while later in reversed order.
It`ll be very similar to the backwards-tape sound.
(& the sung word "and" will indeed sound "dna", "stop" will sound
"pots").
("supercalifragilisticexpialigoric" might sound a little mutilated, though)...
:wink:

[R.G.]

just wanna sample parts of the presence
(let no one hear it for a short while),
and then audibly play timeslices of that "presence"
back a short while later in reversed order.

I think that's what I said.

[puretube]

yes, R.G.: sorry, I didn`t see the whole window of your reply,when I wrote the last post.

Of course, playing back a 3 min. song by swapping the tape direction will sound different than small portions.
But we got to agree, that nobody wants to wait for 16 seconds, or even 64, to get a backward-reply in a live-situation.
Concerning vocals, it all comes down on reversed syllables,
cc. guitar, the short single notes/chords are of interest.
Nobody wants to hear the reverse of a constant volume/pitch super-sustained 20 second note, which has no attack and no decay.

We`re moving in a kinda "TZF"-territory here:
no realtime effect can output the sound faster or earlier than it comes in -
but if you give the pseudo-realtime a liitle delay which nobody will notice,
you`ll enable the delayed signal a chance to catch up with it, and even pass it...

R.G.: these writings are not at all to teach you, but to give the readers some thoughts to tinker about...  

[sir_modulus]

anyone got the schematic for the dano fake-o rev. delay pedal (back talk or wasabi delay?

[sir_modulus]

hey!!! I made a thread that is popular and of some technical merit! congrats to me! And thanks to everyone who was patient and answered my question. To followup, i'll look for a danelectro schem for fake rev. delay, and when i get enough money i'll buy a DD-5

P.S. Who knows...by the time I save up enough for a boss pedal, someone would have already defied causality and i'd have a true reverse delay pedal!

LM 250+

[Peter Snowberg]

hey!!! I made a thread that is popular and of some technical merit! congrats to me! And thanks to everyone who was patient and answered my question.

Good show sir_modulus! Congrats to you from me too.

Take care,
-Peter

[travissk]

I would bet that the Dano pedals are digital in nature... while they might not use a proprietary IC, the build might get complex and there could be some DSP code you can't get to.

[rousejeremy]

I'm amazed nobody has reverse engineered a Backtalk pedal after all these years. It's a great effect.