except of course that it does. The more solid (mass and stiffness) the cabinet the lower the amplitude of resonances.
as you know, speaker dave, any material we choose to make cabinet out of has primary resonace, no way around it. The only way to deal with those resonances is the lower the amplitude. you can't argue against that, please?
Last edited:
I like the idea of trying to isolate the midrange driver from a baffle, as Linkwitz did as an add-on with his Orion speakers (mounted via its magnet from the rear).
I can imagine an enclosure where an internal rigid steel frame fixes each driver at the magnet and the box itself is left floating free around them.
speaker Dave, this topic certainly has my interest. I'll investigate a few models driven by oscillator at resonance and post back. I'd imagine I won't get to it for days or weeks even but I think it's worthwhile.
speaker Dave, this topic certainly has my interest. I'll investigate a few models driven by oscillator at resonance and post back. I'd imagine I won't get to it for days or weeks even but I think it's worthwhile.
As for a prior post, planet10 is entirely correct of course. When I jump I move xx inches up and the earth moves 0.00000xx inches the opposite direction.
Peter Snell did that in his Type A, where the midrange was placed in a cardboard-tube "floating on the baffle". But he was allways ahead of his time. I have to edit this - Peter did NOT mount the magnet to the rear, but the whole midrange-unit/enclosure was decoupled from the baffle and especially the woofer-cab.
Last edited:
I recently saw a video with a interview with David Wilson. Where most high-end manufacturers of loudspeakers direct their efforts towards more exclusive drivers and Himalayan worshipped silver-components, I actually had the feel, that all R&D concentrated around finding the best material for cabinets - and that they are noway near a final composit.
David Wilson was one of the first to use composite materials for loudspeker enclosure, the WATT, a 2 way using ScanSpeak paper/carbon 6' woofer and Focal Ti tweeter, in 1985 he carged $4500 for that bookshelf monitor. They call it M material LOL, it is Corian by DuPont, synthetic marbel but if you charge $20 000 USD for their current 2 way, M sounds way more mysterious and expensive
link to WATT enclosure description, a good read
http://www.stereophile.com/content/wilson-audio-specialties-wattpuppy-7-loudspeaker-page-2
link to WATT enclosure description, a good read
http://www.stereophile.com/content/wilson-audio-specialties-wattpuppy-7-loudspeaker-page-2
Last edited:
For me, it's not a matter of the cost of the final loudspeaker, but the materials. It's years ago when Corian was used in the Wilson speakers - I have tried but with bad results. As I can understand, at Wilson they research in multilayer composits and that's interesting IMO. This is a DIY-site and we have to "spy" all we can in respect to our meager wallets!"
Last edited:
exactly, PeterDupont!
I have looked into Corian too but it seemed so much trouble. It is used for kitchen counter tops here sometimes, very expensive, more expensive than real marble or granite.. but can be moulded apparently so it would make a seemless enclosure
I have looked into Corian too but it seemed so much trouble. It is used for kitchen counter tops here sometimes, very expensive, more expensive than real marble or granite.. but can be moulded apparently so it would make a seemless enclosure
Last edited:
Yes Veikko,
What really interests me about this thread is the fact that it is in many cases holds attention to the laws of physics - and is intriguing because there are so many hints to solutions out of the ordinary way of thinking "wood".
Our work with steel, soft silicone and a third different layer was costly, time consuming, needed a welder - and the cabs weighted 240 pounds.
I'm now thinking about multiple layers of thin plywood with different absorbing/dampening layers inbetween. With a total thickness of maybe 3/4".
What really interests me about this thread is the fact that it is in many cases holds attention to the laws of physics - and is intriguing because there are so many hints to solutions out of the ordinary way of thinking "wood".
Our work with steel, soft silicone and a third different layer was costly, time consuming, needed a welder - and the cabs weighted 240 pounds.
I'm now thinking about multiple layers of thin plywood with different absorbing/dampening layers inbetween. With a total thickness of maybe 3/4".
HI
Just seen this thread. Thought I might add our (commercial)
cabinet construction. We use a welded 1.6mm steel enclosure
which is lined with a layer of bitumen damping pads to which
is added a 15mm layer of a special plaster mixed with fibres.
The plaster expands when it sets putting the steel shell under
tension. Probably not ideal for DIY but possible.
This results in a very stiff cabinet with some inherent damping.
Its also pretty heavy.
We think it works very well judging soley by sonic comparisons
with other cabinet construction methods we have tried.
We plan to do some accelerometer measurements etc to
prove or otherwise the effectiveness of this construction.
I will publish results when we have done the tests for interest
if he thread is still going that is.
Just seen this thread. Thought I might add our (commercial)
cabinet construction. We use a welded 1.6mm steel enclosure
which is lined with a layer of bitumen damping pads to which
is added a 15mm layer of a special plaster mixed with fibres.
The plaster expands when it sets putting the steel shell under
tension. Probably not ideal for DIY but possible.
This results in a very stiff cabinet with some inherent damping.
Its also pretty heavy.
We think it works very well judging soley by sonic comparisons
with other cabinet construction methods we have tried.
We plan to do some accelerometer measurements etc to
prove or otherwise the effectiveness of this construction.
I will publish results when we have done the tests for interest
if he thread is still going that is.
Solid Surface materials like Corian can be made using all sorts of recipes, with different stiffnesses and damping -- sort of like paper in that respect. Even different colours and patterns of Corian have different charateristics. This makes it not near as simple as "using Corian", one has to wade thru the recipes to find the characteristics of each, and i would not be surprised if Wilson actually make/get made their own recipes
dave
What I am interested in is, giving a certain amount of layers - which materials would be best!
