Setting gain on audio interface for measurement mic

[LiberalMedia]

Hi, I just bought a dayton audio EMM-6 measurement mic to use for room correction eqing with REW, how would I go about setting the gain on my focusrite scarlett 2i2?

 

[DanDan]

Some guides to REW and acoustic measurement

AustinJerry's guide has good coverage of using USB microphones.

www.avnirvana.com

 

[BenToronto]

Smart move. But possibly you bought the right mic (on sale for $43 - I should get another one) by mistake. Everybody is buying the UMM that is a USB-powered electret. But smarter to get the EMM (which requires a power supply called "phantom") and a DAC (cheap or just use your sound card)... and all REW users should buy a cheap floor-standing mic stand (very cheap).

Later edit: You have a phantom power source, I have subsequently learned. But for others with the EMM, what you need is a power source. Best move (ahem, ahem) is a mic mixer that has it, as do millions of some Behringer models now being sold second-hand by frustrated amateur DJs. In a big city, lots for sale in Craigs List, and of course, eBay.

The better way lets you know and to control upstream the signal the mic-system is sending to the laptop. And a variety of other tricks too.

BTW, ignore the REW queries about calibration. Getting correctly calibrated only matters for a few parameters and your ears will tell you if your speaker loudness is in the ball-park for your purposes.

B.

 

[jtalden]

The REW internal SPL level can be set various ways. For measurement of the SPL response and EQ settings the SPL level accuracy is not important as it is the shape of curve that is of interest.

Possible methods to set the REW internal SPL level:

• Play PinkPN noise at a loud, but not too uncomfortable level and call that 75 dB. (rough estimate)
• Use an app on a mobile phone for an external SPL reading.
• Use a hand held SPL meter for an external SPL reading.
• Use a DMM meter and loopback cable (TRS to XLR) on your audio interface.

 

[dsnyder0cnn]

Hi, I just bought a dayton audio EMM-6 measurement mic to use for room correction eqing with REW, how would I go about setting the gain on my focusrite scarlett 2i2?

I've been using exactly the same setup. I agree with @jtalden that pink noise at ~75 dB is a good place to start. When I'm in REW's "Check Levels…" option under "Preferences", I select "Use main speaker test signal to check/set levels". I turn up the output on my 2i2 or preamp until I measure about 75 dB using an SPL meter. The meters in REW show output level (-10 dB) and input level. I gradually increase the mic input gain on the 2i2 until the input level reaches -30 dB.

This seems to work well. Going much higher than -30 dB requires me to max out the input gain on the 2i2, which usually results in it going into overdrive. When I'm recording the sweeps, I continue to monitor levels using an SPL meter. If the peak level is much above 85 dB, I turn the volume down a bit and start over.

 

[LiberalMedia]

Thanks for the replies, I ended up matching the gains using an SPL meter

 

[BenToronto]

I've been using exactly the same setup. I agree with....

What is your EMM-6 phantom power source?

B.

 

[BenToronto]

removed

B.

 

[dsnyder0cnn]

What is your EMM-6 phantom power source?

B.

As I said, same as @LiberalMedia . Focusrite Scarlett 2i2 audio interface. It provides 48V of phantom power.