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-   -   Need XLR Y-Adapter / Tap for Mic (https://www.dvinfo.net/forum/all-things-audio/77538-need-xlr-y-adapter-tap-mic.html)

John Rofrano October 15th, 2006 07:23 PM

Need XLR Y-Adapter / Tap for Mic
 
I ran into a situation on shoot today where I couldnít take an audio feed off of the mixer like I normally do. It seems at this hall the mixer was locked up and no one was allowed to touch it. They were only using one mic (Sure SM86) so what I wanted to do was take a feed directly off the mic into my Marantz PMD-660. What I needed (but did not have) was a box that would allow an XLR Thru so the mic could be plugged into the box and out to the PA and also have a second XLR output for the PMD-660. Does such a device exist?

Would a simple Y-adapter do or should there be active circuitry involved so that there is no signal loss? I was tempted to plug the mic into my PMD-660 and feed itís output to the PA but the only outputs are line-level and headphone and I realize that neither of these are the mic-level output the PA was expecting so I didnít even try it.

I will be shooting there in the future so I want to be ready next time with a solution.

~jr

Don Bloom October 15th, 2006 07:31 PM

John, I will admit I'm really really tired so when I read your post I stared at it for about 5 minutes and then said "O yea, it sounds like this..." HA!
Seriously though I don't know if either of these is what you need but these are fron B&H pro video>audio for video>cable and inline accessories.

Comprehensive 3-Pin XLR Female to Two 3-Pin XLR Female Y-Cable - 1'
Comprehensive 3-Pin XLR Female to Two 3-Pin XLR Male Y-Cable - 1'

If these aren't it maybe browse thru that section to see if what you need is there-man they got some stuff I never would have thought of.

Don

Hsien Yong October 15th, 2006 08:30 PM

The Shure SM86 is a condenser microphone and requires phantom power.
The PMD660 could supply phantom power to the SM86 (but I've heard it really drains the batteries). Could you replace it with a SM58? Then you could use the Y cables.

John Rofrano October 15th, 2006 09:18 PM

I had looked at the Comprehensive cables but the fact that the SM86 is a condenser mic complicates things. Since the mixer is already sending 48v phantom to the mic, I was reluctant to just put a Y adapter on and didnít know if I needed some active circuitry (or even passive circuitry) to isolate things.

Since I would be splitting the output of the mic between the mixer and PMD-660, which device should send the phantom power? Well the mixer is already sending it and I canít change that so should I assume the PMD-660 should not? (this seems to make sense) I guess I could try a Y-cable and turn off the phantom power on the PMD-660 and see if that works but I am afraid the 48v coming from the mixer might damage the inputs on the PMD-660.

I did find this Rolls PM50sOB - Personal Monitor Amplifier at B&H which has a Mic In and Mic Thru. The output is headphone level which means itís amplified so thatís no good. I guess I would need a box like this with a line-level out to feed the PMD-660. (like a DirectBox in reverse)

[EDIT] I found this ART SPLITCOM Passive Microphone Splitter Box which looks like it might be the ticket. (ya' gotta love B&H... they have everything!)

~jr

Seth Bloombaum October 15th, 2006 11:43 PM

The spec available here http://www.artproaudio.com/downloads...3_SplitCOM.pdf is not real clear. The schematic doesn't label inputs & outputs... Give ART a call for clarification. You want a splitter that has a direct connection to one output, and transformer isolation to the other.

The direct output will pass phantom, the iso won't. eg. Whirlwind-SP1X2, -SP1X3, -Splitter-L, Pro-Co-MS2 or MS3, etc.

Some alternatives:
A "Y" cable may well work. Modern gain stages on mixers (660 preamp?) will usually handle a simple split without significant signal loss. But you're right to be concerned about feeding phantom down the line to your recorder. You could use an isolation transformer on the line to your 660 to block phantom.

Hsien's suggestion of a dynamic mic is good, but a Y cable will still pass phantom back to your 660 unless you can get it turned off at the mixer, or use another line that isn't phantom powered.

Somebody has the key to that mixer...

Use your own mixer with mic level outputs to the 660 and house mixer.

Power the mic from your 660, take the 660 output and pad it to mic level (30db if it's RCA out, or 50db if it's xlr) and send this to the house mixer.

Mic a speaker cabinet (ouch). But it works.

Steve Leverich October 16th, 2006 02:28 AM

The Art box will do it for you; in the pdf, the two xlr's on the left are your male/female thru connection, mic in and out to the "forbidden" board. Then the transformer out(right side of the drawing) can go to your 660; the transformer will slightly load the mic, but condensers are pretty hot anyway - and your 660 shouldn't load it down much unless it's a true low impedance mic input (not familiar with that model so I'm not sure about that part.

According to this

http://dms.sjmc.umn.edu/Equipment_Gu...D660um_eng.pdf

in the specs at the rear, it claims a 6.5k ohm input impedance for mic, 20k for line. Shouldn't even notice this added to the existing mic signal thru that Art box.

Since there is exactly the same voltage on both pins 2 and 3 of the XLR (48 volts) there will be no DC current thru the transformer and it won't get hot.

Looks like you're home free (except for the $29, that is :=) Steve

John Rofrano October 16th, 2006 05:00 AM

Thanks guys. I just purchased the ART box. Iíll be ready for Ďem text time! ;-)

~jr


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