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Some measurements (current setup with the SVS 20-39PCi)

nelmr

Active Member
Well I played with the REW program and the RS Meter as the mic using the correction file for the meter.

This is with the 20-39PCi and the two main front speakers. I am curious how the bass graphs will work as I play around with the HSU and SVS seperately as well as combined.

Measurements sweeping signals for the bass:


Avearge RTA fullrange


Waterfall plots for bass:


Waterfall plot for fullrange:
 

nelmr

Active Member
By the way what is up with the waterfall plot in full range with regards to the higher frequencies. Is that what a comb filter effect is?
 

Flint

Dog Faced Pony Soldier
Superstar
Waterfall measures the decay rate for sounds sent to the speaker. Longer decay rates are caused by:
1) the speaker system might be slow to stop generating sound (woofer flopping about)
2) driver might have resonances which ring beyond the electrical excitetation
3) the room reverb and echo is causing the sound to bounce around for awhile before the acoustic energy fully disperses
 

nelmr

Active Member
Flint said:
Waterfall measures the decay rate for sounds sent to the speaker. Longer decay rates are caused by:
1) the speaker system might be slow to stop generating sound (woofer flopping about)
2) driver might have resonances which ring beyond the electrical excitetation
3) the room reverb and echo is causing the sound to bounce around for awhile before the acoustic energy fully disperses
Thanks for what the waterfall graphs can help measure. What about the bumping, pointy, comb/step like pattern (even for the faster decays). What does that indicate?
 

Flint

Dog Faced Pony Soldier
Superstar
In general, most of the bumpy frequency response nonlinearities above 500Hz is from comb filtering (assuming the speakers are very good). Comb filtering can be caused by reflections off walls, cabinet edge diffraction, dual parallel driver interaction, and sometimes from a single driver operating at higher frequencies where their wavelengths are shorter than the diameter of the driver piston.
 

nelmr

Active Member
Flint said:
In general, most of the bumpy frequency response nonlinearities above 500Hz is from comb filtering (assuming the speakers are very good). Comb filtering can be caused by reflections off walls, cabinet edge diffraction, dual parallel driver interaction, and sometimes from a single driver operating at higher frequencies where their wavelengths are shorter than the diameter of the driver piston.
Maybe it's time to build those OC703 panels. I have had the OC in the garage for years. I've just been to lazy to buy the wood and build the panels. I even have the cloth and the polyester quilt padding.
 
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