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Multi-Way Conventional loudspeakers with crossovers

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Old 6th May 2008, 02:41 AM   #3481
ScottG is offline ScottG  United States
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Quote:
Originally posted by LineSource



I'm still betting on the 210mm x 15mm RAAL ribbon tweeter, crossed to a 10" dipole midrange, crossed to 3-4 dipole 15" dipole bass. A DIY dipole ribbon might even be better.

For my ears, a midrange that can cover ~80-1,400 is needed for vocal magic.
Hmm, *cake* ..good.
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Old 6th May 2008, 08:12 AM   #3482
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A few moments ago, I realized I could no longer remember the date of the accident - this is the first time that's happened. An emotional moment. I want to thank all of you for your encouragement, support, jokes, wisecracks, and the many, many thoughtful comments.

Physically, I'll be going to the Erie Community Center to continue my rehabilitation. I can walk, but it's slower than it used to be, and there's a noticeable limp when I get tired. Still can't run yet, and going up and down stairs does need a hand on the rail, so carrying things is still a little awkward. I still use a cane for going down stairs, although it's not always necessary, and I tend to forget where I've left it (a good sign, actually).

Endurance and walking speed are well below what they used to be - I zipped all over Zurich and Munich during the 2004 ETF, and managed to outwalk Gary Pimm, who's a few years younger than I am (I was born in 1949). Since I'm 6' 2", it's normal for me to have a long stride and walk faster than most people - but it's not that way now. So the goal of rehab, as I see it, is to get back everything I used to have - comfortable, fast walking for long distances, the ability to run if I feel like it, and enjoy bicycling again.
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Old 6th May 2008, 02:52 PM   #3483
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Quote:
Originally posted by Lynn Olson
Well, the hardest part of the voicing would be getting a good subjective match between drivers with very different emission shapes and sizes, and it sounds like Mr. Auplater has already done that. It's normal to see ripples in the response of line radiators, but it isn't audible all that much from what I can tell. The radiator just sounds "big", which of course it is.

<snip>

Yes they do sound "big"... very realistic and convincing soundstaging... yet they somehow seem transparent sonically..

The fascinating part of my setup (as well as some other lines/OB's I've heard that are well executed) is the lack of localization of the individual drivers. Until I got the setup balanced, you could pick out which driver was "hot" at some distance away. After fiddling with levels, balancing the minimalist xover, etc., the drivers faded away so much so that, at any level, as I walk up to the (large, 6 foot high x 25" winged baffle) I have to literally put my ear up to each driver within 1 - 2" of its radiating surface to tell if it's actually active! Quite unnerving at first, compared to typical box systems. Also, the mating speaker 8 feet away is clearly audible and the image doesn't collapse even standing in front of one speaker and maybe 45 degrees off from the other.

They also sound almost as good from the rear as they do from the front.

2+ years of listening to these, I still find myself occasionally walking over to check and "make sure" all the drivers are actually running... only thing left to do is refinish the 1"+ solid cherry baffles to a high-gloss automotive type finish (they're currently Danish oil satin finish, not quite there)... and I have to radius some of the baffle edges to see if that improves anything...

I hope the healing continues...try to stay away from healthcare as much as possible. I tore the bicep off my right forearm doing yardwork in 2005, had to have it surgically reattached using a redundant harvested tendon from my wrist
(ugh).. so I remember all too well when I regained full use (lots of PT and rebuilding strength..at 55 years, it went much slower than I imagined it would). This from a guy who manages his wife's medical practice....


John L.
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Old 6th May 2008, 04:43 PM   #3484
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Quote:
Originally posted by Lynn Olson
As for my new speaker, in the simplest manifestation, it would be nothing more than a classic 12~15" studio monitor in a big box with a top-mounted horn with a large-format compression driver and a time-delayed supertweeter. The crossovers would similarly be at the traditional frequencies of 700~880 Hz and 6~8 kHz....If the OB thing doesn't pan out, I'll revert to the more traditional big box, but I'm hoping I won't have to do that.
Well if you want to know what your speakers will sound like, just give a listen to the JBL K2 S9800's. That's pretty much what you've described. The 15" woofer has a paper cone coated with Aquaplas, and an alnico magnet with really cool multi-layer pole piece to keep flux modulation to a minimum.

This crosses over to a horn midrange at 800 Hz using a 3" beryllium diaphragm and a neodymium magnet. Finally, at 10 kHz there is a horn super-tweeter with 1" beryllium diaphragm.

We used a pair at the CES a couple of years ago and still have them here at our factory in Boulder. (We liked them enough to purchase them.) They have the "Special Edition" crossover that has much upgraded parts over the original version and we also replaced the Monster internal wiring with Cardas.

They're pretty darned good speakers, but certainly not perfect. The main differences between them and what you are planning to do are probably the open baffle (versus a vented box) for the woofer and the horn profiles. But in my estimation their greatest weaknesses (no speaker is perfect!) will not be addressed by your proposals.

To me the single biggest problem of these speakers is that there is *no way* to get a 15" (or even a 12") woofer to sound natural much past 300 Hz, let alone all the way to 800 Hz. But to each his own.

Let me know if you ever want to hear them. We're less than an hour from Fort Collins. From 800 Hz on up, the beryllium drivers create quite an extraordinary result.
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Old 6th May 2008, 04:56 PM   #3485
SunRa is offline SunRa  Romania
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To me the single biggest problem of these speakers is that there is *no way* to get a 15" (or even a 12") woofer to sound natural much past 300 Hz, let alone all the way to 800 Hz. But to each his own.
Hello, thank you for your interesting mini-review on the JBL sistem.

