Film-Tech Forum ARCHIVE: Weird microphone jack

This is topic Weird microphone jack in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Geena Phillips (Member # 3726) on 09-17-2011, 02:57 PM:

So, for our analog sound, we've got these pretty decent USL units. Now, when our installer put the wireless mic system in, he went from the 1/4" mic-level output on the mic receiver to a line-level input on the processor (this is generally a bad idea, as mic-level signals are MUCH lower than line-level, and the volume has to be JACKED way up for the mic to be audible). After looking closer at the USL unit, I now understand why he did it this way: The dedicated Mic input on the USL is this 9-pin connector that looks like an old computer serial jack. Now, I've done a lot of sound stuff in my life, but I have NEVER seen a microphone jack that looked like this.

Does anyone here have any experience with this kind of jack, and would you know where to find cables for it? I have been completely unsuccessful in this regard thus far.

Posted by Leo Enticknap (Member # 534) on 09-17-2011, 03:12 PM:

Do you mean one of these? If so, you can get leads that will connect d-sub 25-pin to audio to XLR pretty easily (on Ebay, for example); but a quick web search doesn't reveal any ready-made ones for 9-pin d-sub audio. I'm guessing that you might end up having to make up your own lead.

Posted by Robert D Hall (Member # 5674) on 09-17-2011, 03:17 PM:

I dont know if you can buy one. But making one is real EZ. All you need is a 9pin male d-sub

http://www.allelectronics.com/make-a-store/item/DB-9P/D-SUB-CONNECTOR-9-PIN-MALE//1.html

pin 1 is +
pin 2 is -
pin 5 is shild
You wont need any of the other pins.

Posted by Monte L Fullmer (Member # 2797) on 09-17-2011, 03:22 PM:

interesting hookup - never seen it done that way. Prob need a preamp (or what some drive-ins use is a distribution mic amplifier) between mic receiver and then to the processor.

Posted by Geena Phillips (Member # 3726) on 09-17-2011, 03:32 PM:

Fraid not, Leo. That's a 25-pin connector, such as the kind you use for multi-channel connections.

What I'm talking about looks like this.

Posted by Robert D Hall (Member # 5674) on 09-17-2011, 03:45 PM:

Monte i know it works with the output of a cordless mic. But you may be right about just a mic needing a pre amp. But she can all ways try it. It may work with out a pre amp.

Posted by Pete Naples (Member # 761) on 09-17-2011, 04:09 PM:

9 pin D sub for mic input is pretty common on cinema processors, IIRC CP500, CP650 and maybe CP750 have this.

All you need is a cable going from common or garden XLR to the 9 pin D sub connector, as Robert has detailed. 5 minutes with a soldering iron.

Posted by Frank Angel (Member # 248) on 09-17-2011, 04:33 PM:

Easier going the other way -- instead of needing to futz with wiring the 9-pin subD connector to the XLR cable, just get a 9 subD to 9 subD cable and cut the connector off one end. Then you just have to solder the XLR on to the proper leads of that cable and not need to bother soldering the 9pin at all.

As for the mic preamp issue -- if you are REALLY lucky (BIG if), they may have used the subD connector so that one connector can be use for both line-level and mic level inputs. One set of pins outs go to an internal mic preamp and another set of pin outs bipasses that circuit and accepts line-level inputs, both on the one plug. Check for that possibility.

Whatever you do, you never want to try and boost a mic that's plugged into a line level input by increasing the gain. If there is no mic preamp in the circuit, then you can get a fairly inexpensive mic preamp even from the likes of Radio Shack that will do you better than turning the gain up full just to use the mic.

Posted by Steve Guttag (Member # 268) on 09-17-2011, 08:15 PM:

Oh for Pete's sake...

The CP650 and CP750 use real XLR connectors...Dolby on did the 9-pin Dsub thing for the CP500 though the CP650 does have a MUX connector too like the CP500.

Making one of these is not a big deal...as Robert indicates. When we were putting in CP500s and knew the client wanted wireless mics...we made a rack panel that had a regular XLR on it so they could move the wireless receiver to the theatre desired.

If you would rather buy than make...we'll make one for you.

-Steve

Posted by Jake Spell (Member # 5294) on 09-17-2011, 09:26 PM:

We have our mic hooked up. Soldered a spare XLR cable to a D-sub 9 pin pale plug we had laying around in the booth. Super easy. As detailed in the liturature this MIC INPUT only goes to the mic preamp. You can get the Sub-d connector here HERE Just cut the end of an XLR cable or make your own. Either way it should only take about 10 min

Posted by Pete Naples (Member # 761) on 09-18-2011, 03:20 AM:

Thanks Steve, I wasn't certain of the CP750. I've never connected a mic to one. Installed enough of them though!
Am I right in thinking that the XLR on the 650 is for PA use only then?

I never use the onboard analyser on any of them.

Posted by Harold Hallikainen (Member # 5405) on 09-18-2011, 10:23 PM:

I agree that the 9 pin D is a strange connector to use for microphone input. The pin out is shown on pdf page 39 at http://www.film-tech.com/warehouse/manuals/USL-JSD-80.pdf .

Harold