Mark 3 Vacuum Tube Mixer

[ruffrecords]

I have set up a Mark directory to contain all the info about the Mark3 as it becomes available, I have set up three, hopefully self explanatory, sub-directories called modules, 8tracker and monster (for the one metre monster). The prototype 6U PCB layout is in the modules section:

One the left youcan see it is very much like the currebt EZTube Mixer mic pre. It has had some of the tweaks now built into the V2 TLA i.e. internall connections on Molex KK connectors, preset gain pot for gain make up stage moved to near the front panel, tubes moved out of the way of the module case and the 1N4007 series HT diode to prevent accidental incorrect connection of the HT supply.

At the bottom right you can se the three places for Grayhill EQ switches assumed to be common to all EQ types. The actual EQ and its specific controls will be on a daughterboard above these switches. It will be mounted on pillars fitted to the holes labelled P1 thru' P4.

Above the switches you can see the space for the new PCB mounting Carnhill output transformer. This is electrically identical to the VTB 2291 and has its own number which is VTB2473. To the right of the output transformer I have left room for an additional unassigned input transformer.

Above the transformer is the second 32 way connector. Pins have not yet been finally decided but at present there is provision for two outputs (connected to the mic and line in positions of the original 32 way connector), four AUX buses (where the buses are on the original connector) and four pins for AUX power (where the HT and heaters are on the original connector). The reason for this initial assignment is simply to allow the existing mother board to be used for the second connector.

There is also a picture showing how the PCB slides into the Fischer 6U cassette:

Cheers

ian

 

[ruffrecords]

Just in time for Xmas, a blog update on design progress:

http://mark3vtm.blogspot.co.uk/

Note that it should be possible to use the lunch box internal power supply and four of the 6U modules in a 6U sub-rack to make a chunky lunch box.

Cheers

Ian

 

[dipfrik]

Hey Ian,

you wrote in your post, that you  obtained a drawing of the Fischer standard dimensions for this size of front panel.
As *.fpd file?

Cheers, Sven

 

[ruffrecords]

Hey Ian,

you wrote in your post, that you  obtained a drawing of the Fischer standard dimensions for this size of front panel.
As *.fpd file?

Cheers, Sven

Oops, that should have been .pdf.  The ones in the folder are for a 21HP module but I now have ones for a 14HP one and also for its 3U cousin. Do you want copies?

Cheers

Ian

 

[dipfrik]

Hey Ian,

yes, a copy would be great!

Thanks, Sven

 

[ruffrecords]

Hey Ian,

you wrote in your post, that you  obtained a drawing of the Fischer standard dimensions for this size of front panel.
As *.fpd file?

Cheers, Sven

Oops, that should have been .pdf.  The ones in the folder are for a 21HP module but I now have ones for a 14HP one and also for its 3U cousin. Do you want copies?

Cheers

Ian

Here are the Fischer drawings for 6U and 3U front panels, both 14HP wide:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/Mark3/modules/Fischer14HP6Ufrontpanel.pdf

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/Mark3/modules/Fischer14HP3Ufrontpanel.PDF

Cheers

Ian

 

[dipfrik]

Hey Ian,

awesome!

I will start getting quotes for a divided 19" 6U-3U rack this week starting with Schroff.

Thanks, Sven

 

[ruffrecords]

Much overdue blog update:

http://mark3vtm.blogspot.co.uk/

Cheers

Ian

 

[ruffrecords]

Now I have finally settled into my new home and got a bunch of projects finished I have at last had time to think more about the Mark 3 tube mixer. Updated blog here:

https://mark3vtm.blogspot.co.uk/

Cheers

Ian

 

[ruffrecords]

Added a post about the two tube vertical tube preamp used in the 1.4 inch wide module.

Link to blog now included in sig so I don't have to keep copying it.

Cheers

Ian

 

[ruffrecords]

I didn't realize you were working on Mark III.  Fantastic work as always Ian.

I'll take some time and read through in more detail about the project and soak up what I can.

Adam

I have been working on it for over three years on and off (mostly off) but now I have largely cleared the decks I hope to make more rapid progress. I recently purchased some old EELA broadcast desks to use as the basic frames for new mixers simply because it saves a lot of time spent designing my own Maybe by the end of next year.......

