The honeycomb voids filled with sand (or other heavy particles) might sound interesting
(likely requires $100k equipment to determine the optimum fill grade)
Yes. So? What are you trying to say?
High Q, higher f resonances? Maybe.
All I know is my racing dinghy (FD) is built in that technology and is stiff as hell..
Picture of overhead luggage lockers in a Fokker 100.
2-side kevlar laminated honeycomb (pre-preg vacuum autoclave), foam edges, sheeted with plastic foil.
A 1000 bucks for a single front panel, five grand for a complete locker unit.
Stiff as hell, ultra-light, unsuitable for loudspeaker cabinets.
2-side kevlar laminated honeycomb (pre-preg vacuum autoclave), foam edges, sheeted with plastic foil.
A 1000 bucks for a single front panel, five grand for a complete locker unit.
Stiff as hell, ultra-light, unsuitable for loudspeaker cabinets.
Attachments
In my opinion honeycomb panels are not to be used for enclosures,they transfer energy very well from skin to skin through the honeycomb material. A much better and damped material is some of the reticulated foam that is used to make panels, it is fairly low density but stiff and also well damped with high internal loses. Balsa core material is also very nicely damped material with a skin on each side. It is the combination of materials that works not one in isolation. I have played with some very highly consolidated carbon fiber composites that would ring and sound like a piece of metal, not a great material for a speaker enclosure but extremely strong and stiff but with little to no internal damping.
Depending of the personal situation of each of us, there is no perfect answer to chose a technology for Speakers Cabinets. It will always be a compromise between overall size, (thickness of the walls), weight, availability, ease to build and price.
The advantage of sand is it can help to have a very heavy and well damped enclosure, that you can lighten for transport, removing-it from the boxes. It is inexpensive, and and you can throw-it if you move, easily found locally at your arrival. Even if you live on a beach away from all, at the end of the world;-)
Sorry to say this, but the reference to some so calling hi-end speaker designer techniques, made by J.C., seems to me totally inappropriate . First an industrial has access to technologies, machines and materials that a DIY don't. The weight of the enclosure is determinant for the manufacturer, as he have to send his products to the client's homes, and the transport is a big percent of the overall price for him. Not the same if you build your enclosure on site.
The advantage of sand is it can help to have a very heavy and well damped enclosure, that you can lighten for transport, removing-it from the boxes. It is inexpensive, and and you can throw-it if you move, easily found locally at your arrival. Even if you live on a beach away from all, at the end of the world;-)
Sorry to say this, but the reference to some so calling hi-end speaker designer techniques, made by J.C., seems to me totally inappropriate . First an industrial has access to technologies, machines and materials that a DIY don't. The weight of the enclosure is determinant for the manufacturer, as he have to send his products to the client's homes, and the transport is a big percent of the overall price for him. Not the same if you build your enclosure on site.
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There are lots of sound deadening products used for diminishing radiation from motor compartments - washing machines, marine applications - all using CLD techniques. An application to speaker boxes which have less onerous energy regimes seems possible for DIY.
For instance, line a conventional mdf speaker box with thin aluminum sheet stuck on with viscoelastic glue. Better: aluminum - viscoelastic layer - alum glued to mdf. My suspicion is that flashing sheet might be good enough for smaller speakers.
Or, if you're thinking you want to go high-end, as they call it, use a thin sheet of closed-cell foamed aluminum, instead: Very stiff, very damped - all the rage with upmarket architects. Pricey, but what the hey, worth it, of course
. Someone has a thread about it right now. http://www.diyaudio.com/forums/swap-meet/271376-foamed-aluminum.html?highlight=foamed+aluminum
If you just can't bear the thought of having a speaker which only needs one person to lift it you could always tie surplus lead sash weights or fishing weights to the bottom....
Foamed Al is really neat stuff https://www.google.com/search?q="fo...FGMzVoAS8l4H4BQ&ved=0CCsQ7Ak&biw=1366&bih=635
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I had build the walls of one of my studios with foamed concrete. Not expensive at all, very light, and damn efficient: no resonances at all, good isolation if thick enough , and some kind of added damping of resonances inside of the room. I had to bring less glass wool on the walls than habit.Or, if you're thinking you want to go high-end, as they call it, use a thin sheet of closed-cell foamed aluminum, instead: Very stiff, very damped - all the rage with upmarket architects. Pricey, but what the hey, worth it, of course
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You need to read everything available about it --
The error-correction via feed-forward tech as it is called, gives a dynamic range for their amp of 132dB and THD of -118dB at max output rating. Lower levels fall below the A-P limits. The technology used belongs to THX which calls it class AAA. They have 4 international patents on it. It eliminates the crossover distortion in AB amps. BenchMark has an article on it. See their app notes. BenchMark has gone beyond the patents in their app... "
uses multiple networks of local and global feedback in addition to multiple feedforward error correction paths....".
