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#1
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
I want to concentrate on building speakers!
Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster |
#2
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On May 21, 10:31*pm, "Soundhaspriority" wrote:
"ChrisCoaster" wrote in message ... I want to concentrate on building speakers! Seriously. *One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? *And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster Modern speaker enclosures are not really inert; they are absorptive. The unyielding nature of steel plate means that you've got to work on the absorption. Otherwise, at wavelengths much shorter than the enclosure dimensions, the sound coming out of the backs of the drivers will ricochet around and radiate right through the backs of the cones. Steel plate is fine as the outer enclosure. Progressively absorptive materials need to go on top of it, like cork/gypsum/concrete. Acoustically, high density particle board is far superior to wood. Bob Morein (310) 237-6511 ______________________ How about fiberglass insulation? I have seen such inside the dB series of speakers from Canada 15 years ago. I wouldn't just toss it inside, I would line the top, bottom, sides, and rear inside walls of the cabinet with it. The lowest "r-value" I could find, I'm not insulating the attic here, just absorbing waves. Another hangup of mine: MUST a decent speaker be a 3-way? I have always thought so. I'm still a little on edge about having the critical midrange divied up between a large woofer and a tiny tweeter! My arrangement, real simple, is a 8" woofer, 3-4" mid, and a 1" aluminum dome tweeter. 3-way x-over inside. I just feel better about having a "mid-sized" driver handle the "midrange" duties. Enclosed, no vents! -CC |
#3
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On Sat, 21 May 2011 19:38:13 -0700 (PDT), ChrisCoaster
wrote: On May 21, 10:31*pm, "Soundhaspriority" wrote: "ChrisCoaster" wrote in message ... I want to concentrate on building speakers! Seriously. *One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? *And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster Modern speaker enclosures are not really inert; they are absorptive. The unyielding nature of steel plate means that you've got to work on the absorption. Otherwise, at wavelengths much shorter than the enclosure dimensions, the sound coming out of the backs of the drivers will ricochet around and radiate right through the backs of the cones. Steel plate is fine as the outer enclosure. Progressively absorptive materials need to go on top of it, like cork/gypsum/concrete. Acoustically, high density particle board is far superior to wood. Bob Morein (310) 237-6511 ______________________ How about fiberglass insulation? I have seen such inside the dB series of speakers from Canada 15 years ago. I wouldn't just toss it inside, I would line the top, bottom, sides, and rear inside walls of the cabinet with it. The lowest "r-value" I could find, I'm not insulating the attic here, just absorbing waves. You have two different things going on here, sound blocking and sound absorbing. The absorbent side of things must be designed to tune the inside of the box perfectly to provide the smoothest bass possible around the resonance points, so no, more is not better. As for blocking the sound, the standard MDF or HDF does a very good job of that, apart from a few frequencies where panels resonate. The best way to deal with that is plenty of cross-bracing inside the box so that there is very little unsupported flat area. If you want to identify the resonances, build the speaker box but with no holes in it. Stand a smaller, full range speaker inside it and bolt it up. Now sweep some tones on the small speaker and find the frequencies at which you can hear it best. For each frequency, lean on the larger panels with your hand to find where pressure lowers the volume. That is where the internal braces should connect. Finally, of course, make the speaker out of the thickest MDF that is practicable. d |
#4
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
ChrisCoaster wrote:
I want to concentrate on building speakers! Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster MDF. The world didn't end here first ! I/ 3/4 af the way past 22/05 . geoff |
#5
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
ChrisCoaster wrote:
How about fiberglass insulation? I have seen such inside the dB series of speakers from Canada 15 years ago. I wouldn't just toss it inside, I would line the top, bottom, sides, and rear inside walls of the cabinet with it. The lowest "r-value" I could find, I'm not insulating the attic here, just absorbing waves. Lining the walls is about preventing standing midrange waves inside the box, filling the void is about changing (lowering) the Q. Lining the walls "looks bad" in bass reflex math, and is often omitted to maximize efficiency, imo it always does sound better, also with a low x-over. Another hangup of mine: MUST a decent speaker be a 3-way? I have always thought so. A cross-over point is also a problem point. Imo the good compromises are 2-way or 4-way but 3-way fits the available multichannel poweramps better. I'm still a little on edge about having the critical midrange divied up between a large woofer and a tiny tweeter! My arrangement, real simple, is a 8" woofer, 3-4" mid, and a 1" aluminum dome tweeter. 3-way x-over inside. I'd go for a silk tweeter. And - to keep it simple - I'd go for active, considering the actual cost of quality components for a passive x-over it may even be "the economy choice". -CC Kind regards Peter Larsen |
