Anyone know a reverse delay schematic exists?

[sir_modulus]

Anyone know where i can find a reverse delay schematic, you know like the ones used in "Castles made of sand" and "Give it away" (Hendrix and RHCP respectivley)? If possible one that is buildable and is not like 15 parts with digital Cmos chips everywhere?

[Mark Hammer]

There are certainly devices that can do the slow buildup thing, such as the Boss Slow Gear, the PAiA "Gator", and the E&MM String Damper (#1 and #3 areposted around).  A true reverse-tape sound is considerably more complex, however, since things that happen at the start of a note need to be relocated to the end of it.

Several of the more recent digital delay pedals, such as the Boss DD-5 and DD-6 can do it simply by dialing up the effect, and there are mods posted around for getting earlier DD pedals to do it.  Either way you slice it, though, you'll need digital technology to achieve a true reverse effect.

If the cost is prohibitive, there is always your pinky and volume control, though....

[puretube]

there is an analogue way, too - but it will take a whole lotta parts,
won`t be diy-friendly, and ask for a handfull of BBDs
- and schematics probably won`t be available -  :wink:

[loki]

by the way the solos in "give it away" are recorded straight and then put backwards on tape.... so it's not a reverse delay i'm pretty sure of it
so is Are you experienced? by hendrix.... don't remember well castled made of sand, but i think it's post processing as well, i don't think jimi had such a pedal in his arsenal

[puretube]

yes, the hendrix-era was tape-stuff...

[Phorhas]

http://members.shaw.ca/roma/attack.html

Never tried it myself but it seems interesting

[Mark Hammer]

Familiar with the unit, though I haven't built it.

Certainly, the most noticeable thing about a plucked guitar note is that it starts out with a big transient and then fades out, so it is not surprising that units which fade/swell the volume in are used "as if" they were tape reverse units.  But if you think about it, a lot of what takes place to produce the sensation of things going backward are missing.  Here's a partial listing, in no particular order of importance:

1) Any finger glisses on the wound strings as you move to the next note need to be relocated to the start of the "reverse"
2) Normally, harmonic content is richest at the start and decays over the lifespan of the note, meaning that the treble needs to increase in "backwards mode"
3) A plucked note, when reversed, should not only fade in but end abruptly.  Volume-sweller effects can allow for somewhat of an abrupt ending, if they gate (e.g. the PAiA Gator), but chances are good that there is still somewhat of a decay cycle before the note amplitude is low enough to gate off.
3) No pick attack is heard anywhere, including the slight pitch deformation as the pick pushes the string, the clicking of the pick on the string, etc.
4) Finger vibrato generally occurs at the end or decay cycle of the note.  True reverse puts it at the start, such that the string pitch gets more "stable" as the (true) reversed note is played (up until the moment that the pick deforms the string)
5) While not as strictly monophonic as octave dividers, swell-pedals will not handle multi-pluck inputs well.  The Initiation of a swell-cycle has to be a clear. single starting point.  True reverse permits cascaded notes.  So, you could gently strum upwards on a chord on your Gretsch (highest notes first) and the order would be reversed in true reverse.  A swell pedal would requirea single, uniform strum without any perceptible change in note order occurring.

As noted, this is a partial list, but it gives you some idea of the aural "cues" used to perceive an acoustic event as reversed in time.  That is not to say it is the be-all and end-all of reverse effects.  What many may actually want is not the sensation of things going backward but simply a very consistently muted attack for flute-like sounds, something which is just as musically valid as a reversal.  Just don't kid yourself that anything other than either tape going backwards, or a digital sampling that can be played back in the reverse order it was sampled, will create a strong impression of a reversed acoustic event.

Having said that, I'm surprised that no sweller pedals have ever taken the simple additional step of fading in treble along with volume, or the option of fading/diminishing a vibrato effect as the note-event plays out.

The Electro-Harmonix Attack-Delay effect WAS a very complex unit, but a lot of that involved improving the reliability of detecting note presence and not "missing" things.  The unit shows a BBD (MN3007) in the schematic, but this is not for playing an analog sample in reverse (which you can't actually do with BBD's because they are not randomly adddressable like RAM).  Rather, it is for delaying the audio portion a small amount so that by the time a "decision" has been made to swell the note the audio portion has not gotten too far along.  The same process was traditionally used in many of the old click-and-pop removers for vinyl discs to permit better noise reduction without deforming the sound too much.

[Bill Bergman]

Puretube,
what BBD's would it require to make an analog version. Is there a schematic or is it just in theory?

