First Steps - A mixing console

[abbey road d enfer]

If you haven't done, I recommend reading the series of excellent articles by Steve Dove.
http://84.255.203.119/Steve-Dove-Console-Design.pdf
May seem jurassic in some respects but OTOH some things never change.

 

[Bassniac]

This Thread is developing nicely. I would be in for the planing of this console if you decide to go modular with 500 series modules. I want a DIY console myself as a longtime goal.

 

[JohnRoberts]

If you haven't done, I recommend reading the series of excellent articles by Steve Dove.
http://84.255.203.119/Steve-Dove-Console-Design.pdf
May seem jurassic in some respects but OTOH some things never change.

+1.. There is precious little textbook advice covering the kinds of problems you encounter in consoles design, so this is a great resource and comprehensive in scope. I wish this article was available 10 years earlier.  ;D

Today we have off the shelf solutions for some of the brick and mortar circuits he explored in such detail. A modern console is likely to use canned IC mic preamps and IC balanced output drivers (because they are that good now, they weren't back then). 

The EQ is still an area for subjective choices, and the sum bus design is not going to be found in some off the shelf IC applications note (or if you do, probably not worth copying). 

Of course the devil is in the details so you can combine perfect building blocks and still get a sub standard result. How you connect the dots matters.

JR

PS: Yes, I'm the same John Roberts mentioned in the acknowledgments on page 72. I've known Steve for years and he is the real deal. Last time I talked with him he was working with DSP, so not an analog only purist. but he surely knows his way around analog circuits . 

 

[Andy Peters]

where some of this can be easier is using things like altium designer which also run in combination with solid works for metalworking stuff.  Can have a complete circuit and metal work done in computer well before you even make one. It totally cuts down on mistakes but altium and solid works is real pricy in itself

And you still have to be an experienced mechanical engineer to ensure that your Solidworks drawings are manufacturable.

I used QCad to draw a little 2D front panel design based on one of the Hammond extrusions.  I drew out the outlines for a character LCD and a hole for a light pipe (in front of an IR receiver) and a rotary encoder. I even put dimensions on it.

And then I asked the ace mechanical engineer here to help with the mill (no CNC!).  First, he said, "well, the mill uses the upper left as the origin. And it uses inches, not millimeters. And you can't mill a rectangular hole, you'll have rounded corners that you can fix using a file. And the cutting tool will be an 0.125" end mill, so you need to draw a 'cut line' that's 1/16 from your desired opening. And the opening can't be exactly the same size as the outside dimensions of the LCD, it has to be a bit bigger."

I will say that in ten years of working with him, not once has he come to me and said, "How do I do this in an FPGA?"

-a

 

[Bassniac]

And that's why I use Front Panel Designer... It is made for dummies like us who want to design rectangular holes - it is simply not possible with FPD. But at least now I know why... 
To be honest,  making holes a little bit bigger than the components you want to put through them is common sense.

Cheers.

 

[ricardo]

If you haven't done, I recommend reading the series of excellent articles by Steve Dove.
http://84.255.203.119/Steve-Dove-Console-Design.pdf

PS: Yes, I'm the same John Roberts mentioned in the acknowledgments on page 72. I've known Steve for years and he is the real deal. Last time I talked with him he was working with DSP, so not an analog only purist. but he surely knows his way around analog circuits .

John, is there a clean copy of YOUR series of articles on the WWW?

Joshua, the electronic design is the easy part.  ;D

For the rest of it, just budget for MUCH more time & $$$ than you expect or calculate.

 

[JohnRoberts]

John, is there a clean copy of YOUR series of articles on the WWW?

Perhaps if my ego was even larger, or my fan club consisted of more than just my mother (RIP). I'd have one.  I hosted a copy of my RE/P console design article from 1980 here  http://www.johnhroberts.com/des_art_1.pdf because enough people asked for it. I talk about console design in broad strokes, and it's a little dated. (I even spelled bus wrong back then  :-[ ) but I still think the op amp 101 tutorial still has some utility. 

I do not have links to, or copies of all my Popular Electronics kit articles, or the Audio Mythology columns from RE/P magazine (1970s-80s)  I did a scattering of articles in other magazines too, not to mention a bunch for the Peavey house magazine during my 15 years there (not to mention an occasional  health advice column I wrote for the employee newsletter. . )

I'd like to see them too.  ;D There were always questions about who  controlled the copyrights as the sundry magazines changed hands and or whatever... Maybe some day I'll search what's out there. Wayne recently mentioned a site with old kit articles, but I didn't bother to look for my old stuff there.

