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Old May 3rd, 2006, 04:18 PM   #1
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Microphone Recommendation

I just shot my daughter's school play using two AT 897 shotguns set on stands at center left and center right directly in front of the stage. I found the audio to be too directional, and am looking for suggestions. Would it be better to add more of the same type of mic, or use (two?) less directional mics (any specific mic suggestions, if so).

Also, the sound guy said I could hook my Sennheiser G2 transmitter directly into his mixing board; he claimed that the board output was line level, and that would work OK with my Sennheiser transmitter. I was thinking that the mixing board output would have to be mic level otherwise I might damage the Senn transmitter, so I didn't take him up on his offer. Can I use mic or line level input into the Sennheiser G2 transmitters?
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Old May 3rd, 2006, 04:55 PM   #2
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Quote:
Originally Posted by Ken McGrath
I just shot my daughter's school play using two AT 897 shotguns set on stands at center left and center right directly in front of the stage. I found the audio to be too directional, and am looking for suggestions. Would it be better to add more of the same type of mic, or use (two?) less directional mics (any specific mic suggestions, if so).

Also, the sound guy said I could hook my Sennheiser G2 transmitter directly into his mixing board; he claimed that the board output was line level, and that would work OK with my Sennheiser transmitter. I was thinking that the mixing board output would have to be mic level otherwise I might damage the Senn transmitter, so I didn't take him up on his offer. Can I use mic or line level input into the Sennheiser G2 transmitters?
That sort of spaced array is often done with 2 cardioids or 2 omnis. You need to be careful about the spacing between them relative to the distance from the stage - the mics should be at least 3 times farther apart than the closest one is from the sound source. Another option is 2 cardioids on one stand centre stage and back a few rows. arranged in an ORTF or X/Y coincident array. All of these arrangements have potential phase problems when collapsing down the to mono as often happens when video is viewed. So a final mic arrangement to investigate that avoids that problem is a Mid/Side pair consisting of a cardioid and a figure-8 placed very close together.

Your Senn transmitter has an adjustable sensitivity. The least sensitive setting is 0dB which is line level so you could probably take the board feed directly. The problem with that might be that it is a stereo feed to the house - you didn't say if he had a mono or stereo feed available or - but you only have one tranmitter so you'd lose the other channel if a mono mix wasn't available on the board..
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Old May 3rd, 2006, 05:57 PM   #3
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Quote:
Originally Posted by Steve House
The least sensitive setting is 0dB which is line level so you could probably take the board feed directly.
I thought Senn G2 least sensitive is -30. Most
sensitive is 0dB.
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Old May 3rd, 2006, 11:30 PM   #4
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Quote:
Originally Posted by Dave Largent
I thought Senn G2 least sensitive is -30. Most
sensitive is 0dB.
That is correct. 0db attenuation, 30db attenuation, and a few settings in between. 30 db is close to padding a line level down to mic, if the house engineer doesn't hit it too hard it should be fine. You might ask him to peak at -10db or something for your feed, then you're right in the range of mic level (-40 to -50db).
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Old May 4th, 2006, 05:49 AM   #5
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Originally Posted by Seth Bloombaum
That is correct. 0db attenuation, 30db attenuation, and a few settings in between. 30 db is close to padding a line level down to mic, if the house engineer doesn't hit it too hard it should be fine. You might ask him to peak at -10db or something for your feed, then you're right in the range of mic level (-40 to -50db).
Are you talking about the input level to the transmitter or the output level of the receiver? I was checking the manual when I answered earlier and as I read specs, when an input sensitivity is shown as "-20dB" or such that means feeding the device a signal at that level will produce a normal output. An input rated at "0dB" expects being fed a line level signal while one rated at "-50dB" would be expecting a much weaker mic level signal.

OTOH, the receiver's output settings would be just the reverse, with "0dB" meaning it's sending a line level on to the camera while "-30dB" would mean the output is being attentuated down to much weaker mic level.

