Robert Cray's Magnatone Stereo Vibrato sound...

[roseblood11]

Is there any info about the vibrato pedal that Robert Cray uses on stage these days?
He used an old stereo magnatone amp on the record, but his technician built a pedal to replicate that sound with his two Matchless Clubman 35 amps:

Matchless. Clubman 35. I use two of them and then on stage, my guitar tech made something that's actually the exact same unit as the Magnatone stereo vibrato, and so I can run the two amps when I use that effect, it goes from speaker to speaker, side to side in stereo. Before the Matchless I was using Super Reverbs, I like the 4 x 10 inch speakers. See, people talk about guitars, but I like amplifiers. I'd collect amplifiers if I could. I have a lot of Fenders and whatnot. But that's what I like for sounds, I think that's what keeps you in pretty good shape.

(source: http://www.guyguitars.com/eng/interviews/RobertCray.html )

[electrosonic]

No info for your question. Nice sound and great playing. Do you think it is one take?

Is it just me or does the pickup selector move between camera edits between the 2:54 and 2:59 minute mark?

[Kipper4]

Might not be of use but I found this

http://www.lynx.bc.ca/~jc/stereoVibe1.html

[Lurco]

This maybe? http://www.vibroworld.com/news/vol1i1.html  http://www.vibroworld.com/product.html#vib12

[Kipper4]

Theres got to be something like it out there

http://www.youtube.com/watch?v=QOu3Fm6z1XQ

[midwayfair]

I'm pretty sure the old Mangnatone schematics are available on the internet, we could probably come up with something worthwhile.

There's nothing super unusual about the setup compared to other phase shifters; the main thing is that it's stereo. The amp used varistors, but that doesn't mean you can't duplicate the function of them with LDRs or FETs.

Also, something to keep in mind, there's far less pitch shifting out of the real amp (at least the 112) than out of most pedals that claim to copy it when you're in the same room.

The Other Forum has traced multiple circuits that aim to recreate this sound.

[Mark Hammer]

There are a couple of dimensions of "stereo vibrato" to juggle:

• whether "stereo" implies one side vibrato and the other a non-modulated signal, or two channels being modulated
• if both channels modulated, whether they are synced, or modulated independently
• if synced, whether they are anti-phase or some other arrangement (e.g., LFO  outputs are 90 degrees apart)
• the amount/depth of modulation

My gut sense is that one moves closer to an "animated", rather than "seasick" sound if the two channels are either independently and lightly modulated, or modulated in a manner that does not result in a constant anti-phase relationship (i.e., always flat on this side when it's sharp on that side).

It hasn't been released all that long, but this strikes me as a great mod for the MXR Phase 99, that essentially has two P90 circuits that can operate independently and in stereo.  It can operate in series or parallel mode, synced to one LFO or modulated separately.  All that's missing is a dry-lift switch to get vibrato.  Pity they left that one off.

[duck_arse]

from mark's point 3 above, is there a simple way to shift an lfo output by 45 degrees instead of 90, and where on my keyboard is that symbol?

[midwayfair]

There are a couple of dimensions of "stereo vibrato" to juggle:

• whether "stereo" implies one side vibrato and the other a non-modulated signal, or two channels being modulated
• if both channels modulated, whether they are synced, or modulated independently
• if synced, whether they are anti-phase or some other arrangement (e.g., LFO  outputs are 90 degrees apart)
• the amount/depth of modulation

My gut sense is that one moves closer to an "animated", rather than "seasick" sound if the two channels are either independently and lightly modulated, or modulated in a manner that does not result in a constant anti-phase relationship (i.e., always flat on this side when it's sharp on that side).

It hasn't been released all that long, but this strikes me as a great mod for the MXR Phase 99, that essentially has two P90 circuits that can operate independently and in stereo.  It can operate in series or parallel mode, synced to one LFO or modulated separately.  All that's missing is a dry-lift switch to get vibrato.  Pity they left that one off.

It looks like it's just modulating two out-of-phase outputs of two 12AX7s, 180* out of phase:

http://www.magnatoneamps.com/schematics/magnatone_450.pdf

There are a bunch of other schematics on that site.

It's about 400% more complicated than the Magnavibe but not insurmountably so. It's a PSO, so that's easy. Heck, RG's harmonic tremolo circuit could be adapted to do something similar that would be closer to the amp. Or can we make a varistor work somehow?

