Room Acoustics, minimal treatment and measurements


Afternoon all.  Thought this might be helpful to some with wondering if room treatments can help with your 2-channel, and how to help visualize and measure what you may not fully grasp hearing wise.  I am just using a Mac Laptop and cheapo microphone, and REW, and 6 insulation panels.

This is my Step Fathers system, and pretty much empty LARGE  basement listening space.  There is a LOT of echo-reverb-ringing that (to my ears) over excites mid to upper frequencies, like being in a busy store/restaurant. With music, this can in ways help make a recording sound like it's in a larger studio/hall/space, but it also mashes a lot together and can over-color the music.  This results in lost focus and change in ACTUAL recorded acoustics: so an intimately microphoned musician will sound like an empty room, where an empty room sounds like an empty gymnasium.  This, also over-washes a bit of the mid-range and higher bass-losing it's tone and timbre.    Major thanks to @erik_squires who has been gracious to help with this process with dead-on advice.

FULL BASEMENT MEASUREMENTS:
34'long x 22'wide x 10'high

LISTENING AREA MEASUREMENTS:

15'long x 22'wide x10'high

Empty room, no treatments and RT60 plot.  Listening seat is *in the middle of the whole basement space, under an 18" boxed beam.*

 

"Treated" room, with RT60 plot.  Notice the overall mid-upper frequency taming from 700ms of "ring/decay", to 500ms.  Even with this, if you snap your fingers, you still hear a flutter echo.  This is from the whole other half of the basement room behind me, mostly.


Crude room response measurement:



Sketch and measurements of where things are in the listening room:


I hope this is helpful and gives you some things to try out that don't cause major disruptions to your system, until you really determine if and where your issues are and then you can buy and mount things.  My next step is to see where ON the walls I can place absorbing panels, and how many might be needed for a nominal improvement.  My thinking is the bigger issues are the ceiling, front wall, and then 'filling' the space behind the seat just to eat up ambient stray ringing.
 

amtprod

@erik_squires Yea I’ll do a sweep to see that potential dip. Are you thinking there’s some frequency cancelling happening or a cross-over issue?

If there is no bass to mid-bass crossover, then I expect destructive interference (frequency dips) somewhere, either horizontally or vertically. I also expect the 7" drivers would sound much better if not trying to reproduce 20 Hz.

It may be worthwhile talking to Legacy and asking if the woofers actually have a low pass filter. Your measurements, and the impedance charts from Poland suggest the answer is no.

The way to tell without opening your speakers is with an impedance sweep. REW has a way to do this if you make a custom jig, or you can purchase Dayton DATS. Measure the combined impedance, and separately. Take a look at this blog post to understand "High pass impedance" and "Low Pass Impedance"

 

Hey @erik_squires   Attached is a screen shot of the 45degree reading with and without the woofers.  Distance was about 5 feet.

I'll take a look at the impedance sweep. 

That’s really quite good, but seriously what are the woofers doing?  I'd expect at least a 3-6 dB boost when they were engaged.

@erik_squires I know, right???!!! Honestly my little Studio HDs one 8" woofer moves to beat the band...these are like a gentle wafting suggestion.  Which, I get in a way: there are two, in a big strong cabinet, they don't "need" to move a ton to move a proper volume of air.....but in this specific application they are like BARELY moving, barely generating output, and barely making 'sound'!