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Sound absorption - what's audible?

Yeah, I have a couple of drum-kits and there's not really much going down below 40Hz based on my own recordings...
 
What is the problem you are trying to fix? Is it the way your system sounds, or the way it measures? What is the symptom?
 
9designs said:
….decay time is the key issue to fix...what I have now though is bass notes that start and stop...don't blurr/drone into the next…music times so much better...ambience is bigger detail is much better...clarity and layers to the music is huge step forward...get the RT60 short.
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Agreed :).
 
My point was it won't be often that the frequency will get excited in the room... Plus if it has a short decay time it will sound fine.....
 
SteveS1 said:
This. Can't understand what Martin is thinking of here either.

You can minimise the room's negative contributions (we all have them to a degree) by careful set up and positioning of speakers and listening position. The room will make the biggest contribution to what you hear, even if it's not as much fun as box swapping.

After that, if any annoying aspects of the room acoustic persist they can be managed by some attention to physical means such as furnishings or treatments, room correction software or a bit of both. The less that can be left to correction the better, but it too can be very helpful and relatively inexpensive. Provided the kit is competent none of that needs changing to combat room effects, the road to Hell lies in that direction.
Click to expand...

Agreed.

Or you could just use an amp with tone controls and cut the bass when there's boom.
 
That RT 60 is terrible in the low bass - believe me , fixing that overhang will go a long way to crisping and tightening all the bass as well as improving mids etc .. the way to fix it is to eq the peak out , which will in turn fix the RT60.
300ms is a fine cut off point , and even if you did extend the cut off point to 500 - the graph would still be very lumpy with that peak.. you really need to do something about it.
 
Rod, you can't "fix" reverberation by using EQ. All you are doing is removing energy from the signal and in many cases you are being very heavy handed about it. I'm a deal with the problem rather than messing about with the symptoms.

Yes, I know you agree with me, and EQ is helpful..ish.
 
You can fix low bass resonances with eq , if he had to flatten the 32 hz peak the RT60 graph will show it.
Meridian do it with their MRC , they ask you to input a RT60 time for the lower bass under 200hz and use DSP notch filters etc to achieve it
 
Just suggesting a bit of room treatment helps. Even a bit of furniture or a well placed book case. It's going a little far expecting your kids to hold up a panel absorber....but why not?
 
Personally, I doubt that hump at around 30 is a big problem as has been said already.
To get rid of that is a very big ask, but doable with some products.
Question is will you like the result - you may just like what it does without knowing :)
I think this is pretty close to your graph -

sh-wfall.jpg


And the RT60 time of this as a graph :-
sh-rt60-shut.jpg


Interestingly, with that RT60, the time literally doubles if I leave the door open and remove the movable trap from in front of it.
I'm hazarding a guess the door acts as a kind of 'tuned port' for the room :)

I'm fairly certain GIK do some new smallish traps that can be tuned to that low frequency, but their range of absorption is small - obviously.

I absolutely agree with those who say lowering the RT60 to a lower figure will help you.
 
It would be very handy if there were someone nearby with a heap of room treatments, a big van and a liking for home made curry.... see where I'm going with this.

I think I'll put a trap in the one corner where it's easy to do - can't hurt - but first I will do a re-measurement from the new sitting position (further into the room) and with the mic vertical as advised...
 
Sonority: I have to ask: does your room have a maximum length of around 18 to 20 feet? Your room measurement *is* very similar to mine in the lower bass, although it looks cleaner further up the frequency range. If so, would you mind detailing how you have it laid out and what trapping, etc., you are actually using and where?
 
Length around 20' wide 16.5' -Height 13'.
It's a dedicated listening environment so I have a **lot** of traps and treatment.
Lets say it would not happen in a living room environment :)
 
OK, my room is approximately 18'- maybe a tad more - in length, 16' wide I think, 11' ceiling. So a little smaller. Not dedicated though. Got your PMs - will take a look :)
 
A question the the more experienced guys here.
Should you allways measure with the mic vertically?
Or just do it in addition to having it horisontally?
What is the difference, I mean what can I get out of the respective mic position?
 
I think the idea is to measure the room response, so you want little if any of the direct energy to be picked up by the mic. Hence don't point it straight at the speakers or at any nearby wall.
 
For stereo you point it at the speakers and do not forget that the mic will become (more) directional with rising frequency. Not that this matters, as in-room treble measurements are useless. In the bass the typical small-diaphragm measurement mics used are near-perfect omnis.


For surround the mic goes vertical to ensure that all speaker channels get treated with the same mic response.
 
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