A Milestone
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.
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.
Attachments
Lynn Olson said:
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.
Lynn Olson said:
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.
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!
SunRa said:
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.
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!
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!
SunRa said:
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).
Charles Hansen said:
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.
An externally hosted image should be here but it was not working when we last tested it.
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
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
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
diffraction.....
just a small follow up to an earlier comment about the audibility of diffraction: i have full range statics, a dutch brand, an mdf frame. the frame is perpendicular to the stator for about 10mm then is rounded away over about 10mm (less than half an inch). out of curiosity i bought some pvc (i think) grey drain pipe. diameter about 100mm. i installed them the length of the stator (1350 mm) as close to the stator as possible to avoid rough edges.
the differences that i heard are subtle but with well know recordings clearly audible. some new details popped out of recordings. the spatial presentation somehow fills out and becomes more physical, and somehow a feeling of more liveliness and precision. ok it doesn't look very pretty but the cost was about 20 euro. i presume manufacturers could pretty easily provide fancy looking add-ons with a designy look. i presume that at least similar improvements might be available for other loudspeakers if similar approaches add-ons were tried.
just a small follow up to an earlier comment about the audibility of diffraction: i have full range statics, a dutch brand, an mdf frame. the frame is perpendicular to the stator for about 10mm then is rounded away over about 10mm (less than half an inch). out of curiosity i bought some pvc (i think) grey drain pipe. diameter about 100mm. i installed them the length of the stator (1350 mm) as close to the stator as possible to avoid rough edges.
the differences that i heard are subtle but with well know recordings clearly audible. some new details popped out of recordings. the spatial presentation somehow fills out and becomes more physical, and somehow a feeling of more liveliness and precision. ok it doesn't look very pretty but the cost was about 20 euro. i presume manufacturers could pretty easily provide fancy looking add-ons with a designy look. i presume that at least similar improvements might be available for other loudspeakers if similar approaches add-ons were tried.
Charles Hansen said:
Hi Charles, yes, I'd like to hear the JBL K2's. I live in Erie, no more than twenty minutes away from Boulder. You can see my e-mail address midway down the Nutshell High Fidelity website - let's make contact, I'd like to hear the big JBL's. I'm hoping they're in a somewhat higher class than the big TAD system I've heard so far. I appreciate the invite and would like to take you up on it.
I am partial agreement about the big woofers, which is why I'm keeping open the option of a pair of 12" drivers - again, used with a 700~850 Hz crossover. In this frequency range, I am more concerned about box modes than driver resonances.
The box modes in a big studio-monitor (or JBL K2) box are much harder to control, and to my ear, lend an annoying "droning" quality to the sound, a traditional part of the sound of big vintage loudspeakers. These modes are quite apparent when the drivers are pulled and you put your head in the box - you hear a droning, drumming quality to ambient sounds, and the box stuffing and damping, although reducing its magnitude, adds its own dull, murky quality to the droning sound. Many damping materials have their own sonic signature that overlays the basic box sound, resulting in a slow, sodden quality to the lower midrange and upper bass.
I used to be puzzled why these modes in the 300~800 Hz regions were so obstinately difficult to control, until I got MLSSA in 1991 and found it took 2 feet of a wide variety of damping materials to merely reduce the floor bounce by 20~25 dB. I started with what I thought was plenty of damping, several inches of the fancy commercial foam stuff, combined with several layers of audiophile-grade wool felt, and it only reduced the floor bounce by 5 dB or so! It was nearly worthless!
Now, above 2 kHz, then the commercial stuff started to make a difference that was more worthwhile, particularly if you wanted to reduce the slap off the back of the cabinet. But frankly, anything I could buy on the market, had only the slightest effect in reducing the box modes - and the bigger the cabinet, of course, the lower in frequencies these modes are, and the less effective any type of damping, at any price. So all of the fancy damping we see in big box cabinets is mostly effective above 1 kHz, and does surprisingly little below that frequency. What it does do, though, is add odd colorations of its own, which is why lightly damped old-school speakers can sound better than modern, heavily-damped speakers. It's one of those pick-your-coloration things.
All it takes is a little playing around with MLSSA, or any MLS program, and looking at what it really takes to absorb the floor bounce. Since MLS systems can examine the frequency response of the bounce itself (by gating away the direct sound from the loudspeaker), you can examine at leisure what various damping material do in terms of absorption vs frequency. Carpeting, for example, does nothing below 8 kHz - it might as well be glass.
It was this discovery that made me realize just how hopeless the situation with conventional box speakers really is. The only way to get around it is confine the box speaker to very low frequencies (below the first mode) and use a sharp-cutoff crossover to avoid contaminating the more critical region of the spectrum. Otherwise, the box is going to result in murky, opaque, and congested bass - I suspect much of the merit of transmission-line speakers amounts to little more than clever control of box modes in the 300 to 800 Hz region. That's what I had in mind with the Ariel - it was the box-mode region I was most interested in, not the deep bass. Even so, transmission lines have their own set of awkward compromises in this frequency region.
Although I grant that big drivers in the 12 to 15-inch range are starting to get into trouble, with the spider and surround being the first resonance to appear, I feel the box modes are the most prominent and objectionable - and due to the lack of good LF absorbers, the hardest to control. My instinct is that more than 20~30 dB of smooth, broadband absorption is needed, and existing damping and absorbing materials just don't provide that in the box-mode region. Thus, the proverbial "box" coloration which is so noticeably absent in bass horns and dipoles - since we are all so used to this particular coloration, it is most noticeable when it disappears.