#6
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
ChrisCoaster wrote:
I want to concentrate on building speakers! You have a long, slow road ahead of you. Buy the Vance Dickason loudspeaker cookbook... and realize that is just a cookbook and really none of the theory is in there. Read it cover to cover. Build a lot of prototypes and expect most of them not to be very good. Speaker building is one of the last places in the audio design field that remains as much art as science. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#7
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
Seriously. One of my obsessions in this regard is building a speaker
where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor -- minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? Resonance is important, but there seem to be other important factors. Back in 1980, I was doing repair work at Chestnut Hill Audio in Philadelphia. The Dahlquist rep stepped in with "something interesting" to show us. Jon Dahlquist was still at work on the DQ-6, a speaker that never saw the light of day in its intended form. (Jon was very much the Orson Welles of speaker design -- he could never finish anything.) The rep told us about a Weird Occurrence. One of two "identical" prototypes sounded quite different, even though they used the same components. Switching the components (drivers + crossover) did not switch the better-sounding speaker -- it remained with the cabinet. It turned out the "better" speaker was painted with 3M Nextel. It was used solely for cosmetic reasons. The "nappy" paint was apparently suppressing radiation from the cabinet surface. You should have heard the demo speakers. They generated a truly 3D soundfield. You heard instruments not only "outside" the speakers, but in front of and behind them. I've never heard anything like that since. If I were designing my own cone-type speakers, I would do the following... Use the thickest, densest particle board, and brace the hell out of the cabinet. Design to cabinet and position the drivers to minimize diffraction. Paint all cabinet surfaces -- including the rear -- with Nextel. Cover the face of the cabinet -- except for the drivers, of course! -- with Fibreglas. The goal is to get zero radiation from the cabinet surfaces and edges. Another approach would be to free-mount the drivers that don't need baffling. Looking at the other postings, I don't see any bad suggestions. |
#8
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
"ChrisCoaster" wrote in message
... I want to concentrate on building speakers! Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? I've been thinking about a speaker build myself, but I'm thinking this isn't really the forum to discuss ideas. I just want to try my best and see how good it ends up - not reference monitors, but better than typical home stereo speakers. Maybe... Sean |
#9
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
Sean Conolly wrote:
I've been thinking about a speaker build myself, but I'm thinking this isn't really the forum to discuss ideas. We used to talk about that over in rec.audio.tech, and it still is a very good place for it. Sean Kind regards Peter Larsen |
#10
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
Il 22/05/2011 4.20, ChrisCoaster ha scritto:
Now That 5/21 Passed without incident . . . I want to concentrate on building speakers! wrong, you started to build speakers, the world will never be te same. :-) alex |
#11
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
ChrisCoaster wrote:
I want to concentrate on building speakers! Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. It doesn't work that way. The cabinet is part of the deal. You can build large, open back baffles but that just makes the "cabinet" variable size. http://www.linearteam.dk/default.aspx?pageid=winisd (doesn't cover open back designs) How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? MDF is allegedly the least self-resonant material that'll fit on a table saw. At least in guitars, metal is used because it's resonant. -ChrisCoaster -- Les Cargill |
#12
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On May 22, 3:59*pm, Les Cargill wrote:
ChrisCoaster wrote: I want to concentrate on building speakers! Seriously. *One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. It doesn't work that way. The cabinet is part of the deal. You can build large, open back baffles but that just makes the "cabinet" variable size. http://www.linearteam.dk/default.aspx?pageid=winisd (doesn't cover open back designs) How critical is that last factor - minimizing resonance? *And should I build them out of 1" thick steel plate or oak/other wood? MDF is allegedly the least self-resonant material that'll fit on a table saw. At least in guitars, metal is used because it's resonant. -ChrisCoaster -- Les Cargill ______________________ I was just being sarcastic about the steel plate. LOL! Of course I would use wood, it's just that I've heard the sound of too many bookshelf speakers and gotten fatigued by the presence of low-mid "tub"(150 - 300Hz). I want to avoid that. Other ?? I have: Other than the cabinet, how DO mfgs. achieve a relatively flat response - no more than +-3dB from 50~20,000Hz/+-5dB 20~20k? Is there some calibration done to the drivers themselves? To the crossovers? The materials of the drivers themselves, Or, is it the way they wind the copper coils? And what combination of above? I've been told repeatedly that I "will not like" the sound of flat speakers, but my rebuttal time and time again is, my ears and the room are at fault for that! -ChrisCoaster |