Interestingly, one of the circuits that claims to duplicate this uses a dual-gang depth control. Just seems weird to me.

[samhay]

In some ways, it's not so different from a Fender harmonic tremolo.
It wouldn't be too hard to do a low-voltage tube version along the same lines as Rick's vibracaster.

[Mark Hammer]

from mark's point 3 above, is there a simple way to shift an lfo output by 45 degrees instead of 90, and where on my keyboard is that symbol?

. 
There are all sorts of quadrature LFO circuits out there, but they yield outputs at 90 degree intervals.  Personally, I've never seen anything at other than 90 degree intervals.  Not to say it couldn't be done; I just haven't seen it.

[midwayfair]

In some ways, it's not so different from a Fender harmonic tremolo.

The main difference is that it's out-of-phase stages, whereas the harmonic tremolo is in-phase stages. Though I can tell you that the end result isn't so radically different. Actually, if you lift the low-pass filter (like the "bright" mode in the Cardinal), they sound even closer. I can't tell too much of a difference between the bright mode on the cardinal and the blue warbler, for instance, and the Blue Warbler sounds incredibly close to the 1x12 Magnavibe at invisible sound studios.

[duck_arse]

from mark's point 3 above, is there a simple way to shift an lfo output by 45 degrees instead of 90, and where on my keyboard is that symbol?

. 
There are all sorts of quadrature LFO circuits out there, but they yield outputs at 90 degree intervals.  Personally, I've never seen anything at other than 90 degree intervals.  Not to say it couldn't be done; I just haven't seen it.

thanks mark. of course, when I say

45 degrees instead of 90

, what I mean to say is " is there a simple way to shift an lfo output by 90 degrees instead of 180?"

and where is my degrees mark, mark?

[Mark Hammer]

here it is.....45⁰

Not on your keyboard, but on the 2nd row of icons for posting, just above the "undecided" face, and below the centre-justified icon.

[R.G.]

thanks mark. of course, when I say

45 degrees instead of 90

, what I mean to say is " is there a simple way to shift an lfo output by 90 degrees instead of 180?"

There are several. But you're up against the old "Good, fast, cheap; pick any two" problem again. One really nice way to do this is to generate the LFO signal digitally with either a uC or two CD4017 shift registers, and simply generate them 90 degrees ( or any number of 1/16ths of 360) out of phase to start with.

One that will appeal more to the people here is to use a Dome Filter, which is a number of overlapping phase shift stages to generate two outputs, one shifted +45⁰ and one -45⁰ compared to the input. The two outputs stay at relative 90 to each other over a wide band.

[Mark Hammer]

All of which probably provides a stronger case for using two independent unsynced LFOs to achieve the desired aperiodicity.

Now I really want to get my hands on a Phase 99, although with that much stuff stuffed into a 1590B footprint, it will be SMD and largely unmoddable as a result. 

I guess I need to make one, eh?  (....after the Hyperflange  ).

[puretube]

from mark's point 3 above, is there a simple way to shift an lfo output by 45 degrees instead of 90, and where on my keyboard is that symbol?

"simple" shifted outputs-LFOs are in this forum...

if U got a "QWERTZUIOPÜ*" -keyboard, it`s the leftmost key in the 2nd row from the top, right beneath the "escape", when U use the
"capitals"-shift simultaneously...
non-caps-shifted, it is that one:  ^ , 2 keys left of the: " , which is the capshift "2" on named keyboard,
or in other words: left of the ONE, shifted...

[EDIT]: like this: °°°

[puretube]

just searched DIY-forum: "quadrature", by user: "puretube" ... & got this, a.o. ...

[midwayfair]

Can someone help me out and explain why we're discussing 90^o out of phase instead of 180^o?

[Mark Hammer]

Sure.  180⁰ is anti-phase.  So that when one side is at some maximum of whatever is being modulated, whether it be pitch or level, the other is at minimum.  With 90⁰ difference, what you get is one side essentially following suit with the other.  So, left is falling as right is falling and left is rising as right is rising, except lagging behind.  Although there is clearly a directional element to both, the over-here, NO! over-here, NO! over-here aspect to it is reduced with a phase lag, as opposed to phase-inverted relationship between the two modulation sources.

Make sense?

If you want proof of the shortcomings of 180⁰ difference, just see how long you can stand to listen to an Ibanez Flying Pan.  If you can put up with more than3-5min, you're a better man than I.