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Author Topic: Measurement Microphones  (Read 77962 times)

Christopher Wintz

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Re: Measurement Microphones
« Reply #20 on: December 17, 2008, 07:37:17 pm »

Art Welter wrote on Wed, 17 December 2008 18:30

Since I only have, and only tested one of these mics, I would not want to say they all are that bad, but I bet they are not particularly consistent unit to unit..


which is why you pay more for a matched pair.

Interesting input guys.  I'm getting myself a little holiday gift and building out my SMAART work station.  I have the software and computer and am getting a Presonus USB preamp, I'll probably barrow a TC-30 from work until I save enough for as decent measurment mic.  

Do you guys find yourself needing a matched pair very often?  I thought about holding off until I could afford a matched pair of M30's, but I can't think of a test situation where the only thing that affords you is the luxary of not getting up and moving the test point yourself.

Thanks for the input though guys, very cool reading here.

Edit:  What do you guys think about the Lectroacoustics wireless test system?  It seems kinda gimmicy to me.  Does putting a wireless device in the single path really change the frequancy response THAT much?  I mean I know it's going to add a little color, but really?  Is there a dynamic issue at play that I've never heard of (compression during a-d/d-a convertsion...?...)?
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Steve Devino

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Re: Measurement Microphones
« Reply #21 on: December 17, 2008, 11:37:39 pm »

FYI, the TC-30 ad M30 are identical mics other than the color of the case. Eric Blackmer once told me, it seems people need "measurement" in the model to make it real (paraphrasing).

If you do any recording the an M30 or tc30 or QTC30 pair is one of the absolute best recording mics for acoustic guitar, live choir, small orchestras, or drum overheads.

Steve
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Arthur Skudra

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Re: Measurement Microphones
« Reply #22 on: December 18, 2008, 01:15:01 am »

Christopher Wintz wrote on Wed, 17 December 2008 19:37

Edit:  What do you guys think about the Lectroacoustics wireless test system?  It seems kinda gimmicy to me.  Does putting a wireless device in the single path really change the frequancy response THAT much?  I mean I know it's going to add a little color, but really?  Is there a dynamic issue at play that I've never heard of (compression during a-d/d-a convertsion...?...)?
Nothing gimmicky about the Lectrosonics TM400 set.  Being a digital hybrid wireless, they have eliminated the need for the companding circuits used in typical wireless systems.  Companding circuits would make your measurement non-linear.  EV & HME used to make test and measurement wireless systems that bypassed the companding circuit, unfortunately the demand for such systems is very low, and were discontinued.  AFAIK, the Lectrosonics TM400 is the only wireless currently available that is suitable for test and measurement.

In addition to a flat frequency response, linearity of the measurement signal is very important for making accurate measurements of sound systems using software such as Smaart.  As a side benefit, the Lectrosonics wireless is flat down to 40 Hz, most other wireless systems don't go that low.

If you do many large venues, the TM400 can prove to be invaluable!
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Geri O'Neil

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Re: Measurement Microphones
« Reply #23 on: December 18, 2008, 06:59:13 am »

Arthur Skudra wrote on Thu, 18 December 2008 00:15

Christopher Wintz wrote on Wed, 17 December 2008 19:37

Edit:  What do you guys think about the Lectroacoustics wireless test system?  It seems kinda gimmicy to me.  Does putting a wireless device in the single path really change the frequancy response THAT much?  I mean I know it's going to add a little color, but really?  Is there a dynamic issue at play that I've never heard of (compression during a-d/d-a convertsion...?...)?
Nothing gimmicky about the Lectrosonics TM400 set.  Being a digital hybrid wireless, they have eliminated the need for the companding circuits used in typical wireless systems.  Companding circuits would make your measurement non-linear.  EV & HME used to make test and measurement wireless systems that bypassed the companding circuit, unfortunately the demand for such systems is very low, and were discontinued.  AFAIK, the Lectrosonics TM400 is the only wireless currently available that is suitable for test and measurement.