#13
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On May 22, 8:13*pm, ChrisCoaster wrote:
On May 22, 3:59*pm, Les Cargill wrote: ChrisCoaster wrote: I want to concentrate on building speakers! Seriously. *One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. It doesn't work that way. The cabinet is part of the deal. You can build large, open back baffles but that just makes the "cabinet" variable size. http://www.linearteam.dk/default.aspx?pageid=winisd (doesn't cover open back designs) How critical is that last factor - minimizing resonance? *And should I build them out of 1" thick steel plate or oak/other wood? MDF is allegedly the least self-resonant material that'll fit on a table saw. At least in guitars, metal is used because it's resonant. -ChrisCoaster -- Les Cargill ______________________ I was just being sarcastic about the steel plate. LOL! *Of course I would use wood, it's just that I've heard the sound of too many bookshelf speakers and gotten fatigued by the presence of low-mid "tub"(150 - 300Hz). *I want to avoid that. Other ?? I have: Other than the cabinet, how DO mfgs. achieve a relatively flat response - no more than +-3dB from 50~20,000Hz/+-5dB 20~20k? Is there some calibration done to the drivers themselves? *To the crossovers? *The materials of the drivers themselves, Or, is it the way they wind the copper coils? And what combination of above? *I've been told repeatedly that I "will not like" the sound of flat speakers, but my rebuttal time and time again is, my ears and the room are at fault for that! -ChrisCoaster The specific woofer and box tuning is going to affect that high bass peak the most. The speakers designed to be on stands away from the wall typically have more bloom in that region, and if put them against the wall !!! Some of the most successful designs are two ways. For road work I like plywood with proper reinforcements and padding. It's lighter. Plexaglass is not bad for cabinets. If done right. Corning made the best fiberglass a few years ago, itch less. I still have reserve stock, for when you want to get the most out of a very small closed box. Makes the box bigger. Other materials don't do that as well. I more often than not, attach frontal absorbent material around tweeters. Tweeter rings. It makes a big difference in sound anomalies caused by refraction. I go as needed, listening to pink noise. That's for a typical dome tweeter. Afte r dozens of speaker boxes, I have yet to use MDF because of factors including hauling it home it's good stuff. I built one speaker column out of oak. I didn't really make it, had it made from raw wood stock cut down about 1 inch thick, braced and padded. I gave it to my brother for a wedding present. Still sounds great after17 years!! Sometimes I leave the crossover out of the box. I started doing this so I could change values and not have to play take the box apart again. Sometimes many attempts. Sometimes it takes me weeks to adjust values after weeks of listing. Greg |
#14
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
ChrisCoaster wrote:
I was just being sarcastic about the steel plate. LOL! Of course I would use wood, it's just that I've heard the sound of too many bookshelf speakers and gotten fatigued by the presence of low-mid "tub"(150 - 300Hz). I want to avoid that. That's usually not a cabinet resonance, though. That's most often built into the alignment. You need to stop listening to crappy speakers. Other than the cabinet, how DO mfgs. achieve a relatively flat response - no more than +-3dB from 50~20,000Hz/+-5dB 20~20k? They don't. I have never seen any speaker whose narrowband response is that flat, and I have seen some multi-hundred-thousand dollar monitor systems. Is there some calibration done to the drivers themselves? To the crossovers? The materials of the drivers themselves, Or, is it the way they wind the copper coils? And what combination of above? I've been told repeatedly that I "will not like" the sound of flat speakers, but my rebuttal time and time again is, my ears and the room are at fault for that! Well, since they don't exist it's moot. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#15
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On May 22, 9:40*pm, (Scott Dorsey) wrote:
