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tlenthe
Location: USA
Posts: 11
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Posted - Wed Jun 25, 2003 4:58 am
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Hopefully SteveG will pick up this thread/question which started in the cooledit forum.
I am looking for suggestions on how to best mike a live performance of a wind band with the following characteristics:
Location - School auditorium with stage. Seats about 500-700, with relatively low ceiling (10 m / 35 ft) max height from floor to ceiling in front of stage. Stage opening to auditorium about 80 ft wide by 20 ft high. Auditorium seating area about 120 ft square, with floor rising and cieling falling to rear. Rear height of the seating area is about 15 ft. The front of the seating area contains a open area (a pseudo "pit", although it is at floor level) with built in risers leading up to the stage.
The stage area is not really optimized for musical performance. It has no "acoustic shell". Rather, there are rear and side heavy fabric curtains (theater like) and the top is open to the corregated, metal roof structure (about 35 feet) with lighting bars above. There are fairly spacious "off-stage" wings to each side of the stage. In effect, there is a "room" of the stage area connected to the "room" of the seating area with an opening about 80 feet wide and 15-20 feet tall.
Performers - About 70 musicians arrayed around conductor approximately 60 ft wide and 40 ft deep. Instruments include clarinets, flutes, saxaphones, trumpets, trombones, tubas and percussion (bass and snare drum, tympani, triangle, etc.)
An existing recording of our last concert was made with 4 microphones spaced on floor stands about 8 feet high across the open area of the front of the auditorium. If there had been a chorus arrayed on the built in risers, this would have been a reasonable location to capture this chorous. However, with the wind ensemble, this position emphasized the front/center positioned musicians and emphasized an upper bass "roar" of the auditorium, resulting in a very "muddy" sound. Audience noise and applause also was captured at the same approximate level as the musicians. BTW, there seemed to be extensive limiting/compression employed on the resulting CD of the performance, which I assume was used during the recording process. (Beleive me, there was no meaningful post processing done!). Sad to say, we even paid money for this job!
I am hoping to find a better microphone position for our next concert (note that I'm a working design engineer and amateur musician with an interest, but no experience, in recording). We have the benefit of rehearsing in the performance space, so there is the possiblity of some "trial runs" before "game-day". I have read about Blumlein, ORTF, X-Y, M/S, etc. as appropriate techniques in this situation.
What do you folks with real world experience suggest? Anyone in the Philadelphia, PA area interested in this job!? Thanks for your thoughts! - Ted
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ozpeter
Location: Australia
Posts: 3200
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Posted - Wed Jun 25, 2003 8:39 am
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You've done a very good job of describing the scenario - but unless I've missed it, I don't think you've mentioned what constraints there might be on placement of mic stands, and whether there is any reasonable chance of suspending mics from above. That's often the first question - what's allowed? Some halls allow nothing whatever on the floor of the auditorium, others are more relaxed, though sometimes common sense dictates that even under relaxed circumstances there's limits to what is sensible in terms of stands in or near the audience and trailing leads etc.
So, it's often a compromise. I guess when I go into a hall for the first time, I start with a main stereo mic/pair/array in mind (I'm not going to specify type, there have been other debates about that), and try to imagine that I could cause it to be held in the best possible location, never mind how. Then I compromise according to practicalities. The practicalities might require additional mics, for instance if the musicians are going to be set unusually deep or unusually wide.
So where does that main pair go? It's rare to have a lot of choice, but..... at risk of stating obvious considerations.... too far back and you'll be getting to high a proportion of indirect/reflected sound compared with direct. Too far forward coupled with too low, you'll just be getting the front row, with too little reflected sound. Going upwards can help balance front against back (taken to extremes, a mic directly above the first row but 300 feet up is going to be pretty much equidistant from everyone) but again you've got to watch the direct/indirect balance and also musical instruments are largely designed to be best heard horizontally in front of them.
I've often tried to analyse why I place my main pair where I do - part of the mental process I think involves imagining that the musicians are spread between a pair of loudspeakers - where would you sit to listen to those loudspeakers? Then as you add height to that position, go forward in proportion. Hard to explain.
Then additional mics, if necessary and if feasible (does the conductor allow mic stands in the orchestra, for example?) are brought into play to cover whatever inadequacies are inherent in the main pair's position. Factors such as soloists' locations must be considered. But avoid tipping the orchestra onto a vertical plane - in the case of a symphony orchestra, don't end up with the woodwind sounding closer than the strings, etc.
