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"Y" mic cables

luissluiss Posts: 35
edited February 2011 in dbx Archive General Discussion
I just got back from a gig involving a student orchestra. I had massive problems getting enough gain from the string section to be suitably audible during the the pp sections. We had 2 mics on each section...Violins, Violas & Cellos. The rest of the orchestra (woodwinds, brass & percussion) was fine.

We started out with the mics set as AB overheads, but got next to no level. We then lowered them down as close as practical to the stronger members of the sections.

I got through the gig reasonably well as long as I was given decent level from stage. Spelt the whole time on a knife edge, just below feedback.

In total I had 16 open mics on stage, all cranked.

The guy that owns the gear wanted me to use some "mic combiner leads" (2 x XLR F to 1 x XLR M). I said no, we should be fine without them..

I have never used these leads before and am not sure they are a good idea. What is the resulting output impedance of the combined mics and what impact will that have on driving the pre's on the desk?

I honestly don't think more mics would have helped, I was just not getting enough level into the mics I had.

Full size orchestra & a 16 channel Spirit desk + operator who has never done an orchestra before........ we did all right....

Comments

  • GadgetGadget Posts: 4,915
    No, 'Y' combiners would likely have exacerbated the problem through further cancellations. It's really early here and my mind isn't fully active yet, but you could have fallen prey to mic proximity cancellations. When micing with multiple microphones, spacing of the mics can actually cause problems.

    That's why when 2 mics are used in proximity you often find them in X/Y configurations, MS configs and other near coincident pairs instead of open faced spaced mics.

    What mics were used? The pickup pattern can exacerbate proximity issues...

    A simple Google keyword search should start you finding out about coincident mic cancellations and orchestra micing techniques. I'll see if I can't dig something up if I get time, but the weekends are usually balls to the wall for me...

    Gadget
  • luissluiss Posts: 35
    This was definately one of my concerns, however, the placement required by an XY configuration still did not render enough gain for each section. I checked to see if there was any noticable phase cancellations between sections and couldn't hear anything overly obvious. The other issue was the proximity of the FOH stacks. We were unfortunately limited by what the director of the conservatorium thought looked good as apposed to what actually works....

    I should have mentioned that this was an outdoor gig...

    The mics were a mixed bag of 57s, a couple of Beyer mc 930s, some cheapo Australian Monitor pencils, and a few cheap Shures.. Dynamics were used on the brass and woodwinds and the condensors on the strings.

    One of the problems I have with google is that information found is often either incorrect or commercially biast... I'd rather hear from those I can be confident actually know!

    Cheers

    Oh... Any other comments on "Y" combiners? Are they a no no or do they have their place? Do they cause impedence problems?
  • DennisDennis Posts: 801
    luiss wrote:
    ... Any other comments on "Y" combiners? Are they a no no or do they have their place? Do they cause impedence problems?
    I have used them many times when I have run out of holes in the mixer but Gadget's concerns are valid. If you use a wye cable and find that the level appears to be higher with one mic than two, the mic positioning isn't working out for you. Also, use the same model mics with the wye cable.

    The wye cable may not be the correct call for your application but you won't know until you try.

    Dennis
  • GadgetGadget Posts: 4,915
    just be prepared for cancellations... any signal that arrives out of phase on one of the 2 mics by 90 degrees will be totally cancelled for all practical purposes...and then consider just how mwny potential frequencies that is....

    Sounds like you need some super cardioid mics and if thats not possible your stuck with what you have... adding a whole bunch more mics (unless they are MUCH closer) isn't going to make things any better, and wye cables will make a MESS of things...

    G

    P.S. you could ask @ the PSW... they are ïn the know... but expect kinda what I said.. i monitor the site all the time and learn just like everyone else...
  • luissluiss Posts: 35
    It honestly didn'y notice any level reduction with all mics open. I spent quite a bit of time in sound check playing with mutes to see if I was getting any cancelations with particular combinations. Each open mic seem to increase my overall gain, I just wasn't getting enough.