And what combination of above? *I've been told repeatedly that I "will not like" the sound of flat speakers, but my rebuttal time and time again is, my ears and the room are at fault for that! Well, since they don't exist it's moot. But some speakers get remarkably close within a limited range of frequencies; the BBC LS3/5a monitor, for example, can measure pretty damn flat from 125Hz up to about 10kHz in a decent room. Of course, there's almost nothing below 100Hz...and these little half-cubic-foot speaker systems have some remarkably sophisticated engineering in them, including selected custom drivers, a crossover which can match sensitivities in unusual ways, construction from Baltic Birch multi- layer plywood (sometimes sold in the USA as Finnply) with panels damped by pads made from asphalt-impregnated felt, diffraction control around the tweeter...on and on. The thing is, for a really good system *everything* matters. Scott's right -- go get Vance Dickason's book and read it several times. Then look at Martin Colloms's "High Performance Loudspeakers"; it's a book with issues, but he also documents some very good designs from British manufacturers. Then look at Siegfried Linkwitz's designs. Then... ....it's never-ending. Fun, though. Peace, Paul |
#16
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
"Scott Dorsey" wrote in message
... Other than the cabinet, how DO mfgs. achieve a relatively flat response - no more than +-3dB from 50~20,000Hz/+-5dB 20~20k? They don't. I have never seen any speaker whose narrowband response is that flat, and I have seen some multi-hundred-thousand dollar monitor systems. Scott, you are so rarely wrong about anything that I had to mull this one over overnight before commenting. Ignoring the issue of /how/ one measure's a speaker's response, and what that measurement "means"... * Drivers have improved drastically in the past 20 years. A speaker that can't get from, say, 50Hz to 15kHz, within a 6dB envelope, is a pretty bad design. I'd expect a really good speaker's response to fall within a 4dB envelope, or even 3dB. For example, B&W claims +/- 3dB from 56Hz to 22kHz -- on an unspecified measurement axis -- for one of its CM-series mini-monitors. The response for the 800 Diamond is spec'd at +/- 3dB from 32Hz to 28kHz. http://www.bowers-wilkins.com/Downlo...info_sheet.pdf I'm reminded of the Thiel CS-5 which, almost 20 years ago, had a response that looked as if it had been drawn with a ruler. Say what you like about Thiel -- their products are the epitome of "blah"-ness -- but no one ever accused Thiel of lying. * Stereophile's recent review of a Linn speaker is an excellent example of how measurements don't always correlate with what you hear. Of course, I wouldn't own a Linn product unless I was paid a lot of money. And I doubt I'd actually listen to it... |
#17
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On May 21, 10:20*pm, ChrisCoaster wrote:
I want to concentrate on building speakers! Seriously. *One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? *And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster One trick that has been done many time is decouple the driver with some rubber like mounting grommets. Some have mentioned books. I think I got most of what I know from my 4 foot high set of Speaker Builder mags. I started reading s friends set in the early 80's and I was hooked. Many of the top people like Wrote articles over the years. You should be able to get a hold of collections. Not mine. |
#18
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On Mon, 23 May 2011 11:07:46 -0700 (PDT), G wrote:
On May 21, 10:20*pm, ChrisCoaster wrote: I want to concentrate on building speakers! Seriously. *One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? *And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster One trick that has been done many time is decouple the driver with some rubber like mounting grommets. What does that do, and how does it work? I can't picture this any other way than completely wrong. d |
#19
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On May 23, 1:13*pm, (Don Pearce) wrote:
On Mon, 23 May 2011 11:07:46 -0700 (PDT), G wrote: On May 21, 10:20 pm, ChrisCoaster wrote: I want to concentrate on building speakers! Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster One trick that has been done many time is decouple the driver with some rubber like mounting grommets. What does that do, and how does it work? I can't picture this any other way than completely wrong. The idea is to use elastomeric gaskets between the driver and the cabinet, and attach the driver via screws and T-nuts which are decoupled from the cabinet by similar elastomeric suspensions. The intent is to prevent vibration from being conducted from the driver frame to the material of the cabinet. Since most cabinet vibration doesn't come from that source, but from the pressure changes in the cabinet (aka "sound") the decoupling devices create only a small improvement if any. Peace, Paul |
#20
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On Mon, 23 May 2011 12:09:41 -0700 (PDT), PStamler
wrote: On May 23, 1:13*pm, (Don Pearce) wrote: On Mon, 23 May 2011 11:07:46 -0700 (PDT), G wrote: On May 21, 10:20 pm, ChrisCoaster wrote: I want to concentrate on building speakers! Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster One trick that has been done many time is decouple the driver with some rubber like mounting grommets. What does that do, and how does it work? I can't picture this any other way than completely wrong. The idea is to use elastomeric gaskets between the driver and the cabinet, and attach the driver via screws and T-nuts which are decoupled from the cabinet by similar elastomeric suspensions. The intent is to prevent vibration from being conducted from the driver frame to the material of the cabinet. Since most cabinet vibration doesn't come from that source, but from the pressure changes in the cabinet (aka "sound") the decoupling devices create only a small improvement if any. Peace, Paul Ah, a gasket is somewhat different to grommets. But that still makes no sense; the last thing you want is the driver floating in the cabinet. Rigid mounting is most definitely what is needed. d |
