Wasn't completely stupid about it, had the binder sections at the front, carefully aligned so that the backs rose in a straight line, perfectly aligned with, and effectively forming an extension to the speaker baffle.
What this experiment did was give me authority to the sound, it could go loud without sounding loud and raucous, key ingredients of "better" sound. The key aspect that had been modified was to create a path for vibrational energy in the carcase to be drained away, ultimately into the floor mass; also, the nature of the books added damping to the edifice, as well as improving the coupling to the floor. It was very easy to add and take books away, and hear the immediate effect - the subjective "spatial volume" of the sound diminished as the "tower" was reduced ...
Edit: also meant that room effects were much less; I have yet to be made aware of these terrible "room problems" - when the system works properly the room vanishes, it's irrelevant, to me ...
Edit: also meant that room effects were much less; I have yet to be made aware of these terrible "room problems" - when the system works properly the room vanishes, it's irrelevant, to me ...
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???
This said, adding books at the top of my enclosures don't change the sound more than when a fly lands on it. Can have some effect if the enclosure has the weight on an empty carton ?
Yes, a speaker enclosure need to have as much mass as you can allow (action/reaction) to resist at the acceleration of the membranes. Their wall have to offer good phonic isolation, to not transmit the sound from inside to outside and to not enter into mechanical vibrations while they are excited by the chassis of the speakers.
A good method to see what happens is to use a generator at various frequencies, while you put the wall you want to analyse at the top and cover-it with a thin layer of fine sand: you will see the vibration nodes after a while. It will help to find the best places for internal reinforcements.
http://www.dailymotion.com/video/xteigc_resonance-et-vibration-chladni_webcam
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I was wondering how much sound comes off the speaker enclosure i had built for me.... it had plenty of internal bracing. I placed a thick, heavy double layer of 'Moving" blankets over the speaker... sides, top and back. It would attenuate/absorb/block any box sound.... I didnt hear any change with or without the cabinet blanket. So, it can be done without extreme measures..... a cheap sensor for measuring vibration helps. The vibrating sand idea is 
THx-RNMarsh
THx-RNMarsh
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A couple patents look interesting; Google. Look up USA patents: 8,004,355 and 8,421,531.
BTW -- after looking at DAC's for a bit, I see Benchmark agrees that we need to get the signal further out and away from the noise floor. I suggested a higher OP level for the HiEnd would help....maybe 10v? Well, that is what BenchMark has for one of their input sensitivity settings for their new PA. That PA also use the patents above for error correction to an AB class amplifier.
You can read some about it in this latest issue of AudioXpress.com
THx-RNMarsh
BTW -- after looking at DAC's for a bit, I see Benchmark agrees that we need to get the signal further out and away from the noise floor. I suggested a higher OP level for the HiEnd would help....maybe 10v? Well, that is what BenchMark has for one of their input sensitivity settings for their new PA. That PA also use the patents above for error correction to an AB class amplifier.
You can read some about it in this latest issue of AudioXpress.com
THx-RNMarsh
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Christophe,
While I agree that mass can have an effect on the speaker enclosures resonance there is a problem with only looking at mass. Some materials are inherently well damped both from external excitation and also have good internal damping properties but other high mass materials are just the opposite of this. A high density material such as aluminum can be very stiff and also fairly high in mass but at the same time have very little internal damping and also can ring like a bell because it stores and slowly releases that energy. I just think of a massive structure such as a large metal bell, that is obviously designed to ring but it is an example of how mass alone doesn't necessarily dampen any vibrations introduced into the structure. Stiffness, mass and internal losses have to be considered in the choice of material.
While I agree that mass can have an effect on the speaker enclosures resonance there is a problem with only looking at mass. Some materials are inherently well damped both from external excitation and also have good internal damping properties but other high mass materials are just the opposite of this. A high density material such as aluminum can be very stiff and also fairly high in mass but at the same time have very little internal damping and also can ring like a bell because it stores and slowly releases that energy. I just think of a massive structure such as a large metal bell, that is obviously designed to ring but it is an example of how mass alone doesn't necessarily dampen any vibrations introduced into the structure. Stiffness, mass and internal losses have to be considered in the choice of material.
Like most things in this game, everything depends on everything - in my case the weight of the books would have been of the order of 4 x that of the speaker itself - I wasn't mucking around! And I was testing behaviour at high SPLs, a lot more energy is going into the carcase.
How about a sub enclosure ? I've seen some high Xmax cones actually
move a box !
If the cone is moving one way and the box opposite , would that not affect
the resulting output?
On "brit" boxes - my missions are a 3 layer 35mm (3mm plastic/25mm/6mm MDF).
They even line the insides with foam rubber .... they wanted NO
resonance from these cabs. Never seen a Japanese box like the "brit" box.
Sounds like stone when you rap it .
OS
move a box !
If the cone is moving one way and the box opposite , would that not affect
the resulting output?
On "brit" boxes - my missions are a 3 layer 35mm (3mm plastic/25mm/6mm MDF).
They even line the insides with foam rubber .... they wanted NO
resonance from these cabs. Never seen a Japanese box like the "brit" box.
Sounds like stone when you rap it
.OS
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I agree with Kindhornman about pure mass - straight metal, say, is a bad thing ... a very casual experiment with a heavy lump of iron was a no-go - probably on some magnetic effects alone!
