Doubling pedal

[cheeb]

Does anybody know of a pedal that doubles the signal so it sounds like two guitars playing the same thing, like when you double tracks in a recording? I'd like it to be compatible mostly with acoustic guitar, so I guess low impedance would be key (?). Not really an octave or drone so much as doubling. Any ideas or existing layouts?

[aron]

Most times, I have heard double-tracking effects done with a very short delay and modulation. Otherwise, if you want a sound to play in harmony, you get a harmonizer pedal. Another way is to get a looper pedal which will record your guitar and play it back.

[jonathan perez]

super short delay, pan it to the left/right.

[cheeb]

Harmonizing with a looper would be ideal, but I'd like real-time doubling, if it's possible. It's the dynamics that I'm most worried about. Unless I pre-record the segments that I want doubled on a looper and then hitting it, jumping into doubled parts immediately from an undoubled part won't work. It's mostly for coming out of a strummed part into single-note doubled parts. Thanks for the help and the insanely quick reply! Is this Stompbox Instant Messenger?  

p.s. Which delay is short enough to not sound like slapback?

[Barcode80]

that's an easy setting, just set the delay time on your favorite delay to minimum, then play and while playing raise the knob just until you can tell there is delay there. PRESTO!

[cheeb]

Sweeeeeet. I pretty much love you guys. 

[darron]

you might also want to use the delay loop to give the mimic guitar a little bit of difference, like give it a slightly different tone. if you don't have a loop on your delay then just find where the mimiced signal comes out and use a cap/resistor combo to take out some bass or treble?

[d95err]

I'd like it to be compatible mostly with acoustic guitar, so I guess low impedance would be key (?)

Low impedance where? Input? Output?

If you want to plug into a balanced low-impedance mixer input, it's probably easiest to get/build a separate DI-box.

[Mark Hammer]

What people mean by "doubling" can vary from person to person, but one means to achieve something that sounds a bit more like two musicians doubling parts is a chorus effect with a little more delay time.  Most floor-type chorus pedals don't aim for more than maybe 20msec delay at maximum.  If you extend that a bit more (and cut back on the depth to keep it from being wobbly-sounding), it starts to be more like doubling.  Think of the classic Pat Metheny sound.

On most chorus pedals you can do this by locating the clock chip (an MN3101 or 3102), identifying the clock range-setting cap (usually something snuggled right up against the clock chip and in the range of 500pf or less), and increasing the value by 30%-50% or so.  So, for instance, if the existing value is 150pf, consider tacking on a 75pf cap in parallel on the solder side.

The downside to this is that pitch-wobble becomes much more noticeable at longer delays so you will need to cut back on sweep depth a lot. Hopefully the control on your pedal permits this.  The other potential downside is that slowing the clock rate also brings the risk that the clock pulse (whine) will become more noticeable.  Normally the filtering on a chorus is setup to permit the most treble possible before the whine becomes audible, and slowing the clock may bring it under that corner frequency.  You'll see when you get there.

[R.G.]

I remember reading something, maybe a JAES article, that said that the short delay made a more convincing doubling if you fed it a clock LFO that was irregular, like lowpassed  noise, not a normal LFO sweep.

[Mark Hammer]

Aperiodicity is the name of the game, I suspect, when it comes to convincing chorusing and doubling.  I have to say that my home experiments with two cascaded choruses persuade me of this, in addition to whatever is documented in JAES.  The modulation source does not HAVE to be an LPF noise source.  That's merely one among many aperiodic sources.  A couple of unsynced LFOs can probably suffice too.  The key thing is that pitch-goes-up-pitch-goes-down-pitch-goes-up-pitch-goes-down is NOT what you want to be able to hear easily.

I might point out that the counterswept BBDs in the Boss DIM-C result in something that seems to not go up and down (even though it does...just in opposite directions), and that's a big part of why people rave about it.

[Fp-www.Tonepad.com]

the key thing is that pitch-goes-up-pitch-goes-down-pitch-goes-up-pitch-goes-down is NOT what you want to be able to hear easily.

Would a stepping CV controlling delay time work better? not modulating in the sense of an LFO sine/triangle or a combination wave would do, since the pitch shift happens when the delay time is changing gradually, right? why not make it an abrupt change 'a la square wave', with different amplitudes setting delay times but not changing gradually, I can see this happening with a PT2399 I think.

Does that even make sense?

[Mark Hammer]

It makes sense, but is not lilely what the doctor ordered. or else would require some changes that ultimately make it little different from a smoothed noise source or dual asynchronous LFO (or from something like a 40106 set up to provide multiple unsyned medium-slow LFOs to be summed together).

I think the goal is to have smooth changes in delay-time (and pitch) that are hard to notice.  The hard to notice aspect comes about in 3 ways: 1) small changes, 2) gradual changes, 3) irregular changes.  A stepped arrangement would certainly provide a valid and interesting musical effect, but if the goal is to sound like a double-tracked instrument/vocal, stepping won't mimic all that well.