Measuring my speakers

[Pano]

TVR. Yes, mid-size room, fairly dead. But I get identical results measuring amps and pre-amps, too. Maybe they would not show the difference?

[wintermute]

Originally Posted by tvrgeek

You have a big dead room? At 1/3 octave smoothing, or nearfield, they are close. At 1M, 1/24 the differences are large. Below about 200 Hz, I use sweep.

Originally Posted by tvrgeek

Are you sure it is noise, not diffraction, reflection, basket reflections and other nasties?

measuring distance about 1.2M Similar distance to floor and ceiling. The comment about using sweeps below 200Hz tends to fit with what I recall that I could gate lower with the swept sines. I hypothesized that it was actually late reflections of the MLS signal that were messing things up, and that the swept sines weren't as susceptable (exactly the opposite to what I had read).

I just loaded some old measurements (about 2.5 years ago). I could only find one direct swept sine vs mls measurement and it is very close to identical. So maybe my memory is faulty... blue is MLS red is Swept Sine. Only details I have is that the measurement was taken at 1.5M.

Tony.

[lduarte1973]

my latest mesurement , not exactly flat but the best sounding to my ears , i managed to get a almost perfect flat curve but sounded like

[lduarte1973]

slightly different version of xover : woofer & mid 18db 800/4k

mesure.jpg

[tvrgeek]

Originally Posted by Pano

TVR. Yes, mid-size room, fairly dead. But I get identical results measuring amps and pre-amps, too. Maybe they would not show the difference?

I would really hope an op amp or preamp electrical measurement is not influenced by reflections and refraction from the room. I have not had time to play with MLS for electronic testing. I usually just use my old trusty TrueRTA and spreadsheet for calculating harmonic distortion.

[tvrgeek]

Originally Posted by lduarte1973

my latest mesurement , not exactly flat but the best sounding to my ears , i managed to get a almost perfect flat curve but sounded like

Ah yes, Grasshopper, you have reached a major step in your path to enlightenment.

[tvrgeek]

Originally Posted by lduarte1973

slightly different version of xover : woofer & mid 18db 800/4k

Attachment 302197

Not knowing the details, I might think your BSC is coming in a bit early. Maybe crossovers not positioned quite right. Have you measured the system with each driver independently so you can separate the driver/crossover issues from driver/room issues?

[lduarte1973]

i havent mesured the drivers , i´m using the xover points at 800 and 4k they where used in the original (JBL) xover , i tryed several xover points and these sound best to me. do you suggest others ?

what do you suggest in therms of BSC ?

[sba]

REW is a great program. I tested it side by side with HOLMimpulse and got nearly identical results.

Here's a brief and good introduction to measuring speakers--

cpyrighted material removed

Sorry for the poor quality images!

[wintermute]

sorry sba I had to remove the attached article scans, as they appear to be copyrighted material.

Tony.