Totally Mindblowing! (Thanks Ethan!)

[NL5]

Anyone who hasn't done this DEFINETLY should.

My "control" room is a three walled room that opens into a 1000 sqft 12 foot valted ceiling room, that I thought was pretty balanced with few nodes - WRONG!

This little program shows you - http://www.realtraps.com/nti_minirator.exe

At 10khz I have a node about every 2 inches! If I move my head side to side the tone goes from ear piercing to almost non existant!

Now, if I just knew what it all meant!!!!

More reading for me I guess.

Thanks Ethan!

[NL5]

Anybody that wants to help me with how to interpret the data from the program, feel free - it will be greatly appreciated. I didn't notice any nodes in the very low range (below 160hz) - the worst being 10khz.

[pearldrum944]

Cool, thanks for posting that! I have a really bad node at 2.5khz if I move my head to the left 2 inches...

[applejax]

Rick or someone else who knows ALOT about acoustics can help you out on this one... good find though !! Have to try it out tonight!

[Ethan Winer]

Guys,

> At 10khz I have a node about every 2 inches! <

> I have a really bad node at 2.5khz if I move my head to the left 2 inches <

These are not really nodes, at least it's not the same as nodes you get at bass frequencies. What you're experiencing is due to comb filtering caused by reflections off nearby surfaces. This can (should) be treated by placing absorption at the first reflection points on the side walls and ceiling.

Another cause of comb filtering, which cannot be solved with absorption, is tiny differences in arrival time from the left and right speakers. Unless you have the measuring microphone precisely in the middle and exactly the same distance from each speaker, you'll measure peaks and nulls as you report. This is a good reason to use pink noise for higher testing frequencies rather than sine waves. Also, even though you can measure these peaks and nulls, and they really are present, they are not as damaging as you'd think because the response at each ear is different. What you actually perceive is the sum of both channels, which is less compromised than one microphone will show.

--Ethan

[NL5]

Ethan -

Should I have experienced the same "effect" at the very low frequences? Below 160hz, I ddn' notice anthing. I do have an odd room though (see first post).

Thanks!

[xfinsterx]

Originally Posted by NL5

Ethan -

Should I have experienced the same "effect" at the very low frequences? Below 160hz, I ddn' notice anthing. I do have an odd room though (see first post).

Thanks!

You know Gunnar.
My buddy Rick over at Super Digital is a quantam Physics major, and has designed a few beautiful studios too.

You should call him a pick his brain.

503-228-2222

[NL5]

Originally Posted by xfinsterx

You know Gunnar.
My buddy Rick over at Super Digital is a quantam Physics major, and has designed a few beautiful studios too.

You should call him a pick his brain.

503-228-2222

I am going to head over there as soon as I can. I have wanted to check it out for quite awhile.

Thanks for the heads up!

[Ethan Winer]

> Should I have experienced the same "effect" at the very low frequences? <

No, because there the wavelengths are much longer so the distances are likewise much longer.

--Ethan