Anyway, if I'm not tucked into bed in about 3 minutes there's going to be a divorce here, possibly preceded by damage to my person, so I won't ramble further. Over to others.
- Ozpeter
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Wed Jun 25, 2003 10:09 am
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Bands on stages with a proscenium opening with a lot of space behind it constitute a nightmare to record. I've been in this mess a few times before, and I can tell you what the good answer is, but you may not like it... and in this particular situation, you can't do it fully anyway.
The stage tends to act as a giant bass trap, for a start, and if you haven't got good reflecting surfaces behind the band (which you haven't) then a lot of sound is going to get 'trapped' up on the stage. Now, the ideal situation is to get the band right off the stage... (There, I said you wouldn't like it!) but you can't because of the raked seating. So what you do initially is to optimise the acoustic performance - this is the 'get it right at source' bit. The basic principle is to get the instruments that 'project' - ie, anything with a bell on it - further back on the stage, and the less directional instruments further forward. And you use as much of the area in front of the prosc. opening as you can (without people being in danger of falling off the stage front!). You really don't want to be using the depth of the stage - the sound from here is going to be severely compromised. If you can find a way of utilising the pit area as well for any parts of the ensemble, this would be good - pits are put where they are for a good reason!
But this is a compromise. If you can get reflecting screens behind the band on the stage, that would probably help, but with projecting instruments there, perhaps not so much as you might think. The overall principle is to get a balanced sound at one point - around where the conductor is (you will probably need him/her virtually in the audience), and get a crossed pair or M-S array a few feet above above his head - possibly back a little. More compromise - you will almost certainly have to suspend the mics.
And you really don't want the performers spread too wide. With this many of them, they may not like it, but you are going to get better, more coherent results if they are a little closer together than perhaps they might like. And to get a good acoustic balance, you may have to move the sections around a bit. Yes, I know that this is going to cause trouble...
For bands, proscenium arches are a disaster. They are intended to be used by actors, with stage flats that reflect the sound straight out, and quite frankly, they don't even do this very well unless they are very carefully designed. But all that extra space beside the stage, with no flats, is an accident that's found somewhere to happen.
I know that this makes depressing reading - but this scenario happens very frequently. There is one school hall near here that is used frequently for this purpose - and the sound from the proscenium stage is so bad that all bands play in the body of the hall. Fortunately there is no raked seating to contend with. If you really can't move the band, then one of the easier compromises is to suspend a pair of mics from the top of the proscenium opening, angled down over the band. But the chances of getting good pickup from the front of the band is limited. You could try an additional pair in front, but I think that you will compromise the first pair too much.
But really, it would help to know how the band actually sounds in the hall - my guess is that with that proscenium opening, then the sound's not as good as it could be. And if that is the case, you have to fix this first before you'll get any chance of a good recording.
I'm sorry that this is all gloom, despondancy and a lot of hard work even to persuade anybody to try it - but it's been my experience that the only instruments that sound good in this scenario are the soloists, if you have separate mics for them.
I'm not surprised that your previous recording was unsatisfactory - what that guy did was so ridiculous under these circumstances that I think you'd be entitled to a refund. But getting a good result is not going to be as easy as just getting the mics in the best place, I think...
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Wed Jun 25, 2003 2:21 pm
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As an afterthought (and I think that Peter will agree with this), there would seem to be a lot of sense in using a M-S array rather than a crossed cardioid pair for anything suspended, because it's then relatively easy to control the width of the stereo image. And don't even contemplate an ORTF-style array - you are going to have enough of an imaging problem as it is!
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ozpeter
Location: Australia
Posts: 3200
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Posted - Wed Jun 25, 2003 7:26 pm
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Briefly, yes - an MS configuration can be very easy to dangle - I have mine running through a single stereo mic cable about as thick as my finger, which can easily support the mics on its own, and doesn't twist. Only a Soundfield mic can outdo it for danglability, IMHO.
- Ozpeter
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tlenthe
Location: USA
Posts: 11
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Posted - Thu Jun 26, 2003 1:35 pm
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The M/S approach sounds intriguing! Does one need to use one of the specialized M/S mikes or can two units with appropriately switchable patterns (and positioning) be just as effective? Are there particular M/S mikes that have given anyone good (or bad!) results?
