System EQ only as good as your microphone

[jarrods]

I have a dbx 4800 in my system and set EQ using a dbx microphone to be basically flat from 20Hz to 20kHz all seemed OK. Speakers are pair 4344 over pair Sub1500.

Today I took screen shots of the 4800 RTA with the microphone in what I thought was the same position. No longer flat with differences up to 3db. I also have a Dayton EMM-6 microphone and borrowed a friends McIntosh microphone (from the MEN220) so I took captures of them without moving the microphone stand and tip of microphone exact same distance from clasp. All different.

When I did the RTA I pointed the microphone to midway between speakers. Documentation I have seen for dbx and McIntosh suggest this. I have seen other documents and read in forums to point microphone to the ceiling and being omnidirectional that is best way to do it. I took more captures with microphones pointing to the ceiling and again all different.

The quality of the system EQ can only be as good as the microphone. I do not know which microphone to trust most. Many say the Dayton EMM-6 is best but it suggests I need to boost top end more and too me it is already a bit bright so I am inclined to trust the dbx more.

Today I was considering buying a “Dayton Audio OmniMic V2 Precision Measurement System” and have a look at what it thinks the EQ is like using my laptop. But is it just as flawed as the microphones I already have?

Speakers pic is here….http://imgur.com/a/O13gD

Attached PDF is screen captures.

[1audiohack]

Hi jarrods;

Very nice space you have created there!!!

RTA has very limited use in small acoustical spaces. You have to know where it will lie to you and where it can be of good use. I doubt the mic's are the issue.

After looking, those screen shots are more uniform than I had guessed they might be. Are you measuring a single channel at a time or?

By the way I have a DBX 4800 as well. Are you letting it auto EQ?

All the best,
Barry.

[rlsound]

Two different microphones from different manufacturers well most likely have differences even if they are both " omni " patterns.

The patterns are most likely different, look at the polar plots for both mics and see what they look like.

Also, don't rely on " auto eq " if that's what your doing. They might get you close, or way out of the ballpark.