LF must be absorbed and multiple subwoofer do nothing to help to have a good and even decay times accross the FR.
Last edited:
All a sub needs to absorb bass is an opposing phase relationship to the others. The multiple sub technique both trims and adds, with the goal being the middle ground.
decay times needs to be even across all the FR and a subwoofer do not address this at all.
I dont know how to make this more clear and you seem to simply ignore that point.
Decay times are directly related to modal 'strengths'. Controlling modes in a finished small room is quite a task. I've heard diaphragmatic absorbers can be affective although they seem large and static to me. Any type of fluffy insulation or foam is useless. I believe multiple subs and EQ are the way.
That's the last I'll say about it unless you can give me some proof otherwise.
That's the last I'll say about it unless you can give me some proof otherwise.
Last edited:
EQ cannot help for time related issue and resonance in a room. Decay times is a time domain issue, EQ cannot help with time domain issue.
Nobody just use ''any type of fluffy insulation'', you need to use the right foam with the right coefficient absorption for the thickness used.
I need to prove you what exactly? Every studio in the world use velocity and pressure based bass traps and use absorption and/or diffusion to control and reduce room modes, decay times, flutter echo,standing waves etc...
Last edited:
The ultimate damping (absorbtion) is the anti-phase. Multiple subs has plenty.
Just pick the a house with a big room for your toys. Then strip the drywalls and add damping. Most sound proofing technique give you damping. You end up with damping like a studio.
Then you can pick multi subs and or bass traps.
The first step is damping. The next step is flattening FR. Multiple subs with EQ cut peaks and fill valleys. Bass traps only cut peaks.
It's all important fellas. But first start with the design of the room in other words the drywall and damping behind the drywall. Next implement multisubs. Next implement bass traps both velocity and pressure based bass traps (that are limited ONLY to the LF). Finally for minor tweaks (like a small peak or 2), use EQ. I did it in that order, but honestly the bang for the buck for me was implementing multiple subs (minimum of 3, diminishing returns after 4).
This series of articles explains it very easily and well:
Bass Integration guide by Paul Spencer Parts 1, 2, and 3
Best,
Anand.
This series of articles explains it very easily and well:
Bass Integration guide by Paul Spencer Parts 1, 2, and 3
Best,
Anand.
to reduce room decay, subs are useless.
i wont comment either as anyone taking room acoustic seriously knows that. this is acoustic 101
Last edited:
Active damping beats passive damping every time. Even better, do not excite the modes in the first place.
I guess all the studio in the world and acousticians are not aware of your findings. I sure am interested. please tell us more about active damping!
any complete data to share how active damping helps to reduce decay times of Low Frequencies?
lol what?
Last edited:
The question I ask myself is which method is more suited to my subjective preference.
Obtaining a flatter FR will be easier with subs but what about bass envelopment, hence non directional bass. PANO, Do I have this right? Haven't heard subs in action but I did query you about the comparisons.
I would not enjoy extremely non directional bass.
My room has 30 bass absorbers including broadband, panel traps and ceilings stuffed with 3lb per cubic foot glass fibre. I've reduced 12db peaks and dips to 4db. The subjective quality is astounding.
IME, Common sense would suggest that its better to absorb at the surface of reflection-acoutic, rather than cancel in the room after reflection-active.
Obtaining a flatter FR will be easier with subs but what about bass envelopment, hence non directional bass. PANO, Do I have this right? Haven't heard subs in action but I did query you about the comparisons.
I would not enjoy extremely non directional bass.
My room has 30 bass absorbers including broadband, panel traps and ceilings stuffed with 3lb per cubic foot glass fibre. I've reduced 12db peaks and dips to 4db. The subjective quality is astounding.
IME, Common sense would suggest that its better to absorb at the surface of reflection-acoutic, rather than cancel in the room after reflection-active.
frequency response is much less helpful to help you understand your room LF performance then a ETC or waterfall graphs.
decay times is the enemy of rooms LF performance.
adding more subwoofer may very well help for various reasons, but do not help at all for the worst problem of LF performance which is resonance and decay time.
Also, subwoofer is for frequencies under 60hz-80hz normally, while absorption is also needed for frequencies up to 200hz before they become directional.
Also, you dont just need bass traps in a room, you need to deal with first reflections as they totally smear imaging and clarity of mid/highs.
Last edited:
well, maybe you can help me for discussion purposes. I don't plan to do anything more with my room at this time.
I worked on my room over 12 years ago. I looked at Energy time curves, waterfall, impulse response and FR. I did focus more on the change in FR at that time but examined all.
I now measure speakers outdoors(for design purposes) well away from buildings and 15 feet high. It also gives me the opportunity to compare outdoor FR to Indoor FR. This tells me a lot about my rooms FR vs anechoic FR.
I have speaker design specific software which is what I use.
I have room acoustic specific software That doesn't get used much.
But to your comment, FR curves with longer gate times will display larger dips and peaks which is part of the stored energy.
Can you share ETC (waterfall graphs) measurements from your listening position. This will be much more helpful to understand your room resonance.
you can use REW or ARTA.
great
you can also ask at gearslutz studio forum where many professional will be able to help and recommend you.
how thick are your bass traps and your first reflection panels.
do you have a dedicated room for playback? pictures of your space would be great!
Last edited:
And I'd be very interested to see comparisons of sims, out of doors, and indoors results.
Thanks.
Alas, a lot about acoustics is unintuitive, even more so, psychoacoustics (which is what we are really talking about). Pity. For example, almost any stuffing in a room whether identified as a "treatment" or not at home adds to the Sabine value of the room (behind furniture, under cabinets, clothes closets, true felt rug under layers, and apropos bass not least the drywall panels). I rather like deadish spaces and think any Q, in a driver or room, is too much. I seem to recall liking the mono sound of an ancient Karlson-15 in the worlds largest anechoic chamber. I also like the deadish sound of Roy Thomson Hall. The recording should be the source of the music, not "enhancement" from the room. I don't think it is inconsistent of me to also prefer dipoles which excel in ambiance as a result of their total dispersion. Go figure.
Ben
Last edited:
Can you really alter the modal behaviour of a domestic-sized room significantly with practical acoustic treatments? Multiple subs with DSP EQ and delay give the user a great deal of power and flexibility to attenuate peaks created by a room's modes. Wouldn't this have the effect of improving the time domain performance? By putting less energy into modal 'peaks' by multiple sub averaging and the use of DSP, the FR in the bass is flattened, but energy over time will also be reduced.
Last edited:
Dr Geddes' presentation linked in post 20 makes the link expliçit between steady state modal room response and decay. Attenuating the drive signal to the subs at frequencies where there are high Q modes will improve (ie reduce) decay times down to any arbitary level, as well as flattening the FR.
Also, although the point has been debated on DIYA, the physics doesn't appear to support the idea of bass being directional in a domestic room's modal range.
Also, although the point has been debated on DIYA, the physics doesn't appear to support the idea of bass being directional in a domestic room's modal range.
Last edited: