Ry Cooder Green Man

[Helmholtz]

I think the only way to provide identical but opposite phase signals is to use a PI or a transformer.

[Chuck H]

I think the only way to provide identical but opposite phase signals is to use a PI or a transformer.

The PI works but still has the consequence of high output impedance. It's fair to assume that there could be some cable length from the unit feeding the amplifier inputs. I saw an image of Ry Cooder's pedal board and the "green man" is right there on the board (for some reason I don't understand). This is why I think the transformers, probably driven by cathode followers, is the most likely.

[Chuck H]

I think the only way to provide identical but opposite phase signals is to use a PI or a transformer.

Also... These are not intended as opposite phase signals at each output necessarily. Each output has a phase reversal option.

[Helmholtz]

Also... These are not intended as opposite phase signals at each output necessarily. Each output has a phase reversal option.

You can't simply reverse phase with an unbalanced (ground referenced) output using a switch.

Rather each channel must provide identical in phase and out of phase outputs.

I don't think an output/source impedance of maybe 30k should be a problem here.

[Chuck H]

Ok. I just saw a FB post from Shaw Audio where they had one of these things come into the shop. Not much revealed other than it does seem to use transformers for the outputs.


This unusual device came in the shop this week. It is a 2 tube guitar preamp with dual transformer isolated outputs (phase switches on each output), built in an old variac transformer housing. This one belongs to Ricky Skaggs and is nicknamed "The Gray Man". the only other one in existence belongs to Ry Cooder and is called "The Green Man" . Used for driving two two amps and controlling the volume simultaneously with the large knob on top. Also has a tone control on the side.

This post was in 2015. I've since seen another one of these, so that makes three that we know actually exist. It's also reported by a response in this FB thread that Ry Cooder has another similar unit designed to operate four amps but I can't confirm this.

[blind Blake]

Ok. I just saw a FB post from Shaw Audio where they had one of these things come into the shop. Not much revealed other than it does seem to use transformers for the outputs.


This unusual device came in the shop this week. It is a 2 tube guitar preamp with dual transformer isolated outputs (phase switches on each output), built in an old variac transformer housing. This one belongs to Ricky Skaggs and is nicknamed "The Gray Man". the only other one in existence belongs to Ry Cooder and is called "The Green Man" . Used for driving two two amps and controlling the volume simultaneously with the large knob on top. Also has a tone control on the side.

This post was in 2015. I've since seen another one of these, so that makes three that we know actually exist. It's also reported by a response in this FB thread that Ry Cooder has another similar unit designed to operate four amps but I can't confirm this.

Ricky Skaggs had the grey man and by all accounts there are probably now 15 or so built.

[blind Blake]

The PI works but still has the consequence of high output impedance. It's fair to assume that there could be some cable length from the unit feeding the amplifier inputs. I saw an image of Ry Cooder's pedal board and the "green man" is right there on the board (for some reason I don't understand). This is why I think the transformers, probably driven by cathode followers, is the most likely.

The green man is there so when Ry changes guitar he can compensate for that by turning the dial on the green man which of course is the master volume for all 4 amps. it also fattens the tone and essentially is a boost which pushes the amps input a little.

[blind Blake]

Rys setup is feeding 4 amps

[blind Blake]

From Ry Cooder: "I call Green Man. It's a little device that looks like a Variac [variable transformer], but it's a stereo conversion thing. So the guitar goes in mono, and comes out stereo, with tubes and transformers jammed up inside it—it's like something NASA made. It has phase correction in it, too. But on top is this great big volume knob, so if a guitar is low power, let's say, you can turn it up. If your guitar is too hot, you can turn it down. So you have a lot of control over the game.

Then that goes into two amps, and the trick is to find two that sound good together. And not just two amps, but a setup that gives you a summing kind of effect. Suddenly there's an expansion, a harmonic richness that you can get, but you have to have the right combination, and then it can't be too loud for the room. So I use little amps—they're pretty small, but they sound good this way. On “Shrinking Man," for example, I used a tiny little Gretsch Artist and a '56 Fender Super that gives you a real nice, almost hi-fi sound.