Joshua, the electronic design is the easy part.  ;D

It's all electronic design but if I can rephrase that, the individual sub-circuit blocks are relatively easy.. Making tens of them play nice together can be harder. .

For the rest of it, just budget for MUCH more time & $$$ than you expect or calculate.

If even thinking budget this is not the best approach... refurbishing an old console selling for pennies on the dollar is the better economic decision.  Take the money you save and buy a new car.

JR

 

[Gareth Connor]

... refurbishing an old console selling for pennies on the dollar is the better economic decision.

Very true when comparing the cost to that of designing & building a new console to the same performance standard. However, there is one major factor: the pitfall of buying an old console is that the reason why it cost 150K (pounds or dollars) when new is still as valid today as it was when the console was built. Clarostat pots, Sfernice pots, Elma switches, Grayhill switches, and if you can get them, Dialastat switches.... all are at the top-end of the components market, with prices to match.

One of the challenges I regularly face is trying to explain this to customers who have bought a high-end console at a "bargain" price....... and the bringer of bad news is always the bad-guy...... Professionally undertaken refurbishment of old consoles does not come in at bargain prices.

GJC.

 

[Brian Roth]

Anyone thinking about building a desk might enjoy this little article:

http://brianroth.com/projects/m77/m77.html

After I left the company, Serial Number 2 was completed by a guy in Kansas City (with my assistance) and installed in a mobile truck.  Last year, it ended up in Omaha.  You can see that the "truck" version didn't have all of the pretty trimmings:

http://brianroth.com/pix/mb77-june2014/

I used premium parts, but after decades the switches and pots became a bit ratty.  I fought through those issues last year and brought it back to life.  For business reasons (ie, listing stuff in their sales brochure) the Omaha guys opted instead for a somewhat newer API desk for their "Studio A" tracking room to go along with their SSL desk in "Studio B", and now have my desk listed for sale with Duncan Rowe.

Long Story Short....buying an older desk to refurb usually means getting into a lot of crackling switches and pots.  I know, because nowadays I refurb  desks. 

OTOH, building a desk from the ground-up is a seriously daunting task.  Been there, done that, and I don't even have The T-shirt!  <g>


Bri

 

[ricardo]

Very true when comparing the cost to that of designing & building a new console to the same performance standard. However, there is one major factor: the pitfall of buying an old console is that the reason why it cost 150K (pounds or dollars) when new is still as valid today as it was when the console was built. Clarostat pots, Sfernice pots, Elma switches, Grayhill switches, and if you can get them, Dialastat switches.... all are at the top-end of the components market, with prices to match.

On the other hand, designing a big DIY mixer with cheapo parts might mean the parts go wonky BEFORE you finish the desk.

 

[shmuu102]

Ive started down this road before as well;  The design phase is enjoyable.  Component selection is were you start really realize how deep a hole your digging.  Once you get to the mechanical layouts,  you realize your going to need a ladder,  and maybe some friends with a hoist to get you outa this.

IMO, unless you are independently wealthy AND bored, the only way your going to see a finished working mixer is to put together an  open source group to work on it.  That being said,  there's much to learn and enjoy by getting half way done, just dont start buying large quantities of parts until your friends show up with that hoist.

If the design were modular and scalable, you could get many more members joining in.  Maybe even small enough to make a 16ch summing mixer would draw in a crowd of capable people.

(+5 for QCAD,  and CNC is the way to go...  Group buys on switches and knobs MIGHT bring the costs down to something within reason)

 

[JohnRoberts]

Things like metalwork tolerances and thickness of powder coating can bite you hard. I did an inline replacement input/routing module for an existing desk once and the faceplates were a few thousandths too wide. They left the metal shop and went straight to powder coating where they were coated twice adding a few more, then straight to screen printing. By the time I had the finished faceplates in hand and laid out in the frame channel 1 lined up fine with the EQ s and faders but by the time it was down to channel 32 they were off by about an eighth.  Be very prepared for screw ups like that!

+1

;D ;D ;D  That reminds of one console prototype where the production metal used hard tooled forming tools to bend the chassis metal precisely, but the 50 odd strips for the prototype show unit were bent one at a time by the metal shop... despite holding decent tolerance, being + just a few mils off per strip times 50 strips means a shoe horn was needed to force the last strip into the frame.... 

