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Discussion Starter #1
I'm admittedly new to calibration and room measurement, so I hope I'm not making any major blunders here.

I'm getting started on REW, mainly to fine tune my sub crossover and phase, as well as tweak speaker placement for my two-channel music system.

I picked up a Dayton EMM-6 for next to nothing (restock) at partsexpress. I've got two preamps I've demoed it with: a Focusrite Scarlett Solo and a Tascam US-4x4. The Tascam has a bit more headroom on the pre's, I believe, though I've been using the Focusrite because it has RCA outputs - minimizing the number of adapters I have to use.

I'm aware that the EMM-6, being a small condenser, possesses higher self-noise than most of the mics I use for music. I'm also aware that it's a low sensitivity mic. But the noise floor on this thing seems absurd. Without another SPL meter, I'm unable to state what my actual source level is, but at a comfortable/low listening volume, the sound from the speakers is almost undifferentiable from the self-noise. Spoken words right next to the mic are audible, but remain awash in static. With the Focusrite gain nearly maxed out, I get self noise of -20dB. Snapping my fingers or speaking right next to the mic shows my levels creep up to -16dB or so.

I'm concerned I'm not going to get any usable room response data without cranking the speakers beyond what I'm confortable with. I know I don't need loud signals for calibration (though I imagine it helps), but will a VERY persistent self-noise throw it off?

So my primary questions are:
  • Is there a better way that I can assess the severity / effect of the self noise of this mic?
  • Is it conceivable that I've got a dud mic? It was a restocked item, but it didn't appear to be used.
  • Am I unduly worried about the effect of the self-noise? Is it less of an issue than I'm making it out to be?
 

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Can’t say I’ve ever heard of anyone lodge noise complaints of such magnitude with this mic. Since you’ve verified it with two interfaces, and if your other mics work fine with those interfaces, I think the only conclusion is that it’s defective. Maybe you can return it for a refund.

Regards,
Wayne A. Pflughaupt
 

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Discussion Starter #4
Can’t say I’ve ever heard of anyone lodge noise complaints of such magnitude with this mic. Since you’ve verified it with two interfaces, and if your other mics work fine with those interfaces, I think the only conclusion is that it’s defective. Maybe you can return it for a refund.

Regards,
Wayne A. Pflughaupt
Thanks for confirming I'm not crazy. I don't have a frame of reference for measurement mics.


BTW, nice bike in your avatar! Looks like a vintage Yamaha 650 twin?

Regards,
Wayne A. Pflughaupt
Indeed it is! It's currently in a less-glamorous heap of parts in the garage while I wrap up a rebuild of the engine top end.
 

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Well, I was having the same problem a few days ago. It seemed odd that the meter on my interfase was way up. It was connected to a Metric Halo ULN 8 that I use for recording music and it's very clean. So, I decided to hear the mic with my voice and headphones and indeed it was pretty noisy. I connected other condenser mics like an Akg 414, Audiotechnica 4040, etc, and they all register very low noise. The measurement with the Dayton seems right because I tried with the 414 in omni and got a very similar curve.
I too thought I had a defective mic. I just checked the specs and yes, the Dayton EMM6 S/N Ratio is 70 db A-Weighted and the C414 is 88 db A-Weighted,
That's an 18 db difference. I guess for the price it's a good mic but I will definitely check the specs when I purchase a new measurement mic.

Regards
 

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Hi. I had a similar experience with the USB version UMM-6, and wrote a review on Amazon:
"I purchased it for accurately measuring the frequency response of my home and car audio systems. Its direct USB output is quite convenient. However, its background noise is so high that the test signals' volume must be very high to ensure that I am measuring the systems' response and not the microphone noise spectrum. Definitely not adequate for environmental noise level measurements unless used in very noisy places..."
So, yes, this microphone is quite noisy. It works well for REW swept frequency response measurements, for instance, but definitely not for sound level metering nor for recording.
 

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Discussion Starter #7
Huh, thanks for the anecdotal accounts. Perhaps I'll plug it back in and see what the noise spectrum actually looks like in a quiet room.

If it's fairly flat, then at least that white noise won't color the measured room response. I guess in that case, I'd just need to run my speakers much louder than I usually do to perform the frequency sweeps and pink noise for RTA.
 

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Huh, thanks for the anecdotal accounts. Perhaps I'll plug it back in and see what the noise spectrum actually looks like in a quiet room.

If it's fairly flat, then at least that white noise won't color the measured room response. I guess in that case, I'd just need to run my speakers much louder than I usually do to perform the frequency sweeps and pink noise for RTA.
I know that this thread has gotten quite stale, but I thought I'd provide an update. The mic was a dud. It's self noise would increase steadily over a 2-3 minute period after applying phantom power until anything but the loudest noises were inaudible. I exchanged it for a new EMM-6, and the replacement unit is working perfectly.
 
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