But the Green Man is the answer to everybody's prayer. I used to have a hell of a time with amps and electric guitars, because they were always so strident and brittle and loud. There was always that one speaker blasting away and yelling at me! I couldn't stand it, and then finally, Danny McKinney, who's a friend—he makes the retro Standel amps—I told him, “This is what I need. Can you do that?" He says, “Oh, sure." So he made this thing, and it's the answer. I use it onstage, I use it when I'm at home, I use it in the studio, and it's an incredible device. To get a big sound, and spread it out so it's not so pointy and not so goddamn insistent—it just sort of fills the space up and you can really deal with these low-power guitars that have a sweet sound, like say a Premier or a funny old Teisco. Nobody had ever heard the richness of these instruments before, because they always play them through an amp that's hitting you over the head. Now, I get this harmonic content coming out of these funny old electric guitars. That finally opened it all up for me.
"

[Chuck H]

But the Green Man is the answer to everybody's prayer.

I used to have a hell of a time with amps and electric guitars, because they were always so strident and brittle and loud. There was always that one speaker blasting away and yelling at me! I couldn't stand it,..

and then finally, Danny McKinney,.. made this thing, and it's the answer.

I use it onstage, I use it when I'm at home, I use it in the studio, and it's an incredible device. To get a big sound, and spread it out so it's not so pointy and not so goddamn insistent—it just sort of fills the space up and you can really deal with these low-power guitars that have a sweet sound, like say a Premier or a funny old Teisco.

Nobody had ever heard the richness of these instruments before, because they always play them through an amp that's hitting you over the head. Now, I get this harmonic content coming out of these funny old electric guitars. That finally opened it all up for me.
"

I broke it down so it could be digested more concisely. This is clearly a "preamp". It allows for a hotter preamp sound to be fed into amps that aren't turned up to loud levels. Or are, but the Green Man output is turned down (you'll notice that in all pics Ry has it set low). There are similarly vague descriptions offered by Dan's Gear Depot who it seems has (or had) one for sale and characterizes the tone control as being able to increase the gain like a tweed amp (which they really don't do). And a lot of floral subjective terminology.

https://reverb.com/item/53767444-req...ry-cooder-2021

No one has ever said what this thing actually does without using subjective terms like "get a big sound, and spread it out so it's not so pointy and not so goddamn insistent" or (from the Gear Depot FB site) "As an attenuator/boost/EQ to match different guitars to an amp or amps" or "As a splitter to enhance/smooth a two-amp setup". Well it's certainly not an attenuator for any amp you plug it into because you can't attenuate an amps output from it's input. Though this seems to be what's implied in some subjective statements.

So this is a preamp. You can't make a non master volume amp sound big while it's quiet by adjusting the level at the input. So the Green Man is making the harmonics and dynamics on it's own and feeding this to the amps it's plugged into. (<period) How it's arranged is anyone's guess without better descriptions or an actual schematic.

What's reported is that:

It's the answer.

It has a big sound that is spread out.

It's not pointy or insistent.

It's an attenuator.

It's a boost.

It's an EQ.

It enhances and smooths.

It allows you to hear the richness of cheaply made vintage guitars.

$5000 seems cheap now.

[blind Blake]

It's the answer to the ultimate question of life, the universe, and everything, I'll take 5 of them!

[Mick Bailey]

A question arises over the output transformers, as their spec could have an influence over the tone.

[Helmholtz]

"As an attenuator/boost/EQ to match different guitars to an amp or amps" or .....".

Strictly speaking any voltage divider ( a vol.pot is typically wired as a voltage divider ) in the signal path is an attenuator.
My guitar volume is an attenuator as well and even allows to attenuate amp power output down to zero.

So in this context attenuator should be understood as the opposite of boost.

[Chuck H]

Strictly speaking any voltage divider ( a vol.pot is typically wired as a voltage divider ) in the signal path is an attenuator.
My guitar volume is an attenuator as well and even allows to attenuate amp power output down to zero.

So in this context attenuator should be understood as the opposite of boost.

I understand and agree. Above I was pointing out that in most commentary regarding these devices it's inferred that it gives the amp more harmonics and a richer tone at lower volumes. Which, of course, it doesn't. The amps are doing what they always do at lower volumes and it's this preamp that is generating the "harmonics" and "richness". Turning the preamp down does attenuate signal to the host amps. So this is accurate.

[Chuck H]

Apparently a picture of the insides of one of these exists. This is a post from The Gear Page. That might help a little. Maybe not because the nature of the build would make it impossible to see routings accurately.