I appreciate SteveG's comments on the location of the performers. I have to admit that as one of the musicians, I don't really know how the band sounds in the house itself (Although listening to student bands there, I haven't noticed substantial "boomi-ness"). As for moving the performers, I suspect that is beyond my control (except perhaps for suggesting a closer-in seating).
As for hanging locations, does one typically have to use some type of fly-wires to get the desired location? In this setting, hanging in the stage area will cause the location to be a little in front of the conductor. On the otherhand, hanging from a lighting catwalk will be over the first row of seats, almost 30 feet away from the performers. When one DOES hang a microphone, how do you trade-off the mike cable length vs. the use of a remote pre-amp? I'm visualizing that run to from the mike to the mixer/recorder can easily exceed 100 feet when hanging the mike.
Aside from the aesthetic drawbacks, what are the issues in attempting to use some type of floor stand/boom for these "over the conductor's head" mike position ?
Thanks again for all your feedback!
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Thu Jun 26, 2003 2:45 pm
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tlenthe wrote: |
The M/S approach sounds intriguing! Does one need to use one of the specialized M/S mikes or can two units with appropriately switchable patterns (and positioning) be just as effective? Are there particular M/S mikes that have given anyone good (or bad!) results? |
I know that oz uses some rather posh Sennheisers that are designed for the job... and it is an unfortunate fact of life that you are likely to end up with slightly 'variable' results unless you use a pair of mics that do have pretty well-matched characteristics. You can cheat somewhat, and use a crossed pair of cardioids, and matrix the results afterwards, and that's what I've done a couple of times. In principle, I have a couple of mics that probably would make a M-S pair, but they are different... we had quite an interesting discussion about this a while back, complete with some theory (and my badly drawn pictures!)
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I appreciate SteveG's comments on the location of the performers. I have to admit that as one of the musicians, I don't really know how the band sounds in the house itself (Although listening to student bands there, I haven't noticed substantial "boomi-ness"). As for moving the performers, I suspect that is beyond my control (except perhaps for suggesting a closer-in seating). |
It's very easy to get 'used' to the sound of a venue - it's usually when you get the recording home that you really start to notice what's wrong. You wouldn't neccessarily notice the problem on the stage itself - but if you get the impression that you're getting a sort-of 'closed in' sound on the stage, that's not good news... Had a bizarre situation once where a bass player jsut couldn't be heard in the hall. We asked him to turn up his amp, and he said that he couldn't - it was already deafening him! And when I went on to the stage, I knew what he meant! The stage trapped virtually all the bass - it bounced nicely between the side walls, and if you stood in an antinode, it really was deafening.
Stuck his cab out in front of the opening - all problems went away, except that now, he couldn't hear himself play!
But really, the only way to tell how much difference it will make is to try it, and see what the differences are. You will have to find out from the powers that be just how much they want a good recording - if they want it badly enough, they'll try a few of the things I'm suggesting. But with all recording situations like this, you have to use your ears in the venue itself. Sometimes sticking a finger in one ear and listening in mono can help, believe it or not. And it is much easier if you are neutral about what you're recording. Familiarity breeds poorer listening discrimination, as a rule.
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As for hanging locations, does one typically have to use some type of fly-wires to get the desired location? In this setting, hanging in the stage area will cause the location to be a little in front of the conductor. On the otherhand, hanging from a lighting catwalk will be over the first row of seats, almost 30 feet away from the performers. When one DOES hang a microphone, how do you trade-off the mike cable length vs. the use of a remote pre-amp? I'm visualizing that run to from the mike to the mixer/recorder can easily exceed 100 feet when hanging the mike. |
I haven't used a catenery wire system for so long, I can't remember! The usual approach is what I'd guess that oz does, which probably involves a tall pair of steps, or whatever. Find out how they change the light fittings, and use that! You have to be really careful with ceiling fittings, though. This is not a good place to have an accident!
With a nice loud band, you can run 100ft mic cables into a preamp without any problems at all, assuming that you've got decent mic cables, and any phantom power draw isn't too great, which would lose you some polarising volts. Long mic cables do have disadvantages in some situations, but there are rather less of these than you'd think.
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Aside from the aesthetic drawbacks, what are the issues in attempting to use some type of floor stand/boom for these "over the conductor's head" mike position ? |
If you can get big enough ones - like the ones KMA used to make - you might get away with it. But small ones fully extended can be a nightmare, because they're not stable. If you have to use samll extended stands, then you have to find a way of fixing them to the floor so that people won't trip over them and knock them flying. If you have to put them in an audience thoroughfare, then leave somebody with them to guard them until everybody is seated. Unless you can get mics suspended, recordings with an audience are a real drag, IMHO. Get a couple of soloist mics fixed firmly somewhere, and make the soloists go to them if you can - this makes life a lot easier for you (but not them!)
