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Mic'ing a Choir for Live Sound,Regarding 3:1 Rule

Discussion in 'Vocals' started by samuraisoundman, Aug 27, 2007.

  1. Hello:
    I have a question that I want to post to professionals in mic'ing acoustic performances. Over the years, I have been an avid sound recordist and live sound mixer for several years. Most of that in what would be considered 'pop' music performances. I am now facing a challenge in presenting live sound for a small-to-mid-sized choir (varies between 10-24 singers, plus 1 or 2 soloists, depending on the gig).
    When I was starting out doing this many years ago, I was taught that I should ALWAYS observe the "3:1" rule with mic placement. This was not really an issue when close-micing amps and drums, horn sections, and the like on my 'pop' gigs. But, I have noticed over the past few years, many times on this very site, posts that ridicule this rule! The posters cite different reasons (typically mic polar patterns and new developments in audio technology), and some were actually nasty about it when others posted questions about this. So, please help me with this dilemna:
    I am micing said choir within traditional church/cathedral environments,
    with limited gear. At this time, my mics are a pair of CAD Equitek E100
    hypercardioid condensers. I have found these to be robust and stable in less-than-ideal environments (SE humidity and very reflective acoustics), and fairly smooth on-axis. Feedback has not been an issue.
    I run them into a pair of Grace 101's. On some stages, I can't get that 3:1 separation. In other words, if I were to place the mics, say 6 feet from the front of the choir, I can't get the mics 18 feet apart. Maybe 10-12, max. When I am doing this, I seem to lose the mens' voices (they're in the back risers), and the sound is dominated by the women (their tends to be 2-3 the # of ladies, anyway). I thought that pulling the mics back and raising them up more (6 feet back, 7 feet up) would cause the mics to "see" a bigger picture, if you will. But with only a 2:1 ratio, it doesn't sound that 'natural'. And I have gotten pretty good results from these mics with smaller choirs (6-10), in smaller venues.
    In a nutshell, as the choir gets bigger (towards that 24 number), the sound gets worse. I think that my problem is phase cancellation from the mics being too close together. But according to some posts on RO, hypercardioids should not exhibit this problem. Am I crazy? I would like to take the music director any feedback from this post and show it to her.
    I have been their 3rd sound person in as many years, and she had the same complaints about us all. I have been the first one to try to explain to her that the mics are too close together, she thinks that I'm crazy.
    Please help !!!
     
  2. RemyRAD

    RemyRAD Well-Known Member

    Believe it or not, you might be going through "condenser microphoneitis" this is a situation I have encountered & diagnosed numerous times especially for rock-and-roll style gospel pop recordings. People are inclined to put up their fine studio condenser microphones on the choir. Who wouldn't? Me for one. Why? Much because of the reasons you describe and because of close proximity to louder pop style instruments that include rock-and-roll style drum sets and judiciously electrified guitars and basses, that appear to overtake the choir microphones quite easily.

    To correct these situations for PA and to make fine sounding recordings, like my " Yolanda Adams, Live in Washington DC", here I go again..... I recommend Shure SM57's or the slightly high-frequency extended higher output version the Beta 57. While these microphones offer standard cardioid (SM57) and super cardioid(Beta 57), patterns, you'll find that your choir will now sound better and more cohesive, especially if you're utilizing quality microphone preamps. Your problems will be solved. Dynamic microphones have a more limited bandwidth than their condenser cousins. This all works in your favor when trying to record the human voice. There is already a presence rise in these particular microphones which also helped to accentuate the singers. Generally little equalization, if ever, will be needed. Your choir director will believe you are a genius and they would be correct. Especially when your chorus shines. And everybody will be shaking their heads going "wow"." The choir sounds that good and you are only using SM57's? Wow??? I didn't think it would sound that good on those microphones." The last excerpt is a typical response I've gotten on numerous occasions. Try it. You'll like it.

    And they say men never ask for directions?
    Ms. Remy Ann David
     
  3. Thank you for the reply, Remy.
    I have read your posts here for some time...very insightful. Actually, I have a case full of 57s/58s to try that with. I was going to try what my business partner suggested, which was to place a pair of his NT-5s in an ORTF configuration...
    But if I can place a pair of SM57/58s, flanking the front sides of the choir, and aimed inward, it would be visually less obtrusive than a big rig in the middle of the stage.
    Not to kick a dead horse, but what are your feelings regarding the 3:1 rule? Doing a search on the subject, I found many different opinions on this...
     
  4. RemyRAD

    RemyRAD Well-Known Member

    Like many, I have generally tried to follow the 3: 1 rule but I'll tell you, it really doesn't hold water in many situations. I have done lots and lots and lots of television news, games and political talking head show broadcasting where the news anchors sit next to each other but their microphones are still at least 3 feet apart. It doesn't matter. The nasty sounding phase cancellation you get from 2 of the Omnidirectional condenser microphones that are 3 feet apart is still completely unacceptable sounding. In fact it's awful. Even worse if you have one of those modern-day consoles that offers dynamics processing on each and every input Channel, like the SSL Aysis Air console. If you cannot stereo strap your 4 to 5 news anchors/sportscasters/weather forecasters and they are all trying to chitchat at the end of the show, you will be mixing your ass off to some truly horrible sounding phase cancellation on everything.

    When dealing with putting microphones on drum sets, the 3: 1 rule can either improve or detract from your sound. It really all depends on what kind of microphones you use, where you place them, etc.. And in the situation of drums, you might be using a lot of compression/limiting/gating/downward expansion, etc., which will generally overcome phase cancellation problems.

    Lots of compression on lots of microphones that are left open are a huge source of phase cancellation problems. Good mixing and technique can thwart those problems, regardless of the 3: 1 rule. Besides, I break most of the rules anyhow.

    Rules are for when the brains run out
    Ms. Remy Ann David

    I'm down over 50 pounds! Who wants a date with a hot engineer? And I never spoke to Jenny Craig.
     
  5. Cucco

    Cucco Distinguished Member

    In this case, abandon the 3:1 rule. It is not applicable on larger sound sources such as chorus.

    First, you're not mic'ing a single instrument (which is one of the stipulations of the 3:1 rule). This is the biggest issue.

    Second, a spread of that distance with such directional mics is going to sound horrible. There will be a giant hole in the middle and no low frequency reinforcement.

    A near coincident pair or coincident pair with adequate flanks should do just fine. Go with your instinct to use the ORTF (even if it's with SM57s). I tend to agree with Remy, if you're going to reinforce a choir (which I'm not quite understanding the need to reinforce a >20 person choir in a church...), use a lower sensitivity, bandwidth constrained mic such as a 57.

    If you want to avoid a large center mast, simply space (rather evenly) your 57s over the choir at a distance and height which seems logically appropriate. For height, you want to be high enough so that you "see" all of the choir members and then angle down enough that as many of them are on axis as possible.

    The real joy of using a tight patterned dynamic in a situation like this is that with a little distance and strategic placement, phasing shouldn't be a large issue.

    But again...for large ensemble like this, throw out the 3:1 rule. It does not apply.

    Cheers -

    J
     
  6. Thanks, Jeremy.
    "A giant hole in the middle and no low frequency reinforcement" is exactly what I'm hearing.
    The reason that I "need" to mic up the choir is that they perform in (2)
    situations:
    A) With a 5-piece rock band, complete with a live drummer...and,
    B) As a traditional choir with simply electronic keys. It's wierd down here in the Bible Belt because the congregations many times EXPECT to hear these choirs amplified.
    In any case, you and Remy both replied to my inquiry with some great suggestions. I will take a pair of 57's and ORTF 'em.
    Thanks again.
     
  7. JoeH

    JoeH Well-Known Member

    Funny how everything can go full circle, even with microphones and technique. When I first started professional live sound (wayyyyyy back in the stone age, in 1976), I had no other mics available to me other than SM57's and 58's, and we often had large choirs to amplify for bigger crowds and complicated shows.

    I didn't know any better anyway, and I knew it wasn't for serious recording, so I reluctantly used the 58s (Which seem to have a slightly better blend than the 57's, perhaps due to the metal ball grill?). Using at least two, sometimes four, in closer than the 3:1 rule, we'd get great results for the PA, very often getting the kind of gain one needs for a good belting Gospel choir to be heard over a kickin' band. The only real caveat is to try to NOT pick up soloists instead of the blend of the choir. That's always a tough trick.

    Over the years I've moved on to more esoteric condenser & ribbon mics for recording & broadcast, but looking back, I have to admit: Remy's right on with this advice, esp for live PA and reinforcement.
     
  8. Thanks, Joe!
    Thanks to all of your posts, I've realized that you can have too much of a good thing. Sometimes a bigger, broader-responding mic is not so good in a given situation. My partner (who posts here too much) has offered me Beyer M130/160s, Rode NT-5's, 421s, and many others to try. He won't let me say his name, but he was shocked at Cucco saying to try the 57s. "He has Beyers and NT-5s, like I do!" He DID predict that Remy would say the Shures, go figure. She made fun of his "awdicks"(i5) mics once...LOL!!!
    We're going to try a couple of SM58s on a center stand to start with, and play with the positioning. Hopefully, what works with a cranked-up bunch of ex-members of Southern Rock bands turned Contemporary Christian
    players will work for the traditional choir! I'll post the results. Thanks again.
     
  9. Cucco

    Cucco Distinguished Member

    :lol:
    Well...you didn't mention that you had access to Beyers and NT5s...so I didn't mention them.

    Besides, for live sound work, I don't know that I'd use either of those. Recording...yes. The Beyers sound quite nice on choir.

    Truth be told, if I were doing live sound as my primary goal, I'd go with Schoeps CMC 6 MK 4's as my over head of choice. I've used them many times before and had a very easy time predicting the feedback frequency and thus being able to avoid it all together. Plus, they pick up a LOT of nuance from the choir and have a beautiful off-axis response that helps bring out the broadness of a choir instead of focusing into the choir.

    But...you didn't mention if you had them either. :lol:

    J
     
  10. No, Cucco, I didn't mention the Beyers and the Rodes because they are not mine. My partner has no problem letting me try the NT5s, but he felt that they would be too sensitive in that situation. And he's super-anal about his Beyers. He says that they do not travel well and will break his heart if they get damaged. And travel they would. We are scheduled to travel around the South starting next month, hitting a variety of religious venues over an 8-week period. So I need a rugged, flexible mic rig that will work in several different types environments (some outdoors). I think that the Shures are my best bet. But thanks for the tips on the Schoeps, if I had the bucks, I'd give 'em a try... :lol:
     
  11. Simmosonic

    Simmosonic Active Member

    Just thought I'd chime in here on a couple of points:

    1) The 3:1 rule was devised by Lou Burroughs, you can read about how he came across it in his book "Microphones: Design & Application" - still one of the best books you'll find on microphone design (if you can find it, it's been out of print for years). I don't have access to my copy right now, but I recall that his initial calculations suggested something like a 10:1 rule would be required to prevent audible comb filtering. However, after doing tests with lots of listeners, it became apparent that most listeners were happy with ratios as low as 3:1. So it's not surprising that sometimes the 3:1 rule doesn't work!

    2) I'll support the suggestions for trying SM57s in this application - especially when you've got a band to contend with. I had to do it myself with a live choir many, many moons ago (in the days when I was too incompetent to realise I was incompetent). It was a smallish choir, about 20 singers, and I put a pair of SM57s in XY stereo (crossed at 90 degrees) about 45 degrees up from the centre, mounted on a lighting truss about 2m away. In those days, a pair of cardioids at 90 degrees was the only stereo microphone technique I knew of... Because it was a semi-outdoor gig (actually, it was a venue called the 'Ambitheatre' at World Expo '88 in Brisbane, Mr Spearritt's fine home town), I added a touch of reverb. That would've almost certainly been a vocal plate from a Yamaha SPX90, with about 2.5s Rt and a predelay of 35ms (long enough to allow the direct sound to reach the audience before the reverb came up behind it), to make things big but clear.

    The memory of seeing the choir's musical director turn to me with a big grinning thumbs up still haunts my inner audiophile...
     
  12. Just a quick note to thank all who posted feedback on my situation. We ended up with two very useable rigs. The first involved a pair of SM57s
    on stereo mic bar configured as close to ORTF as possible. Between the physical dimensions of the mics, and the fixed spacing of the bar's mounting hardware, it was a bit of a compromise. This was in a large auditorium/cafeteria, with about 300 in attendance. No 101's here, just an Allen&Heath GL2 rack mixer. Lots of 'slap' in the room, band with Fender Twins, pounding drums, etc. The choir rocked!

