How to do freq measurements?

Schris22

I always see guys that have freq measurements of their room. I was wondering how you guys did this? what equipment is neccessary and software.


Thanks,

Chris

bknauss

Rat shack SPL meter, test disc with lots of frequencies, and excel. Take measurements, record the dB and the frequency, make a graph. Other methods might be easier, but they generally require expensive software and equipment.

Schris22

oh. I always thought that someone had a freq sweep and some microphone with a ratshack meter and somehow recorded anything.

If it's manual, I guess it'll take a while. I have an avia disk but can't remember if it had a full frequency sweep.

Chris

tryrrthg

You can run this free software off your computer with a rat shack SPL meter. I have yet to use it, but it is my understanding that the software plays a tone for a few seconds while the rat shack meter "settles" in on the reading, then the software records it to the computer. After a few minutes you have a generated sweep. I would only use it on a subwoofer though...

The software is designed to be used in conjuction with the Behringer Feedback Destroyer or or TAG McLaren processors. It's a great tool to have to get your sub dialed in just right.

michael_w

I use Room EQ Wizard as well. It's fairly hand and easy to use. All you need is to connect an spl meter to your computer's mic in and then use the audio out to your preamp. Not the greatest way because you're chucking a computer in the signal path and using it as a source, but it's good for getting a general idea of the response.

Pretty much all you have to do is get the spl meter calibrated with the program so that when your speakers are playing a 75dB tone the program sees it as 75dB. Once you have that you hit a button and it does a full sweep (or a designated x hz to x hz) in about two seconds and you have a graph.

.Jon

BABY thats a sexy program. tanks for pointing that out. i was planning on getting a spl meter soon, but now i have an easier to use it.

tryrrthg

This Page has some nice links explaining how to hook up and use Room EQ wizard, and the BFD.

Holydoc

I have a CD full of 1hz steps ( every 10 seconds) from 10hz to 200hz. Along with that high tech stuff, I use SPL meter, EXCEL, and beer. Setting the SPL on a tri-pod in my seat, I run the CD while recording the decibel range within Excel. EXCEL does the work of compensating for the SPL's inaccuracies and plotting out the bass response.

To run from 10hz to 100hz usually takes me about 15min from setup to plotted graph. Or in layman's terms... a couple of beers.

Now that I think about it, maybe the beer is the cause of that one null spot in my room.

Schris22

Actually holydoc your thread reminded me that I needed to do this for my own room, but I didn't want to hijack your thread so here we are.


Anyway, Thanks for all the responses, i'm moving back home for the summer so I'll just wait till then to buy the necessary cables and the such for connecting all these things together. I'm sure they are cheap ratshack cables to connect everything.

Chris

michael_w

All you need is two cables that go from 1/8" headphone jacks (asuming that's what your soundcard uses) to rca's. I use my laptop, spl meter and a tripod simply because it's easier than using my desktop.

I'd definatly reccommend giving it a shot if you have an spl meter. It's interesting to see what kind of response you actually have in room. This program helped me point out a null of about 15dB between 55 and 65Hz so I'm glad I took the time to play with it

Lowell_M

Holydoc wrote:

I have a CD full of 1hz steps ( every 10 seconds) from 10hz to 200hz. Along with that high tech stuff, I use SPL meter, EXCEL, and beer. Setting the SPL on a tri-pod in my seat, I run the CD while recording the decibel range within Excel. EXCEL does the work of compensating for the SPL's inaccuracies and plotting out the bass response.

To run from 10hz to 100hz usually takes me about 15min from setup to plotted graph. Or in layman's terms... a couple of beers.

Now that I think about it, maybe the beer is the cause of that one null spot in my room.

Where did you get the CD?

Holydoc

a_mattison wrote:

Where did you get the CD?

Woo Hoo! I found it:

http://www.realtraps.com/test-cd.htm

Lowell_M

Holydoc wrote:

Hmm...forgot where I downloaded the testtones from. There are so many places. Then I burned a CD. So that you do not have to search around, I have uploaded them for you.

http://members.cox.net/holydoc/stereo/test-cd.zip

Awesome! Thank you!

Holydoc

a_mattison wrote:

Awesome! Thank you!

Look at my post again. I found the website. Now I can get rid of the test tones from my webspace.