XTZ Room Analyzer II Pro

[crwilli]

Randy, You should also run each channel alone to see what that looks like.

[chessman]

Originally Posted by crwilli

Randy, You should also run each channel alone to see what that looks like.

XTZ allows an "anechoic" measurement, somehow done in room, but with the room effects removed. Are you thinking I should run that test on individual speakers to see if the output is roughly even?

[jdandy]

Originally Posted by crwilli

Randy, You should also run each channel alone to see what that looks like.

Craig.......The XTZ Quick Guide states, "When making final adjustments, make sure signal is applied to all speakers and subwoofers in the system you wish to calibrate. Making separate adjustments to each channel will not accomplish a well-balanced end result."

[crwilli]

I am not familiar with this system. My experience with REW suggests measuring one channel at a time to eliminate comb filtering in the mids and upper ranges. For subs, I understand you can or should (?) measure them all.

Also, does this system also apply corrections? If so, it makes sense then to measure all.

[chessman]

Originally Posted by crwilli

I am not familiar with this system. My experience with REW suggests measuring one channel at a time to eliminate comb filtering in the mids and upper ranges. For subs, I understand you can or should (?) measure them all. Also, does this system also apply corrections? If so, it makes sense then to measure all.

XTZ suggests corrections for room modes below 250 H, and will even model the predicted result. Using additional software it will allow direct exportation to XTZ's own DSP processor. When I started my first Room Analysis it revealed a room mode at 25H and suggested a -12 dB cut at 25 H with a Q of 6. Even though I have a Velodyne SMS-1 bass parametric equalizer, it would not have integrated with my "stereo" sub set-up because my signal runs [source] to [preamp] to [active crossover] and then splits among right and left mains and two subs. I got lucky because the subs themselves happened to have the ELF adjustment mentioned in earlier posts. The curve I posted was the result after I had attenuated 25 H using ELF. It worked so well that XTZ reported no modes found. Room Analysis is the only test that suggests DSD "fixes," but it does not measure above 250 H. Basically if you have comb filtering problems you need to decide yourself where to add absorption panels. First reflection points are the obvious suspects. After that esthetics may govern more than anything else because sound acts more like rays than waves above 250 H, i.e. every surface is involved so percentage of wall covered is what matters. The RT60 measurement is key here because you want a RT60 of about .4 seconds like Georges has in his room (above RT60 of .4 add panels to lower it). Since my RT60 numbers split so radically I have more learning to do to figure out what to fix.

[chessman]

Originally Posted by crwilli

I am not familiar with this system. My experience with REW suggests measuring one channel at a time to eliminate comb filtering in the mids and upper ranges. For subs, I understand you can or should (?) measure them all.

Also, does this system also apply corrections? If so, it makes sense then to measure all.

One additional thought regarding comb filtering - I think it is impossible to eliminate in a small room because with the "ray effect" and the complexity of the reflections one cannot adjust the speakers closely enough. Instead I think you have to focus on equal decay time as revealed by RT60 measurements.

Disclaimer: I am not an acoustician, nor did I stay in a Holiday Inn Express last night.

[crwilli]

Originally Posted by chessman

One additional thought regarding comb filtering - I think it is impossible to eliminate in a small room because with the "ray effect" and the complexity of the reflections one cannot adjust the speakers closely enough. Instead I think you have to focus on equal decay time as revealed by RT60 measurements. Disclaimer: I am not an acoustician, nor did I stay in a Holiday Inn Express last night.

Ha! Nor did I and nor am I !!!

[GaryProtein]

Originally Posted by chessman

Gary, any idea why my RT60 is so short for some frequencies and then over 4 seconds for 4,000H and 8,000H?

FOUR seconds?? Do you have a reverb machine in there?

I have no idea why such high frequencies would have such a long ring.

Are you sure it isn't 0.4 seconds?

[antipop]

Randy, that first graph looks really good

As mentionner by Craig, I would run each channel separately to see the balance between each speaker.

As for the RT60, try an impulse test and see if there is a strong second impulse and the distance. The 4s is very odd. Is it consistent over several measures ?

You should do a test between 125Hz and 10kHz to see if there is another room node at those frequencies.

I believe it would be worth your time to try some measures in REW

[antipop]

BTW GIK has a very good introductory video to REW. You should check it out

[ame=http://www.youtube.com/watch?v=e4uSR3cUUSY]Room EQ Wizard: REW Room Measurement Tutorial - YouTube[/ame]