# Wildly Different Measurements



## Mark Fuller (Aug 5, 2014)

Hello folks,

Incorporating some 31 band White EQ's on my mains for my home mastering studio and having some very strange results with a new EMM-6 I bought from Dayton Audio.

Got the mic's cal file from Dayton working. Got a loopback cal for my USB interface. SPL level tests all aligned with my handheld meter (no line out from the meter's mic unfortunately).

I'm attaching a picture showing 2 sweeps done 1 minute apart both on the left channel. Everything is identical. No changes to any part of my system.

The results are insanely disparate as you can see.

This is a pro 2 way monitor system with stereo subs that's working perfectly, btw, and I use it all day every day.

Can anyone suggest what the I am seeing, or what is causing this insanely different result?

Thank to anyone who can suggest where I'm screwing up.


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## JohnM (Apr 11, 2006)

The general trend looks more like crosstalk, check the input channel selected is the one the mic is connected to. Also make sure there is no monitoring active on the interface, nothing from the mic should be getting back to the speakers.


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## Mark Fuller (Aug 5, 2014)

Thanks John,
Double checked all my gain structure. No mic clipping, no signal looping through, no crosstalk (Audient ID14 via USB/ASIO). Upped the output to speakers and brought down the mic input a bit. Seems slightly better.

Doing 4 sweeps per-measurement and am seeing averages that are useful. Single sweeps are stillquite different.

My room is about dead quiet so it's not ambient intrusions.

Anyhow, am making some useful measurements with multiple sweeps and averaging the results.


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## JohnM (Apr 11, 2006)

Worth attaching an mdat file for some measurements to give them a once over, single sweeps are sufficient to get very repeatable measurements so there may be something amiss.


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## Mark Fuller (Aug 5, 2014)

Just did 4 single-sweep measurements.
Things look pretty stable above 70 hz, pretty flaky below.
Mdat file attached.

My concerns for measuring are primarily 1K and below and especially 200hz and under, fyi.


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## JohnM (Apr 11, 2006)

Those measurements look good, there isn't much output to speak of below about 55 Hz so some variation below that which is mostly noise. There is a problem with the soundcard cal though, the ripples in it are clear signs of feedback - some monitoring is active, which is very bad for the measurements. None of the mic signal should get back to the output. Need to remove that cal file and make sure the monitoring is disabled.









Edit: As a PS, V5.19 has been released now so you should update from beta 12.


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## Mark Fuller (Aug 5, 2014)

Monitoring is definitely disabled but let me make another cal file of the interface. Thanks John!


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## Mark Fuller (Aug 5, 2014)

John, new interface cal file and it looks clean. Low end roll off looks good.

Attached a new mdat file made subsequently. Things look alot more consistent.

Each channel's measurement was made with 4 sweeps each. They looked very similar doing one at a time so I went ahead and made this new set.

Does it look like it's operating correctly? 

I really appreciate your assistance today. 
Will update now, too.

mark


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## Mark Fuller (Aug 5, 2014)

Apologies but I'm not finding the V5.19 installer. 5.15 is the latest I see in the downloads area.


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## JohnM (Apr 11, 2006)

Measurements look good. REW release versions are at http://www.roomeqwizard.com/#downloads


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## Mark Fuller (Aug 5, 2014)

Thank you!


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