Measurement microphones

[ShinOBIWAN]

I'm looking into upgrading my very basic Behringer ECM8000 mic to something more accurate.

In the past I've hired out an Earthworks measurement microphone + pre-amp but at £9 per day its pretty expensive and I'm at the stage where I'd like to redo some measurements but the mic is out on loan so I'm stuck playing the waiting game until its returned and can be loaned out again.

I've briefly looked into the big names in measurement mics and it seems Earthworks, Bruel & Kjaer and GRAS are the ones to own. My problem is finding places on the web that sell these microphones as well as pricing.

Could folks post places they've found for these brand or others they'd recommend so as to help me and maybe others who have similar queries.

 

[ShinOBIWAN]

To get things started here's one place in the UK that hires out a range of very high quality measurement microphone and pre-amps. This is at a price though of course:

http://www.gracey.com/prod-06a.htm

 

[pinkmouse]

You can try my mate Pete, at Crystal Pro Audio. He gets S/H measurement mics in occasionally, and quite often has other interesting stuff in as well.

Oh, and I might buy your ECM off you as well.

 

[CrisTUFR]

ShinOBIWAN,

There's always the option of going DIY, and having your mic calibrated by a pro. I have a helpful wiki page up here with a small list of project links:

http://support.supermegaultragroovy.com/wiki/index.php/Microphones

I hear that some DIY mics outperform the ECM8000, and I've seen correction curves for capsules (WM61a, in particular) that demonstrate they need far less correction to get flat.

Even with a great microphone, you still need to get calibration data for it. I picked up an Earthworks M30 a few months ago, and had to pay extra for the calibration file to ensure it's flat.

As far as I know, you don't need to go overboard with the preamp (AFAIK, the Earthworks preamp costs a few grand). Most preamps are very flat over the entire audible frequency range, and you can get away with the built-in preamps that come with a lot of the USB-/FireWire-powered audio devices on the market. (I was surprised by this fact too, but it came directly from Earthworks...)

I use my Earthworks mic plugged into a MOTU Traveler right now, but I think one could easily get away with a far cheaper device (Like an Edirol UA-25 or FA-66).

Hope this helps,

Chris

 

[ShinOBIWAN]

You can try my mate Pete, at Crystal Pro Audio. He gets S/H measurement mics in occasionally, and quite often has other interesting stuff in as well.

Oh, and I might buy your ECM off you as well.

Thanks Al,

I've sent him an email so here's hoping

 

[Depth Charge]

There's always DPA mics (http://www.dpamicrophones.com), they mostly do stuff for recording (they have some very interesting articles on micing techniques etc as well) but also do a reference mic (4007/4004) for measurements and such like. I think it uses a Bruel & Kjaer capsule, I could certainly be wrong though. Do a froogle search, I think they cost about £1100 or so. They have also just launched a cheaper line of mics (4090/4091) along the same lines. I think they are somewhere in the £300 - £350 region.

Alternativly you could mod an ECM8000 (http://www.homerecording.com/bbs/showthread.php?t=111051&page=1&pp=25) and then perhaps send it away for calibration. I'm thinking of getting a few ECM8000s for modding to do some recording. Apparently they can sound about as good as some of the cheaper Earthworks stuff.

 

[ShinOBIWAN]

There's always DPA mics (http://www.dpamicrophones.com), they mostly do stuff for recording (they have some very interesting articles on micing techniques etc as well) but also do a reference mic (4007/4004) for measurements and such like. I think it uses a Bruel & Kjaer capsule, I could certainly be wrong though. Do a froogle search, I think they cost about £1100 or so. They have also just launched a cheaper line of mics (4090/4091) along the same lines. I think they are somewhere in the £300 - £350 region.

Alternativly you could mod an ECM8000 (http://www.homerecording.com/bbs/showthread.php?t=111051&page=1&pp=25) and then perhaps send it away for calibration. I'm thinking of getting a few ECM8000s for modding to do some recording. Apparently they can sound about as good as some of the cheaper Earthworks stuff.

Interesting stuff, thanks for that.

Do you know any place in the UK that sells the Panasonic electrets?

