Will a down-firing subwoofer reduce that great low "punch" you get in movies/music, due to the fact that its not actually facing you anymore?
I know low freq. sounds aren't directional, but, I still would think that air movement is (to an extent).
I don't want to lose that "punch" or "impact" bass.
I know low freq. sounds aren't directional, but, I still would think that air movement is (to an extent).
I don't want to lose that "punch" or "impact" bass.
I reckon you do lose some impact, but I think because it's so tightly 'coupled' with the floor you also get more output, maybe.
My sub is downward firing and you only get direct impact through the air when cranking it to insane levels. At low levels it still pulsates my sofa though, and my floor is concrete. Those low frequencies will always reach you
My sub is downward firing and you only get direct impact through the air when cranking it to insane levels. At low levels it still pulsates my sofa though, and my floor is concrete. Those low frequencies will always reach you
So, a mental experiment here then:
Place your subwoofer 5 feet from you, with the driver facing you, play a high volume "impact", kick bass, whatever.
Now, place a 5x5x2 foot thick concrete wall 5 inches in front of the subwoofer, repeat.
You're saying the "impact" will remain exactly the same? No physical differences?
Place your subwoofer 5 feet from you, with the driver facing you, play a high volume "impact", kick bass, whatever.
Now, place a 5x5x2 foot thick concrete wall 5 inches in front of the subwoofer, repeat.
You're saying the "impact" will remain exactly the same? No physical differences?
I know but like if you cross it skyhigh at like 200 Hz, I'm not sure the 100-200 Hz octave would sound good in a downfiring design. Not omnidirectional anymore...
But under 80 Hz, I seriously doubt you would lose any punch, you will probably gain some punch especially corner loaded, you'll have so much headroom.
But under 80 Hz, I seriously doubt you would lose any punch, you will probably gain some punch especially corner loaded, you'll have so much headroom.
You're sure about that? I thoughed it was more up like 100-120 Hz.
@Drfrink: What do you mean with low punch? Punch isn't low, more like 70 Hz and up
My 18" sub (with bigger Xmax) crossed @ 80 Hz doesn't gives as much punch at the chest as my 15" from 65 to 120 Hz anyways. The 18" is more into totall body movement except the chest.
Mvg Johan
Bear with me here... I know this is quite unrealistic...
Just to establish what some people are saying, you don't lose anything by going with a downfiring design, when it comes to felt bass impact.
So, right now, in a blind test, people wouldn't notice the difference between a subwoofer placed 12 inches away, pointed directly at their chest and the same subwoofer, with the driver pointed in the opposite direction, with the back of the cabinet 12 inches from their chest.
A few more assumptions:
1. You are deaf (I know, poor guy, blind AND deaf)
2. A repeating 50hz "blast" at 125 spl is being generated.
3. You are sitting directly in the center of a room with optimal acoustic characteristics.
You're telling me, the average person will have no idea when its pointed at them or away from them?
Just to establish what some people are saying, you don't lose anything by going with a downfiring design, when it comes to felt bass impact.
So, right now, in a blind test, people wouldn't notice the difference between a subwoofer placed 12 inches away, pointed directly at their chest and the same subwoofer, with the driver pointed in the opposite direction, with the back of the cabinet 12 inches from their chest.
A few more assumptions:
1. You are deaf (I know, poor guy, blind AND deaf)
2. A repeating 50hz "blast" at 125 spl is being generated.
3. You are sitting directly in the center of a room with optimal acoustic characteristics.
You're telling me, the average person will have no idea when its pointed at them or away from them?
The directionality of the sound is directly related to the frequency, not the direction that the speaker is facing. Below 80 Hz or so the radiation pattern of the speaker is 360 degrees (unless the baffle is at least 7 feet across). At those frequencies the ear/brain is unable to determine the direction of the source (unless your eardrums are separated at least 3.5 feet). If you can detect either the directionality of the sound or the speaker radiating plane you're hearing sound above 80 Hz; get a better crossover.
Facing the speaker downward will primarily result in additional boundary loading, so you'll get higher sensitivity, especially as you go lower in frequency. If the driver is close enough to the floor you will get some air mass loading, which will lower the speakers passband.
Facing the speaker downward will primarily result in additional boundary loading, so you'll get higher sensitivity, especially as you go lower in frequency. If the driver is close enough to the floor you will get some air mass loading, which will lower the speakers passband.
Thanks for that good explanation Jim.Jim York said:
I can hear where my sub is if I put it's level too high, my sub is crossed at 50hz. I guess this is the parts above 50hz which the 2nd order filter leaves in at too great a level. I am planning to try and make a 2nd order active filter, to work in series with the one in the plate amp, giving 24db/oct.
I think a steep x-over makes a lot of sense when crossing over to ported speakers at their natural roll-off (as they roll off at about 24db/oct). And I seem to have a little too much at around 50-60hz, which is partly caused by this effect I think.
I do feel that downward-firing and forward-firing crossed at 50hz 2nd order sound different, for whatever reasons.
If you want to use the floor to lower the box fb the area of the total perimeter of the gap between the box and the floor should be no more than the driver Sd. You can get better results if the ratio is made as small as 1:3. This not only will lower the passband but also will serve as a LP filter, which is quite helpful in the case of a 2nd order electronic filter on the input.
The problem with a 2nd order LP is that the ear is far more sensitive to sounds above 80 Hz than those below, and 2nd order filtering just isn't enough to remove an adequate percentage of the higher frequency content to compensate for that.
Yes, you well may be able to hear a significant difference between a direct and indirect radiated 50 Hz tone, but the difference lies in the harmonic content of what you're hearing.
The problem with a 2nd order LP is that the ear is far more sensitive to sounds above 80 Hz than those below, and 2nd order filtering just isn't enough to remove an adequate percentage of the higher frequency content to compensate for that.
Yes, you well may be able to hear a significant difference between a direct and indirect radiated 50 Hz tone, but the difference lies in the harmonic content of what you're hearing.
Thank You, BillFitzmaurice.
The perimeter of my case is 124 cm (35x27cm), Sd = 500cm2, if we suppose S=1/3*Sd, i.e. 166cm2, it means that tha gap should be 13mm !
I'm not sure, but it seems to me than 13mm is quite low.
Before - I've thinking about 4-5cm, than gives 496-620cm2 or 1/1-1.25/1 of Sd.
The perimeter of my case is 124 cm (35x27cm), Sd = 500cm2, if we suppose S=1/3*Sd, i.e. 166cm2, it means that tha gap should be 13mm !
I'm not sure, but it seems to me than 13mm is quite low.
Before - I've thinking about 4-5cm, than gives 496-620cm2 or 1/1-1.25/1 of Sd.
13mm would be at one end of the scale, as would be 5cm. Experiment with where it works best. It is possible to calculate the effect in WinISD, as a 4th order reflex, but it's not easy with all the variables present. What happens is that the air volume between the box and the floor is the front chamber, and the area of the opening is the vent, but calculating the effective duct length is very involved, much more so than just trying different leg lengths and measuring the result.
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