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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.
 

128x128amtprod
mapman's avatar
mapman
21,865 posts
 

Yes if teh speakers are operating properly then your measurements indicate teh speakers need help with the lowest octaves in a room that size.  Also yes he probably does not realize what he is missing.  Adding a powered sub or two properly almost always helps complete the entire musical experience even in scenarios less bass deprived than this one.  Cheers!.

erik_squires
15,805 posts
 

I was wrong btw, I found I think a polish sight that says the min impedance is 4 Ohms, but still, with bi-amping you can set levels independently. 

The site also noted poor off-axis integration, a potential sign of the effects of the overlapping woofer/mid-woofs, so I really think at the very least, bi-amped with an EQ in front of the woofer amps is going to give you everything you need.

mapman's avatar
mapman
21,865 posts
 

Always a good idea to make sure the mains are operating properly before adding subs. So if bi-amping with EQ is what is neded for that, definitely do that first and see where you land. What make and model are the speakers again? If they turn out to be too problematic in that room at some point, it may be time to look at alternatives that might be implemented to their fullest more easily. It really all depends on what the end goal is. Also of course how much time and money you are willing to invest.

 

Also I would say that you are starting out with a much larger than normal bass deficiency.  Can optimizing the speakers alone resolve that?   Probably to some extent.  THen from there its a question of is that good enough or time to add powered subs to finish things off.

erik_squires
15,805 posts
 

If this was my system, I'd bi-amp, using a miniDSP as an active crossover in front of the amps.  It sounds really good.  This is going to give you the ability to properly high pass the mid-woofers, low pass the woofers, which will improve off-axis imaging and overall smoothness, give you a lot of extra headroom AND let you equalize the 12" drivers to function as subs.  Also, I'd plug the ports, which will raise the -3 dB a little, but also slow down the rolloff below 100 Hz significantly.

Fortunately, plugging the ports just takes a pair of clean socks.  I suggest organic cotton ... :D  Really anything that closes the ports and doesn't get lost. 

You may seriously want to try plugging the ports and re-measuring anyway.  You may find this extends the bass in just the right way.

erik_squires
15,805 posts
 

OP:

To confirm what I thought I read in the polish site, can you measure the frequency response for 1 speaker 45 degrees off axis? 1 to 2 meters away (3 to 6’) is fine. I want to see if there’s a major dip there.

If you see a big dip, unplug the woofers and see if it vanishes.

Thanks!

 

Erik

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