slap back????

[doug deeper]

anyone know of an easy analog slap back schem?
i just want to mod it for "choppy feedback"
doug

[ExpAnonColin]

To do slapback, you're probably going to need a bucket brigade... and that just gets complicated.  Or, you could have a voltage controlled 555 timer that would emit a single click on the hit of a note, which would be too complicated, and sound pretty terrible.

But it would click back.

-Colin

[Mark Hammer]

A simple slapback need not be that complex, actually.  Obviously more than a simple fuzz, and there is also the matter of having the BBD/clock-chip combo, but if you have said components, there isn't all that much to it besides a dual op-amp for input buffer/splitter and mixer/output stage, a 2-3 pole lowpass built around a single transistor before the BBD, and another after.  Take a look at the datasheet for the  MN3007 or 3207, take a look at the BOSS BF-2 or CE-2 (and imagine omitting the LFO), and you'll get the idea.

A great many analog delays use companding to reduce noise, and fairly complex filtering (often as many as 8 poles of lowpass) but a lot of that is really intended to be able to produce large bandwidth repeats at long delays that will hang in there for more than one or two repeats.  A slapback, generally requires either only a single repeat or very minimal recirculation, and any sound quality issues are reduced since the "event" is over with so quickly.  Moreover, with long delays you get to hear the delayed version without the realtime version obscuring any sonic quality problems.  With a slapback, the wet signal takes a bit of a backseat to the real-time signal.

All of this is the long way of saying that you shouldn't mistake the complexity of what is needed to produce a decent analog delay at 300msec+ with what is needed to produce acceptable slapback at 60msec.

Tom Gamble used to have a schematic posted at an earlier version of his EFM site, but he took it down.  I thought it was a bit too simple, but even once you factored in a bit more lowpass filtering, it still wasn't all that more complex than putting together something like the Zombie Chorus.

[Ed G.]

anyone know of an easy analog slap back schem?
i just want to mod it for "choppy feedback"
doug

Does it HAVE to be analog? I love the PT-80 which sounds analog and can get good slapback sounds.
For even more simplicity, try FP's Rebote delay, which uses the same chip, but a simpler circuit, no companding, etc.

[doug deeper]

not really easy...so much as small....i have this silver tone w/ very little extra room....i thought it would be cool to through this in so i could have slap back then crank the repeats for feed back while my tone is clean.
doug

[LP Hovercraft]

Have any of you checked out the Danelectro Reel-Echo?  It does some gorgeous slapback like a tape machine pretty convincingly, but since it's digital, getting pitch bends out of adjusting the speed time is out of the question.

[puretube]

...who says that?...

[puretube]

...who says that?...   SORRY, double hit...




//www.puretube.com

[moosapotamus]

The PT2399 is digital, but does pitch-bending quite nicely. If you go to my web site, you can hear a few clips of me twiddling the delay knob on my PT-80. A little while ago there were some interesting discussions about adding an envelope follower and/or an LFO to the PT-80 to get some nice automated weirdness happening. I guess that might work with the Rebotes, too.

~ Charlie