Topic: narrow brick room, mic config?

[georgeh]

my choices of mics, mg 20 or mg21. ran cards(mg20) din, sounds too muddy/low end, for my taste. would you all say run xy or maybe run the hypers instead?

[vanark]

XY will cut down on some of the muddiness, but I might try narrowing the angle some as well.  You've got stuff bouncing around the room.  If it was me, I'd use the Point At The Stacks method.

[NOLAfishwater]

what he said. XY, narrow pattern, hypers

[georgeh]

thanks.
if anyone is interested, http://bt.etree.org/details.php?id=523028, this is the show i was referring too. and the venue is city limits in
del ray bch fl.

[boojum]

Define "narrow." 

[georgeh]

Define "narrow." 

best guess, 50ft wide by 200ft long, with the "brick walls" I didn't notice any  acoustic tiles or such on the sides either. I tried to set up dfc about twenty feet back from stage, which would have been fine, but was asked to move back, which really made a difference in the sound quality. The venue seems pretty good about where you can set up, this was the sub dudes request to have me move back.

[georgeh]

venue info http://www.citylimitsdelray.com/venue.php
mentions stage width, add probably 15ft to each side (?)

[Brian Skalinder]

I should preface by saying there are two general approaches to our type of recording:  capture as much direct sound as possible, or capture the sound and environment  as best as possible to duplicate it during playback.  An example of the former:  stack taping;  the latter:  ORTF at some reasonable distance.  My assumption for this post:  we want to achieve the latter, i.e. record the performance in a way that, upon listening with a good playback system, provides us the feeling of "being there".

Check out the link to Williams' Sterephonic Zoom (SZ) in the stickied thread at the top of the forum.  It's not the be all end all, but may help provide an understanding of how the configuration impacts the mic array's characteristics, and therefore impacts the results.

Based on Williams' SZ, you should know that running coincident (0 cm spacing, i.e. XY) and reducing the included angle will produce a very wide stereophonic recording angle (SRA).  For example, 0 cm with 70º included angle will produce an SRA of approximately ±100º.  That's plus or minus 100º from the mic array's center line.  So if you're standing and looking down the center line of your mic array towards the sound source, -100º is just behind and over your left shoulder, and +100º is just behind and over your right shoulder:  a total span of 200º.  From your recording position, does the sound source span 200º?  I highly doubt it.  The result:  using a narrow included angle in a coincident configuration will help reduce reverberant sound (room boom), but you'll end up with a very mono recording because both mics will be picking up nearly the same sound.  (FWIW, the only way you'd have a soundstage of anywhere near 200º is basically by running on-stage.)

Personaly, I'd run hypers to help minimize reverberant sound.  And a good starting point is to use a configuration with an SRA that's close to the width of the sound source.  Here's what I'd do...

• Guesstimate the width of the sound source from the recording position, in degrees.  Someone here mentioned long ago that a closed fist at arm's length covers approximately 10º.  For the sake of discussion, let's say we've guesstimated the sound source spans approximately 60º from the recording position.
• Using the Williams' SZ graph for hypercardioid mics (pg 10, Figure 10), find the SRA that closely matches the width of the sound source.  In this case, an SRA of ±30º closely matches our sound source width of 60º.
• Since I want to minimize reverberant sound ("room boom"), I want to use as small an included angle as is reasonable -- this ensures I pick up more direct sound and less reverberant sound.  So, follow the SRA ±30º plot line to a point where the included angle (on the vertical axis) is relatively small.  The plot line and graph end at ~50º included angle, so that's the included angle we'll use.
• Where the SRA ±30º plot line hits ~50º included angle on the vertical axis, note the spacing on the horizontal axis (~50 cm).  This is the spacing we'll use.

So, what does this tell us?  Using hypercardioids, a spread of ~50 cm and included angle of ~50º will produce an SRA of ±30º.  This basically will provide complete stereo coverage of our 60º wide sound source -- not far too much stereo coverage (like 0cm, 70º, which would produce a very mono recording), or too little.  Alternatively, we could achieve an SRA of ±30º using hypercardioids by spacing ~33 cm wide with a 100º included angle -- meaning we still have complete stereo coverage of our 60º wide sound source...not too much, not too little -- but the wider included angle means we'll pick up more reverberant sound in the process.  Which, of course, in this case we want to avoid.

So...that's what I'd try.  Again, this is just one of many potential starting points.  Results may vary using different microphones due to differences in the polar pattern.  Try something, see how you like it, then adjust next time based on your perception of the results.

