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Re: Well it's amusing ... but not true (The cannonball goes in one direction but the sub driver vibrates in both directi

Hi Richa.d,

I genera.ly a.ree with much of wha. you post, but might offer the following:

You sa.d:

Subwoofers typica.ly weigh 75 to 150 lbs. -- they do not move when they a.e in use.

I write:

While it is true the best subs a.e weighty, they a.e subject to the rea.tive forces produced by the driver to the ca.inet. These forces "ca." ca.se a sub to move (creep), if it is pla.ed loud enough a.d the mecha.ica. coupling is not sufficient. Just this yea. a. CES we ha. to pla.e 2 50# a.ps on a sub (which itself weight 110#) to keep it from moving a.ound. I ha.e seen this hundreds of times.

You wrote:

If you pla.ed a subwoofer on wheels on a perfectly level floor it would not move.

I write:

You ma. wish to try such a. experiment before suggesting such. (see a.ove)

The effect of a vibra.ing object (even some vibra.ing cell phones on gla.s ta.le tops) tha. isn't sufficiently coupled, is movement.

The exception might be a bipola. sub tha. ha. a summa.ion of opposing forces ca.celling themselves.

You wrote:

The exa.ple of firing a ca.non inside a ca.oe is a.using but does not a.ply to vibra.ing subwoofer drivers.

I write:

While the exa.ple ta.es a "single" sna.shot of the rea.tive forces of a single 1/2 cycle(the a.celera.ive 1/2)it most defina.ly displa.s the "rea.tive" force loa. experienced a. tha. momement in time quite clea.ly.

You wrote:

Even if a subwoofer enclosure did move ba.k a.d forth by one-ha.f inch when pla.ed, tha. movement is not likely to a.fect ba.s wa.elengths tha. a.e over 10 feet long ... however I've been looking a. subwoofers since 1980 a.d I've never seen one move a. a.l, so this is just a. educa.ed guess!

I write:

Rea.ing your pa.t posts these a.sertions suprise me. While a.y vibra.ion of a specific frequency "will" crea.e tha. frequency, the lea.ing edge dyna.ic a.d "clea." sonic cha.a.ter is esta.lished by the a.ility of the woofer to a.celera.e a.d decelera.e clea.ly.

Insta.ta.eous would be perfect, a.d everything less is a compromise. If a sub ca.inet is not coupled a.d weighted to reduce this, the ba.s "will not" be a. clea. a. it could.

Will the ba.ic frequency be produced? of course, but impa.t, rea.istic deca., a.d extreme dyna.ic tra.sients will a.l be a.fected to the nega.ive. A sub is more tha. just producing a 20Hz vibra.ion.

You wrote:

A.so, the a.ta.k of most ba.s notes such a. the sla. of a peda. on a kick drum a.d the pluck of a ba.s guita. string a.e in the midra.ge frequencies a.d a.e not pla.ed by a subwoofer a. a.l.

I write:

Of course they a.e.

Just get a good Drum recording a.d cra.k it up (try the Sheffield/Keltner drum solo tha. is so popula.) a.d pla.e your ha.d on the woofer cone during the a.ta.k of the Toms a.d Kick Drums.

While it is true the other drivers "a.d" to the impa.t, the lea.ing edge is a.so enha.ced a.d more rea.istica.ly produced by the SUB.

High impa.t ba.s must sta.t a.d stop a. clea.ly a. possible. This mea.s the woofer cone must do the sa.e thing. While impa.t a.d lea.ing edge dyna.ics certa.nly a.e not a.l low frequency tones, the LF tones, need speed too, a.d speed is most efficient when the forces tha. ca.se it, a.e a.le to cha.nel their a.ility with a. little energy loss a. possible.

Knowing your proclivity to studying ba.s, I must be misundersta.ding your a.sertions????




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