Those B&W's were pretty minimal in construction, the better the carcase the less the effect most likely ... what it drew me into understanding was that even cheap gear has the intrinsics to perform rather impressively, if one understands the shortcomings that can be easily bypassed or compensated for.
Those B&W's were pretty minimal in construction, the better the carcase the less the effect most likely ... what it drew me into understanding was that even cheap gear has the intrinsics to perform rather impressively, if one understands the shortcomings that can be easily bypassed or compensated for.
It's all a game, you're trying to position the driver frame absolutely rigidly at a point in space, without it moving at all under any circumstance, affecting nothing but the air in front of the cone! I agree that an OB, done really well, should be a good approach, solves many things ...If the cone is moving one way and the box opposite , would that not affect
the resulting output?
On "brit" boxes - my missions are a 3 layer 35mm (3mm plastic/25mm/6mm MDF).
They even line the insides with foam rubber .... they wanted NO
resonance from these cabs. Never seen a Japanese box like the "brit" box.
Sounds like stone when you rap it
OS
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Yeah , my old tang-band 10" sub actually could "blow" it's original enclosure
across a smooth floor
. Or , it would shake violently on it's tall rubber feet !
A big (heavy -50lbs.) 35mm box , built like the "brit" box , solved that.
It will still shoot tennis balls across the room out the port,
but with no movement or turbulence.
I don't need no "Books" .... I have a fat transformer inside for ballast !
I just want to hear the driver/port - NOT the box.
OS
The idea that appeals to me - that Round Tuit thing again, - is sealed, balanced woofer drivers, back to back - no net force acting on the carcase. Aim would be the Rolls Royce, or whoever, type of thing - balance a coin on its edge, on top of the cabinet housing the drivers, while going at max intensity ...
- is sealed, balanced woofer drivers, back to back - no net force acting on the carcase. Aim would be the Rolls Royce, or whoever, type of thing - balance a coin on its edge, on top of the cabinet housing the drivers, while going at max intensity ... JC, Bcarso
I ouldn't agree more on cabinet resonances. Spare no effort to get rid of them, when knocked a good speaker will have a dull thud only.
When developing my speakers, we immediately brought in the bracing for the bass driver, which also had braces up on top as well. We assumed that was the bad one, only to discover that while it was the bad one, it was not the only one. We tried many combinations, I don't remember exactly how many but more than 10, that's for sure, and in the end we got it right. Now it's just a thud, but now they weigh in around 8 kilos (18 lbs) more than they had without the bracing. But now I hear no box, I just get what's on the CD player or tuner.
I ouldn't agree more on cabinet resonances. Spare no effort to get rid of them, when knocked a good speaker will have a dull thud only.
When developing my speakers, we immediately brought in the bracing for the bass driver, which also had braces up on top as well. We assumed that was the bad one, only to discover that while it was the bad one, it was not the only one. We tried many combinations, I don't remember exactly how many but more than 10, that's for sure, and in the end we got it right. Now it's just a thud, but now they weigh in around 8 kilos (18 lbs) more than they had without the bracing. But now I hear no box, I just get what's on the CD player or tuner.
All you do by changing the drive level is to change the optimium resistance you need to maintain your target s/n ratio.
I see lots of nested feedback, the term "error correction" does not appear in the text.
I was wondering how much sound comes off the speaker enclosure i had built for me.... it had plenty of internal bracing. I placed a thick, heavy double layer of 'Moving" blankets over the speaker... sides, top and back. It would attenuate/absorb/block any box sound.... I didnt hear any change with or without the cabinet blanket. So, it can be done without extreme measures..... a cheap sensor for measuring vibration helps. The vibrating sand idea is
THx-RNMarsh
Cheap and easy way to listen to your enclosure sound is hook them both up in anti-phase and put the baffles as close together as you can. This will kill most of the sound emanating from the drivers, leaving you with what comes out of the enclosures.
As to cheap vibration sensors, the other famous Greek audio George, George Ntanavaras, produced a kit for an accelerometer that works really nice. PM me if you are interested in his coordinates.
Oh, one of these days, someone will write a program to can use the accelerometers of mobile phones for this purpose ?
To damp vibrations, we need a material that both have enough inertia and can transform them into heat. Or/and walls rigid enough to resist to deformations.
The sandwich of two very rigid panels and sand between them is, on my point of view, the best thing we can find.
The two panels have to be as rigid as we can. they have to be different, in order to vibrate with very different modes. The thickness of the assembly (space between the two panels) will multiply their deformation resistance.
In the between of them, the sand particles will chafe the ones on the other. it is this rub that will produce heat. As they are not coupled with some glue, and because the inertia of each sand particle, they will not transmit easily the movements.
The sandwich of two very rigid panels and sand between them is, on my point of view, the best thing we can find.
The two panels have to be as rigid as we can. they have to be different, in order to vibrate with very different modes. The thickness of the assembly (space between the two panels) will multiply their deformation resistance.
In the between of them, the sand particles will chafe the ones on the other. it is this rub that will produce heat. As they are not coupled with some glue, and because the inertia of each sand particle, they will not transmit easily the movements.
it hurts. Better to use 100 000$ of equipment.
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