[georgeh]

thanks Brian.
and yes, sometimes it is just try and try again till it works

[boojum]

Brian has pretty much covered it.  The Williams SZ is a great time saver.  It enables eliminating a lot of crazy ideas and starting from a point of proven ideas.  As for the sound bouncing off the walls: I would assume there will be a lot of folks in the room soaking up reflections to a great degree.  Bodies are great for sound deadening. 

You will probably do very well with the formula first time.  And, as Brian has pointed out, next time will be even better.

Go for it!

Cheers

[Ekib]

I don't think it's just the size of the venue and even the material ( in this case brick ) are the only thing that matters. I have noticed that the way the PA ( or speakers ) are configured makes a hell of a difference also.
Some venues have the PA hanging pretty high , other have them stacked on the floor ( not all way through , but surely not hanging ).

Sometimes by standing at a certain point you only catch a certain part of the speaker sound. That could be the case if you're getting too close for example.

Than I know brick room venues that have great sound , others that suck.

The man behind the soundboard could be important too .

Brian's calculation's are surely interesting but I don't believe you can approach a recording in a mathematical way at all. At least not all the way...

In fact , I have been standing at the same spot in a certain venue and some recordings came out absolutely amazing and others very mediocre...

[Brian Skalinder]

Great points, Ekib.  Please note they're not my calculations -- they're Williams'.  I'm just passing them along as a reference point, as someone did for me some time ago here on TS.

I may not have made myself clear in my previous post.  I didn't mean to suggest one could use Williams' SZ to determine how a recording will sound using a given configuration in a given environment.  Certainly, the environment in its entirety comes into play:  sound source (including on-stage amps, sound system, mix), room acoustics, recording location, height, mic patterns, mic configuration, crowd density and positioning, etc.  But the Williams' SZ does provide useful information about a given mic configuration's stereophonic recording angle (SRA).  A given mic configuration's SRA doesn't change from environment to environment, but the SRA one wishes to use in a given environment may change.  Using Williams' SZ, one may understand how the mic configuration impacts the SRA, and therefore -- combined with experience -- make a more informed decision about which mic configuration to employ from one environment to the next.

[Ekib]

Great points, Ekib.  Please note they're not my calculations -- they're Williams'.  I'm just passing them along as a reference point, as someone did for me some time ago here on TS.

I may not have made myself clear in my previous post.  I didn't mean to suggest one could use Williams' SZ to determine how a recording will sound using a given configuration in a given environment.  Certainly, the environment in its entirety comes into play:  sound source (including on-stage amps, sound system, mix), room acoustics, recording location, height, mic patterns, mic configuration, crowd density and positioning, etc.  But the Williams' SZ does provide useful information about a given mic configuration's stereophonic recording angle (SRA).  A given mic configuration's SRA doesn't change from environment to environment, but the SRA one wishes to use in a given environment may change.  Using Williams' SZ, one may understand how the mic configuration impacts the SRA, and therefore -- combined with experience -- make a more informed decision about which mic configuration to employ from one environment to the next.

Not to forget anyone's personal taste ! What's a great recording is to someone could be a different experience to someone else.

I thought these calculations were yours ! Nevertheless I think they're pretty impressive .

As any serious taper , everyone's looking for the perfect recording. But one thing I learned in all the years I have been taping ...it's more luck than anything else. Sometimes everything falls into each other for some reason...
Even during a gig it's hard to tell sometimes how a recording turns out. I have made recordings under poor circumstances ( when it was overcrowded for example and I had to tape at a bad place ) and they turned out awesome. Than some gigs I had what I thought the perfect place and it turned out disappointing.
That's the reason some band or artists that matter to me , I tape them at 2 or 3 different gigs.

[Gutbucket]

City Limits is a tough room in my experience. 

Position in the room is always most important in my book for any location.  I've had great results from the stage-lip there but if that's out you really need to get to your original position right at the forward most tables.  Even there, the sweet spot isn't large. The general line of thought which Brian outlined excellently above (more directional pattern with a narrower included angle offset by a wider spacing) has the best chance of working well from near there.

If you are farther back, the slap off the walls combined with the directivity of the hanging FOH array muddies things quickly.  The sound absorbing gobo-like bodies of the crowd are all below the echo fest happening over their heads in the room.  The strategy suggested above may help somewhat, but the sound becomes rapidly diffuse back there and is not simply bouncing off the sidewalls so the increased directivity of the hyper caps may not help as much as you'd like, though their rolled off low end response may still be beneficial.   

The only possibility I've considered for running from farther back is from the upstairs balcony rail (typically a more expensive VIP area).  That spot is even farther back in the room, but  there are delay-line speakers hanging from the ceiling focusing direct sound on that area and the center rail is at the apex of that stereo triangle.  I have never been up there so I have no idea how it sounds, but it's worth a shot and could potentially work really well.