Cheers

Ian

 

[ruffrecords]

Holger and I have been cooperating on a new pinout for the 32 way DIN connector. The idea is to address some of the limitations of the current Eurochannel pinout and improve flexibility. It will be adopted for the Mark III and is described in the latest blog entry.

https://mark3vtm.blogspot.co.uk/

Cheers

Ian

 

[ruffrecords]

I just updated the Mark III blog:

https://mark3vtm.blogspot.co.uk/

Cheers

Ian

 

[boji]

Little late to the party Ian, but I dig your motherboard-  Straight forward,  and those power rails look nice.  I look forward to your progress. Also excited to see how you handle 0V and if tube design requires the same massive bus bars as found when using VG methods.

 

[ruffrecords]

Little late to the party Ian, but I dig your motherboard-  Straight forward,  and those power rails look nice.  I look forward to your progress. Also excited to see how you handle 0V and if tube design requires the same massive bus bars as found when using VG methods.

0V problems are more likely to be affected by amplifier class than by type of mixing. OP amps with their class B output stages have an average power supply current that is directly proportional to signal level. Class A stages, which is what is  most commonly used in tube designs, have an constant average power consumption. The level of dirty current in a class A circuit is therefore significantly less than in a class B one.

Cheers

Ian

 

[ruffrecords]

Blog updated.

https://mark3vtm.blogspot.com/

Cheers

Ian

I also worked out how to make the pictures bigger so I have been back to many of the old posts and updated them.

 

[boji]

Looking good, Ian.
Jealous of all your PCB real estate!

 

[ruffrecords]

Another overdue blog update.

https://mark3vtm.blogspot.com/

Cheers

Ian

 

[Tubetec]

Great work Ian ,
Very interesting to see the evolution ,from the previous generation boards .
I see cooling and airflow is aided by vents ,with cool air coming in at the end and exiting at the top ,convection currents doing the work and not a noisy fan .
The console frame looks great too , the horizontal -30 degree-vertical gives it a very 50-60's look .

My own personal view on the collet knobs is ,while their the  best you can get from a functional and accuracy perspective ,they do look a little 'Noddy in Toytown' with the bright colours
From the optic and haptic perspective  I feel they look a little too modern for whats going on inside the module ,  Of course its all an individual taste thing ,and anyone who buys one of Ians modules is free to add what ever window dressing they want .

I did find a tremendous Chinese shop lately ,litterally hundreds of thousands of small electronics parts, a selection of knobs/dials ,repro bakelite ,cheap ,hundreds and hundreds of varieties in almost any colour , Theres something about the bakelite ,where you can group different functions by different knob type ,it provides a visual cue as you reach out to touch the dial ,you know exactly where you are ,the tactile feedback from dials would allow a blind person to learn how to use the console very quickly . I'll post a link to the Chinese parts megastore when I find it , ,you could buy all kinds by the bag typically plastic knobs were cents , bakelite between 10c- 1 euro each depending on size ,a bit more for larger 40-50 mm ones ,

 

[ruffrecords]

My own personal view on the collet knobs is ,while their the  best you can get from a functional and accuracy perspective ,they do look a little 'Noddy in Toytown' with the bright colours i thonk

Interesting you think the knobs are collets. They are not. They are modern push on types made by Sifam - the kind you find on most high end mixers. Maybe it isjust my poor photographic skills.

From the optic and haptic perspective  I feel they look a little too modern for whats going on inside the module ,  Of course its all an individual taste thing ,and anyone who buys one of Ians modules is free to add what ever window dressing they want .

I am not trying to make it look like a 1950s console - there aren't any with 3 band EQ and routing modules to copy. They were all very simple really. Having said that, the first studio interested in having one asked if I could do bakelite knobs.

I did find a tremendous Chinese shop lately ,litterally hundreds of thousands of small electronics parts, a selection of knobs/dials ,repro bakelite ,cheap ,hundreds and hundreds of varieties in almost any colour , Theres something about the bakelite ,where you can group different functions by different knob type ,it provides a visual cue as you reach out to touch the dial ,you know exactly where you are ,the tactile feedback from dials would allow a blind person to learn how to use the console very quickly . I'll post a link to the Chinese parts megastore when I find it , ,you could buy all kinds by the bag typically plastic knobs were cents , bakelite between 10c- 1 euro each depending on size ,a bit more for larger 40-50 mm ones ,

Given the above request for bakelite looking knobs I would be very interested in this.

Cheers

Ian