It also uses regulated SMPS technology.
I have inquired about obtaining one or two of them. Along with their ADC1 and DAC2, And, with 24b/96+ music files will be pretty nice, I should think.
THx-RNMarsh
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What parts of the measurement were improved over using an anechoic chamber?
Loose sand has been used in at least one commercial product many many years ago (Wharfdale??).
-RNM
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Open-cell foamed aluminum is likely better.
(the stuff has been around for decades)
My listening room is one storey up nowadays (fckng kids, cat)
All the walls are oldfashioned brick, even the inner ones, but wooden floors.
Due to a bathroom mishap right above it, the ceiling had to come out anyway.
Also renewed the floor, and installed Hawaphon plus rockwool in the floor/ceiling cavities. Inside of the door is also lined with Hawaphon.
(whole lot cheaper if bought in bulk)
Korff AG - Hawaphon
I gathered a couple of loudspeaker manuacturers use it for absorption purposes.
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Error correction it is not called, piles of feedback I see. The plots in the patents don't even approach those numbers. Dick please read and understand all their patents and then come here and discuss the technology one on one, don't just repeat their hubris.
EDIT - for instance claim 10 directly from the patent class B with massive feedback "10. The amplification system of claim 1, wherein said second amplifier is operated in Class B mode."
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US 8,421,531 does show the Quad/Walker feedforward bridge
but I can't imagine how its a valid patent
the 1979 Vanderkooy and Lipshitz "Feedforward Error Correction in Power Amplifiers" JAES paper shows power combining "AC Bridge" and balance equations in terms of abstract Z
the THX patent using C,R in their patent where Quad uses R, L has to be "obvious to those skilled in the art" given the analysis, bridge balance equation in Z, corrective networks shown in the '79 paper
but I can't imagine how its a valid patent
the 1979 Vanderkooy and Lipshitz "Feedforward Error Correction in Power Amplifiers" JAES paper shows power combining "AC Bridge" and balance equations in terms of abstract Z
the THX patent using C,R in their patent where Quad uses R, L has to be "obvious to those skilled in the art" given the analysis, bridge balance equation in Z, corrective networks shown in the '79 paper
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Dave Wilson used sand in one of his enclosures, decades ago, as well. I just don't like the hassle of using sand, but it works pretty well I guess.
Kindhornman, thanks for your 'measured' input. I realize this might be your area of expertise. For the record, my Wilson Sasha speakers weigh a lot. Even my WATT 1, are amazingly heavy for their size. Wood, just does not compare.
Kindhornman, thanks for your 'measured' input. I realize this might be your area of expertise. For the record, my Wilson Sasha speakers weigh a lot. Even my WATT 1, are amazingly heavy for their size. Wood, just does not compare.
There is a feedforward path mentioned that of course should not be confused with feedforward error correction, a la Black from ~1929. But I see the patents mention Vanderkooy's 1980 AES paper, which probably mentions Black.
Owen Jones (Andrew Jones' brother, AJ having worked with Fincham at KEF and Infinity), has been busy patenting for some years now. As so often, the pitch is that, as a physicist he is unencumbered by traditional approaches to audio that so mislead the rest of us
On an older boosted-rail patent, something that closely resembled an ST breadboard that had crossed my desk in about 1990, said patent which Fincham was enlisting the help of friends to promote, an amplifier guru wrote to me, after he reviewed the patent: "The claims are suitable as a wrapper for dead fish." He rarely is moved to such rhetoric, and the tenor of the comment indicates just how annoying he found things---although we concurred that nothing emanating from the USPTO would surprise us anymore.
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I dont care about the patents. I put it up for you and others to see it there is something in it for you. You might also want to read the other available literature from the designers of Benchmark amp. And the review/description in AudioXpress. They show curves of thd and describe the circuit also. Looks very very good on paper.
Like I said they use the patent and do more/other things as per the other mentioned sources. Read it all then decide.
THx-RNMarsh
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