How does a...

[Paul Marossy]

delay pedal convert a mono signal to a stereo signal? Does it just divide the signal in half and send it out each input, or is more complicated than that?
I've only dealt with mono stuff so far, I want to mess around with stereo imaging a little bit, but I want to understand exactly how it works first.
Also, if you have two stereo delays, what is the best way to route them to an amplifier? I'm thinking the FET Blender circuit I built a little while ago would work well for this kind of situation.
Any opinions, advice? Thanks!  

[Paul Marossy]

Oh, I forgot to mention that I want to use both delays, but not at the same time. But I want to route them through one device to an amplifer...

[downweverything]

i believe its more like two delay circuits off one input.  the left out should be a little different then the right out to create a stereo space.  lots of times its just an offset difference making one delay signal come slightly after the other.

[Nasse]

Old reverb, phase, chorus and flanging fake stereo trick is delayed signal panned hard at right stereo channel and same signal but inverted (opposite phase) panned at left, or vice versa. But I doubt this does not work for longer delays. Maybe ping-pongin between channels or two different delays for each channel is what works. Just loaded few VST soft techno synths with this kind of delay. Long delays can sound killer in mono too, listen to old Shadows records.

I have been planning a simple stereo system for regular guitar amp (mono). For my idea you need few things: 1.) Put your guitar amp line out to a digital reverb with realistic enough room simulation stereo program. 2.) Two "satellite" speakers, perhaps two small guitar speakers in small enclosures, placed at left and right side of listening situation. Connect speakers in series, but another in reversed phase. 3.) Power the speakers with mono amplifier. 4). Feed the mono amplifier with difference of left and right channels of digital reverb. 5) Adjust volume as you like

I have not tried this but if digital reverb is "good" enough it will work well. Or so I believe. Good luck

[Nasse]

Oops I have had too long day at work today. If I remember right pseudo stereo for two channels is sometimes made by summing straight signal and delayed signal for right channel, and left channel is made by subtracting delayed signal from straight signal. Not very clearly said but anyway.

But my second idea is another story. :roll:

[Paul Marossy]

I was thinking that it may be a pseudo stereo circuit, something that would fool the human ear into thinking that it's a stereo image...

[Rob Strand]

>delay pedal convert a mono signal to a stereo signal?

It actually doesn't do that.  What it does is perform the modulation (or whatever) such that left and right channels are done differently, and in such a way what produces a pleasing result to the ear when listened to on a two channel (ie. stereo) system.  So it's really a "scheme" which sounds good.  It's worth pointing out that some of those schemes don't sound so good with head-phones because the left and right signals are isolated and don't combine like they do with speakers in a room.

For chorus units a common method is to output the dry + delay on one channel and dry- delay on the other - with this method there is no chorus when you *listen* on a mono system because the opposite delay phases cancel!  An alternative method is to put dry into one channel and delay into the other (this solves the mono problem).  However, this method doesn't sound good on head-phones - you have pitch shift in one ear and dry in the other.  Yet another scheme is to use separate delay units for each channel.  In this case the each output is generated using dry + delay but  the delay part is generated from different delay units.  The modulation for each delay unit is such that the pitch shift is upward on one channel and downward on the other channel (and visa versa).  The extra delay and more complicate LFO means you usually only see this in digital effects.

[moosapotamus]

... An alternative method is to put dry into one channel and delay into the other (this solves the mono problem)...

If anyone's curious to know exactly what this kind of pseudo-stereo sounds like, give a listen to the Wavy Gravy. I recorded a few stereo clips. They're posted on my site. Sounds pretty good, IMO.

~ Charlie

[Nasse]

This answer is about original question, what makes it tick? Another technique that has been used for "pseudo stereo" for two speaker channels is band-pass or comb filtering. Different frequency bands are attenuated or allowed to pass, so that responses are about opposite in each channels. It probably works for full mono mix multi-instrument tracks, instruments that have different freq range are heard more or less in left or right speaker. But dont know if this works for solo instrument. But phase sifter is indeed a "comb filter", so it can be used instead of multi-channel band pass filter.

Elements are the same, sum and difference, phase and delay.