Calibrate speakers with RS SPL...

doctorcilantro

I have never tried active compensation for freq. response.

I was thinking of generating all the test tones at the listed frequencies (at the link below), and calibrating them to 83db SPL using Replay Gain (-20db for 0dbfs).

Measure each sine wave with Rat Shack SPL meter, and use the given error correction values.

Then use a parametric EQ to adjust for error found in each speaker.

I'll use a directx 10-band parametric EQ, but not sure how to cover (average) the 30+ measurements/adjustments that may need to be made.


http://home.comcast.net/~audio-worx/page3Electrical%20RoomTx.html

Any ideas?

DC

thsmith

Why not make it easy and use Room EQ Wizard (REW), you have the RS SPL and computer and if your sound card supports analog in and out (not mic) you are ready to go.

http://www.hometheatershack.com/forums/rew-forum/11707-room-eq-wizard-rew-information-index-links-guides-articles-stickies-please-read.html#post103867

doctorcilantro

Thanks! I'll take a look at this. I've got 1/4 inputs on Lavry AD-10 and EMU1212M. I don't yet own a RS SPL meter; doesn't it have RCA outs. I think I have an RCA>TRS cable around though.

DC

thsmith

doctorcilantro wrote: »

Thanks! I'll take a look at this. I've got 1/4 inputs on Lavry AD-10 and EMU1212M. I don't yet own a RS SPL meter; doesn't it have RCA outs. I think I have an RCA>TRS cable around though.

DC

yep, RCA out of RS meter to RCA on sound card.

You load the RS SPL comp file into REW and it does it all.

Here is on of my graphs using REW for SVS Ultra before any EQ or placement work, just an example. Makes testing quite fast and easy. The HTS folks are more than willing to help.

doctorcilantro

This stuff look sperfect, thanks.

Can I use REW for 20hz-20kHz frequency response calibration? I'm downloading it now to play around with it (at work ; )

DC

thsmith

doctorcilantro wrote: »

This stuff look sperfect, thanks.

Can I use REW for 20hz-20kHz frequency response calibration? I'm downloading it now to play around with it (at work ; )

DC

Yes, but remebre the RS meter is only good enough for up to 3Khz. You will need something like the Behringer ECM8000 Microphone and phythom power to cover full range freq sweeps and the HTS site has a calibration file for this mic as well/

http://www.guitarcenter.com/Behringer-ECM8000-Microphone-100887330-i1126588.gc

and for power

http://www.guitarcenter.com/Behringer-XENYX-802-Mixer-103845053-i1153499.gc

thsmith

BTW, I have my BDF DSP1124P for sub eq, midi cable and mono phono to RCA connectors for sale at the FM

thsmith

Oh yeah, with REW you can save your measurement files and send to other people to play with for filters and so forth. Theres a guy on the HSU forum I am helping. He sent me his and this is what I sent back to him.

doctorcilantro

Thanks for posting that info. I have an EMU 0404 besides my 1212M and Lavry unit, as well as phantom power unit, so I will pick up the ECM8000 on sale at GC. I'll report back this weekend on how it went.

My wife's not real big on passive room treatments right now so this should work and save a bit of cash in the long run.

DC

doctorcilantro

BTW - if I use the mic w/o SPL meter, I would use 0bfs at -20db which I believe is 83db SPL. Not sure of the Dolby 75db mentioned in the FAQ, I 'm only familiar with the standard used by ReplayGain.

"The audio industry doesn't have any standard for listening level, but the movie industry has worked to an 83dB standard for years.

What the standard actually states is that a single channel pink noise signal, with an RMS energy level of -20 dB relative to a full scale sinusoid should be reproduced at 83 dB SPL (measured using a C-weighted, slow averaging SPL meter). In simple terms, this means that everyone can set their volume control to the same (known, calibrated) gain. "

http://replaygain.hydrogenaudio.org/calibration.html

DC

thsmith

doctorcilantro wrote: »

BTW - if I use the mic w/o SPL meter, I would use 0bfs at -20db which I believe is 83db SPL. Not sure of the Dolby 75db mentioned in the FAQ, I 'm only familiar with the standard used by ReplayGain.



http://replaygain.hydrogenaudio.org/calibration.html

DC

You got me, IDK. If you post any graph support over at HTS they will mention the 75db stardard for posting graphs.