Reverse effect, designing/ideas

[disto]

ok so this is something i have been thinking about for a while, i think its will be very difficult and im probably stupid for even asking and posting this here. but it might get some people thinking and im interested.

right the idea is to create a reverse effect similar to the danelectro talkback or the boss dd-6.

if you think about a recorded signal, the attack of a single guitar note is very short and the decay is very long. if you reverse the sample then the attack would appear very long and the decay very short.

so using cubase i took a sample, used some volume control to create a smooth long fade in and created a reverse effect.

my proposed design is as follows.

• you would need to detect when a note is played
• then this should trigger a fade in

i think you might be able to do this with a studio compressor but im not sure i dont own one so i cant test it out, i might try in cubase tomorrow.

well what do people think? any ideas how it could be done?

im sorry if i havent explained my idea that well if anyone is unsure just ask.
i made a little flash demo here showing the samples in cubase it shows the single notes and chord samples.
the first sample (highlighted in red play the sample forward then backwards) the second (in green plays the sample forward but using a volume fade in to create a reverse sound)
the flash sample player can be found at - http://distofx.co.uk/reverse.html

[sfr]

I believe this is what the Boss Slow Gear is supposed to do - fade in each note.  There's info and a layout for this at Topoppicione.  (I'm sure I spelled that wrong)  There's one at GGG as well, but the topoppicione one removes the Boss switching, making for a smaller board and allowing you to use any bypass method you wish.

For the "faux' backwards-ing, (volume swell) the best I've used was the attack/decay filter section of an Electro Harmonix HOG.  Although that pedal is rather pricey if that was the only thing on it that you wanted to use.  (But I think the rest of the pedal pays for the price of entry rather well.) 

Couldn't an adapted Dr. Quack type circuit do this effect in a simple fashion?  One where the gain of the op-amp stage is changed by the envelope follower part, rather than the changing the range of a tone control filter with it?

I'm unfamiliar with the Dano Talkback, but the DD-6 is a delay, and achieves it's backwards effects by actually reversing the audio played back by the delay, doesn't it?  Which inhibits the "live" effect, and also makes it difficult for the DIYer to achieve (at least, the DIYer used to working in the analog realm) 

Honestly, for almost anything I'd want a "backwards" effect live, I can accomplish it with a volume pedal, unless I was singing. 

[disto]

great i will have a closer look at the slow gear do you know if there are any audio samples anywhere?

[RaceDriver205]

One day when I finally order from smallbear, ill complete my Attack/decay device. I forget who its by its been so long. Apparently it does just what you want. Ah, string damper was what it was called.

[Paul Perry (Frostwave)]

The main problem, as I see it, is detecting exactly when you want to 'reverse'.
Same as when you are trying to decide when to do the dividing, in an octave-down circuit.
*IF* you can decide when the attack occurs, then you can make a reverse soundign device by
1. compressign the signal
2. generating an envelope (slow attack, fast decay) whent he attack occurs
and 3. using the envelope output to control a voltage controlled amplifier to impose the 'reverse' envelope on the compressed signal.

Maybe a footswitch (quick acting momentary, not a heavy duty thumper!) could be used to trigger the envelope.

[sfr]

Ran across this when I was looking for some other info today. 

I don't really know exactly what it does - but the name makes it sound like it might be something similar to what's being discussed here; and it's certainly easy enough to breadboard up. 

[disto]

hmmm yeah thanks sfr that seems promising i think i need to do some serious breadboarding soon.
surly using a footswitch to trigger ther envelope would mean you would either need to be very good at when you trigger it (ie. not to early or late). how do effects such as the Dr Q or compressors trigger. couldnt i use a threshold to set the sensitivity and trigger the attack decay circuit?

