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Widely Distributed Speakers

Discussion in 'Live Sound [BG]' started by -Asdfgh-, Nov 14, 2018.


  1. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    In a couple of week I am doing light and sound for a band that needs to balance acoustic instruments against acoustic drums in a church. I have yet to receive firm information on the type of speakers over and above a photo, or amp power (in any format let alone RMS) so I anticipate taking my PA, but the installed speakers will be less intrusive. But the speakers are arranged into a row on each side of the church, and even if I had the speaker models and amp power, I have no idea how to calculate the SPL as compared to a typical arrangement. Granted that's likely a complex question, only fully answered by a full simulation of the space, but are there any rules of thumb? Otherwise I will assume no gain from additional speakers (no +3dB or +6dB as no coupling). Would that be reasonable? Against the drums I'd ideally like to have 110dB SPL (@1W) with 3dB of headroom available, even if I don't push over 105dB, and assuming typically inefficient installation speakers I expect that would need in the region of 250-500W RMS. Luckily (in this instance) lots of bass isn't required.

    In terms of PA, taking just a pair of speakers, I can have 500W into two 95dB SPL (@1W@1m) speakers on tap, so that should be plenty, but would be less discreet if required.
     
  2. Wasnex

    Wasnex

    Dec 25, 2011
    IMHO, you need to advance the room and listen to the installed system. Many places of worship are a boomy mess, so a pair of speakers are probably not going to be sufficient to provide quality sound if the place is very large and has poor acoustic qualities.

    The speakers arranged into a row down each side of the church could be a great improvement, or sound awful. They will work well if they are capable of sufficient volume and decent fidelity, providing each speaker is delayed back to the main speakers near the stage. Unfortunately, it's fairly common to see installations in which no attention is payed to the time element of sound. You may be better off with your speakers if the installed speakers are not properly delayed.
     
    Last edited: Nov 15, 2018
  3. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    I mixed there three years ago (time flies!) but that was just a vocal mic for chat, and some linking backing tracks, so nothing very taxing on loudness. But it's a three hour drive so I'm not going to be able to do much more than rely on my recollections. It's moderately reverberate, but much less than Wakefield Cathedral!

    I doubt they will have anything close to 250-500W RMS which might be needed through the small speakers, though. 500 fantasy Watts, perhaps. Without someone sticking a meter in front of the drums I can be sure exactly how loud they are, but it's into the occasional pain territory so I'm estimating up to 115dB. Effective reduction in the reduction over distance due to reflections is beyond the computational resources I have available unless I ask my friend who simulates such spaces for a living.
     
  4. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    Oh, if the time element was considered in the installation I'd be amazed, and another reason to consider ignoring the installation speakers.
     
    Wasnex likes this.
  5. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    generally speaking, a site visit is in order. Anything else is speculation. To my way of thinking... 105 dB at 1m is pretty freaking loud in an acoustic support setting... hopefully for you, this isn’t a pickup band comprised of bluegrassers, folkies and a metal head drummer...
     
  6. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    A site visit again would be great but not practical due to distance, even if my car was currently functional (in for repairs two days before the gig)

    It's a Japanese influenced band, so think several people with drums two feet across and two feet tall, and a shamisen (Japanese banjo) competing. Put it this way, they take a supply of ear plugs... for the audience. A good, strong taiko player can induce pain at ten feet, so over 105dB at that distance and the one time I measured it there were peaks to 120dB at 1m, and quite a significant level down to 20Hz, which was the limit of the microphone I was using.

    A significant issue is getting enough signal or isolation of the shamisen microphone, as it isn't viable to use a contact microphone on the body as that is thick and doesn't resonate. An internal microphone would be preferable, but these are vintage instruments. Luckily the shamisen is only having to directly compete in two pieces. One is quieter, hence maybe 105dB on stage, but the other I may have to accept a barely audible shamisen as the mic will end up picking up a lot of the drums, and aesthetically I am limited in isolating the shamisen.

    When the quieter piece was played in a cathedral I had the shamisen about forty feet from the drums as that worked well in terms of dramatic setting, which helped with isolation, but even then the drums get everywhere.

    Luckily I've mixed the band maybe two dozen times so I have an idea what I'm getting into.
     
    Last edited: Nov 15, 2018
  7. Wasnex

    Wasnex

    Dec 25, 2011
    Usually without delay compensation that sort of installation winds up making things worse, especially for music.
     
