Finally, I'm done with my racked MIDAS PRO4 strips!

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Marc Girard

Well-known member
Joined
May 15, 2005
Messages
113
Location
Montreal, Canada
Hello all,

Two or three years ago, I started this project.  Me and a friend bought an old MIDAS PRO40 Console from a local audio shop...  The legend says it used to be the board for the Electric Light Orchestra when they toured in Canada.  None of the less, I examined this board and I realized that it was all top quality parts in there.  Sowter transformers, Penny & Gilles faders, C+K pots, etc...  All hand assembled, this stuff was great.

Here's a picture of the board when we just bought it.  It's a little roughed up, but it was in working condition.

3.jpg

After running around to get me a copy of the schematics, I bought a power supply from JLM Audio.  Joe Malone is second to none, great support!  He helped me to find the correct PSU I needed for my two strips that I wanted to rack up.  I was completely green, the only thing that I constructed back then was my very first GSSL.  Thanks again Joe.

1.jpg

Here's the section I wanted to keep.  I didn't have any use for the AUX sends, panning and bussing.  While building my GSSL, I stumbled on a post about a guy who racked two Yamaha PM1000s strips.  Those photos inspired me as they looked good and were fonctionnal.  (And they were contained in a 2U.)

2.jpg

After testing my PSU with my strips, I loaded Photoshop and mocked up a quick look for my rack...

rack-drawing.jpg

M'yeah!  That could work!  Now, I needed to learn the ways of the jedi and use Front Panel Designer to make this happen.  The cuts were to close to the sides needed precision.  Here's the final results in FPP:

front-panel2.gif

Sent this design to FPP and waited a month.  Here's what arrived thru the mail to my great surprise:

panel2.jpg

Here's a quick test to figure how the thing would look!

panel3.jpg

A few days later, I finished assembling the front panel, it looked exactly like I wanted, boy was I excited!

panel-finished.jpg

After a good start the project got on hold (end of 2006).  I did some tests with the Par-metal box that I ordered and I haven't thought about the box height.  The front panel takes a full 2U but NOT the box that's bolted at the back, it's a little smaller to accomodate the various screws and such.  So, my original MIDAS strips were too close to the side for me to be able to close correctly the box!  Damn was I bummed out.  After a while I thought to myself: let's just build it up in a SKB case with the front face bolted on.  The problem with that solution was that I couldn't access easily my electronics...  So it stayed that way to a few months, if not a few years...

Time passed by and I got back into DIY with another GSSL build.  My neighboor next door was interested in doing some DIY too so he gave me a hand.  The GSSL looked awesome ( You can take a look here-> http://www.groupdiy.com/index.php?topic=32324.0 ).  Now, armed with my experience we decided to check out the MIDAS again.  We tried assembling the box in reverse (back plate for front) and it worked!  It was tight but it did work!

I thought->  If it worked reverse side up, that means that I just have to get rid of that lame quarter inch metal border like I did for my meter in my GSSL!    So, I reassembled everything up once again this time, we cut the sides and there it was, a functional box for my MIDAS! (Some 3 years later!)

So, the last weeks were like a marathon!  I worked on that thing all day to get it finished...  Here's the final shots:

finished-1.jpg

finished-2.jpg

finished-3.jpg

In the end, I used the transformers from the output strips to balance my signal on the output and it sounds glorious!  That box as no less than *5* transformers...  (2 Sowter inputs, 2 Sowter outputs, 1 Amveco power).  It's heavy like a mofo but we don't care, as long as it sounds good!  I'll post some inside shot soon, I need to troubleshoot the strip at the top, I've got a ground buzz when the output pot is in the middle position and it goes away when I'm at the max!?!?    Maybe just a bad pot, ah those surplus stores!

So, it's a happy end for a project that took way too long!  Flames and comments welcome!

Marc Girard
www.marcgirard.com
 
Ah, cool !

It's a bit like my racked pair of DDA channelstrips, although I didn't use such a nice frontpanel, but the idea is the same, haha. I have used a JLM PSU for it too, although I consider to replace it with keith's design 9k psu , so I can use my JLM psu for another purpose (2 rails aren't used right now). Joe's great guy indeed ....

Yes nice work !
 
great work Marc

I have some PR chanelstrips here maybe you can help me?
I looking for the correct wiring for the 3360 and 3257 Sowter.
i want to use them but i can't find any info about wire colors
who is who??? where is my primary...
 
Yes, as promised, here's a shot from the inside...  Not the cleanest job but it works!  (well, sorta!)

guts-1.jpg

The bottom strip works like a champ!  The top strip works too but with a strange ground loop noise that I just can't get rid of...  I don't know why, I'm still looking for a solution.  Might simply change the damn strip after all, we'll see.

All: Thanks for the kind words!

Creal: Frankly, I'm not an expert at transfos.  I traced my wiring by looking on the board itself and going by deduction.  I know for a fact that Sowter have a very nice support for their product, you tried emailing them?  Last time I tried, I received an answer from Mister Sowter (the grandson) himself!  Give it a try.

Until then, cheers!

Marc Girard
www.marcgirard.com
 
very pretty job!!!
I'm interresting for you buy two channel of Midas PRO40 if he remains you has sell contact me by PM there

thank you

Greg
 
hi Marc

thx for reply

Creal: Frankly, I'm not an expert at transfos.  I traced my wiring by looking on the board itself and going by deduction.  I know for a fact that Sowter have a very nice support for their product, you tried emailing them?  Last time I tried, I received an answer from Mister Sowter (the grandson) himself!  Give it a try.

i will do like you and 'trace' the PR strips.
 
heres some  info  for the input trannie

http://i133.photobucket.com/albums/q47/gevermil/3360.jpg

My bud has a pro4 thats discreet
 
Question:  I mounted JLM Audio's PSU in the box itself with an Amveco toroidal transformer.  I noticed that most high-end mic pres have their PSU on an external box.  I think I understand why, I have a very low hum in my MIDAS pres when I run them hot (I mean, VERY hot).  Would it be best for me to mount the PSU externaly?  Or simply shield the toroidal transformer???  Thanks in advance!

Marc Girard
www.marcgirard.com
 

Latest posts

Back
Top