Hello GDIY

UPDATE

Given this thread is very informative, we are expanding our list to include Langevin & RFT Lorentz/WSW. We are looking for any European Tube Console designers particularly excluding Italy and Russia as we already have a story. Any direction is appreciated. MAIHAK.... love these designs!

we are hoping to get some insight into both the REDD console and history as well as the RCA tube console history. Any direct insight would be remarkable for our goals.

Thanks and Be Well :)

Wall
« Last Edit: April 04, 2021, 01:51:26 PM by matriachamplification »
If you are curious, you'll find the puzzles around you. If you are determined, you will solve them.
Erno Rubik


JohnRoberts

Re: Audio Historians - REDD/RCA
« Reply #1 on: March 11, 2021, 10:44:52 PM »
I never heard of the REDD console, but my father was a recording engineer for RCA records working in NYC. I went into one work with him at his studio one Saturday back in the mid 50s, when I was still a young snot nosed puke, and he was still alive.

He left a bunch of technical papers/notebooks but mostly from while he was working at western Electric in the 30s, not too much (anything) about RCA.

JR
Cancel the "cancel culture", do not participate in mob hatred.

Re: Audio Historians - REDD/RCA
« Reply #2 on: March 11, 2021, 11:39:55 PM »
I never heard of the REDD console, but my father was a recording engineer for RCA records working in NYC. I went into one work with him at his studio one Saturday back in the mid 50s, when I was still a young snot nosed puke, and he was still alive.

He left a bunch of technical papers/notebooks but mostly from while he was working at western Electric in the 30s, not too much (anything) about RCA.

Hello John

Thank you for replying. I should clarify we are looking for research into the REDD team at EMI.

I do recall you had mentioned your father and RCA in the past. I would love to hear some details about your day at RCA> Do you mind if we send you a PM to discuss?

Wall
If you are curious, you'll find the puzzles around you. If you are determined, you will solve them.
Erno Rubik

pucho812

Re: Audio Historians - REDD/RCA
« Reply #3 on: March 12, 2021, 03:54:22 AM »
I have some REDD documentation.  I also have RCA documentation but on their late 1960's solid state stuff using melcor 1731, api 2520 and rebranded 2520's with RCA on them.  The rca stuff is because I tech a rca desk that a client and friend owns here in L.A. . it's one of 5 ever made and it's sister desk is in the country music hall of fame.
The redd stuff is redd app notes and so forth including the famous redd 37.

Is there some documents you would like?


You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

Re: Audio Historians - REDD/RCA
« Reply #4 on: March 12, 2021, 05:52:51 AM »
I have some REDD documentation.  I also have RCA documentation but on their late 1960's solid state stuff using melcor 1731, api 2520 and rebranded 2520's with RCA on them.  The rca stuff is because I tech a rca desk that a client and friend owns here in L.A. . it's one of 5 ever made and it's sister desk is in the country music hall of fame.
The redd stuff is redd app notes and so forth including the famous redd 37.

Is there some documents you would like?

Hello Puncho!

Yes we would love any documentation you have. Thank you.

You can email me at [email protected]
If you are curious, you'll find the puzzles around you. If you are determined, you will solve them.
Erno Rubik

JohnRoberts

Re: Audio Historians - REDD/RCA
« Reply #5 on: March 12, 2021, 09:00:48 AM »
Hello John

Thank you for replying. I should clarify we are looking for research into the REDD team at EMI.

I do recall you had mentioned your father and RCA in the past. I would love to hear some details about your day at RCA> Do you mind if we send you a PM to discuss?

Wall
I do not encourage PMs, here is fine.

Not too much to share... I recall seeing a life sized statue of "nipper" the iconic RCA dog (his master's voice) in the studio foyer... 

That day my dad had a technician working. He was melting wax on microscope slides so they could look at the grooves made by a record cutting stylus under the microscope. As I recall he was cutting up small chunks of wax and adding them one small chunk at a time until the slide was completely covered. I asked him why didn't they just measure out the needed amount of wax by weight? He asked me to stop bothering him. :-(

That's about it, I was very young < 10YO.

JR
Cancel the "cancel culture", do not participate in mob hatred.

Re: Audio Historians - REDD/RCA
« Reply #6 on: March 12, 2021, 01:02:48 PM »
Thanks John!
If you are curious, you'll find the puzzles around you. If you are determined, you will solve them.
Erno Rubik

pucho812

Re: Audio Historians - REDD/RCA
« Reply #7 on: March 12, 2021, 02:26:23 PM »
Hello Puncho!