#21
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
PStamler wrote:
On May 22, 9:40 pm, (Scott Dorsey) wrote: And what combination of above? I've been told repeatedly that I "will not like" the sound of flat speakers, but my rebuttal time and time again is, my ears and the room are at fault for that! Well, since they don't exist it's moot. But some speakers get remarkably close within a limited range of frequencies; the BBC LS3/5a monitor, for example, can measure pretty damn flat from 125Hz up to about 10kHz in a decent room. Of course, there's almost nothing below 100Hz...and these little half-cubic-foot speaker systems have some remarkably sophisticated engineering in them, including selected custom drivers, a crossover which can match My LS3-5As are MDF and lined with 1/8" lead on the inside ! And I made the crossover with the real auto-transformer rather than the resisitive version ;-) geoff |
#22
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On May 23, 4:18*pm, "geoff" wrote:
My LS3-5As are MDF and lined with 1/8" lead on the inside ! *And I made the crossover with the real auto-transformer rather than the resisitive version ;-) geoff _______________ Video shielded, ehh? -CC |
#23
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
"ChrisCoaster" wrote in message
... On May 23, 4:18 pm, "geoff" wrote: My LS3-5As are MDF and lined with 1/8" lead on the inside! And I made the crossover with the real auto-transformer rather than the resisitive version Video shielded, eh? No, Superman shielded. Lead does not block magnetic fields. |
#24
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Now That 5/21 Passed without incident . . .
On May 23, 5:25*pm, "William Sommerwerck"
wrote: "ChrisCoaster" wrote in message ... On May 23, 4:18 pm, "geoff" wrote: My LS3-5As are MDF and lined with 1/8" lead on the inside! And I made the crossover with the real auto-transformer rather than the resisitive version Video shielded, eh? No, Superman shielded. Lead does not block magnetic fields. _______________ Dohh! Shows how much I know. Guess video shielding is irrelevant nowdays, given most CRT tube TVs have been raptured to the scrap yard. LOL! -CC |
#25
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Now That 5/21 Passed without incident . . .
On May 23, 2:34*pm, (Don Pearce) wrote:
On Mon, 23 May 2011 12:09:41 -0700 (PDT), PStamler wrote: On May 23, 1:13 pm, (Don Pearce) wrote: On Mon, 23 May 2011 11:07:46 -0700 (PDT), G wrote: On May 21, 10:20 pm, ChrisCoaster wrote: I want to concentrate on building speakers! Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster One trick that has been done many time is decouple the driver with some rubber like mounting grommets. What does that do, and how does it work? I can't picture this any other way than completely wrong. The idea is to use elastomeric gaskets between the driver and the cabinet, and attach the driver via screws and T-nuts which are decoupled from the cabinet by similar elastomeric suspensions. The intent is to prevent vibration from being conducted from the driver frame to the material of the cabinet. Since most cabinet vibration doesn't come from that source, but from the pressure changes in the cabinet (aka "sound") the decoupling devices create only a small improvement if any. Peace, Paul Ah, a gasket is somewhat different to grommets. But that still makes no sense; the last thing you want is the driver floating in the cabinet. Rigid mounting is most definitely what is needed. Well, I agree, but there was a time in the 1980s when there was a fad for using elastic gaskets and rubber grommets to float the driver. Again, the supposed justification was to keep vibrations from the driver from being conducted to the cabinet. Personally I favor a nice lossy cabinet made from MDF or thin-ply plywood such as Finnply, and absorption on the panels to damp down their vibrations, plus strategically-placed bracing. Given good attention to those factors, conduction from the drivers to the cabinet will have little effect. Peace, Paul |
#26
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
ChrisCoaster wrote:
On May 23, 4:18 pm, "geoff" wrote: My LS3-5As are MDF and lined with 1/8" lead on the inside ! And I made the crossover with the real auto-transformer rather than the resisitive version ;-) geoff _______________ Video shielded, ehh? -CC Nuke.... geoff |
#27
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Now That 5/21 Passed without incident . . .
PStamler wrote:
Well, I agree, but there was a time in the 1980s when there was a fad for using elastic gaskets and rubber grommets to float the driver. Again, the supposed justification was to keep vibrations from the driver from being conducted to the cabinet. My KEF R105/2 had the gaskets and grommets. Don't know about my current R107s... geoff |
#28
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Now That 5/21 Passed without incident . . .
