nicksense

The Version 9 Green Pre
« Reply #20 on: June 28, 2004, 10:29:28 AM »
Does anyone know if you could put 4 pre's in the box.  From the pics it looks like it might be a little tight, but still feasible.  If all 4 fit, is the PSU cabable of providing enough power?

Nick


HiString

The Version 9 Green Pre
« Reply #21 on: June 28, 2004, 10:37:03 AM »
Peter,

I'd definitely be interested in at least 2 boards, possibly more if you decide to make them available.

Not that I haven't made boards in the past, but at present there's just too many other things getting in my way.

ChrisO

 :cool:
"Humans are analogue beings"

"Digital information lasts forever......................or maybe five years.

Whichever comes first"

FredForssell

The Version 9 Green Pre
« Reply #22 on: June 28, 2004, 11:43:28 AM »
Does anyone know the appox date of the A.M.E.K/RN design?

I ask because the design is an advanced version of a design by Graeme Cohen (AES Preprint #2106) presented in the early 1990.  

The Cohen design did not include the creative use of bootstrapping to increase the common-mode input impedance and it used a slightly different scheme to set the operating point of the front-end diff-amp, but by and large it is the same as the Green.  I just wondering if Cohen is the orginator of this circuit, as I believe he is.

I know there are other manufacturers making preamps based on the Cohen circuit who made small modifications to it, but RN's mod of bootstrapping to increase CMZ, and then using common-mode choke and shunt caps to approx input transformer behavior is the only one that I'd call a really modification.
Fred Forssell

hitchhiker

The Version 9 Green Pre
« Reply #23 on: June 28, 2004, 11:47:16 AM »
I'd like to get 2 boards.

Lance

moosapotamus

The Version 9 Green Pre
« Reply #24 on: June 28, 2004, 11:54:56 AM »
I'd be interested in 4. :cool:

Seems like four channels could be probably be squeezed into a 1U rack case... 4 cards 77mm wide each plus ~58mm for the power supply will take up 366mm (~14.4 inches). So, should be able to leave at least ~76mm (3 inches) between the preamps and the power supply. Does that sound about right?

~ Charlie
moosapotamus.net
"I tend to like anything that I think sounds good"

jeroddumas

The Version 9 Green Pre
« Reply #25 on: June 28, 2004, 12:12:20 PM »
I'll take 2 of the boards.  Been waiting on these.

Jerod
genius is the highest level of insanity

dmlandrum

The Version 9 Green Pre
« Reply #26 on: June 28, 2004, 12:22:26 PM »
I think you could talk me into four of them. :green:
Darren Landrum

Be comforted that in the face of all aridity and disillusionment
And despite the changing fortunes of time,
There is always a big future in computer maintenance.

The Version 9 Green Pre
« Reply #27 on: June 28, 2004, 12:25:05 PM »
4 for me (why scimp?)
its not there yet,
www.frankrobertanderson.com

Mbira

The Version 9 Green Pre
« Reply #28 on: June 28, 2004, 12:45:13 PM »
Congrats Peter on the success of your bench test!  I look forward to seeing it come to fruition!

Joel

 :guinness:

As for PCB's, I'll be happy with a PDF file...
Joel Laviolette

Rattletree   |  https://www.rattletree.com
The Rattletree School of Marimba | https://www.learnmarimba.com

StrayCat

The Version 9 Green Pre
« Reply #29 on: June 28, 2004, 02:58:50 PM »
I'm in for two channels at least, I was knocking in the black market and was directed here.  :grin:

Paul
Later
Chemira Music Studio


b3groover

The Version 9 Green Pre
« Reply #30 on: June 28, 2004, 03:15:35 PM »
I would love four boards, pete.  Thanks!

peterc

The Version 9 Green Pre
« Reply #31 on: June 28, 2004, 05:22:58 PM »
There is one consideration when mounting the PCB horizontally in a 1U case. The 4700uF electrolytic can be quite tall, depending on brand & voltage.

