Questions For Fairchild Inventor

Please help me get a list of questions together for an upcoming chat with 670 guru Rein Narma.
Post here.

Thanks!

Do you have a good clear accurate 660 manual and schematic?

I bought two of the good reprints and would donate one (or both) so you two guys are both on the same page.

I had questions but will have to find where I lost them.

Yes PRR, I have a whole cd ROM full of stuff as well as the original fuzzy version that I use to correct errors on redraws.
Thanks for any questions.

cj

Questions:

- What other tubes were considered for the vari-mu stage, besides 6386's?

- The compressor it was originally based on - was that a Siemens? Model number?

Jakob E.

everything was handmade, right?
so...how many hours did it take to build 1 unit in the factory.

Question:

--- How did you chose the audio transformers used? Only based on published manufacturer specs or did you do extensive listening tests/comparisons?

--- Was there any other varimu tube types considered at the time other than 6386?

Got a couple of questions here,

Please describe the approach/procedure that was taken in building the compressor, eg. step 1 generate block schematic ? -> implementing established circuit and modularise? trial and error to test/modify the circuit and schematic? etc..........

How long was the nulling period for the circuit's biasing? Method of approach? Was there anything else he would of done differently today?

Mr. Narma's approach/tips for building prototype circuit efficiently/effectively?

eg. biasing multiple stages first then couple them together or ???

Easiest/quickest way of estimating essential information for building tube amps eg. working out the biasing resistor value for any tubes based on the data sheet, consideration of loading effect for coupling stages, when to add feedback?

Thanks!

PRR
I also have quite a bit of Fairchild information/diagrams that I`ve collected over the years. However, I`m sure when it gets to switching this thing on for the first time I will be seeking advice.

The main question topic that I can think of right now is:

Why is there a tapped pot on the control amp input ? Is it essential that it is tapped?

Another one!

Why is the power supply regulated in some parts & not others ? Surely any advantage gained in the regulation will be wasted when the rails that do the negative biasing rails are fluctuating with the local mains supply !

I would like to know what the original mandate for creating the compressor was? why did he design it in the first place? Im sure it wasnt for bass guitar etc.... for radio announcers? program? sorry if this is common knowledge to some, but the original design concepts are not always what you get in the end.

CJ, are you coming to NY to talk to Narma, or will this be a phone call?

NYD

On the other recent Fairchild thread CJ said that Mr Narma was travelling to California.

Looks like this is really going to happen:

"Hi Chris, as soon as my schedules are reasonably firm, I will let you know.
No compensation is required, I feel honored that my over fifty year old design is still of interest.
Best regards, Rein"

So I am bumping this to let you kow to keep those questions coming in.

I offered Rein $100 per hour and he declined. Nice guy, ehh?

[quote author="CJ"]No compensation is required, I feel honored that my over fifty year old design is still of interest.
[/quote]

Doesn´t he knows that his over fifty year old design is probably the best varimu cmpressor ever?

..If he's in Northern Cal, I wonder if he'd like to have a gander at the one I was just working on... :wink:

Keith

Yeah, and can you believe he had no idea about it's on going glory?

When I told him about the $30,000 price tag on ebay units, he just about had a heart attack. He had no clue as to the popularity of this beast.

But I guess once he designed it, he just moved on to the next project.
Supposedly at age circ 80, he still resides on the boards of three different companies. Heavy into cable TV, wireless, etc. His secretary says he is a human dynamo and sharp as a tack even today.

I wonder how many he has in his basement?

This is sooooo cool CJ!!!

Yeah I am pretty jazzed. I hope I don't get too nervous and make a total fool out of myself.
I have had a 2 by 3 foot schemo on my wall for the last three years. Sometimes I find myself staring at it for hours, totally spaces me out.

Especially the x plus y and x minus y thing that I still haven't figured out.

I am going to see if he will let me cam corder this meeting.

:thumb:

Yeah, tape it, that would be kick ass!

[quote author="CJ"]
I am going to see if he will let me cam corder this meeting.

:thumb:[/quote]

coooool :sam: