Tube Mixing Consoles

[NewYorkDave]

Based on a suggestion made on the Lab, I'm starting a thread in which we can share technical information about tube mixing consoles, their topologies, design and operation principles and constituent parts and sub-systems. I'll start by posting some links.

Langevin console wiring and layout diagrams, courtesy of "Vintage Pro Audio."
http://vintageproaudio.com/Doc+Schematics/langevinwiring1.jpg
http://vintageproaudio.com/Doc+Schematics/langevinwiring2.jpg
http://vintageproaudio.com/Doc+Schematics/langevinlayout.jpg

A block diagram of a Bill Putnam custom console.
http://groupdiy.twin-x.com/albums/userpics/10031/PutCon1.pdf

Photos of a Universal Audio console (lifted from an eBay auction):
http://groupdiy.twin-x.com/thumbnails.php?album=57

A detailed description of David Sarser's custom console, built circa 1960 for his NYC recording studio.
http://reevesaudio.com/studiothree.html

PRR's mirror of the scan of the monumental Radiotron Designer's Handbook (aka "the big red book"). Chapter 18 offer a summary of the audio mixer technology of the early '50s.
http://headfonz.rutgers.edu/RDH4/

More to come.

 

[RoyM]

It isn't really pertinent but you reminded me of this: http://www.vintec-audio.de/. Although I don't know if anything will ever come of it.

Roy

 

[alk509]

[quote author="RoyM"]http://www.vintec-audio.de/[/quote]

That's sick.

And I don't mean "cool"-sick, but "you got something wrong with you"-sick.

Peace,
Al.

 

[pucho812]

That vintec console was mentioned before around these parts. If I ever decide to move to alaska or pther points of cold temps I will by it for my studio as I would not need a heater just the console. :green:

 

[NewYorkDave]

Hot off da scanner...

The entire "Sound Mixers" chapter from the rare first edition of the @udio Cyclopedi@.

12MB PDF--Right-click and save to your hard drive

Note the error on the Magnasync mixer schematic: the plate resistor for the output stage was left out. The output amp would not work as drawn.

 

[soundguy]

I dont have much interest in such a project, but if I did, I would likely think about trying to figure out some kind of design where the channnels fed a passive buss off of a EL84 with maybe a 6sl7 before it. Its intensely overkill but is there a less than pragmatic way to use a power tube like an EL84 feeding a buss? If you used a transformer with a dual secondary, you could pull a direct out and feed the buss from the same point in the block. That would be really cool. I would presonally use a lundahl on the input to the makeup amps, I think the sound of the input channels would largely determine what kind of makeup amp you used. I could easily see years of experimentation to get something really amazing going on.

designing the stuff yourself brings 100 times the satisfaction but easily adds 10 times the time. when you design it and it sucks, you cant blame some dead guy for it sucking...

dave

 

[cuelist]

[quote author="soundguy"]If you used a transformer with a dual secondary, you could pull a direct out and feed the buss from the same point in the block. That would be really cool. [/quote]

Yup - that's a very cool idea, and not only for tube stuff!

 

[Family Hoof]

[quote author="soundguy"]designing the stuff yourself brings 100 times the satisfaction but easily adds 10 times the time. when you design it and it sucks, you cant blame some dead guy for it sucking...

dave[/quote]
Quoteworthy! :thumb:

 

[jcb]

Can we have some info on Broadcast Consoles, some European Desks, and maybe some of that EMI Valve Desk info like the one(s) the Beatles used?




:grin:

 

[soundguy]

omg

 

[Family Hoof]

[No message]

 

[solder_city]

jcb, you think this guy just poops out info on your command? for petes sake, look at the huge amount of info that has already been posted! read and absorb it, that should keep you busy for a long time. oh, and how about saying 'thanks' before 'give me more'? :roll:

 

[fazeka]

Yeah, sadly he just doesn't f*cking get it. :roll:

 

[solder_city]

he must be a young guy, todays kids take it for granted that they can get any info they want on the internet. they just assume it magically materializes. us older guys who remember when you couldnt just log on and download, know that somebody out there took the trouble to find the info and make it available to others.

 

[jcb]

I'm sorry if that request seemed rude or overbroad, it just appeared that some of you already had such incredible info within easy grasp I assumed that it would easy to share it. I apologise for my assumption. I'm kinda of new here.

I, for one, am already grateful for all that has been posted so far.

I just thought there might also be some info floating around about RCA or CBS consoles.

I also thought people might be able to do some posts which compare and contrast some of the great old valve desks.

 

[soundguy]

if they were so great, people would be using them. The fact is, tube consoles were designed for primarily mono use and the limitations of their most common designs most certainly did not survive the leap to stereo and that is why they pretty mcuh dont exist anymore. Many were also designed with completely different operating levels in mind. What you are failing to realize despite repeated suggestion is that if you want to have a functional tube desk you are going to need to DESIGN IT yourself, and design it to fit your needs as there arent lots of designs to base it off of. You can take bits and pieces from here and there and combine it into something that works for you.

Do you want to have a coversation about designing a console or do you just want to talk about old consoles because they are really two different discussions. You still havent laid out what you need in your console. Looking at some stone age design is surely not going to answer that for you. For one, they are all mostly mono with no routing. Useless for %99 of the modern world.

dave

 

[NewYorkDave]

I'd like to keep this thread on the topic of old tube consoles and general principles, not hashing-out of a specific DIY project. The last time that came up, all that resulted was a long pointless thread that went in circles.

So, back to the topic at hand. Here's some info from L@ngevin about the various types of constant-impedance mixer controls.

2.75MB PDF: right-click and save to your hard drive.

The question often comes up: how were PANPOTS implemented in the old constant-impedance mixing systems? The short answer is, it wasn't easy. Here's an excerpt from an email I wrote to a friend addressing that topic.

The old-style constant-impedance panpots consisted of two constant-Z attenuators of special complementary tapers, the outputs of which sum to constant power in all positions. Here's the curve that was established way back in the '30s, which still serves today.

http://www.widescreenmuseum.com/sound/fantafig1.gif

Since the source sees the two attenuators in parallel, a build out resistor of Z/2 is added so that the source still sees 600 ohms instead of 300. This increases the insertion loss of the panpot by 6dB in addition to whatever minimum loss it possessed in the first place. (Zero for bridged-T, 6dB for ladders). You COULD get around this if you used a mix buss of twice the impedance that needed to be seen by the source feeding the panpot, but that doesn't seem to have been a popular approach, if it was ever used at all. Besides, since booster amps were usually fixed at 40dB of gain, they usually had to lose some extra signal anyway to maintain headroom before clipping (admittedly at the cost of S/N).

Here's information from L@ngevin on their panpots, showing circuit types:

900KB PDF: right-click and save to your hard drive.

Thanx to PRR for the webspace to host the L@ngevin files.

 

[jcb]

Thanks NewYorkDave. I think you have the right idea to keep the thread on topic.

BTW, have you done a lot of work with Langevin consoles? Having looked inside one of their amps, I can say that the build quality was great and something you'll rarely see in some of the newer pro-sumer pieces. The one I took apart had very hefty transformers (forgot the brand) but I think it had black-plate DuMont valves, IIRC.

I think I may have read that some famous recordings done by Frank Sinatra came off consoles that had only three channels, but that might have been the tape tracking machine that only had three channels. I dunno, I forget.

Re: Mono---Some people still prefer the sound of mono records, but understanding how pan pots were developed and implemented is something that is good to examine.

Thanks again NewYorkDave.

:grin:

 

[NewYorkDave]

I've never been inside a Langevin tube console, but PRR has.

http://www.groupdiy.com/index.php?topic=4332

http://www.groupdiy.com/index.php?topic=1154

When you read that Sinatra's records were made on a 3-channel console, they're referring to output channels, what we'd call a 3-buss console today. The number of input channels was likely more than three, but there would be three outputs to feed the inputs of the 3-track Ampex recorders that were commonly used at the time. I believe Frank did most of his "classic" records with Bill Putnam.

Panpots were relatively rare, although as you can see, they did exist. The usual approach was to provide switches to assign the input to one or more of the output busses of the console. Four busses were not uncommon: three to feed the multitrack recorder, and a fourth for a simultaneous mono mix.

 

[soundguy]

[quote author="NewYorkDave"]I'd like to keep this thread on the topic of old tube consoles and general principles, not hashing-out of a specific DIY project. [/quote]

sorry my bad. I thought the whole point of this was to help the guy build something.

punching out.

dave