Just finished, racked MCI JH-500 Modules

[user 37518]

Hey Guys!, just finished racking some MCI JH-500 modules i had available, i initially made this with the intention of selling them but after all the hard work i had to do, now im not sure..... but i want to hear the opinion of hardcore DIY'ers like you guys!

They are 2 MCI JH-500 rev D modules, racked in a 19" 3U custom made steel rack enclosure, it has a JLM audio power supply with custom made heatsink, plus an extra regulator board, it uses +/-32V for audio, +/-15v for diff amps (although they are now at +/-17V), 24V for LEDs and 48V phantom. I has both line and mic inputs with switchable phantom power, i added an LED at the top right to display phantom status, phantom is engaged/disengaged by pulling/pressing the gain knob. It has a switched pot at the top left, which is a Trim knob, located at the latest amp stage of the module, so the module can run hot and use that to lower the output so the DAW doesnt clip. EQ assign switch serves as a selector for Mic or Line input

The mic input has a Jensen input transformer, the line input is electronically balanced, output is transformer balanced, i included original MCI JH-500 output transformers i got from an MCI frame, all inputs and outputs are +4dBu balanced.

They have been fully recaped, all solder points have been resoldered, cleaned switches and pots, fixed every glitch, cleaned every knob.

Audio cable is Belden, power transformer is Hammond, it has double fused Bulgin AC inlet, Neutrik gold connectors.

The modules are originally 1 meter (40inches) long, so they had to be cut, the rack is powder coated steel, laser engraved. The whole thing weights around 12-15 Kilograms (25-32 pounds)

 

[Greg Norman]

Fantastic work!

I have a 500c module that I have had on my shelf for almost a decade now- with the idea I would do the same.  This would be a super great thing to have.  That preamp (with the jensen transformer) and LC eq is a good combo.  If it weren't for the millions of iffy/noisy switch contacts, molexes and VCAs that board would have a much better reputation in my opinion.  Definitely on par with API, Helios and the like...

What did you use to cut thought the MCI faceplate?

 

[user 37518]

Hey Greg, thank you very much for your comments!!!, you are partly right about the switch contacts, molexes, etc... however after fixing all that stuff this console is the sweetest thing i've ever heard. I dont have a problem with my VCAs which are the golden DBX202c, those sound great, they were used also on SSL consoles, and a lot of different equipment, although to be fair, some of the older MCI consoles have black 202 VCAs which can be quite muddy, fortunately there are only gold ones in my console.

And yeah i think that the not so great reputation of that board are the molexes, because soundwise, i think its one of the best boards ever made!, but like I said, there are ways to deal with that issue, and after you do, this board just rocks!!!!

C modules like the one you have, have an inconvenient when you are planning on racking them, and that is that they dont have the diff amp on board the module, instead they have the meter buffer on board, the diff amp is located in the middle motherboard of the console. If you are only planning on using them as Mic pre's, then you dont have any problem, but if you plan on using them also for line signals, then you have to either make a diff amp board, or use some kind of line input transformer. Older MCI revisions in fact used transformers for the line-in, but Cs never did, so i've never really tested using a transformer instead of the diff amp with a C.

I will probably going to be racking several C modules in the future, because i have plenty of them, good news is that i also have the original diff amps that go with them.

I cutted the modules with an angle grinder, its not that easy, but not that complicated...

 

[shubidoowa]

Beautiful !! did u sell it eventually ?

 

[user 37518]

I was planning to sell them, but i havent hehehe i used/tested them on a project i had recently, they worked flawlesly.

I might sell them in the short future, still undecided wheter i should keep them or not, i mean i have a console full of these so its a bit overkill.....