Could we blend a thin plywood with a automobile lead-dampener? Would it be better to damp the inner-side of the cab? Would there be any sense in blending four layers of really different dense materials - and in which order?.
I bet my trousers, that we could end up with a cheap, not-to-thick plate!
Could we blend a thin plywood with a automobile lead-dampener? Would it be better to damp the inner-side of the cab? Would there be any sense in blending four layers of really different dense materials - and in which order?.
I bet my trousers, that we could end up with a cheap, not-to-thick plate!
That seems to be the popular oppinion.
That is exactly what I have been arguing for. But the only way to lower the amplitude is through viscous loss.
Any other electrical engineers out there? Anybody want to explain how positive and negative reactances cancel at resonance? Why the Tacoma Bridge fell down? Why skyscrapers sway at a certain frequency? How much energy it takes to keep a clock pendulum swinging?
David S.
Audio Note's Peter Qvortrop uses Russian Birch for his best enclosures. He claims to have had it designed along the lines of the way a guitar resonates. I'm not quite sure I understand exactly what he's talking about and I don't think it would be easy to persuade me there's any merit to it. Yet for well over $100,000 for a pair of 2 way 8" speakers, he could have made it out of many other materials. I heard it about 4 years ago at an audio show and was not impressed. At the time he kept mumbling about how lousy the room was.
Do we need electrical engineers? As a matter of fact, we need the engineering guys that computerize the way a tower acts when vibrating! In a lesser scale, but the outcome will probably be the same, considering old, proven formulas.
We want the pressiorized/underpressiorized air inside the cabinet to be stable, not to interfere with the membrane of the speaker going in and out relative to the frontplate. And the outside of the cabinet making no vibration added to the perceived sonic impression in the listening position.
Quite a quest! Any suggestions?
Living in Denmark, I have known Peter Q for many years. The best thing he ever did for me was to introduce me to Peter Snell, which I visited at his plant many, many years ago. PQ "bought" some of the inner secrets from the Type E, which later on was a part of his Audio Note family. I still have great respect for Peter for his very intelligent way of marketing towards the wealthy, that this part of "hi-fi" can survive on. Nevertheless, making a musical instrument is quite another way of treating wood. You don't want linear frequency, you want to obtain a certain sound, that would measure like **** if you measured anywhere on the surface with a transducer.
To even think of letting the cabinet into the equation of the final loudspeakers performance is just way out of my thinking.
To even think of letting the cabinet into the equation of the final loudspeakers performance is just way out of my thinking.
Hello,
The question was asked “any other electrical engineers”? No not here, I am mechanical. I agree that type of building construction can be mission critical. I do know that ductile moment steel frame buildings do not work well for research labs with electron microscopes.
My job is to isolate vibrating mechanical equipment from the structure no matter how well the structure performs. I believe there can be some knowledge transfer to speaker construction.
Isolation pads made from cork and rubber are effective isolators as well as springs of carefully selected deflection. Where some people go south is with welded or bolted connections to the structure that short circuit the vibration to the building or in this case the speaker box.
Another trick used for vibration isolation is to use F=MA to our advantage. Motion or vibration can be seen in the coffee cup sitting on the conference room table and be noise in the critical conference room. The forces generated by vibrating equipment or in our case speaker are finite. Increase the mass by 5 times results in reduced acceleration and peak amplitude; they are reduced by a factor of 5. A pump can be an example, mount the pump on a concrete filled base to increase the mass then support the pump + base assembly on spring isolators. This approach has a dramatic reduction in building transmitted vibration and noise. Linkwitz and others (including me) isolate drivers from the enclosure with closed cell rubber gaskets (No screws are used because they are acoustic short circuits.)
Big heavy speakers with heavy magnets may help in reducing acceleration and amplitude. I have not seen any use of added mass to the speaker assembly with the intention of reducing acceleration and amplitude of the basket motion.
I have seen massive turn table bases with vibration isolation pads. Same concept.
Engineering is an iterative process, it is not complete until the client runs out of time or money!
DT
All just for fun!
The question was asked “any other electrical engineers”? No not here, I am mechanical. I agree that type of building construction can be mission critical. I do know that ductile moment steel frame buildings do not work well for research labs with electron microscopes.
My job is to isolate vibrating mechanical equipment from the structure no matter how well the structure performs. I believe there can be some knowledge transfer to speaker construction.
Isolation pads made from cork and rubber are effective isolators as well as springs of carefully selected deflection. Where some people go south is with welded or bolted connections to the structure that short circuit the vibration to the building or in this case the speaker box.
Another trick used for vibration isolation is to use F=MA to our advantage. Motion or vibration can be seen in the coffee cup sitting on the conference room table and be noise in the critical conference room. The forces generated by vibrating equipment or in our case speaker are finite. Increase the mass by 5 times results in reduced acceleration and peak amplitude; they are reduced by a factor of 5. A pump can be an example, mount the pump on a concrete filled base to increase the mass then support the pump + base assembly on spring isolators. This approach has a dramatic reduction in building transmitted vibration and noise. Linkwitz and others (including me) isolate drivers from the enclosure with closed cell rubber gaskets (No screws are used because they are acoustic short circuits.)
Big heavy speakers with heavy magnets may help in reducing acceleration and amplitude. I have not seen any use of added mass to the speaker assembly with the intention of reducing acceleration and amplitude of the basket motion.
I have seen massive turn table bases with vibration isolation pads. Same concept.
Engineering is an iterative process, it is not complete until the client runs out of time or money!
DT
All just for fun!
Well, a lot of engineering frontiers happen from the hands os employees, that uses time after dark!
Last edited:
- Status
- Not open for further replies.