Yes we would love any documentation you have. Thank you.

You can email me at [email protected]

Ok as I sift through to find the redd stuff,  in the tech documents section under RCA, there is a document uploaded by Ethan on my behalf as it was too big a file. He converted it.
The pdf is an rca document that belongs to an rca desk I have had the joy of driving and teching. The doc is for a card called uoab which is short for universal operational amplifier board. The board itself consists of discrete voltage regulation and a 2520, 1731 or rebranded 2520 rca discrete opamp. It was the documentation given to the engineers in the field and is the center piece of the desk I mentioned.  It basically describes the card and all the different ways one connects it up to get a mic pre or line amp or summing amp and so on. It is very detailed.  They really enjoyed fixed gain with attenuation on the back end of those things. 
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

Re: Audio Historians - REDD/RCA
« Reply #8 on: March 12, 2021, 02:48:34 PM »
Noted, searching the RCA forum now.

We have a massive proponent to our program dedicated to Dick Sweetenham. The connection between our Tube RCA rebuilds into opamps followed up with Helios. Great transition!

I have been looking for a template to build our console design document off of and this is a great opportunity to make this happen.

REDD Documentation seems to be more scarce to find.
If you are curious, you'll find the puzzles around you. If you are determined, you will solve them.
Erno Rubik

pucho812

Re: Audio Historians - REDD/RCA
« Reply #9 on: March 12, 2021, 03:21:51 PM »
Noted, searching the RCA forum now.

We have a massive proponent to our program dedicated to Dick Sweetenham. The connection between our Tube RCA rebuilds into opamps followed up with Helios. Great transition!

I have been looking for a template to build our console design document off of and this is a great opportunity to make this happen.

REDD Documentation seems to be more scarce to find.

some more than others. REDD did a lot of field notes and such.

what's interesting with Sweetenham is the following. Sweetenham, Neve, porter, the holy trio of early British solid state consoles of Sound techniques, Neve LTD, and Trident all read the same trade magazine called wireless world and in one issue, they did an article on transistors and the 3 transistor amplifier. They published a generic circuit in the magazine.  They all read that article and all studied the circuit. It became the backbone of their work for a long time. They all applied the concept and circuit to an extent in that article and all came out with very different sounding results.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.


ruffrecords

Re: Audio Historians - REDD/RCA
« Reply #10 on: March 12, 2021, 05:20:18 PM »
some more than others. REDD did a lot of field notes and such.

what's interesting with Sweetenham is the following. Sweetenham, Neve, porter, the holy trio of early British solid state consoles of Sound techniques, Neve LTD, and Trident all read the same trade magazine called wireless world and in one issue, they did an article on transistors and the 3 transistor amplifier. They published a generic circuit in the magazine.  They all read that article and all studied the circuit. It became the backbone of their work for a long time. They all applied the concept and circuit to an extent in that article and all came out with very different sounding results.

I have heard this apocryphal story several times but I have never yet been able to locate the particular issue of Wireless World in which this article is supposed to appear. I suspect it is a myth - unless you know otherwise.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: Audio Historians - REDD/RCA
« Reply #11 on: March 12, 2021, 05:38:54 PM »
... I suspect it is a myth ...


Thank you for saving me the time of searching, given you have already been on the lookout the Wirless World article. A fun myth though! 
If you are curious, you'll find the puzzles around you. If you are determined, you will solve them.
Erno Rubik

Re: Audio Historians - REDD/RCA
« Reply #12 on: March 12, 2021, 05:44:18 PM »
I know a fair amount about the REDD desks : REDD 17, 37, 43, 51, & 59

I got access to all the documentation that came with those desks about 30 years ago, back when no-one knew what a REDD47 amp was. 
I think I was the first (and then sadly the only person) who was interested in chatting with Len Page who had started REDD back in 1955.  No-one had thought to ask him questions and, shortly after getting insights from him, he sadly passed away.

Anyway, most of the important stuff I've posted on this forum.  Before here, I was talking about it on other fora.

Releasing a few schematics (RS124 & TG Limiter are 2 I can think of) got me in hot water and ended up costing me a couple of good friendships with old timers from Abbey Road.

I think it's important to share info, but at my age, I need real friends rather than temporary internet kudos.

So, I can absolutely answer basic questions, but I won't publically publish or privately send any more documentation/schematics for the desk eq's (pop/classic), the "brilliance" box, Individual mic eq boxes, the original curve bender, shuffler, Fairchild 660 mods,  later V72 mods done on Kingsway Hall 37 desk, Solid State modules tried/auditioned in 37 desk, Custom REDD.51 desk in transfer room  etc.  etc. 
Sorry.
That'll have to be up to someone else, I paid my dues...  ;)


P.S.  I'm having internet logging on issues and haven't been able to reply to your email yet Wall

:)

Hinson O'Boogie. 
« Last Edit: March 12, 2021, 07:05:06 PM by Winston O'Boogie »
D. J. H.

The standard way to reduce much of the noise and distortion in audio gear in 1955 was to have a couple of beers.
 Anything else was too fiddlesome and too expensive.

pucho812

Re: Audio Historians - REDD/RCA
« Reply #13 on: March 12, 2021, 05:53:37 PM »
I have heard this apocryphal story several times but I have never yet been able to locate the particular issue of Wireless World in which this article is supposed to appear. I suspect it is a myth - unless you know otherwise.

Cheers

Ian

 if memory serves correctly it would be the year 1961 and would be articles by R. Tobey and J. Dinsdale
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

Re: Audio Historians - REDD/RCA
« Reply #14 on: March 12, 2021, 06:11:31 PM »
Found the article :) Thanks Puncho!

Noted on all fronts Boogie. My internet is only started working again today after a week. When your internet is better we can talk. This info gives me some insight into discussions.

Schematics, to be honest, I would LOVE, but are not as important as learning about Len Page and the team.

If you are curious, you'll find the puzzles around you. If you are determined, you will solve them.
Erno Rubik

Re: Audio Historians - REDD/RCA
« Reply #15 on: March 12, 2021, 06:20:08 PM »
some more than others. REDD did a lot of field notes and such.

what's interesting with Sweetenham is the following. Sweetenham, Neve, porter, the holy trio of early British solid state consoles of Sound techniques, Neve LTD, and Trident all read the same trade magazine called wireless world and in one issue, they did an article on transistors and the 3 transistor amplifier. They published a generic circuit in the magazine.  They all read that article and all studied the circuit. It became the backbone of their work for a long time. 


The Sound Techniques solitary amp used throughout the desks and designed by Geoff Frost is nothing like the Helios and Neve 3 transistor amps.

Likewise, the Helios EQ was not based on REDD but was just a Pultec circuit scaled up 2.5 times in impedance but with less insertion loss.
Sound Techniques also used the Pultec scheme but kept it a lower impedance as their amps were designed for lower source Z.

Although fine engineers, a lot of what Geoff Frost and Dick Swet.  did was just winging it.   They developed their own individual amps based on current technology and collective knowledge.

The Helios 3 transistor little amp:  From a good source who was VERY familiar with the earlier Olympic desks and then the Helios no. 1 which went into Olympic -  is that, the new Helios was "off" in terms of headroom and character of distortion.  Rumor at the time was that there was a silly drafting error.  The first Olympic desks had run on negative rails and, Helios were contemplating positive power with the new company and, in the shuffle of things, the 2 resistors that bias up the first transistor were accidentally reversed.
It was never changed and that's how it's stayed and always been.

Happy accident?  No idea.  I never fiddled with the amp with those 2 resistors switched places.
« Last Edit: March 12, 2021, 08:22:22 PM by Winston O'Boogie »
D. J. H.

The standard way to reduce much of the noise and distortion in audio gear in 1955 was to have a couple of beers.
 Anything else was too fiddlesome and too expensive.

Re: Audio Historians - REDD/RCA
« Reply #16 on: March 12, 2021, 06:38:23 PM »
 OK got it Wall.

Well, one thing that was new with the eq's in the desks after the REDD.17 was in the insertion loss.  They're passive eq's of course so, need gain.

Backing up a bit:

The REDD.17 was based on designs by Peter Burkowitz of EMI Cologne.

Before that, Len Page had put together the REDD.1 which was their first proper mixing desk of sorts.  Except it was mostly housed in racks.  The racks contained the RS.61 amplifiers which were 2 rack spaces per amplifier.
Len was excited with what Peter was doing using the German 'Danner' cassette amps so they collaborated on the REDD.17 which was the first stereo desk.  This was 1955/1956.

The EQ in it was based on two, series connected Bridged "T" eq's , one for the top. one for the bottom. 
It was mostly a Burkowitz design but with input from Len Page.

Being two series connected Bridge "T" eq's,  the insert loss was double.  This was common at the time.

So, a +/- 10dB for the top, plus a +/- 10dB for the bottom = 20dB insertion loss.

What EMI Hayes came up with before the REDD.37 was built in 1957, was to stack two bridge "T"'s in parallel, one on top of the other.
And as long as impedance requirements were met. there was now only 10dB loss.

On Impedance at EMI, I see a lot of info here and there that has it slightly wrong. 

EVERYTHING in the studios had a built out impedance to 200 ohms.  This fed the passive eq's, faders, etc.  All was fine as far as frequency response and level. 
BUT, this was always fed into a bridging amplifier of at least 2K.  Nothing was ever "terminated" in 200 ohms.

Also, their operating level was to a different standard and is about 4 - 5 dB below our current standard.
This is why an amp such as the R.47 or V72 with a +18 dBu headroom as measured by our standards, was fine for them.  It was equivalent to a + 23dB max headroom to them.

Finito.


Edit: typos.

« Last Edit: March 12, 2021, 08:17:30 PM by Winston O'Boogie »
D. J. H.

The standard way to reduce much of the noise and distortion in audio gear in 1955 was to have a couple of beers.
 Anything else was too fiddlesome and too expensive.

pucho812

Re: Audio Historians - REDD/RCA
« Reply #17 on: March 12, 2021, 06:50:24 PM »
OK got it Wall.

Well, one thing that was new with the eq's in the desks after the REDD.17 was in the insertion loss.  They're passive eq's of course so, need gain.

Backing up a bit:

The REDD.17 was based on designs by Peter Burkowitz of EMI Cologne.

Before that, Len Page had put together the REDD.1 which was their first proper mixing desk of sorts.  Except it was mostly housed in racks.  The racks contained the RS.61 amplifiers which were 2 rack spaces per amplifier.
Len was excited with what Peter was doing using the German 'Danner' cassette amps so they collaborated on the REDD.17 which was the first stereo desk.  This was 1955/1956.

The EQ in it was based on two, series connected Bridged "T" eq's , one for the top. one for the bottom. 
It was mostly a Burkowitz design but with input from Len Page.

Being two series connected Bridge "T" eq's,  the insert loss was double.  This was common at the time.

So, a +/- 10dB for the top, plus a +/- 10dB for the bottom = 20dB insertion loss.

What EMI Hayes came up with before the REDD.37 was built in 1957, was to stack two bridge "T"'s in parallel, one on top of the other.
And as long as impedance requirements were met. there was now only 10dB loss.

On Impedance at EMI, I see a lot of info here and there that has it slightly wrong. 

EVERYTHING in the studios had a built out impedance to 200 ohms.  This fed the passive eq's, faders, etc.  All was fine as far as frequency response and level. 
BUT, this was always fed into a bridging amplifier of at least 2K.  Nothing was ever "terminated" in 200 ohms.

Also, their operating level was to a different standard and is about 4 - 5 dB below our current standard.
This is why an amp with a +18dB headroom was fine for them, it's equivalent to a +23dB max headroom in modern terms.

Finito.


Edit: typos.

were they doing a 0dBm  operating level like what was happening in the u.s. during that  era before the +4dBu standard?
« Last Edit: March 12, 2021, 09:20:51 PM by pucho812 »
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

Re: Audio Historians - REDD/RCA
« Reply #18 on: March 12, 2021, 06:55:03 PM »
Another silly error, this time with EMI

The first desks with the "new" eq were the REDD.37 desks for St. John's Wood, Kingsway Hall, and for Europe.

The design engineer(s) had forgotten to take into account of the dcr of the shunt inductors and so, the full 10dB of cut didn't quite make it there.
This was only corrected later for the small REDD.43 desk, and for the 3 X REDD.51's.

None of the UK '37's, including the one left in Studio 1 after 1964 which was later owned by Lenny Kravitz, reached full cut.

I don't know if EMI Pathe or EMI Cologne '37's were modified/corrected with adjusted resistor values.
 
 
« Last Edit: March 12, 2021, 07:02:11 PM by Winston O'Boogie »
D. J. H.

The standard way to reduce much of the noise and distortion in audio gear in 1955 was to have a couple of beers.
 Anything else was too fiddlesome and too expensive.

Re: Audio Historians - REDD/RCA
« Reply #19 on: March 12, 2021, 06:57:29 PM »
were they doing a 0dBm  operating level like what was happening in the u.s. during that  era before thw +4dBu standard?

Rather than referenced to .775 V  as we do now. - they referenced to, something like .447V, give or take a bit of a volt. 
« Last Edit: March 12, 2021, 07:00:40 PM by Winston O'Boogie »
D. J. H.

The standard way to reduce much of the noise and distortion in audio gear in 1955 was to have a couple of beers.
 Anything else was too fiddlesome and too expensive.


 

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