The Version 9 Green Pre

[nicksense]

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]

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

 

[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.

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.

 

[hitchhiker]

I'd like to get 2 boards.

Lance

 

[moosapotamus]

I'd be interested in 4.

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

 

[jeroddumas]

I'll take 2 of the boards. Been waiting on these.

Jerod

 

[Consul]

I think you could talk me into four of them. :green:

 

[frob]

4 for me (why scimp?)

 

[Mbira]

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...

 

[StrayCat]

I'm in for two channels at least, I was knocking in the black market and was directed here. :grin:

Paul

 

[b3groover]

I would love four boards, pete. Thanks!

 

[peterc]

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

 

[Svart]

count me in for 4 too.

 

[Kev]

[quote author="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. [/quote]

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.

 

[peterc]

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

 

[moosapotamus]

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

 

[Eric H]

[quote author="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.[/quote]
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]

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]

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 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