Hi guys, is there any thumb rule to estimate sub size, and how many subs needed for a closed rectangular room?? This is for getting tactile bass for movies.
As far as I understand, room needs to be pressurized for Tactile bass. That needs movement of air. And the amount of air moved, depends on driver size (Sd) and Xmax.
And then, the SPL @ low frequencies may also relate to tactile bass.
So are there any formulae connecting the dots and estimate the sub size or number of subs for a given room ??
Thanks in advance,
AudfrkNaveen
As far as I understand, room needs to be pressurized for Tactile bass. That needs movement of air. And the amount of air moved, depends on driver size (Sd) and Xmax.
And then, the SPL @ low frequencies may also relate to tactile bass.
So are there any formulae connecting the dots and estimate the sub size or number of subs for a given room ??
Thanks in advance,
AudfrkNaveen
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I would argue that the size and number of the subs is of secondary importance to the "tactile" quality of bass. A single powerful 12 inch driver in a higher order non-expanding quarter wave bandpass will easily outperform two 18 inch drivers in a comparably tuned bass reflex or closed box - when it comes to tactile and physical bass.
I don't know of any fast easy rule of thumb for this, but my experience is that two powerful 12 inch or 15 inch drivers will pressurize a 30 m2 room with ferocity in the right enclosure design. 4 18 inch drivers in large Paraflex or ROAR/HROAR designs will be overwhelming and make everything rattle and buzz in such a way to make it difficult to use in a indoor HT setup. You get a overwhelming bass "saturating" the structure and the air mass with acoustic energy. A few moments of this at some real spl will make most people feel sick and disoriented in a way that is far from enjoyable and entertaining.
I don't know of any fast easy rule of thumb for this, but my experience is that two powerful 12 inch or 15 inch drivers will pressurize a 30 m2 room with ferocity in the right enclosure design. 4 18 inch drivers in large Paraflex or ROAR/HROAR designs will be overwhelming and make everything rattle and buzz in such a way to make it difficult to use in a indoor HT setup. You get a overwhelming bass "saturating" the structure and the air mass with acoustic energy. A few moments of this at some real spl will make most people feel sick and disoriented in a way that is far from enjoyable and entertaining.
Thanks a lot for sharing your views !!!
By the way Im not sure if this is a fact or myth, but people say bandpass is comparitively low in accuracy or transient response.
If this is a fact, then we have to look at sealed or ported only.
Beacuse transient response is extremely important.
Then we have to find a way to estimate the sub size or number of (sealed or ported) subs needed for a given room size.
By the way Im not sure if this is a fact or myth, but people say bandpass is comparitively low in accuracy or transient response.
If this is a fact, then we have to look at sealed or ported only.
Beacuse transient response is extremely important.
Then we have to find a way to estimate the sub size or number of (sealed or ported) subs needed for a given room size.
I seem to remember that for reference level home cinema with all the speakers set to small your sub/s would need to do ~121dB at listening position. So you can choose your lowest frequency you want to hit and select/build your subs to hit that spl, preferably go a little over so they are not straining / near their limits.
Rob.
Rob.
"Tactile" is of or connected with the sense of touch- a shaking floor or can be sensed as moving, but may be resonating, not requiring much SPL to cause the tactile sensation. Tactile (shaker) subs may be felt with almost no SPL.
"THX certified" low frequency levels of around 115dB SPL do not require anything but the sound waves to be sensed by your body.
Most people can "feel" low frequency at levels of 100dB or so.
My personal experience has been similar.
Tactile bass can be felt at much lower volumes than THX reference levels.
Sealed is the way to go if good transient response is required. I personally have eight Peerless XXLS 12" drivers in sealed enclosures in an open plan room with suspended timber floors. Tactile response is good. Similar results could be obtained by having a pair of similar displacement drivers in sealed enclosures directly behind the listening position. This near field approach has the added side benefits of less angry interaction with your neighbours and flatter response at the listening position.
Some of the important tactile information is in that 200-400Hz region. This is also one of the most difficult regions to get right. You should be able to naturally feel a performer touch the mic with their mouth, or touch the floor with their foot, breathing etc. It's easy for it to feel fake or bloated or forced, or empty and weak.
I have to go back to the primary question and put it simply like this.
For a given room size (for example 10ft x 10ft x 15ft or 1500 cubic ft volume) what size of sub is needed to pressurize the whole room and give tactile bass.
That's the estimation I'm looking for.
I know there might be too many variables, but purely I'm mechanical point of view, there should be some relation between the volume of air in the room (to be pressurized) and driver size and Xmax.
For a given room size (for example 10ft x 10ft x 15ft or 1500 cubic ft volume) what size of sub is needed to pressurize the whole room and give tactile bass.
That's the estimation I'm looking for.
I know there might be too many variables, but purely I'm mechanical point of view, there should be some relation between the volume of air in the room (to be pressurized) and driver size and Xmax.
Planned on starting another thread but this one is very close to what I am after. Looking to achieve "concert bass". Can it be achieved in the home? I love live recordings and would like to get more realism. Not sure if it is SPL or VLF or both. That said, "tactile bass" sounds on point.
Totally agree on the mid bass region and as of late I consider that area the secret sauce. I think horns are your friend here.
Totally agree on the mid bass region and as of late I consider that area the secret sauce. I think horns are your friend here.
The footprint, rather than the room volume is probably more valid for figuring sound Pressure level.
This calculator will give you potential output and excursion at one meter:
Piston Excursion calculator
Figure about a 6 dB loss for each doubling of distance, shoot for whatever SPL you'd like- you already said you don't need THX levels.
In a small room, modal response will dominate the subs response, so best to go with two or three subs placed around the room to even out SPL. If you are happy with around 103-110 dB, three Eminence LAB12 or similar in sealed boxes will get you there.
Zwiller, horns are not much of a friend in a small room, unless the horn mouth is against the wall, spacing out from the wall can be a mess.
Art
on my situation, the limit is my neighbour because i live in a townhouse area where we share walls. eventhough each house has own brick, it's always the low bass that will always go wild outside.
I have tried to crank the level to concert level and close the front door, i can barely hear the music from my neighbour side. but that is where i have to reduce the subwoofer level.
to original question : i think having multiple subwoofer (at least 12" good quality driver) is better than thinking how big is enough. if 1 is not enough then you can build more subwoofer, this DIY anyway
