Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[gpiccolini]

Hello Klaus,
I have a Gefell CMV563 and a M582. I feed them with a N61 PSU and stock cable. They sound nice to my ears and I'm happy with them. Problem is the cable, which need work. Knowing a little about tuchels I decided to buy a new and probably better cable from ebay. Now, some months later (I moved and built a new studio), I discovered the cable doesn't work due lack of connection on the center pin. I think I've read somewhere that CMV only uses 5 pins and the remaining one is for the UM57 to change polar patterns. I googled a bit but wasn't able to find cable diagrams for any of these miss so I decided to ask here if it's possible to make my mics work with a 5 wire cable...
thanks in advance
Guillermo

EDIT: solved. Found the answer here: http://www.powertechnik.com/tubelife-2571.phtml

[klaus]

Unlike the UM57, which uses the same power supply as the CMV563, you will not use the center pin (6) of the power supply or, a sixth conductor in your CMV563 cable: pin 6's function is to provide polarization voltage to the rear diaphragm of mics which have remote controlled multi-pattern functions, like the UM57.

As there is no rear diaphragm polarization circuit in the amp of the 563, there is no need for that function.
Bottom line: disregard pin six and wire up your mic cable accordingly.

[gpiccolini]

thanks
weird thing is both mics refuse to work with that cable that has the 6th pin with no connection. The old one has it connected and both mics work. It has to be something else, but for sure I have tested continuity on both cables and all pins are ok except for this pin in the new one...

[klaus]

On the questionable cable: make a continuity and short test, pin to pin, end to end, no mic or power supply connected.

[gpiccolini]

I did it before posting but I just did it again (continuity) before reading your answer and all pins seem ok. Regarding short test I understand it (english is not my first language as you may guessed) as to test if there is continuity in another pin or pins besides the intended one, which I also did, and it seems ok.
I'm scratching my head about this cable
One thing that comes to my mind is to measure voltages on the cable, I suppose the way to do it is referencing all other pins to 0V... It's my first test on a tube mic PSU

[klaus]

My standard procedure in situations like yours:

* Measure B+ and heater output of voltages at the power supply connector (no mic or cable connected- the voltages will be too high, because the load has been removed); if good:

* Measure output of voltages at the female end of the mic cable (cable connected to power supply); if good:

* Measure audio conductor output continuity at the power supply's XLR -3 audio male: do you get a few ohms resistance between pins 2 and 3? (This can vary from ca. 3 Ω to ca. 30 Ω, depending on mic, output transformer and cable length); if good:

* Start trouble shooting mic functions (first among them: proper supply voltages/continuity traced to the proper pins of the mic. This is a commonly overlooked test- all the voltages are there, but on the wrong pin(s).

[gpiccolini]

Thanks a lot Klaus!
I was very busy but at the end I made it work.  120V wasn't arriving at the end of the cable, so I adjusted the somehow loose female connector in the PSU and the problem was solved. The connectors in the new and old cables are a little different (at least in color) and that could be the reason that the new one didn't worked with the PSU connector as it was while the old one did. Now I have 2 working cables and I'm a happy guy...
...well, not only for that, luckily
thanks again
G