Question on hovering a woofer above the floor
in [Live Sound]
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From: Peter Larsen on 18 Jun 2008 01:13 Phil Allison wrote: > ** Not one tiny bit true. You do better with electronics Phil. Kind regards Peter Larsen
From: Arny Krueger on 18 Jun 2008 07:13 <BobFlintstone(a)home.com> wrote in message news:sprd5454h1t1jhla9mekdseu2gnih2kaag(a)4ax.com > I want to build a custom sub woofer, 35 to 180hz, in a > box that will look like a floor tom, (octagonal) to add > to a set of electronic drums. (TD-8) > > I have the speaker, the 150 watt amp module, and the > recommended box plans (2.5' ^3). The specs say the box > shall be ported, tuned at about 30hz. and should output > 115db maximum. > > Since a standard 16" floor tom is about 2' ^3, that's how > I got this idea... > The speaker will face down on the bottom, (the legs of a > standard tom put the bottom around a foot off the floor, > so this is the scale I am thinking of.) > Question: How will the distance between the floor and > the woofer affect the sound? It will add a notch to the frequency response around 500 Hz, and certain multiples thereof. Whenever the distance from the woofer to the floor and back to the woofer is an odd multiple of 1/2 wavelength. > Is there anything you guys can recommend or any tips you > may have? For the smoothest bass, put the woofer as close to the floor as possible, within reason.
From: Arny Krueger on 18 Jun 2008 07:19 "Arny Krueger" <arnyk(a)hotpop.com> wrote in message news:IradnT4_p_ricMXVnZ2dnUVZ_u2dnZ2d(a)comcast.com > <BobFlintstone(a)home.com> wrote in message > news:sprd5454h1t1jhla9mekdseu2gnih2kaag(a)4ax.com >> I want to build a custom sub woofer, 35 to 180hz, in a >> box that will look like a floor tom, (octagonal) to add >> to a set of electronic drums. (TD-8) >> I have the speaker, the 150 watt amp module, and the >> recommended box plans (2.5' ^3). The specs say the box >> shall be ported, tuned at about 30hz. and should output >> 115db maximum. >> Since a standard 16" floor tom is about 2' ^3, that's how >> I got this idea... >> The speaker will face down on the bottom, (the legs of a >> standard tom put the bottom around a foot off the floor, >> so this is the scale I am thinking of.) >> Question: How will the distance between the floor and >> the woofer affect the sound? > It will add a notch to the frequency response around 500 > Hz, and certain multiples thereof. Whenever the distance > from the woofer to the floor and back to the woofer is an > odd multiple of 1/2 wavelength. >> Is there anything you guys can recommend or any tips you >> may have? > > For the smoothest bass, put the woofer as close to the > floor as possible, within reason. But, on first reading, I didn't notice that you were going to roll the top end off at 180 Hz. That would tend to make the notches due to the floor bounce kinda moot. Your basic idea Bob - make a woofer that simulates the acoustic position of the bottom of the drum seems kinda intrigueing. Visually, you might be able to fly the electronic drum under people's visual radar. IMO, worth a try.
From: gwatts on 18 Jun 2008 09:45 Peter Larsen wrote: > BobFlintstone(a)home.com wrote: > > >> The speaker will face down on the bottom, (the legs of a standard tom >> put the bottom around a foot off the floor, so this is the scale I am >> thinking of.) > > If you want any loudspeaker unit to have a long service life then place it > vertical, the rear suspension _will_ sag in a horisontal mounting and > eventually a reconing will be required, either from the sag or from > oonsequential voice coil melt down. So all those ceiling-mounted background music and announce systems that have been working for decades... oh never mind. After about a year with the new, dual-18 subs in the PA I worked started making little scratchy noises, clearly evident when you'd mute everything but the subs. We never changed their position from truck pack to use, always kept them so the drivers were vertical. Once we noticed the scratchy noises we took some time at a load out to rotate every 18 by 180 degrees in their mounting holes (and didn't put a screwdriver through any of them!) and at the next show: No Scratchy! We then modified the cabinets so they moved and trucked on their backs, and never had scratchy again. The moral of this tale: Big drivers need to be rotated at proper intervals and/or stored horizontally. I'd suspect trucking them horizontally helps with preventing voice coil damage when you drive through potholes and over curbs, but I've never done definitive testing to verify this.
From: BobFlintstone on 18 Jun 2008 19:52
On Wed, 18 Jun 2008 07:19:25 -0400, "Arny Krueger" <arnyk(a)hotpop.com> wrote: >"Arny Krueger" <arnyk(a)hotpop.com> wrote in message >news:IradnT4_p_ricMXVnZ2dnUVZ_u2dnZ2d(a)comcast.com >> <BobFlintstone(a)home.com> wrote in message >> news:sprd5454h1t1jhla9mekdseu2gnih2kaag(a)4ax.com > >>> I want to build a custom sub woofer, 35 to 180hz, in a >>> box that will look like a floor tom, (octagonal) to add >>> to a set of electronic drums. (TD-8) > >>> I have the speaker, the 150 watt amp module, and the >>> recommended box plans (2.5' ^3). The specs say the box >>> shall be ported, tuned at about 30hz. and should output >>> 115db maximum. > >>> Since a standard 16" floor tom is about 2' ^3, that's how >>> I got this idea... > >>> The speaker will face down on the bottom, (the legs of a >>> standard tom put the bottom around a foot off the floor, >>> so this is the scale I am thinking of.) > >>> Question: How will the distance between the floor and >>> the woofer affect the sound? > >> It will add a notch to the frequency response around 500 >> Hz, and certain multiples thereof. Whenever the distance >> from the woofer to the floor and back to the woofer is an >> odd multiple of 1/2 wavelength. >>> Is there anything you guys can recommend or any tips you >>> may have? >> >> For the smoothest bass, put the woofer as close to the >> floor as possible, within reason. > >But, on first reading, I didn't notice that you were going to roll the top >end off at 180 Hz. That would tend to make the notches due to the floor >bounce kinda moot. Yes, the amp module has a high cut that goes between 40 and 180hz, so I figure for drum power I better leave it up at 180. I confess I don't know why they have 40hz, there's not a lot of sound below that! >Your basic idea Bob - make a woofer that simulates the acoustic position of >the bottom of the drum seems kinda intrigueing. Visually, you might be able >to fly the electronic drum under people's visual radar. IMO, worth a try. > I think it might be cool! Every decade or so I have a good idea.... Now to read up on jointing octagonal cabinets... |