So Sennheiser isn't following this convention on their transmitter sensitivity settings, instead calibrating it as attentuation instead of sensitivity with 0dB being the most sensitive and -30dB or whatever being less sensitive?
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Old May 4th, 2006, 03:39 PM   #6
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[QUOTE=Steve House]That sort of spaced array is often done with 2 cardioids or 2 omnis. You need to be careful about the spacing between them relative to the distance from the stage - the mics should be at least 3 times farther apart than the closest one is from the sound source. Another option is 2 cardioids on one stand centre stage and back a few rows. arranged in an ORTF or X/Y coincident array. All of these arrangements have potential phase problems when collapsing down the to mono as often happens when video is viewed. So a final mic arrangement to investigate that avoids that problem is a Mid/Side pair consisting of a cardioid and a figure-8 placed very close together.QUOTE]

I didn't mix down the audio, so there were no phase problems due to the relatively close spacing of the mics (this would only occur with a mixdown to mono, correct?). But, the directional nature of the at-897's caused a noticable loss when the actors were significantly off axis. Could I have used the same mic placement with two cardioids or omnis as long as I don't mix down to mono? Can anyone offer specific, reasonably low cost mics for this application? Thanks!!
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Old May 4th, 2006, 04:33 PM   #7
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[QUOTE=Ken McGrath]
Quote:
Originally Posted by Steve House
That sort of spaced array is often done with 2 cardioids or 2 omnis. You need to be careful about the spacing between them relative to the distance from the stage - the mics should be at least 3 times farther apart than the closest one is from the sound source. Another option is 2 cardioids on one stand centre stage and back a few rows. arranged in an ORTF or X/Y coincident array. All of these arrangements have potential phase problems when collapsing down the to mono as often happens when video is viewed. So a final mic arrangement to investigate that avoids that problem is a Mid/Side pair consisting of a cardioid and a figure-8 placed very close together.QUOTE]

I didn't mix down the audio, so there were no phase problems due to the relatively close spacing of the mics (this would only occur with a mixdown to mono, correct?). But, the directional nature of the at-897's caused a noticable loss when the actors were significantly off axis. Could I have used the same mic placement with two cardioids or omnis as long as I don't mix down to mono? Can anyone offer specific, reasonably low cost mics for this application? Thanks!!
Well, phase problems occur most often when mixing to mono in post but it can occur later as well if the person viewing your tape or DVD happens to have a mono TV or if it's broadcast and the station or cable company collapses it down to mono.

Cardioids or omnis would be far better for the placement you had than shotguns. I have a pair of Audio Technica AT3031's that are cardioids and are very nice sounding mics. The AT3032 is a similar mic with an omni pickup pattern. They run about $200 each, inexpensive yet definitely pro quality. One problem you'll encounter with any mic is going to be due to the distance from the speaker. If it was a band concert or orchestra or something like that the placements we're talking about are fine. But for spoken dialog, any mic is going to be problematic that far from the speakers.
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Old May 4th, 2006, 05:43 PM   #8
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Ken, do you have phantom power available for
a mic?
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Old May 6th, 2006, 06:38 PM   #9
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Quote:
Originally Posted by Dave Largent
Ken, do you have phantom power available for
a mic?
Yes, I am using a DVX 100 and a PD170, so both provide phantom power. For the shoot I reference above, I fed both Senn rx signals into my DVX, and recorded ambient sound (at a low and a higer level) using my PD170 with a single shotgun mounted on the camera.
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Old May 6th, 2006, 06:54 PM   #10
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Quote:
Originally Posted by Steve House
Are you talking about the input level to the transmitter or the output level of the receiver? I was checking the manual when I answered earlier and as I read specs, when an input sensitivity is shown as "-20dB" or such that means feeding the device a signal at that level will produce a normal output. An input rated at "0dB" expects being fed a line level signal while one rated at "-50dB" would be expecting a much weaker mic level signal.

OTOH, the receiver's output settings would be just the reverse, with "0dB" meaning it's sending a line level on to the camera while "-30dB" would mean the output is being attentuated down to much weaker mic level.

So Sennheiser isn't following this convention on their transmitter sensitivity settings, instead calibrating it as attentuation...?
Steve, I was addressing not input sensitivity but transmitter input level. The original poster reported that "...the sound guy said I could hook my Sennheiser G2 transmitter directly into his mixing board; he claimed that the board output was line level..."

My wireless experience is with Lectrosonics, Sony and Sennheiser, all seem to use adjustable attenuation at the transmitter to adjust for different volumes coming from the mic so as not to overload and distort at the transmitter's preamp.