I use a Rubycon 85 degC 16v part, this the lowest voltage Rubycon I can get. It stands 30mm off the PCB. So 30mm + 1,6mm + 6mm PCB mounting pillar = 38mm. So ideally the case has to be 40mm high on the inside.

A 6v 4700uF cap can also be used, I'm sure that it will be shorter than 30mm.

Just something to keep in mind..........

Peter
If opportunity doesn't knock, build a door.

Svart

The Version 9 Green Pre
« Reply #32 on: June 28, 2004, 05:34:59 PM »
count me in for 4 too.
Welcome to the GroupDIY leper colony! when something falls off, we just replace it with a tube!
occupation: General Electron Mayhem

Alesis X2 information repository:
http://www.theopiumdenproductions.

Kev

The Version 9 Green Pre
« Reply #33 on: June 28, 2004, 05:41:27 PM »
Quote from: "FredForssell"
Does anyone know the appox date of the A.M.E.K/RN design?
I ask because the design is an advanced version of a design by Graeme Cohen (AES Preprint #2106) presented in the early 1990.  


Hey Pete,
have you got an answer for Fred on this one.
I'm not new my hard drives so I can't go looking for any original schems.

I think that the only schem I have seen for this was infact your re-draw on CM2000.

How can we date this ??

I have always found the bootstapping and the common mode and the input gain/attenuator arrangement difficult to explain.  I gues this is why I like this project so much.
It's easy and interesting, all at the same time.
Kev
DIY Factory

peterc

The Version 9 Green Pre
« Reply #34 on: June 28, 2004, 05:55:39 PM »
Quote
FredForssell wrote:
Does anyone know the appox date of the A.M.E.K/RN design?
I ask because the design is an advanced version of a design by Graeme Cohen (AES Preprint #2106) presented in the early 1990.  


My schems do not have a date on them. I got them in 1991. They are marked "Issue 1".

Thats all I have.....

Peter
If opportunity doesn't knock, build a door.

moosapotamus

The Version 9 Green Pre
« Reply #35 on: June 28, 2004, 07:26:10 PM »
Quote
There is one consideration when mounting the PCB horizontally in a 1U case. The 4700uF electrolytic can be quit tall, depending on brand & voltage.

Almost looks like there might be enough room to lay it down on it's side, if need be.

~ Charlie
moosapotamus.net
"I tend to like anything that I think sounds good"

Eric H

The Version 9 Green Pre
« Reply #36 on: June 28, 2004, 08:20:50 PM »
Quote from: "FredForssell"


I know there are other manufacturers making preamps based on the Cohen circuit who made small modifications to it, but RN's mod of bootstrapping to increase CMZ, and then using common-mode choke and shunt caps to approx input transformer behavior is the only one that I'd call a really modification.

I was wondering about those inductors...I see :)
Thanks for pointing out the bootstrapping --I haven't seen that done from an opamp to a BJT --very interesting.
Thanks for the eye-opener, Fred

-Eric

synthi

The Version 9 Green Pre
« Reply #37 on: June 28, 2004, 08:39:49 PM »
Peter,

4 more for me!
Maybe 8 If I can fit them vertically in a 2U or 3U rack...
Whats the size for the pcb?

Thanks!

Synthi.

b3groover

The Version 9 Green Pre
« Reply #38 on: June 28, 2004, 10:57:46 PM »
I may take 8 as well, instead of four.  I mean, what the heck?  It looks like a fun project.

Count me in for 8.

peterc

The Version 9 Green Pre
« Reply #39 on: June 29, 2004, 03:09:36 AM »
The PCB is designed to work either in a 1U (horizontally) or 2U (vertically)  box. The PCB is 210mm x 77mm.

My normal box is 300mm deep, so this leaves ample space for XLR's & PSU in the back end.

Peter
If opportunity doesn't knock, build a door.


 

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