    The second situation was in a large stone-and wood Episcopal cathedral in Florida. No band, but a large pipe organ. This time we used a pair of NT-5's, which were able to be ORTF'd better on said mounting bar. This turned out very nicely. The cathedral's tech (also the local NPR station audio tech) had shot a video of the presentation, using the feed from my 101's. He was surprised at the detail the Rodes displayed.

    P.S.: That Lou Burroughs "Microphones" book is what got me started on this. I aquired my copy back in the early 70's from "Warehouse Sound", the first mailorder 'pro audio' store I'd seen. Wish I still had that book...

    Now I'm awaiting a better mic bar to arrive. I've ordered the Sabra-Som dual-mic rig. Once again, my thanks to all who provided advice!
     
  13. Cucco

    Cucco Distinguished Member

    You'll like the Sabra Som. It's very convenient and very flexible. My only gripes with it are minor -
    1 - I wish it had the larger studs for mic mounting. It's annoying to have to constantly use adapters
    2 - I wish the base were a little more sturdy. I have 4 of them and all 4 have broken in the same place. It's nothing that a little 2500 lb epoxy can't fix though and make stronger than ever.

    Cheers -
    J.
     
  14. Thanks for the heads-up; I'll get some epoxy to have onhand. Are there any other decent mic bars out there that don't either cost $200+ (the Neumann) or don't have enough positioning flexibility (K&M, Offstage,etc.)?
     
  15. Cucco

    Cucco Distinguished Member

    The SabraSom (IMO) is one of the best on the market, period.

    I got a few different hexagonal bars from http://www.smallparts.com which allow me to change the width (up to 3' wide for wide AB setups). I went with drop hardened steel as it seemed to be the most acoustically dead.

    I've flown it as high as 22' in the air with a pair of Schoeps CMC6's or a pair of Gefell M296s without too much fear. (First time, there was some nail biting...I would never do it this high when there were patrons/audience members around.)

    I also use the AEA protractor bar for ORTF positioning. It's a glorified Atlas Stereo bar.

    Cheers-
    J
     
  16. Thanks. I'll stick with that then. We have a couple of the Sabra-Som shock suspensions, and find that they are pretty good.
     
  17. aracu

    aracu Active Member

    About that 3 to 1 rule, if you record with all your mics on
    separate tracks, you can either synchronise them later in
    a sequencer, by lining up the waveforms, or adjust them to
    be out of sync to your liking.
     
  18. aracu

    aracu Active Member

    About that 3 to 1 rule, if you record with all your mics on
    separate tracks, you can either synchronise them later in
    a sequencer, by lining up the waveforms, or adjust them to
    be out of sync to your liking.
     
  19. Simmosonic

    Simmosonic Active Member

    This can be very effective, especially if there are only one or two microphones to synchronise *and* you place them with the intention of synchronising them later.

    As an example...

    One month ago, in the studios of Music Nepal (Kathmandu), I made an album of 'ghazal' singing - a wonderfully lugubrious form of Indian music with vocal, harmonium and tabla. I captured the vocal and harmonium with a single Neumann U87 in omni mode (the singer also plays the harmonium, and will take care of the voice/harmonium balance at least as expertly as I could), and used a TLM103 cardioid on the tabla.

    I placed the TLM103 about 25cm above the tabla to get the desired balance of the left and right hand drums along with the desired LF response (ever so slight proximity boost at that distance). Knowing I was going to synchronise the tracks in mastering, I angled the rear of the tabla mic to reject as much of the voice as possible. Why? The singer rocks back and forth and side to side while singing, which makes it virtually impossible to synchronise two microphones because the time differences between them keep shifting as he moves around. The closer you get them to sync, the worse the comb filtering becomes!

    Although the TLM103 was capturing the majority of the tabla sound, in mastering I treated it like a spot mic, delaying it to put it in time with the tabla spill captured by the vocal/harmonium mic (almost exactly 3ms, as it turned out). Very, very simple and very effective. The end result has all the solidity of a direct-to-stereo coincident recording, and there are no comb filtering problems as the singer moves around.

    Having said that, considering the distances between the microphones and their instruments, I was well within the 3:1 requirement.
     
  20. aracu

    aracu Active Member

    The classical and folkloric music of India is a very beautiful
    and rich world. I've been listening to recordings of the sarangi
    player Ram Narayan. Sometimes the recording quality has
    problems but the music is always exceptional.
     

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