"Room EQ Wizard"
 

Hi,

I have a room in need of serious treatment!

Has anyone used this...
http://homepage.ntlworld.com/john.mulcahy/roomeq/ ?

I would just give it a spin, but my SPL meter is long gone.
Might be time for a new one, I guess.

Failing that, does anyone have any ideas for measuring
room response (on the cheap!). Something that
can be done with a cheap measurement mic and a decent
soundcard would be nice.

I'm currently playing with the usual zero cost options to
change the acoustics, like carpets, wall hangings etc. but
not getting too far, and I'd like to go some way to identifying
where the problem frequencies are.

I know what I should be using, but finances won't allow...

Ta,

Glenn.

"Room EQ Wizard"
 

On Fri, 31 Mar 2006 20:49:54 +0100, "Glenn Booth"
wrote:

Hi,

I have a room in need of serious treatment!

Has anyone used this...
http://homepage.ntlworld.com/john.mulcahy/roomeq/ ?

I would just give it a spin, but my SPL meter is long gone.
Might be time for a new one, I guess.

Failing that, does anyone have any ideas for measuring
room response (on the cheap!). Something that
can be done with a cheap measurement mic and a decent
soundcard would be nice.

I'm currently playing with the usual zero cost options to
change the acoustics, like carpets, wall hangings etc. but
not getting too far, and I'd like to go some way to identifying
where the problem frequencies are.

I know what I should be using, but finances won't allow...

Ta,

Glenn.

Don't bother with room eq - it doesn't work, and it can't work for
very good reasons. Rooms are not unflat because of "frequency
response"; they are unflat because of standing waves or modes. The big
feature of these is that the response you measure at one point in the
room is totally different a couple of inches away.

Try this test - play a constant tone at 150Hz or so on your system,
and walk around the room. What happens? Now, think - how would you
equalise that?

The measures you are already taking are absolutely the right ones. The
more irregular you can make the surfaces the better. Once you have
that right, play with the reverberation with soft furnishings. Thick
rugs in front of the speakers are always good. If you have poor
imaging, put some on the walls beside the speakers too.

d

Pearce Consulting
http://www.pearce.uk.com

"Room EQ Wizard"
 

Hi,

"Don Pearce" wrote in message
...

Don't bother with room eq - it doesn't work, and it can't work for
very good reasons. Rooms are not unflat because of "frequency
response"; they are unflat because of standing waves or modes. The big
feature of these is that the response you measure at one point in the
room is totally different a couple of inches away.

Thanks Don. I wasn't planning to use it to EQ the room, just as a
blunt instrument to identify the problems; a sort of analysis tool. I'm
aware that EQ is not the solution.

Try this test - play a constant tone at 150Hz or so on your system,
and walk around the room. What happens? Now, think - how would you
equalise that?

Since you ask, I'd buy a dentist's chair and strap my head down. It might
just work up to about 2kHz :-)

The measures you are already taking are absolutely the right ones. The
more irregular you can make the surfaces the better.

That's a big chunk of the problem - smooth walls. I'm going to try
big book shelves on as much of the walls as possible.

Once you have
that right, play with the reverberation with soft furnishings. Thick
rugs in front of the speakers are always good. If you have poor
imaging, put some on the walls beside the speakers too.

It's an odd room; the imaging is ok, even though the room geometry
seems to suggest it shouldn't be. The problems I have are somewhere
in the bass region. My best guess is that this is due to the room
having a kind of mezzanine leading off it, about 3.5m deep, over an
adjacent room, which is leading to weird behaviour at (vaguely)
50 and 100 Hz.

Thanks for the feedback.

Regards,

Glenn.

"Room EQ Wizard"
 

REW will do you for measurements with a mic and a decent full-duplex
sound card. It is very useful and revealing.

Kal

On Fri, 31 Mar 2006 20:49:54 +0100, "Glenn Booth"
wrote:

Hi,

I have a room in need of serious treatment!

Has anyone used this...
http://homepage.ntlworld.com/john.mulcahy/roomeq/ ?

I would just give it a spin, but my SPL meter is long gone.
Might be time for a new one, I guess.

Failing that, does anyone have any ideas for measuring
room response (on the cheap!). Something that
can be done with a cheap measurement mic and a decent
soundcard would be nice.

I'm currently playing with the usual zero cost options to
change the acoustics, like carpets, wall hangings etc. but
not getting too far, and I'd like to go some way to identifying
where the problem frequencies are.

I know what I should be using, but finances won't allow...

Ta,

Glenn.

"Room EQ Wizard"
 

On Fri, 31 Mar 2006 22:21:27 +0100, "Glenn Booth"
wrote:

Don't bother with room eq - it doesn't work, and it can't work for
very good reasons. Rooms are not unflat because of "frequency
response"; they are unflat because of standing waves or modes. The big
feature of these is that the response you measure at one point in the
room is totally different a couple of inches away.

Thanks Don. I wasn't planning to use it to EQ the room, just as a
blunt instrument to identify the problems; a sort of analysis tool. I'm
aware that EQ is not the solution.

OK - but you don't need special software - even Audacity which is free
will do. Generate a minute of pink or white noise and play it through
a speaker at reasonable level. Record it with a microphone in the
room, but *not* a stationary one. Walk around the room with it, move
it high and low, while you record. Then select the entire recording
and look at an FFT of the frequency response.

What that recording technique will do is remove any standing wave
effects and hopefully expose anything like a Helmholz resonator -
which is what you suspect the mezzanine is doing.

You will also see the frequency response of the speakers, of course.

d

Pearce Consulting
http://www.pearce.uk.com