2k dip in my room at the listening position. Need diffusors?

[Funkster]

I just ran a bunch of tests on my room and have a small dip just under 2k at the mix position. Could this be caused by not having enough diffusion?

Other thoughts?

Thanks!!

[ciro]

Recently I did some measurements changing only the speakers height;
2" up/down makes diifference in this mids near 1/2k here (small room - a bit more than 4' distance speakers/mixing position).

Ciro

[Funkster]

Cool! Good to know. Thanks for the reply Ciro!

[Funkster]

I guess I should mention that the similar dip shows up in three different sets of monitors. A smaller set, which are on top of my main monitors, and a set of mini speakers inbetween them.

[Glenn Kuras]

How big of a dip is it?

[Ethan Winer]

Originally Posted by Funkster

I just ran a bunch of tests on my room and have a small dip just under 2k at the mix position. Could this be caused by not having enough diffusion?

Measuring mid and high frequencies accurately is very tricky. If you move the microphone even one inch the response will change. Then there's averaging. Did you use 1/3 octave averaging? Averaging is not good for low frequencies, but it's needed for mids and highs. Even when the room is acoustically perfect you'll measure peaks and nulls if the microphone is not precisely the same distance from both loudspeakers.

--Ethan

[Funkster]

Hi Guys! Thanks for the reply.

I should probably go into my testing a bit. I know that this is certainly not the ideal testing method, but it is what I have and has always worked well enough for me to be familiar with what's going on in my room and do what I can about it. I did slow sine sweeps and use the peak holds on my meter. I used an omni-directional test mic that I've had the good fortune of testing using calibrated Audio Precision and SMAART systems a few years ago so I know is flat. I did several tests in in the general head location of the mix position with different angles on mic because I know that can play a part.

Regardless of my testing methods, or any other factors, I thought the results definitely highlighted an issue in the 2k area.

Here are three of the graphs of what things generally looked like with all the tests.

Main monitors:


New mini monitors:


$7 ipod speakers I picked up at walgreens across the street:


Seems like something weird obviously going on at 2k huh?

Thanks for your input!

[Ethan Winer]

Originally Posted by Funkster

Seems like something weird obviously going on at 2k huh?

Okay, you're already averaging at 1/3 octaves. Good. You know what I think this is? Your speakers! A lot of speakers have a dip somewhere in the "harshness" range around 2 and 4 KHz intentionally to sound smooth. Some speakers have dips as deep as 8 dB.

What speakers do you have? The nest step is to measure at high resolution without averaging. Then if all the dips are at slightly different frequencies, which is hidden in these graphs, you'll know it's the speakers. Also, try micing a foot in front of each speaker. That gives more of the speakers' response and less of the room's.

--Ethan

[bpape]

It could certainly be speakers, though I doubt 3 pair would all do it. It's possible though.

I'm thinking possibly some comb filtering off of the desktop?

Bryan

[Glenn Kuras]

Originally Posted by bpape

It could certainly be speakers, though I doubt 3 pair would all do it. It's possible though.

I'm thinking possibly some comb filtering off of the desktop?

Bryan

Yea I was thinking the desk also. Maybe try to throw a thick blanket over the desk and rerun the test.

[Funkster]

Great ideas guys! Will do.

Thanks!