I've found the Earthworks M30 available for around £370 inc shipping and taxes from the US. The M50, which is the one I hired, is around £1000. My budget is around £300 so no M50 for me.

I'd like to give the ECM8000 mod a try though before I but down hard cash.

 

[nemestra]

Do you know any place in the UK that sells the Panasonic electrets?

Hi Shin,

I got a few Panasonic capsules from Vikash many moons ago when he was first experimenting with them. Don't know of any UK source. Pinkmouse suggested a UK group buy from Digikey some time back I think. Meanwhile Vikash has made kits available, no experience of them, but see the following threads for info on sourcing capsules and for the kits:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=50666&highlight=

http://www.diyaudio.com/forums/showthread.php?s=&threadid=16330&highlight=

A little cheaper than the pro alternatives...

James

 

[David Gatti]

Have you looked at Bamberg Labs' calibrated Panasonic mic & preamp?
It's what I use.

http://www.bamberglab.com/mic_probe_preamp.shtml

 

[Vikash]

Do you know any place in the UK that sells the Panasonic electrets?

http://www.madaboutsound.com/prod_det.asp?product_id=10

 

[ShinOBIWAN]

Have you looked at Bamberg Labs' calibrated Panasonic mic & preamp?
It's what I use.

http://www.bamberglab.com/mic_probe_preamp.shtml

Thanks for the link David but it appears they are out of stock at the moment.

 

[hifi]

Maybe off topic but why do you need absolute accuracy above 10-15kHz ?

Most drivers used in that range are already pretty well behaved and not many designs calls for crossover work that high.

 

[ShinOBIWAN]

I've found another contender in the LinearX M53.

http://linearx.com/products/microphones/m53/M53_1.htm

Price is around £250 shipped and tax inclusive. Also comes with individual calibration file which is very useful as the generic ones always tend to be off to a certain degree.

The main reason for all the fuss is capturing room impulse responses for DRC and the Behringer ECM8000 just isn't good enough for this. I worked with the hired Earthworks M50 when I did my initial setup some months ago but I've since tweaked the positioning of the speakers and re-did the room impulse captures with the ECM8000 and the results are greatly inferior to M50 and especially with regards to the top end resolution.

What DRC does is filter all the audio through a modified version of the original room response, so you can imagine the problems that an inferior microphone can introduce.

 

[ShinOBIWAN]

Maybe off topic but why do you need absolute accuracy above 10-15kHz ?

Most drivers used in that range are already pretty well behaved and not many designs calls for crossover work that high.

Read the post above this one.

Like you said it wouldn't matter if I were only measuring speakers but with DRC (digital room compensation) it matters greatly.

 

[soongsc]

Interesting stuff, thanks for that.

Do you know any place in the UK that sells the Panasonic electrets?

I've found the Earthworks M30 available for around ?70 inc shipping and taxes from the US. The M50, which is the one I hired, is around ?000. My budget is around ?00 so no M50 for me.

I'd like to give the ECM8000 mod a try though before I but down hard cash.

Go to the PRAXIS site, and send them an email. They will deliver the WM-61a mic cap with wires and the callibration file. Calibration is 10Hz to 46K amplitude and phase. Each mic has a file. The service is quick. You can also ask about additional requirements. They even calibrate for a specific mic amp design, and will provide some sensitivity adjustment factors for a few different mic amps.

 

[ShinOBIWAN]

Thanks to Vikash, I've got my hands on one or two WM61a capsules. Top bloke and check out his website:

www.madaboutsound.co.uk

I'm going to try to mod my ECM8000 as per the instruction in the link earlier on in this thread. If any thing it should be interesting!

I'm going to hold off on any purchase until I've at least tried this mod and heard the results.

 

[davidsrsb]

Mounting of the capsule is critical at high frequencies. I use a 50cm metal tube of the same diameter as the capsule. I am not sure if the tube needs to be filled with sand to damp it.

 

[DarkOne]

A while ago I've been looking for measurement microphone too, but when I saw measurement mic supplied with TacT room correction I began to scrape my head and think what is it about.

They give you simple computer microphone for $2

 

[davidsrsb]

That simple computer microphone is probably a very flat respoce electret , converted to a very uneven result by the housing. It is hard to put any sort of guard over a mike insert without ruining the responce