I must say, though, that I have some serious doubts as to how well you can record this band and play in it at the same time...
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ozpeter
Location: Australia
Posts: 3200
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Posted - Thu Jun 26, 2003 5:09 pm
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Ozpeter's main stereo pair suspending primer:
Try to make up a fitting that will enable you safely to suspend your pair from the mic cable itself. Either use a stereo cable, which can be a great timesaver, or prepare two cables by taping them together at frequent intervals, ensuring they are flat and untwisted first. Find a short mic stand stem - maybe one from a Tandy desk stand, which should unscrew from the base, and use two cable ties to attach the mic cable to it securely. Then screw on a T bar, or whatever holds your mics, and check that if you hold the whole thing up by the cable it will hang straight and that the mics can be suitably positioned.
Scenario one: A straight drop down. This is of course easy. It assumes that you've got the means to attach the mic cable to something directly above the point where your mics should be. Chief hazard is that there may be a tendency for the cables gradually to twist so the mics are no longer pointing in the desired direction. I don't usually have much of a problem with this, but try to rig good and early to allow the cable to settle, allowing you to adjust before the rehearsal begins, either by rotating the cable at the fixing point or by rotating the mic stand stem relative to the mic cable.
Scenario two: Fixing to a sling across the auditorium. This relies on having suitable well-anchored fixing points either side, high enough up so that you don't have to stretch the sling tight to get enough height at the mic. I have two long lengths of nylon rope, with a spring clip attached to one end of each. I also have two 3' loops of similar rope, also with a spring clip attached. I thread the loops through the attachment point either side and then through themselves - no knots required. I lay one half of the sling across the auditorium floor with the spring clip in the middle, and use cable ties and tape to secure the mic cable to the sling, with the cable extending about 18" beyond the spring clip to allow it to dangle vertically down by that much, when the whole thing is complete. Because you've laid it across the hall you can see where to finish attaching the cable to the sling. Now make a small loop at the end of the sling nearest the attachment point, and clip it into the premade loop you attached earlier. Do the same the other side using the part of the sling to which the mic cable is not attached. Raise the whole thing high enough so you can still reach the mic end of the cable from the floor of the auditorium, then attach and align the mics on their little post. Then raise the sling towards the final position, making a new loop to fix into the clips each side - don't take out the earlier loop, just in case you let go of the sling - that way your mics won't hit the floor! It's perfectly possible to do this whole thing single handed - I've done so at least 100 times I'd guess.
Scenario three: Vertical drop and pull. You do this if you can't get the mic to the right spot with a straight drop down. So you drop the mic down from the best available point, with a cord attached to the mic cable a few feet up from the mic end, the cord being dropped down from another suitable point either in front of the mic cable to pull the mics forward, or behind if that's appropriate, or you might have the mic cable a bit to one side and the cord a bit the other side, or even work diagonally, depending on the available fixing points.
Overall comments: If unsure find out in advance what safety requirements the auditorium has. Always bear in mind that you could literally kill someone if you don't make the suspension safe. Would you let your child sit beneath it?! Beware of anything that might cut or chafe ropes, and watch out for the heat from light fittings. Don't suspend mics, or remove them, if people are in the auditorium below. You've got to get there early and be prepared to leave late (pack up everything else first, then take down the suspension last). If you are not totally sure you can hang the mic without risk to yourself and others, use a stand.
- Ozpeter
BTW I use Sennheiser MKH series mics, in a Sennheiser piggyback clip and cat's cradle. You just point the whole thing at the performers, and there you are. I use a MZA-MS1 preamp/matrix box also from Sennheiser UK, perhaps no longer available sadly, and hefty starquad cable (Canare?) with 5 pin XLR's wired as stereo. I often use runs well in excess of 100', even through dimmed lighting rigs, with no problems.
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ozpeter
Location: Australia
Posts: 3200
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Posted - Sat Jun 28, 2003 10:10 pm
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And another thing - I've just come across this useful primer on live recordings mainly in the context of classical - might be handy to anyone feeling their way into this area.
http://www.tonmeister.ca/research/pubs/martin00.pdf.
- Ozpeter
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