    I'm starting to think the only problem we had was extremely quiet source material. Student string players , outside and nervous. I did notice that we were getting audible chair creaking and general stage noise spill...
  • luissluiss Posts: 35
    Why super cardioid? I would have thought the narrower pickup would have made it harder to capture a large section of source material.
    Are you thinking super cardioid in the context of cancelations? (less spill - less interaction?)
  • GadgetGadget Posts: 4,915
    Yes cancellations... and no it wouldn't necessarily manifest itself as a lowering of overall gain, but a loss of some frequencies totally...not ALL frequencies... like for instance... if a clarinet was 1.1253 ft close to one mic than the other... it would cancel that frequency...not ALL frequencies.. but THAT frequency... and if you think about it.. think of all the possible combinations... and you'll see why we get concerned...

    I think your right.. it's a no win cituation :?
  • luissluiss Posts: 35
    thanks.

    Before we have to do it again I'll re-examine the entire approach.

    Next week is a big band... Maybe we'll have the 260 by then. Hope so..

    My next question is, how to mic up a big band. I know I should post this stuff on PSW, but I find that place a little condescending. Having two different forums, one for the "pros" and one for the rest of us alienates me..
  • GadgetGadget Posts: 4,915
    :mrgreen: gadget likes this :mrgreen:
  • DraDra Posts: 3,777
    Was the orch in a "bowl" or have a shell in place? Conductors often only want a couple of ambiance mics out front to take the natural mix of the instruments, assuming he has the full compliment in each section. But with the speakers placed to "look good", have fun with that.

    DRA
  • GadgetGadget Posts: 4,915
    Ya... but as the OP said with kids and timid playing... all bets are off...Hey, how big is the big band? and are they kids as well?
    G
  • luissluiss Posts: 35
    Dra wrote:
    Was the orch in a "bowl" or have a shell in place? Conductors often only want a couple of ambiance mics out front to take the natural mix of the instruments, assuming he has the full compliment in each section. But with the speakers placed to "look good", have fun with that.

    DRA

    The "stage" is a flat bit of gravel next to a small dam. The audience is separated from the stage by the water and are about 75 meters away. I'll take a photo and post it.. Strange place for a gig..

    I ran into the client in a cafe yesterday... Told him what I thought of his requirement for placement of the stacks. He replied with slimy diplomacy....
  • luissluiss Posts: 35
    Gadget wrote:
    Ya... but as the OP said with kids and timid playing... all bets are off...Hey, how big is the big band? and are they kids as well?
    G


    I'll have a stage plot tomorrow...
  • GadgetGadget Posts: 4,915
    Oh ya I remember now... across the river...yuck... :mrgreen:
  • DennisDennis Posts: 801
    luiss wrote:
    The audience is separated from the stage by the water and are about 75 meters away.
    The audience was over 225' away from the band?? That was a challenge...how exactly did you have the sound system set up?

    Dennis
  • GadgetGadget Posts: 4,915
    I could be wrong.. may be someone else.. but I distinctly remember a series of discussions with someone that had that exact setup. The performance space was on one side of the river, the audience on the other...lots of problems with reflected energy and coverage issues...slapback eco... sounded like a drag...
  • luissluiss Posts: 35
    Not I. But may have been the guy who did it before me.... Same PA, different owner & operator.
  • luissluiss Posts: 35
    Dennis wrote:
    luiss wrote:
    The audience is separated from the stage by the water and are about 75 meters away.
    The audience was over 225' away from the band?? That was a challenge...how exactly did you have the sound system set up?

    Dennis

    Conventional 2 x stacks. 1 S410 on each side with 2 x 408 stacked on each.

    The audiene is also sitting on a hill with the lowest point lower than the stage and the highest higher than the stack.

    Vertical coverage isn't too bad, although the top of the hill is lacking. Horizontal coverage is pretty crap. The S408 has a 75 deg H dispersion, which really doesn't cut it. Especially when we are forced to place the stacks too close togeather.

    This week I'm trying to get us there earlier to try the S408 arrayed side by side. We will then have 150 deg a side. I'm hoping this will provide better coupling and give us some better projection too.

    Any thoughts? Anyone?
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