In addition to a flat frequency response, linearity of the measurement signal is very important for making accurate measurements of sound systems using software such as Smaart.  As a side benefit, the Lectrosonics wireless is flat down to 40 Hz, most other wireless systems don't go that low.

If you do many large venues, the TM400 can prove to be invaluable!


Amen. Absolutely some of the best money I've ever spent. That and a tablet!

Geri O
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John Roberts {JR}

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Re: Measurement Microphones
« Reply #24 on: December 18, 2008, 09:47:19 am »

Arthur Skudra wrote on Thu, 18 December 2008 00:15

Christopher Wintz wrote on Wed, 17 December 2008 19:37

Edit:  What do you guys think about the Lectroacoustics wireless test system?  It seems kinda gimmicy to me.  Does putting a wireless device in the single path really change the frequancy response THAT much?  I mean I know it's going to add a little color, but really?  Is there a dynamic issue at play that I've never heard of (compression during a-d/d-a convertsion...?...)?
Nothing gimmicky about the Lectrosonics TM400 set.  Being a digital hybrid wireless, they have eliminated the need for the companding circuits used in typical wireless systems.  Companding circuits would make your measurement non-linear.  EV & HME used to make test and measurement wireless systems that bypassed the companding circuit, unfortunately the demand for such systems is very low, and were discontinued.  AFAIK, the Lectrosonics TM400 is the only wireless currently available that is suitable for test and measurement.

In addition to a flat frequency response, linearity of the measurement signal is very important for making accurate measurements of sound systems using software such as Smaart.  As a side benefit, the Lectrosonics wireless is flat down to 40 Hz, most other wireless systems don't go that low.

If you do many large venues, the TM400 can prove to be invaluable!


Putting a 2:1 compander in your audio path doubles the frequency response errors of that path between the compressor and the expander.

The compressor at the mic squashed the signal 2:1, at the receiver it gets expanded back out 1:2. Any errors in that wireless link get expanded too.

So if that path is a little sloppy, it becomes more sloppy.  The -3db point now becomes a - 6dB point. Note: if the path has known problems the compander can be designed to be less sensitive to certain frequency regions but I doubt many (any?) go to that much trouble.  

JR


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Christopher Wintz

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Re: Measurement Microphones
« Reply #25 on: December 18, 2008, 10:52:28 am »

That makes alot more sense now.  I was kinda wondering what was up.  I have heard of using companding before as a means of reducing single noise in comms lines, but I didn't realize that wireless units alos compand, thanks guys.
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HarryBrillJr.

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Re: Measurement Microphones
« Reply #26 on: December 18, 2008, 11:57:25 am »

They have a new mic clip now.
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Harry Brill Jr.
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HarryBrillJr.

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Re: Measurement Microphones
« Reply #27 on: December 18, 2008, 12:06:34 pm »

It's a 1/2" to 1/4" adapter with an O ring on the 1/4" side.  Seems like it would work since the seal is maintained.
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Mesadude

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Re: Measurement Microphones
« Reply #28 on: December 18, 2008, 12:47:50 pm »

anyone who ever worked with Josephson C-550?
They claim it's the most accurate measurement microphone ever made..

I love the other Josephson's i've tried so far, but never got to use the C-550.

http://www.josephson.com/c550.html

Thanks.

Willem
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Jake Hogberg

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Re: Measurement Microphones
« Reply #29 on: December 18, 2008, 04:31:33 pm »

Shocking...my 50$ behringer mic has the same frequency response as both of my 600$ m30's, although I can't speak for the phase. Can't argue with that. Plus, having the best measurement mic (which might not be any better) WILL NOT matter unless you have the best signal path, and even more importantly, a complete understanding of making acoustic measurements and interpreting them. Just my opinion.
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Re: Measurement Microphones
« Reply #29 on: December 18, 2008, 04:31:33 pm »


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