However, I think it is the first time I've heard a statement like the one above. Could you please give more details? What are the reasons, from your experience, that discards a 15' or a 12" driver above 300Hz?

Thank you!
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Old 6th May 2008, 05:15 PM   #3486
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Originally posted by SunRa
What are the reasons, from your experience, that discards a 15' or a 12" driver above 300Hz?
Once a diaphragm enters break-up modes (moving non-pistonically), it is by definition resonating and adding its own colorations on top of the original music signal.

Many people enjoy certain colorations and spend most of their time tuning their system to "balance" these colorations to achieve a sound that is "pleasing" to them.

In my experience this can work well as long as the system is restricted to playing only certain types of music (or recordings) that the system has been tuned for. But if you play other types of music then the colorations will make it difficult to enjoy the music.

Here is a simplified example of what I am talking about. Imagine a system with a really nice single-ended triode connected to moderately efficient speakers (say 94 dB or so). It will probably sound great playing string quartets, harpsichord music, folk singers, and chamber orchestras. Very sweet and delicate, with a nice focus and naturalness. But it would sound awful playing Led Zeppelin or even a full orchestra playing a "large scale" piece of music.

Most systems only sound good playing certain types of music and/or recordings. In my experience it is because almost nobody combines truly neutral components at each link in the chain. Instead, they try to "balance" the sonic result with various methods, from cables to room treatments to loudspeakers.
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Old 6th May 2008, 05:24 PM   #3487
SunRa is offline SunRa  Romania
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Thank you for your fast reply!

I wasn't aware that the break-up point of a 12" driver is in the 300-700 region, but it makes sense.. An 8'' driver has a breake-up point of about 1500 Khz if I rememer corectly.

I think I just assumed that 12" and 15" just have a well controlled break-up mode, especially paper cone, high-quality pro drivers like the Alnico model in your JBL system.

More to think about..

Thank you!
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Old 6th May 2008, 05:35 PM   #3488
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Quote:
Originally posted by SunRa
I wasn't aware that the break-up point of a 12" driver is in the 300-700 region, but it makes sense.. An 8'' driver has a break-up point of about 1500 Hz if I remember correctly.
The break-up frequency of a diaphragm will depend on its size, its profile, and the material from which it is made.

An 8" driver made from polypropylene will usually have its first break up mode down around 500 Hz. A paper cone will boost this up to around 700 Hz or so. A metal (aluminum) cone will boost this to 1500 or 2000 Hz.

The only way to get a 12" cone to move pistonically up to 700 Hz is to make it from something very rigid (like metal). Most 12" drivers use paper cones and will break up more in the 300 Hz range. A polypropylene 12" will break up down around 250 Hz or so.

The other thing to consider is what sort of coloration is imposed by the resonant signature of the material. Polypropylene sounds very "dead" and "murky", losing a lot of dynamics and detail, although it is also generally not overtly offensive (ie, "grainy" or "harsh"). Paper can sound relatively good in break-up mode, but not nearly as good as a purely pistonic driver.

One problem with pistonic drivers is that they very clearly let you hear the problems with things upstream. All of a sudden those "wonderfully transparent" $10,000 speaker cables are revealed to be bright, etched, and threadbare. Just the ticket for a polypropylene midrange, however (assuming you are into "balancing" your system).
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Old 6th May 2008, 06:21 PM   #3489
mige0 is offline mige0  Austria
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Quote:
Originally posted by Charles Hansen


The break-up frequency of a diaphragm will depend on its size, its profile, and the material from which it is made.

An 8" driver made from polypropylene will usually have its first break up mode down around 500 Hz. A paper cone will boost this up to around 700 Hz or so. A metal (aluminum) cone will boost this to 1500 or 2000 Hz.

The only way to get a 12" cone to move pistonically up to 700 Hz is to make it from something very rigid (like metal). Most 12" drivers use paper cones and will break up more in the 300 Hz range. A polypropylene 12" will break up down around 250 Hz or so.


Charles, I fully agree with the sonic impacts you describe but I definately dont agree with the breakup related frequencies mentioned in your last posting.

Below the CSD of a Peerless 12" (830669) of current production. This one does have a paper cone.


Click the image to open in full size.

As you can see the breakup is clearly at around 1.5kHz (exceptional clean below ! ).
Measurement was taken in an relatively small OB - so please dont juge the FR from this.

Greetings
Michael
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Old 6th May 2008, 06:27 PM   #3490
KSTR is offline KSTR  Germany
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Are those breakups really that low? And isn't the first breakup mode often from the surround (in a typical HiFi-LF-driver with soft surround), that's what I read in some Klippel papers? From the datasheets of pro drivers with paper-based cones I don't see much things happen (in the impedance plot) that low -- of course we don't know how much smoothing is applied...

I measured a Peerless XXLS 12" with alu cone, the first mode is clearly from the monstrous rubber surround (at ~900Hz) while the true cone breakup seems to start way up higher, the biggest peak at ~3kHz. The otherwise identical XXLS 12" but with a "floppy" nomex cone shows a nasty breakup (very visible in the FR plot and in the impedance) at ~500Hz.

... I just see Michael has brought up the Peerless SLS 12", a "known good" driver that doesn't seem to break up that low....

- Klaus
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