Subject:Acoustic Mirror Question - i hope someone can clue me in

Posted by: Spheris

Date:7/10/2003 4:09:04 PM

I'd like to make an impulse of a flat curve eq test tone I was given by a wavelab user

tried it the straight way, but got garbage out of it

At a bit of a loss any help appreciated

Subject:RE: Acoustic Mirror Question - i hope someone can clue me in

Reply by: Rednroll

Date:7/10/2003 5:02:24 PM

Copy this link into your browser and read or type in the search window at the top of the webpage and you'll find a ton of Sonic Foundry articles describing how to make impulses.

http://www.sonicfoundry.com/support/SupportProduct.asp?FamilyID=24&Family=Plug%2DIns&TopicID=106&DetailID=751

BTW: What is a "flat curve EQ test tone"? Sounds like Pink noise to me.

Subject:RE: Acoustic Mirror Question - i hope someone can clue me in

Reply by: captn_spalding

Date:7/10/2003 9:38:10 PM

Curiosity has got the best of me. I have to ask. What are you trying to do? I use Accoustic Mirror a bit and have even created impulse files of a couple of my favorite performance spaces. There must be some aspect of this I don't uderstand because I don't know what it means to create an impulse file of a test tone. Do you intend to use the "flat curve EQ tone" (what is that by the way) to create an impulse file of a space or microphone, etc instead of the tones supplied by Accoustic Mirror? If so, why do you think that will give better results?


..spalding

Subject:RE: Acoustic Mirror Question - i hope someone can clue me in

Reply by: Spheris

Date:7/10/2003 10:47:51 PM

Theory is a flat linear tone, stepping from 1hz to 24khz

to level out errant frequencies, its only a theory right now but I guess we'll find out
have used the same with the arboretum ionizer on the mac. interested to find out if the mirror can take some of the hassle work out of it and save some steps

Subject:RE: Acoustic Mirror Question - i hope someone can clue me in

Reply by: Geoff_Wood

Date:7/11/2003 2:33:15 AM

Are you trying to do a graphic analyser thing ? If you are trying to eq a room with it (if you can with AM) be aware that non-linearities in rooms are due to room modes in the time domain, and are not fixable by eq. That being said, you can notch out troubling frequencies, but that does not eq the room.

If you are trying something different, disregard the above....


geoff

Subject:RE: Acoustic Mirror Question - i hope someone can clue me in

Reply by: Rednroll

Date:7/11/2003 9:35:37 AM

"Theory is a flat linear tone, stepping from 1hz to 24khz "

I think there's some problems with your theory. "a flat linear tone, stepping from 1hz to 24khz." This is known as a "Sweep". The problem with this is that it's only playing one frequency at a time. So things like Phase cancellation and addition are not going to be true because you're not getting the whole picture of what goes on with audio. That's why Pink noise is used. Pink noise is a linear response of the entire frequency spectrum playing at once.

Subject:RE: Acoustic Mirror Question - i hope someone can clue me in

Reply by: Spheris

Date:7/11/2003 11:01:04 AM

Geoff, I thank you for the info and nothing gets disregarded in learning new things, all info appreciated


Red, can you tell me a bit more about this if you have the time. I was previously doing matching with a true linear tone generator (all steppings at -3db) which was my relative understanding of a flat sweep (i could be mistaken, still learning and experimenting)

so all the details I can gain are much appreciated as to whether I am on the wrong track with this.

Subject:RE: Acoustic Mirror Question - i hope someone can clue me in

Reply by: Rednroll

Date:7/11/2003 1:11:59 PM

I found a tech paper, which should help you out a lot. I work for JBL in the design group for developing premium audio systems for automobiles. I do similar activities for tuning theater surround systems. This paper gives a description of what Pink noise is and how it is used in tuning automobiles for optimal sound. It sounds like you're trying to achieve this same type of thing to acoustically tune a studio. All this information applies, the only major differences is that you have less obsticles in tuning a studio monitor system, compared to an automobile. (ie no road noise, less acoustical reflective surfaces, speaker placement and size is a minimal concern). This is a pretty well written document and describes pretty adequately one facet of my design duties.

One of the most important facts that it mentions is that you can tune the system to have a "flat" response, but further explains, "flat" is less than desireable. If you listen to a "flat" tuned system it won't sound very good to you, because your ears don't have a flat response.

I haven't used Acoustic mirror that much, so I'm not sure you'll be able to achieve what you're trying to, but this article should be able to help you along with your theory.

http://www.audiocontrol.com/techpapers/techpaper101.pdf

red

Subject:RE: Acoustic Mirror Question - i hope someone can clue me in

Reply by: Spheris

Date:7/11/2003 4:07:35 PM

Red, the whitepaper was exceptionally helpful

now the last question is why does my impulse of the pink noise display this odd buzzing?

:)