This a good object lesson for one-off DIY consoles, +0/-X for strip width tolerance or they might not all fit...  If you don't tell a metal guy otherwise they will aim for +/- X.

JR

 

[sodderboy]

I wonder if a used Allen & Bradley live desk would suit this need.  Plenty of sends/buses, simple discreet topology, no crazy expensive switches in them, normal some 500 racks to the line inputs and bang!  The older A&B are kind of a sleeper console.

It's one thing to have a vision, and it is another to travel a vision quest.  I know plenty of busy producer/engineers who would love a custom desk but are not interested in the costs of doing it themselves or hiring it out.  They find what works best for them and book it or buy it because they need their work-minutes to make music.  If the goal is to learn console circuits and construction then have at it.  We are always looking to bring engineer converts to the dark side of tech ;-)
My advice would be to scale-up the design.  Buying faders is not an early step!  Make some dsub summing circuits that you hate, then make them better before buying console parts.  Make a mini 4 ch mixer with one send and one stereo bus that you like, then scale it.

And as said, on the bench is not the same as slid into a desk, so perhaps traditional channel modules are not important.  The older Neve 80 series monitor sections were panels of 8 channels that plugged into the frame on an umbilical harness.  That style of construction avoids aggregated dimensional errors.  There are 5 panels on each row rather than 40.

The old-school RCA desks were kinda like your layout, not so greedy with buses and sends, designed by the engineers using API building blocks of 550, 312, and 325.  The face was a single panel with all pots mounted on it, cutout for the EQ's, and the desk was made from a shop bench with all the 300 card cages bolted into the angle iron frame.  Institute of Audio Research had one that we fumbled on way back in the day.
 
Mike

 

[pvision]

It's a great ambition.  I think I'd start by building an eight-channel bucket plus two channels and a very simple centre section / mix bus / monitoring section. And a simple psu for just those bits

After that I think you'd see the good & bad parts and appreciate the scope of the project

Nick Froome

 

[ricardo]

It also brings some kind of magic to the room, it's the first thing people see and want to take pictures in front of. It brings some kind of legitimacy I guess lol.

This is further incentive to buy a big 2nd hand famous name desk.

You could cut a 72 channel down to 36 or less and get enough premium $$ working parts & spares.  And all the hard mechanical bits are done for you.

More than enough scope to spend the rest of your life swapping all the circuitry & routing to what you want.  Pre 1980 probably best cos the routing would still be with wiring & switches rather than evil digital logic.

 

[Gareth Connor]

Three months since the last post......

Has this discussion died, or is it simply resting and awaiting the wake-up call?

 

[abbey road d enfer]

Three months since the last post......

Has this discussion died, or is it simply resting and awaiting the wake-up call?

It is the way most of these threads end up. Over the years, in this and other forums, there's regularly some guy who's all pumped up with the idea of designing their take on analog mixer, and regularly, he figures out that the task is almost insurmountable and gives up, facing the daunting challenge.
The situation today is much different than 40 years ago, because the level of expectation is much higher, not much in terms of audio performance, but a mixer designed today must include some of the features that have become standard over the years, such as some kind of automation and reconfigurability. The justification for making a new analogue desk is to produce something that is significantly better than the run-of-the-mill that asian factories churn out at mind-blowing low-cost.
In addition, as you are perfectly aware, sourcing switches and pots has become a major hassle. Only the knob budget on a mixer is about the GDP of a caribbean island.
Most successful analogue mixer designers succeeded because they did not know it was impossible. The last one was Greg Mackie with the 8-bus.

 

[Holger]

Yeah Abbey, I didn’t knew that it was impossible, that’s why I did it.

I’ve built a 12 channel tube mixer which took almost 2000 hours to complete it.
Assumed you have 4 extra hours per day to tinker it would take 500 days to build such a device.

And you are not sure at the beginning that the result will even be close to your expectations.

 

[Gareth Connor]

The situation today is much different than 40 years ago, .....

Hmmmmm........ 40 years ago..... 1975..... funny you bring up that year.... it was when I built my first mixer, and yes, no-one had told me it was impossible It was small (in electronic terms) at 5-channels, but it worked and was inspirational. By the time I got to the 9th mixer I still did not believe in "impossible".

40 years on, and the view has changed a little.

 

[JohnRoberts]

Three months since the last post......

Has this discussion died, or is it simply resting and awaiting the wake-up call?

Let sleeping dogs lie...

JR