[barclaycon]

Still trying to gather info for this unit.
Some of the circuitry is similar to the RM68 noise gate and if I remember rightly there was some service data with this gate about measuring attack time and component selection.
Anybody have it ?
(I've got the schematic - it's the rest of the stuff I'm after).

[hobiesound]

hiya,

for all that don't have the roger mayer RM68 schematic :
http://www.schematicheaven.com/effects/rogermayer_rm68_noisegate.pdf

greetings,

Thomas

[dustbro]

I'm searching now for a unit to dissect.. the RM57 and rm58 I have access to cant really be poked and prodded like I want to do cause they are in use every day. Anyone have a line to one they are willing to let go?
Working on a layout ATM cause it's quite possible to slap it together and tweak around till I figure out what some of the mysterious trimmers do.

[barclaycon]

for all that don't have the roger mayer RM68 schematic :
http://www.schematicheaven.com/effects/rogermayer_rm68_noisegate.pdf
greetings, Thomas

Hi Thomas. Thanks very much for the link.
The actual information I'm looking for is the extra pages that came with the gate. The stuff about attack time and which components to change to drive a 600 ohm load etc etc.
Does anyone have that ?
It will actually be useful in trying to piece together the info for the RM57.

[Rob Flinn]

I used to have 2 or 3 diagrams for the RM58, but can't seem to find them.   I was trying to put it together on veroboard aboutg 5 years ago, but never got it finished.   I'll have a dig round if they are of use to you Martyn ?

[barclaycon]

Yeah. It's the stuff about attack time and component selection I'm after Rob.
I've got the RM68 noise gate schematic.
I used to have some of those gates but sold them a few years back.
Now the compressor, that's a different story.
Somebody has just told me that one sold recently for over $6,000 (!)

[dustbro]

Somebody has just told me that one sold recently for over $6,000 (!)

yup
perfect candidate for a clone.

[Biasrocks]

Somebody has just told me that one sold recently for over $6,000 (!)

I'm not sure if it actually sold for that amount but they were asking 6.6K for one.

Ridiculous.

But, you can ask anything you want.

I agree, another character compressor in the arsenal would indeed be sweet.

Mark

[barclaycon]

I'm searching now for a unit to dissect.. the RM57 and rm58 I have access to cant really be poked and prodded like I want to do cause they are in use every day.

Dan. Is it at all possible to check some of the transistors on one of those units?
(Might mean pulling out a card or two).
I think I've got a line of what most of them are, but maybe if I give you a list of what to look for....

[dustbro]

maybe if I give you a list of what to look for....

Send away! I'll definitely check it out

[barclaycon]

To bump this...
Dan (dustbro) - can you please PM me your email so I can send you the schematic with the data I have so far.
Peter (peterc) - can you do the same. I would appreciate your help.
If you PM me an address I will send you the info I have.
Thanks.

[barclaycon]

Quote from: barclaycon on June 11, 2009, 10:25:28 pm
maybe if I give you a list of what to look for....

dustbro wrote:

Send away! I'll definitely check it out

Dan, can you PM me an email address to send it to.

[analogguru]

So what about we are talking here now ?
The RM57, the RM58 (Compressors) or the RM68 (Noise Gate) ?

Looking at the guts of the RM57 presented here:
http://www.flickr.com/photos/daveygee/2918090546/in/set-72157607776991626/
there appears no big difference to the RM58 maybe a different transformer 120V/240V.

The driver-card design in the RM58 is definitely stolen from the HELIOS-console which itself is very well documented here:
http://recforums.prosoundweb.com/index.php/mv/msg/16023/0/928/0/
the same circuit was used by roger mayer in his octavio too.

I can´t see a big problem to figure out everything needed to build a clone of the RM58 with all of the available infos.  RM68 shoudn´t be a problem too.  A much better pcb including the driver can be easily done on a single-sided eurocard (160mm x 100mm) when there is enough interest.  Even the (insane) release switch can be replaced by a 10M potentiometer (I have enough of them).

@barclaycon
I´ll send you PM with my e-mail adress, maybe I can be of help.

analogguru

[barclaycon]

Well, we are talking about the RM57 and RM58 Compressors which, as you say, are essentially the same beast. The RM68 noise gate is mentioned because it has some similar circuitry and we are trying to find out the components used.
As has already been mentioned, Roger Mayer refuses to help in any way and I would not recommend contacting him as it is a very unrewarding experience!
The schematics available don't give any clues as to line-up, and some of the transistors are not identified.
So that is where we are right now.
Hopefully Dan can have a look at his unit and identify some of the parts.

Thanks for the RM57 pictures link - very helpful.
I notice that one of the 2N3820 FETs has a red mark painted on it which would seem to suggest it is a selected part. What the criteria is for that I don't know. It is the same FET as used on the noise gate and I remember some detail being given in the RM68 literature. That's why I was asking about it.

I think the release 'switch' was only used on the RM58. On the RM57 it was a 2M2 pot.
I didn't find the HELIOS  driver circuit you described.
Can't say that I see the similarity with the Octavia circuit (?).
Thanks for your help.

[analogguru]

For more info on the Roger Mayer Octavio read this:
Octavia History - Truth revealed ?
this:
Octavia Evolution courtesy of Roger Mayer
and this:
Roger Mayer Octavia Octavio
and look at the:
Tycobrahe Octavia schematic
and the
Roger Mayer Octavia schematic

This is the wrong Helios schematic where all came from:
http://vintageking.com/site/files/images/schem_V69-1973-2-Var-1.jpg

Here is the proof of my theory (scroll down for the handdrawn trace of the Tyco-enginieers):
http://wc6w.50webs.com/wc6wvint/index.html?fr411.html

(At least) during this period of time RM was nothing more than a solder-jockey.

I will try to find some time to draw a readable schematic of the RM58.

analogguru

[dustbro]

Should be getting the RM58 in the mail today. I'll give you an update shortly.

[barclaycon]

Thanks for all the info fellahs!

I can see the similarities with the Helios Line Driver - albeit opposite polarity.

Look forward to your findings Dan

[Biasrocks]

I came across this while searching for Mayer schematics

http://analogguru.an.ohost.de/193/schematics/RogerMayer_RM58-Driver.gif

Mark

[barclaycon]

Excellent stuff Mark.
Thanks

[analogguru]

I came across this while searching for Mayer schematics

http://analogguru.an.ohost.de/193/schematics/RogerMayer_RM58-Driver.gif

Mark

Ooops.... I really forgot that I put this already online..... I think that I am getting old.

analogguru

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