speaker responce(bit O.T.)

[EdJ]

Hi,
while changing a speaker yesterday i was a bit curious if you could hear a difference in sound when a speaker is placed on top of another speaker`s magnet.in short:i couldn`t hear any difference.
But when i asked my son to take the new speaker off of the otherone`s magnet we were both very surprised to hear the enourmous change of sound comming from the speaker while lowering it to the floor!
I asked my son to hold the speaker upwards and lowering and holding it steady for a while and then lowering it a bit further to finally put it on the floor.
While i allways liked this speaker(one from a Lab L5)the sound was so much richer,fuller holding it 1 meter from the floor then it was 20 centimeters from the floor and on the floor it sounded just crap.
Then,being on the floor a while,we both thought it didn`t sound that bad at all but,lifted 1 meter from the floor the sound was superb in comparison.
Has anyone had the same expiriences and can someone explaine to me why this happenes and perhaps where i can read more about this on the Internet?Please.
Thanks very much in advance,
Ed

[Mike Burgundy]

I'm guessing the lifted speaker had a more transparent sound, and the floor position sounded boomy.
If you put a speaker closer to the floor, the floor starts working like a reflector, so you essentially have a second sound source as far as your ears are concerned (making it more efficient decibelwise as well). This works best for lower frequencies, but since these are also more susceptible to soundwave interference you just might end up with a comb-filtered low end (notice a slight phaser-like thing going on in the sound when playing while lifting/lowering the speaker? Bingo)
The speaker is still putting out exactly the same frequency response, it's just room acoustics playing with you.
These effects will become more prononced as your floor gets more reflective - concrete, wood, tiles all sound rather different than ankle-deep carpeting. In fact, thick carpeting might just dampen reflections to the point that youre actually hearing *more* of the speaker when it's further away from the carpet.
hih

[petemoore]

any surfaces like a floor or wall limmit the directions in which the sound waves can be dispersed.
 The widest dispersion [a raw speaker hanging in the air] will give the lowest amplituce sound wave in any/all directions.
 byt boxing the speaker the waves are focused more in one direction [if you happen to be in front of the cab] it will be louder
 putting that cabinet on the floor 'scoots' the sound waves straight out front increasing markedly their percieved [and real] amplitude [if your'e in front of it.
 putting a speaker in the corner adds yet another wave focusing 'device' and percieved and real sound wave pressure levels can be 'increased' actually focused more to go out 'frontways'...
 The football  coaches Horn is a perfect example of this physics lesson.

[Mark Hammer]

In this era of headphones, dorm-room minisystems, and 7.1 home theatres with subwoofers, the fine art of speaker placement seems like a distant echo from the past.  There is, however, a huge huge literature from the 50's through the 80's on speaker placement and the fine art of where to stick your stereo speakers in a large listening space so that they yield balanced response and decent imaging.  Go to your local public library.  Chances are pretty good if they are like the one in my city, the audio books are a little out of date.  That's good in this case.  They should provide reams of info on how location, and distance from a flat or angled surface can alter frequency response.

It gets more interesting, though.  In the late 70's, the band I was in was possessed of two DIY nuts, myself and the bass player.  As a result, we collectively decided to build our entire PA system from scratch to save money.  The speakers consisted of a 15" in a folded-horn bass bin on each side, plus a pair of separate "home plate" shaped/sized tweeter cabinets that each housed 4 dome tweeters, angled for better dispersion.  When the separate tweeter boxes sat atop the bass bins, located so that a plumb line would have had the tweeter domes and woofer voice coil perfectly aligned, it sounded like just about any E-V Eliminator of that era: loud, strident, harsh, typical club sound.  Just by accident one time, though, and I forget what the circumstances were, we elevated the tweeter bins so that they were a couple feet above the bass bins, and all of a sudden the sound magically transformed into high quality audio.  Sweet, transparent, balanced.

I'm going to speculate here, but it seemed to me that the listener gets a combination of sounds arriving from two sources.  In essence this is a battle of two wavefronts.  Of course the nature of 2-way systems is that there is some overlap in the midrange, and for some reason the distance played a big part in what happened with that midrange when the two sources were summed by the ear at the typical listening distances.  We found that the distance was critical, which only reinforces my gut sense about how sound images are formed from multiple sources.

That's an interesting phenomenon, but the question is what lesson you draw from it, and how you respond to it.  Obviously, a one-box-gives-me-everything speaker is easy to manufacturer, market, transport, and set up.  I think, however, that such systems make assumptions about listening distance and circumstance which aren't necessarily true in all cases.  I would not for one moment suggest the distance that produced clearer sound for us was any sort of ideal driver spread, but it WAS the ideal spread in that space at that listening distance. I think the fact that studio speaker manufactuers/engineers distinguish between "near-field" and other types of monitors lends creedence to the view that optimal driver spread in multi-driver systems depends on listening distance.

No one seems to talk about it much, but there is probably something different about various sorts of speaker arrangements in guitar amps beyond merely wattage, resonances, magnets, cone size, etc.  Play a 2x12 vs a 4x10 and they feel very different at the same distance frm the amp.

[EdJ]

Thanks for the replies!
When i red my subject over i realized i jumped my conclusions about the second magnet not making any difference in sound.
I will repeat it with A/Bing the sounds at different distances from the floor and listen for changes in tone between one and two magnets.
Funny how things go;while in 1978 i was convinced a distortion pedal made all the difference i find myself merely changing picks of different material which,to my ears,seem to make a much bigger change in tone.
Not that i will stop making new pedals;the addiction to them is just too big.
But the last few years i feel that,for me,it is far more important(tonewise)how i feel at the moment then what is at the end of my fingers and beyond.Would this mean that i am finally getting a bit of a grasp at the instrument or am i just becomming deaf?
Greetings,Ed

[Hal]

hahahahahahha WOW I feal like a moron....

first time I read through that I was thinking "could there be wires in the floor with magnetic fields getting in the way?"

::sigh::  I need to think a little less sometimes.

nice posts everyone, though.