  8. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    Taiko, if it were me I would put a small diaphragm condenser or something like an Audix Vx-5 super -card condenser close in on the Shamisen and just mix to the level of the drums. I’ve done Taiko many times. I do a lot of sports events. Taiko is a frequent choice for the starting line scene... getting isolation on the Shamisen is the trick,but you already know that.

    This troop of youngsters includes wind flutes and some kind of Japanese Marimba. Overall I overhead mic’d The marimba thing with an MDC (Rode NT-3) and centered a pair of Behringer security reference mics (ECM-8000) in XY at center front. It worked OK. The youngsters are actually harder than the adults. The adults hit harder but are more consistent. The kiddies are a Fader riding episode. Fun though...

    Good luck with it!
    D6C0F640-920E-4F0A-BF7B-9BFCAF03EC7F. 37A28B10-AC06-415C-8F8C-44D9B486E567. 9619843E-F360-429C-84FC-BFFDB71F7CC2.
     
    Wasnex likes this.
  9. Wasnex

    Wasnex

    Dec 25, 2011

    There should be no need to mic the drums...probably goes without saying.

    In some instances, the placement of the speakers and position in which the samisen player stands can help. The idea is to align the arrival of the sound from the samisen and the speakers to the audience. Easier to work things out if you have a digital board with delay. If the samisen is a unique and special part of the show, I would consider having it out front as close to the audience as possible. If this placement is chosen, the sound of the samisen will arrive before the sound of the speakers unless front fills are used, so delay can't help.

    I haven't worked with a samisen, but I have worked with a banjo and found it to be a challenging instrument to amplify or reinforce. Lot's of EQ was required and keeping the instrument a significant distance from any speakers was required to prevent feedback. Best results were achieved with contact pickups on the skin of the instrument or small clip on condensers like AKG C519M, Shure Beta 98H/C or Audio Technica ATM350A mounted on the instrument so the spacing was very close and consistent. It doesn't appear that either of these are an option for you.

    If you are using a stand mount mic and the player will can be immobile, I would suggest using a mic with the tightest possible polar pattern. Shure KSM137 or KSM141 has a tighter cardioid pattern than many other small diaphram condensers. You might try a hypercardioid dynamic as well. If the player moves around, a mic with a wider polar pattern may give more consistent results, but will likely reduce gain before feedback.
     
  10. Wasnex

    Wasnex

    Dec 25, 2011

    For the marimba and other mallet instruments, instead of centered, pointing straight down, try lowering the mic slightly, moving it to the bass side, and aiming it back about 2/3 of the way towards the treble side. This works because typically a mic's polar pattern will widen at low frequencies and narrow as the frequency increases. The ideal height and angle varies by instrument and is tied in with how many octaves the instrument covers. Some experimentation is required to find the ideal mic placement.
     
    Last edited: Nov 15, 2018
  11. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    Good to know. I don’t get much for mallet action here. The pics were from a couple of seasons ago. Last season I selected a paid of super cardiod LDC’s and went stage right and left with them. That was best yet for me. I moved their flutes off to one side and the marimba gizmo off to the other. Very accommodating troop.
     
    Wasnex likes this.
  12. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    Definitely no amplification of the drums.

    The shamisen is played from kneeling, and in the past I've had the player kneel side on to improve rejection of sound from the drums, but the player normally plays purely acoustically so getting him to be close enough to the microphone has proved challenging. I'll check the specs to see which microphone I have with the tightest pattern of the two types of dynamic, two shall diaphragm condensers and the large diaphragm. The condensers have switchable response but I can't remember if any are HYPERcardoid.
     
    Wasnex likes this.
  13. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    Thanks for the input.
     
  14. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    I'll qualify what I said by saying he's not used to playing with a microphone so often doesn't get close enough. Having said that, the 'plectrum' technique is such that you can't get in very close, although closer than some of the traditional biwa techniques would allow. What a shamisen would soundlike with an internal mic I'm not sure, as it is then a closed box, unlike a guitar. We did try mounting a gooseneck microphone, but it needs to be in a way that doesn't mark the instrument, and doesn't get in the way which proved impossible even before considering the need for him to walk on from offstage and then kneel down, which would additionally require wireless.

    When it has been purely the shamisen, the best option proved to be an old Radio shack Crown-type PZM, as it is very discreet, and picks up well enough, and even with a hemi omni pattern, enough to amplify it. The same type works perfectly with koto, which is only ever solo. As long as he knows his mark he can come on, place the koto on the mark, and the PZM is right under the sound hole.
     