So, the house sound guy's claim that a wireless link with a Senn. G2 would work fine is only true if the signal is down in the neighborhood of mic level before it hits the transmitter preamp, could be padded with an inline pad, or in the transmitter, or both, but such audio needs to be monitored at the receive end and the house engineer needs to be using an output of his board where he can actually see a level display.
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Old May 6th, 2006, 07:02 PM   #11
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Quote:
Originally Posted by Ken McGrath
...Can anyone offer specific, reasonably low cost mics for this application? Thanks!!
Boundary microphones also known as PZMs are often used for this application. People like them because they don't have to be in the audience, they have a sort of hemispherical response at mid and higher frequencies that works fairly well at the front end of the stage. Their directional response can be improved at lower freqs by mounting them to a flat surface, they are often mounted to 1/4" clear plexiglass at sizes up to 2' x 2'.

Crown makes the best PZMs, as far as I know...

Or move the 897s further away, so they are covering more of the stage. Some testing would help you find the right distance. Or, mount them at the front corners of the stage/proscenium pointed inwards, again, test it out.
Or a small diaphram cardoid condensor that is in the audience but closer than the shotguns.

An hour spent wandering around a rehearsal with a mixer, headphones and a couple mics will tell you a lot about micing in that hall!
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Old May 6th, 2006, 07:26 PM   #12
 
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Quote:
Originally Posted by Seth Bloombaum

Crown makes the best PZMs, as far as I know...
Crown makes the only PZM's, and most often, boundary mics are made slightly differently. PZM, or "pressure zone microphone" is a trademark of Crown, and uses a larger surface to generate the pickup area/boundary. Boundary mics generally have their own body and plate.
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Old May 6th, 2006, 08:21 PM   #13
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Shure makes some boundry layer mics, (Microflex?) that I've used on conference tables, stage floors, and stage overheads. They are nice, a bit smaller than the 7 Crown PZM's that I own, but I would still go with the Crown. It's been a stage standard for... a long time. Good for "STOMP" like shows, but if using it in performance, mounting it on the stage floor by itself will be an issue, you'll pick up alot of movement noise. Put it on a piece of foam or felt, up a few inches, and it'll be better. For bigger productions, shotguns work, but I have someone on the catwalk or near the stage, constantly aiming it. This will also work with parabolics if you're careful about it.

You can take the line output from the board, as long as it is unpowered. (i.e. not comming out of a powered amp). A colleague took the stage box monitor output, not knowing if it was powered or unpowered. It pretty much fried his transmitter (Sennheiser EW300 G2). The line (locking mini-to male mini to 1/4" adaptor) started sparking about an hour before the show, the internal board inside the transmitter melted. Defeinitely a safety hazard. Make sure it is an unpowered line level. I've never had a problem with blowing transmitters, especially Sennheisers, but bring the dB to -30 on the unit. BTW - how are you going to do that? Is it the bodypack with a series of adaptors or the plugon directly into an XLR male output?
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Old May 6th, 2006, 09:11 PM   #14
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Quote:
Originally Posted by Daniel Wang

You can take the line output from the board, as long as it is unpowered. (i.e. not comming out of a powered amp). A colleague took the stage box monitor output, not knowing if it was powered or unpowered. It pretty much fried his transmitter (Sennheiser EW300 G2). The line (locking mini-to male mini to 1/4" adaptor) started sparking about an hour before the show, the internal board inside the transmitter melted. Defeinitely a safety hazard. Make sure it is an unpowered line level. I've never had a problem with blowing transmitters, especially Sennheisers, but bring the dB to -30 on the unit. BTW - how are you going to do that? Is it the bodypack with a series of adaptors or the plugon directly into an XLR male output?
I was going to use the bodypack; actually, I hadn't considered using the plugon, but I can see no reason that would not work as long as I pad it to -30dB or so.

What is the difference between a powered and unpowered line level output?
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Old May 7th, 2006, 07:27 AM   #15
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I have had good results mounting 897's at the foot of the center of the stage in an X configuration with the mics at about 90 degrees to one another. The actual angle is determined by the size of the state and mic distance from the stage. The X pattern allows picking up sound from the sides without a drop-off in the center.

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