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In Reply to: RE: Absolute Sound/ Bonsai posted by email@example.com on March 11, 2017 at 15:26:58
One pair of speakers in a room is part of Ivor's BS rules. It isn't based upon reality.
When they discover the center of the universe, a lot of people will be disappointed to discover they are not it. ~ Bernard Bailey
> One pair of speakers in a room is part of Ivor's BS rules. It isn't based
> upon reality.
Actually it is. An undriven speaker will act as a Helmholtz resonator. If
having just the one pair of speakers in a room is not an option, you can
minimize the effect of the other speakers on sound quality by shorting
their terminals together. If their drivers try to vibrate in sympathy,
this generates a back EMF that holds the cones still.
I know for sure that having a Piano or Guitar in the room causes audible ringing of those Instruments.
One dealer in my area not only keeps multiple pairs of speakers in the room, but also a grand piano. It's a loft style place which he also uses for piano teaching and recording, and the acoustics are terrible for auditioning speakers anyway.
The best dealer in my area never has more than one pair of speakers in any of their demo rooms, or at least none that I have seen when I'm there. A couple of other dealers in my area have a main demo room with just one pair of speakers, and then some secondary demo rooms where you might see two systems set up, e.g. one long wall and one short wall, or one system set up but another pair of speakers tucked away to the sides or back of the room.
The craziest places I've seen were in the big electronics shopping areas of Hong Kong and Tokyo, where it seems commonplace for audio shops to have way more gear than what can reasonably fit into their space. The worst I saw was one floor of an electronics department store in Akihabara that literally had a long wall packed full with dozens of expensive high end speakers, and there was no demo room, just a love seat in the middle of floor surrounded by shelves and stands of stuff. For auditions they just pulled a pair a pair of speakers out a foot or two. I watched some older gentleman trying to listen quietly to a violin piece with a dozen or so shoppers noisily milling around the floor.
I'm 99.9 % sure I have that Linn tips on Hi-fi paper. Between shoveling snow I'll try to dig it out tonight. There are some other things that might be of interest in that.
I try not to be a horder but I've never thrown anything away concerning stereo stuff away.
Good eye, or ear BubbaM!...Mark K.
because we're gonna demo the Air Tight Bonsai's next."
Yep. that's what I'd expect to hear in just about every high-end stereo store I've ever visited. :-)
So all the speakers have a common board. with shorting plugs for all except one pair. And the amp sockets with wire pigtails to plug in the one speaker pair in use. (naturally without buffering.. so the chances of blowing up some amps, or speakers is to look forward to...)
If one used reasonable wires.. It MIGHT not kill the sound more than having all the speakers resonating. LOL
How could that be the case for a sealed speaker enclosure? If a room has, say, one other set of 2-way speakers (even with a small port on the back of 'em) somewhere in the room how much effect could slight vibrations of their static drivers have on the sound when another pair of speakers is being demo'd? Seems to me that its very unlikely that it'd make much difference.
John is correct, a loudspeaker, sealed box or vented is a resonant system which can be driven internally (as per normal) or externally. In the latter case, just as a diaphragm wall or floor mode does, driving that resonance takes away energy from the room sound pressure .
For a loudspeaker in a room, at bass frequencies, it is measurable but usually small and like he said terminating the speaker (as it is when connected to an amplifier), kills the Q of the resonant absorber.
Can you point me towards somewhere that shows the measurements you referred to?
I don't think i ever saved any of them, a problem taking a lot of measurements i guess.
> How could that be the case for a sealed speaker enclosure?
A sealed speaker is still a tuned resonance system. Note the difference
when you try to move your speaker's cone with the terminals floating or
> Seems to me that its very unlikely that it'd make much difference.
In your opinion, but not those of others, of course. BTW, the terminals
shorting is not as effective for midrange units and tweeters, as these
often have a series resistor in their feed from the crossover.
Then the 'high end listening rooms' in most if not all stereo stores on this earth are 'Helmholtz Hell Spaces'. :-)
That's why I like the dealers I go to - they knew this decades ago and set-up the rooms properly. You want to listen to different speakers - they take the ones in the room out and bring in the next pair. Not flip a selector switch. But let's be practical here - people have home theater and in theory the front left and right speakers (and or the sub) will get the center channel and rear speakers vibrating.
And indeed, with most speakers rather poorly pair matched - the left speaker could make the right speaker vibrate out of step as well.
Walking into most showrooms or audio shows the first thing you do is stand against a wall and clap your hands - if you hear ANY kind of an echo - the room sucks. (Clap Echo test). No echo and the room is probably decent enough without an immediate need for room treatments (perhaps none).
That's certainly the case of almost every dealer's demonstration room that I have been to in the USA.
However not every one on this Earth. If you crossed the Atlantic to the UK most (all?) high end dealers will only have the pair of speakers that you are auditioning in the space. Which is one reason why serious auditions here are by appointment so that they can set up the system.
If you want to compare , say, a couple of speakers, the second pair will be held nearby in e.g. an ante room to swap in with the first being removed.
This has been the situation for the last 30+ years.
> Then the 'high end listening rooms' in most if not all stereo stores on
> this earth are 'Helmholtz Hell Spaces'. :-)
It was a high-end dealer who first told me about the shorting the speaker
terminals tweak 40 years ago. But when it comes to big-box stores, you are
Maybe the stores I've been too aren't quite classy enough, but I've never been in a stereo store that has ONLY the single pair of speakers in the room during an audition. Sure, the better stores generally aren't wall-to-wall speakers, but usually there is at least a couple of pairs present.
Interestingly, I have two acoustic guitars in my listening room at home and from time to time I will hear them ring in sympathy with the music I'm playing, but can't say it has ever really bothered me. But, while I enjoy good sound, I gave up being an obsessed purist a long time ago. Its a lot more fun these days to just enjoy the music.
Many things in the room will resonate, shelving, dishes,
windows, lamps, cabinets, walls, ceilings, on and on. If you did a slow
audio gen. sweep, at volume, you'd notice things buzzing/ringing at many
frequency's. Try shorting THAT out :)
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