    Wasnex likes this.
  15. Wasnex

    Wasnex

    Dec 25, 2011
    Probably a totally unrealistic recommendation because they are both somewhat rare and expensive, and also require a bit of time to identify the best placement: EAP System - Ehrlund Microphones

    I friend of mine went through several high-end pickups and mics for string bass and the Ehrlund was by far the best sounding option. He spent a couple of hours with a stethoscope to find the ideal position for the pickup. The pickup is held in place with non-marking putty. Once the ideal placement is identified, the pickup is brutally honest so it's not a good choice for instruments with poor acoustic qualities. As far as contact pickups go, the Ehrlund is as close to the sound of a mic as I have heard, but maintains the superior isolation and gain before feedback of a contact pickup.
     
  16. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    I tried with a reasonable good quality stick on acoustic pickup which attaches with beeswax (warm not hot). The body of a shamisen is something like 1/4 inch thick and solidly constructed, so even with the maximum gain, it was barely registering.

    In theory a piezo attached to the rear skin might work, and I have large, flat sensors in my parts box, but that would likely pick up a lot of movement noise and attachment without damaging the skin would be difficult.

    Sometimes it's possible to get shamisen relatively cheap with damaged skin which would be an opportunity to fit an internal microphone, although the quality of the sound would be difficult to guess ahead of time. The tricky bit is finding someone in the UK who could then reskin with appropriate material. I did ask a banjo repair person, and they weren't confident.

    The only viable location for a gooseneck is at the upper side of the neck/bowl joint, so as to avoid sleeves getting in the way (kimono issues).
     
  17. Wasnex

    Wasnex

    Dec 25, 2011

    Internal mounting would work fine as long as you have experimented to find the ideal positioning of the mic. A piezo could be permanently mounted to the inside of the upper skin as well.

    I would not expect a contact pickup to work on the body since most of the sound emanates from the membrane. I have seen some very small piezos that could possibly be mounted to the bridge with a bit of putty. The pickup I am thinking of was encased in wood and made by Barcus Berry a long time ago...very small and apparently discontinued. I did find many really cheap rod pickups and also an article on how to cut them if you can't find one that is already cut to size.
    How to Cut a Rod Piezo
    Three String Rod Piezo

    I am sure you know, loading piezos with 1-3Meg ohms is typically necessary to get a good sound...consider Radial PZDI if you do this sort of work regularly. Selectable input impedance and the thru can be set between parallel or buffered. Works great as a regular DI as well.

    Here's a video on a shamisen pickup...a quick Google search for "shamisen pickup" will produce hits for the pickup in the video.


    Here's a webpage that might give you some additional ideas. Check out the AKG C411
    Banjo Pickup
     
  18. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    Indeed. It's a pretty thick body.

    Ah - trying on the bridge didn't occur to me, as it's not a fixed bridge!

    I have a couple of Award-Session MB-10s, which are pretty similar to the Gordon Giltrap GG-10 for acoustic guitar use, so they should do the job (well one, plus a backup). I will check the large size pieozo discs I aleady have (3/4" across) to see if they can be mounted onto an animal skin membrane without causing marking. I got the discs to make extra triggers for my Alesis DM5s, but haven't used them. If that looks reasonable I can solder on a connection and check the sound quality (although not through a shamisen before the day) as an option. I was originally thinking of the back skin to ensure it's not visible, but it might work behind the bridge, especially if I add something on top to disguise it.

    The other bare pizeos I have are all for under saddles, so I doubt they would work on the bridge.

    The other is a fully productised contact pizeo, much of the same size as the bare pizeos, which sounds great on my acoustic guitars, but would have a taller profile, due to it having an RCA connection built in, so would be more visible. more likely to get in the way, and due to weight, more likely to fall off the instrument with a given amount of wax or other material attaching it.

    But great ideas - thanks so very much. I nearly had the tools to do the job, but wasn't considering all the options, and so was being a bit blinkered.
     
    Wasnex likes this.
  19. Wasnex

    Wasnex

    Dec 25, 2011
    Good luck and I look forward to your gig report :thumbsup:.
     
  20. -Asdfgh-

    -Asdfgh-

    Apr 13, 2010
    UK
    I ended up ordering a Behringer ADI-21. I've used my old MB-10s on piezos before with reasonable results, but the ADI-21 has 3.7MOhm input impedance, is cheap, and the shamisen player might then buy it off me... Saying that, I have a spare preamp from an acoustic guitar in my spares box I'd completely forgotten about... but that I did have planned for my short scale EUB build.
     
    Wasnex likes this.

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