@ Earl, I'll take this to the other thread.
The room can not see the difference. Yes, view them as energising the room as a sub might. You'll be limited by their placement options. A separate sub (at least) would be a good move IMO. The powerpoint presentation would make a good read if you haven't already.
Below the lowest mode a room behaves like a pressure chamber but this is irrelevant for the discussion. The lowest mode for a room of 4x5x2.5m is 34Hz. It will be lower the bigger the room gets.
The best locations for subs is not necessarily where the mains are. Mains should be placed for best imaging, subs should be placed for lowest point-to-point differences within the listening area. Best case they also act as active absorbers, reducing modal ringing.
Hi Earl,
That's some nifty software you got there. Did you also look at how modal decay is affected by the process?
It would, but we've all been there. Those days are behind me, hallelujah...but we are on the same page Markus.
Thanks - no I did not look at the modal decay, but I suspect that it being a minimum phase system, as the frequency response is made smoother the modal decay will follow suite.
If you want the best solution IT IS BASS TRAPS.. Most people are simply using inferior commercialy driven products that arent very effective or do nothing at all..(ie)light weight foam wedges.. EQ is a good tool to show improvement for the problem but bass traps will sound better by reataining your systems characteristics..
The challenge is you need many bass traps including ones with High Density Insulation(2lb per cubic foot) and 1/8" and 1/4" thick panel traps.. I'm planning a room for a friend based on this were the traps are built into the new framed wall and ceilng with alternating insulatiuon trap and panel trap..
In an existing room you might need 20 or 30 large 4" thick traps plus some panel traps and this is were the problem is as most will get a few and wonder why there isnt a big improvement and give up.. the waves are large and need to absorb going in and absorb refected wave coming out.. Then there's the cosmetics but making then yourself will help..Mine are diy wood frame and fabric covered.. Picture shows 4 traps spaced apart from each other behind the speaker and attached to back wall is a wood panel trap to reduce even more energy that otherwise will come off wall strong..Room has 20 plus bulk heads and Absorbers hidden in ceiling behind fabric..
My room was measured with ETF and Cal Mic and watched and listened to the response smooth out and the ringing stop and now listen to recordings a better way.. Audio Keen People that listen in my room find it a complete JOY with the Focused soundstage and spatial information and balanced bass.. When turned up It's loud in the soundstage and not loud in the room if you know what I mean..
Off Topic some what but If you were to consider this than the rooms diffused energy will have to be considered and theres 2 camps on this.. Some want some or a lot and others want none or very little.. most recordings already have ambient information built in, fake, or real and this built in information revealed more in a more dead configuration..
If you follow Ethan Winer on other forums, he has a deep understanding of this topic and helpful.. I read his comments with passion but watch some get scared away as he also sells treatments so could be taken as a sales pitch if he says you need more bass traps by I chuckle inside becasue I know he"s being honest and it's driven by passion..
Cheers, Joel
The challenge is you need many bass traps including ones with High Density Insulation(2lb per cubic foot) and 1/8" and 1/4" thick panel traps.. I'm planning a room for a friend based on this were the traps are built into the new framed wall and ceilng with alternating insulatiuon trap and panel trap..
In an existing room you might need 20 or 30 large 4" thick traps plus some panel traps and this is were the problem is as most will get a few and wonder why there isnt a big improvement and give up.. the waves are large and need to absorb going in and absorb refected wave coming out.. Then there's the cosmetics but making then yourself will help..Mine are diy wood frame and fabric covered.. Picture shows 4 traps spaced apart from each other behind the speaker and attached to back wall is a wood panel trap to reduce even more energy that otherwise will come off wall strong..Room has 20 plus bulk heads and Absorbers hidden in ceiling behind fabric..
My room was measured with ETF and Cal Mic and watched and listened to the response smooth out and the ringing stop and now listen to recordings a better way.. Audio Keen People that listen in my room find it a complete JOY with the Focused soundstage and spatial information and balanced bass.. When turned up It's loud in the soundstage and not loud in the room if you know what I mean..
Off Topic some what but If you were to consider this than the rooms diffused energy will have to be considered and theres 2 camps on this.. Some want some or a lot and others want none or very little.. most recordings already have ambient information built in, fake, or real and this built in information revealed more in a more dead configuration..
If you follow Ethan Winer on other forums, he has a deep understanding of this topic and helpful.. I read his comments with passion but watch some get scared away as he also sells treatments so could be taken as a sales pitch if he says you need more bass traps by I chuckle inside becasue I know he"s being honest and it's driven by passion..
Cheers, Joel
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Then you might also want to look into active absorption (e.g. CABS) which Ethan does not sell
Then you might also want to look into active absorption (e.g. CABS) which Ethan does not sell
Well, my room is done
Point with Ethan is that When he says you need many bass traps to fix the bass problem to acceptable point then he is right based on my first hand experience..Fact that he sells them is only a problem for the ones that havent tried it yet.. But dosent really matter because they're easy to build and look nicer than his anyway..
If your talking about more active subwoofers to fix the problem common sense tells me that bass traps are better as long as you go all the way with the amount. I mean it takes a lot of bass trap around the room and in corners to have it work so with the complex propagation of waves It stands to reason that many active subs will be needed in a complex set-up.. Then you would have to look at the cost difference.. I certainly would listen to someones active absorbtion setup for curiousity
I would never use an EQ in a Hi End 2 channel system but I would for descrete sub with class D amp used in 5.1 because here adding foreign colour and noise wont matter much and more controlled and even response will be more important
Two can give fairly good results when you know how to use them and if SPL is not a major factor these can be quite cheap and not that big.
I'm intrigued and be nice to have a weapon to help some people with they're room.
I'll look into this more
Its all about the amount of absorption. Bass traps end up having very little, so you need a lot of them. An active absorber can be many many times more effective so you would need less. Multiple subs and sound absorption are both try to achieve the same result. They just do it in different ways and one works better at some things and the other at other things. Best is a well damped room (LF only!) AND multiple subs. This achieves an ideal that no other solution can do.
Instead of relying on common sense I trust real data more: Double Bass Array (DBA) - The modern bass concept!
Like Earl said, the best approach is to do both.
In my experience the frequency range around and above the Schröder frequency is an even bigger challenge. Here speaker directivity, passive absorption and excess-phase correction are probably the only viable options.
In that post he was talking about SBA not DBA so the point is moot.
It's works remarkably well even with rater large deviations from the requirements. Alternative approaches and their effectiveness are described in the AES Convention Paper 8312, "Subjective Preference of Modal Control in Listening Rooms".
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