Don Pearce wrote:
On Mon, 23 May 2011 11:07:46 -0700 (PDT), G wrote: On May 21, 10:20 pm, ChrisCoaster wrote: I want to concentrate on building speakers! Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? -ChrisCoaster One trick that has been done many time is decouple the driver with some rubber like mounting grommets. What does that do, and how does it work? I can't picture this any other way than completely wrong. d Why not hang the speaker from 4 or 6 short bungee cords? That should effectively decouple it from the surrounding cabnetry. |
#29
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Now That 5/21 Passed without incident . . .
geoff wrote:
My LS3-5As are MDF and lined with 1/8" lead on the inside ! And I made the crossover with the real auto-transformer rather than the resisitive version ;-) The lead isn't for shielding, it's for mass. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#30
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
On Sat, 21 May 2011 19:20:07 -0700 (PDT), ChrisCoaster
wrote: I want to concentrate on building speakers! I've only built a few pair over the last several decades, with, in retrospect, hardly acceptable results. I've quite often wanted to do more, but the more I've read and researched the topic, the more knowledge it takes to do it well (like most anything else). I've seen speaker designing and building come up occasionally on RAP as well as of course rec.audio.tech, so check the archives in that "Google Groups" interface. Seriously. One of my obsession in this regard is building a speaker where the only part you hear sound from are the transducers/drivers/ cones/whatever, NOT the material they're mounted in/bolted into. How critical is that last factor - minimizing resonance? And should I build them out of 1" thick steel plate or oak/other wood? Not mentioned in the thread so far is each cabinet wall/floor/top made of two layers of wood/MDF/whatever with sand filled into the space in between. What others say about damping internal reflections still applies. That's one reason cabinet dimensions are never a cube (the internal reflections have the same resonant frequency in all three dimensions!), and are generally some nonharmonic ratios (such as 1 : cube root of 2 : square of the cube root of 2). Having "researched" so much audio stuff (yet admittedly only applied very little), I've found interesting parallels such as studio room design (now being touched on in the "cost to build studio" thread) follows pretty much the same rules as a speaker cabinet, though the "room nodes" are of course at lower frequencies due to the longer distances involved. I've read the already-mentioned Dickason and Collums books, and have a collection of the the Speaker Builder magazines, as well as the earler (and concurrent) Audio Amateur magazines which included speaker building before the publisher decided to spin off that topic into its separate magazine. They apparently got integrated back in the more recent incarnation of AudioXpress and whatever name change it went through, but I don't have many issues of that and I don't know how much it covers speaker building, if at all. There's lots of stuff not mentioned in the thread so far. I think just about everything is covered in the above material, but there's also lots more freely available on the Web. Yet another detail is the baffle step, which is described (among many other places) he http://sound.westhost.com/bafflestep.htm That's a pretty decent site, it's surprising how much audio electronics stuff he's written up, not to mention the page on CF lamps. For good online resources, I stumbled on http://diyaudio.com a year or two ago, and it's got lots of people with lots of knowledge and experience, including some recognizable names, authors and designers in the audio field. There's surely some 2-way versus 3-way arguments there, and there's a separate forum for designing speakers with full-range drivers. For crossovers, line-level and power audio elctronics has gotten so cheap it's almost a no-brainer to do active crossovers, instead of the traditional passive crossover in the cabinet. The filters are more easily done at line level, nd each driver can be run directly with its own amplifier. Also with good forums and presumably good off-the-shelf cabinet/crossover designs for the drivers they sell is Parts Express: http://techtalk.parts-express.com/ I just glanced at Madisound (the other big driver mail-order supplier in the USA), I see a forum there but it's much smaller. There's several DIY loudspeaker mailing list(s) and forums that have been aroud for many years - just google. Almost forgot - namebrand specific, but several posters are former employees and designers, with a lot of good technical info such as the reasons for various design decisions: http://www.audioheritage.org/vbulletin/ -ChrisCoaster |
#31
Posted to rec.audio.pro
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Now That 5/21 Passed without incident . . .
Scott Dorsey wrote:
geoff wrote: My LS3-5As are MDF and lined with 1/8" lead on the inside ! And I made the crossover with the real auto-transformer rather than the resisitive version ;-) The lead isn't for shielding, it's for mass. Yep. I thought I'd go one better (or several better) that sheet bitumous padding. geoff\ |
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