Accurately measuring sub distance

[brucemck2]

Is there some easy way to measure the distance of the sub(s) ... some way to eyeball the maximum height or the 25% height of the impulse repsonse or similar?

Documentation in new version says distance measurement is accurate for mains but not subs ...

Reason for asking is that I've got an indeterminate amount of latency in my sub chain (from insertion of a QSC DSP-30 as a crossover and PEQ) so that the physical distance in feet in the room doesn't match the "effective" distance.

[mojogoes]

Quote......
Reason for asking is that I've got an indeterminate amount of latency in my sub chain (from insertion of a QSC DSP-30 as a crossover and PEQ) so that the physical distance in feet in the room doesn't match the "effective" distance

Could you please translate that seriously though!

[brucek]

Yep, it's called System Delay feature.

See this thread part way through where I describe it.

Any questions after reading it, post here.

brucek

[hasse_swe]

brucek wrote:

Yep, it's called System Delay feature.

See this thread part way through where I describe it.

Any questions after reading it, post here.

brucek

hi!
i was also thinking of trying the distance feature...but...

how do we use it who have the ecm8000+Xenyx802+soundcard?
we can't use the "use left channel as reference" because there is no way to loop
one channel on the mixer without it sending 48v on the input? (that pobably will toast soundcard?)

so..just looping one channel directly on the sound card will not really be accurate because then we
don't incl. mixer in the chain?....or am i missing something?...

/Hasse

[brucemck2]

BruceK ... will the system delay feature accurately measure the distance to a sub?

I could set the sweep to begin at (say) 100hz rather than 10hz or 20hz and go as high as 500hz if that would change the answer to "yes"

[brucek]

so..just looping one channel directly on the sound card will not really be accurate because then we
don't incl. mixer in the chain?....or am i missing something?...

Depends on how significant you feel the mixer response affects the total picture. If you think it matters, then you're out of luck using the left channel for soundcard calibration for response measurements. But that doesn't stop you from using the left channel loopback when you want to test speaker distance using the System delay feature. Just loop the soundcard left channel and do the test.

With respect to XENYX 802 mixer when taking measurements using the cal file or left channel methods, I don't feel it's that significant.

If I take my two soundcard cal files (one with the mixer in the loop and one without) and compare them using the same scaling that I would in a response measurement they aren't too different.

I simply changed the cal files to text files and then graphed them with a zero normalized scale that represents a 45dB-105dB spread. The mixer is down about a dB at 10hz and about 2dB at 5Hz.

Myself, I've switched to the left channel calibrate method.

compare mixer with no mixer.jpg

brucek

[brucek]

BruceK ... will the system delay feature accurately measure the distance to a sub?

No, full range speakers only.

brucek

[hasse_swe]

brucek wrote:

Depends on how significant you feel the mixer response affects the total picture.

Myself, I've switched to the left channel calibrate method.
brucek

you're probably right...no meaning to be too picky about accuracy..
ok...if it's good enough for you...then for certain good for me also...
i'll go that route also for convenience...
/H