For me, the charm of OB isn't so much the dipole radiation pattern, with the claim to less room coloration (which I am not all that sure of), but the more genuine advantage of side-stepping a prominent coloration in a very important frequency range - upper bass and lower midrange. True, driver colorations remain, but I feel these are much milder in the 300~800 Hz region than the much more noticeable 1~4 kHz region, where small-format midbass drivers are commonly used.
By the way, I'd like to thank John Janowitz for the information and graphs on the AE Speaker Lambda TD-15M. That certainly look like a contender - let me know if you're considering Alnico, that would make it even more attractive, and would justify a higher price. (I can't believe I just said that!)
In my experience, Alnico isn't so much about adding a guitar-friendly coloration, but more about noticeably better rendition of instrumental subtleties and a more palpable, in-the-room quality to the instruments - a palm sliding across the surface of a drum, the sound of wood in the cello, more vivid tone colors that sound less artificial and more real. The difference is most apparent in the 200 to 1 kHz region, from what I heard.
In the amplifier world, this isn't a clever type of coloration you can add, but more a matter of reduction of distortion, or an improvement in a power supply. Alnico does something better, and I don't know what it is, although my guess is something to do with back-EMF's induced in the magnet structure. It does sound very much like better core materials in audio transformers, for those of you who have auditioned different transformers.
In my experience, Alnico isn't so much about adding a guitar-friendly coloration, but more about noticeably better rendition of instrumental subtleties and a more palpable, in-the-room quality to the instruments - a palm sliding across the surface of a drum, the sound of wood in the cello, more vivid tone colors that sound less artificial and more real. The difference is most apparent in the 200 to 1 kHz region, from what I heard.
In the amplifier world, this isn't a clever type of coloration you can add, but more a matter of reduction of distortion, or an improvement in a power supply. Alnico does something better, and I don't know what it is, although my guess is something to do with back-EMF's induced in the magnet structure. It does sound very much like better core materials in audio transformers, for those of you who have auditioned different transformers.
Re: Measurements, and PHL 1120 as a midrange
http://www.diyaudio.com/forums/showthread.php?s=&threadid=6363&highlight=
Old post with brief comment on PHL1120, more on Audax PR170M0.
FlorianO said:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=6363&highlight=
Old post with brief comment on PHL1120, more on Audax PR170M0.
Lynn Olson said:
My wish list to John_J for a wide bandwidth 10" dipole midbass would include:
* NdFeB magnet.. BL ~17
* Smaller NdFeB motor size would be less restrictive rear waves for best dipole
* NdFeB with high flux would allow BL > 17 in an underhung motor
* 8mm linear Xmax
* curvelinear profile kevlar-in-paper treated cone. Long kelvar strands also seem to reduce breakup
* MMs ~40 grams
* two 8 ohm voice coils...series 16 ohm for high Qts dipole and 8 ohms for MTM
* Qts ~0.6 with 16 ohms
* Le < 0.2 mH
* long phase plug / heatsink
* ~94 db/watt @1m
I stiill have about 20 Lambda 15" Dipoles and several 99db SPL DIY dipole ribbon tweeters, so I just need a full-voice 10". I also have Lambda TD15Ms, but vocals do not sound right on them with the 1.4K xover frequency I tried to capture those lovely sopranos.
I wonder what type of DIY speaker Charles Hansen would build? My ears agree that 800 Hz xovers are not the best solution. LR8 at 80Hz and LR4 at 3Khz sounds pretty good on long ribbons.
Linesource,
I live near you....can I hear one (or two) of your Dipole15's?
I'm in Santa Clara. You can PM me at chris_mercurio@hotmail.com.
Thanks,
C
I live near you....can I hear one (or two) of your Dipole15's?
I'm in Santa Clara. You can PM me at chris_mercurio@hotmail.com.
Thanks,
C
Lynn Olson said:
Wow -- great post! I agree 100% with everything I snipped out, and have independently reached the same exact conclusions.
I left in the things that I don't fully agree with. First of all, in my estimation the TADs are overall better than the K2's. We have them both at the factory, so you can compare them for yourself if you like. But if you didn't like the TADs, I'm not sure you will like the K2's any better.
This will take a bit of planning, as you have a bum leg and I'm now paralyzed and in a wheelchair. So we will have to do it at a time when there are some able-bodied people around to help move things. Also, the TADs have been playing non-stop since the CES and are fully run-in. In contrast, the JBL's have been sitting unplayed for over six months now. It would probably take several days of continuous play to get the JBL's back up to snuff.
Finally, while the box resonances are a huge problem (and one big reason why mini-monitors have their charms!), I find that the diaphragm resonances of *any* driver running in break-up mode to be audibly problematic. So in my opinion, both problems need to be solved.
Please note that we (Ayre) used the Linkwitz-designed Audio Artistry Beethovens at a CES many years ago. At that time he was using the ScanSpeak paper cone midranges. I urged him to try some different drivers for that application (such as the then-new SEAS metal cone models), and he eventually took that advice with the advent of the Orion. In that design he has minimized the problems of both cone resonances and box resonances to achieve a very fine result, although I agree with your reservations regarding dynamic restrictions and complex multi-way crossovers (especially implemented with the ubiquitous op-amp approach that SL seems to find no problems with).
I'll contact you privately.
salas said:
It's a great way to go if you have an extra $50,000 or $100,000 lying around.
I developed a much less expensive method when I was designing speakers over 20 years ago.
One method that works (although it is somewhat cumbersome to build and use) was described by Keith Johnson in Speaker Builder magazine back in (I think) 1988. The cover showed a contraption that looked like a pair of scissors with electret microphones attached. You could probably duplicate that setup for around $100. It won't give you the lovely pictures that the lasers will, but it will tell you a lot about the cone behavior if you can figure out how to interpret your results properly.