[dr]

.....I'm going to try to put together a knock-off of the DanElectro reverse pedal-the one I'm borrowing has the Princeton PT2395 and a ram chip (looks like a static ram)......doesnt look that difficult....(famous last words...).....I never could get the Attack Decay/String Damper to work right, or the Slow Gear clone, and this Dano  :)sounds pretty darn good for what it tries to do.....

[disto]

.....I'm going to try to put together a knock-off of the DanElectro reverse pedal-the one I'm borrowing has the Princeton PT2395 and a ram chip (looks like a static ram)......doesnt look that difficult....(famous last words...).....I never could get the Attack Decay/String Damper to work right, or the Slow Gear clone, and this Dano  :)sounds pretty darn good for what it tries to do.....

wow that sounds good dr will you let me know how it goes?

ive never actually heard the dano or infact any of the volume swells would you be able to send me a audio clip of the dano?

i opened my Dr q to try and see how the filter was triggered but haven't had much luck yet. slightly off topic the Dr q has no connection to ground on the mono out socket, i thought this was weird. anyone know why? doesn't the out need to be grounded?
my thinking was if i could work out how the Dr q triggered the filter then i could get it to trigger the attack/decay string damper circuit mentioned earlier but if Dr said it wasn't very good maybe thats not such a good idea. has anyone else got that or the boss sg-1 to work? i think i found a circuit for the sg-1 on buildyourownclone http://www.buildyourownclone.com/swell.html

[JimRayden]

i opened my Dr q to try and see how the filter was triggered but haven't had much luck yet. slightly off topic the Dr q has no connection to ground on the mono out socket, i thought this was weird. anyone know why? doesn't the out need to be grounded?

Use the enclosure, Luke...

----------
Jimbo

[RaceDriver205]

my thinking was if i could work out how the Dr q triggered the filter then i could get it to trigger the attack/decay string damper circuit mentioned earlier but if Dr said it wasn't very good maybe thats not such a good idea. has anyone else got that or the boss sg-1 to work?

Im told they both need practice to play them properly. I wish id get round to getting parts from smallbear, then I could tell you first hand.

[Mark Hammer]

I've posted this before, but it warrants repeating and I'm too lazy to look for it

Normally, when you pick a note, the harmonic content occurs at the outset, when the most energy is put into the string.  Very shortly thereafter, the inertia of the string itself, plus what the bridge and body do, result in much of that harmonic content disappearing.  The string itself also threatens to stops vibrating completely, so we facilitate the continued vibration`movement with our fret fingers, introducing varying degrees of finger vibrato.

So, authentic "reverse" effects, done in analog, need to accomplish three distinct tasks:

1) Produce a ramp-up volume effect, analogous to a string fading out; something done already by the Slow Gear, PAiA Gator, and other units.

2) Shift the brunt of the harmonic content to the *end* of that ramp-up to simulate the brief sputter of pick attack.

3) Introduce some vibrato at the onset that fades out shortly thereafter.

That's a pretty tall order, but nonetheless necessary for *convincing* tape reverse effects.

[Jaicen_solo]

Actually i've thought about this a lot, because I use this type of effect quite often.
Racedriver, the device you're thinking about is indeed called the Attack Decay. It was a project published by E&MM (I think Mr Hammer has the scan, at least that's where I got my copy). FP did an improved layout for the design which was up at Tonepad for a while, but it disappeared.
I myself planned to build it, and got so far as buying the parts but then I bought a Flextone amp with the reverse echo effect, which pretty much solved all my problems

To address some of Mr Hammer's suggestions:
1: The ramp up is pretty easy to achieve using an envelope detector, but it needs a much longer ramp up time than a typical env filter to sound convincing.
2: When a guitar string is plucked, it produces an assortment of odd and even harmonics, over time this decays to even order harmonics.
I suggest that it may be possible to imitate this using a high threshold distortion device. Basically, as the output increases toward maximum, it starts to clip. Obviously this would take a lot of fine tuning but it could produce the desired effect.
Alternatively do what danelectro did and just add a burs of white noise at the end of each envelope