[puretube]

any BBD...

the schematic is in my head and on sketches...
parts of it are finished...
it`s based on a tube-thing (of course) by H. Dudley ("Mr. Vocoder"),
who used capacitive storage disks (principally similar to the oil-can-delays), and dates from the late `30s..., and the theories of a certain mr.
Applebaum iirc.....

>move your delay - the time will follow<

[Bill Bergman]

To bad we can't see inside your head :shock:

[Mark Hammer]

Ton, I assume you're talking about a reverse emulation and not an actual reverse.  Unless you have access to stealth technology that the rest of us don't, I know of no way to take the FIFO structure of whatever sample passes through a BBD and make it go in the opposite direction.  That's not to say it couldn't *sound* pleasing or inspiring, but given the many distinctions between a sound that is actually played back in reverse to how it occurred and the many ways in which aspects of that could be mimicked, I think you may need to spell out a little more clearly what part of the "reverse sound" territory you plan to carve out.  No "state secrets", just a better sense of what aspects you won't cover may well be enough.

If there is a BBD involved, my guess is that somewhere in there is a plan to derive information about the "timbre-map" of the incoming signal and "re-map" it in reverse.

[puretube]

i call it:
>time multiplexed scanning<

(sorry-I`M in a terrible mess at the moment: while I was answering to the "Safety-backup-thread, the PC crapped out on me: black screen - eek)

[Bill Bergman]

"time multiplexed scanning"  ahhh.... the old TMS.... that makes sense.

[Peter Snowberg]

:? time multiplexed scanning? I'm still in the dark as to how you can get backwards out of a BBD. Any enlightenment please?

Take care,
-Peter

[puretube]

soon....
1stly, gotta get rid of this pc-sh*t...  :evil:  :evil:  :evil:

[Bill Bergman]

Puretube,
make sure you have the latest windows revision updates on your PC. My wife's pc crapped out last week due to viruses and out of date security measures.

[puretube]

I`ve been wondering, that my McAffee didn`t offer an update
(on my "trouble-PC", win98SE with relative fresh updates)
for the last 7 days;
the PC I`m writing this with my new laptop(winXP) bought sat. - updates on sunday, Norton-stuff from yesterday, doesn`t show abnormalities yet  :lol: ;

"fun" thing: the other PC crapped out while responding to the back-up thread immediately before I wanted to unpack&install my new USB 160GB
storage-device (bought half an hour before) for safety-backup purposes;

other fun: changed my forums (various) email-notification addresses last night (to eventually find/filter out where the spams originate...);

greatest fun: while that happened, I was burning an "absolutely most important data" DVD on this laptop with stuff from the other PC, that I had only copied this very morning!!! (to take with me for my little 1 week
holiday-trip...).
Of course all triple virus-scanned, and including all mails...

sorry, got to finish my tax-declaration by tomorrow...


btw.: before I forget what this thread was about:
be aware, that time is being sliced in BBDs...   :idea:  :?:  :idea:

[puretube]

oh yes,
and does somebody remember the question I posted a little while ago:
"what happens, when switching between 2 diff. delay-times
very fast, and with varying duty-cycle?"

that was related to this topic, and even has some close resemblance with the argueing we had with Z.Vex recently, cc. phase-transition/movement/splitting/reversing/shifting.....

[puretube]

oh, and Mark:
remember you have a great schem. in your archives,
which can generate double/half frequency (don`t remember the name - some Japanese "harmonizing" circuit with 3 BBDs, producing glitches, however...) ?

That one also needs to know in advance, what to playback twice as fast as what came in...

>know what and how you chop when coming in,
remember where you put it (when), and know when
(where and how), to spit it out<

[travissk]

The Line 6 DL-4 (and Echo Pro if you're into rackmount) do reverse delay, as do the Boss units. If you're into digital stuff, you could use some sort of a microcontroller or DSP chip. It's probably easier just to buy the effect than to go the digital route however; here's some units that do it if you're in a hurry:

Line 6 DL-4 and Echo Pro
Boss DD-5
Digitech Digidelay
Danelectro Back Talk reverse delay
Danelectro Wasabi delay (these two Danos might not be great choices, haven't read any reviews and I'm looking to get rid of the 2 dano pedals I own)
Various rackmount units.

On all the RHCP stuff I've seen (I have two live DVDs it's on) and heard, Frusciante just plays a solo without any delay... and he has a DL-4. I want to eventually get a DL-4 or Digidelay, but I can't imagine it would be easy to play reverse solos live. Sounds cool, though