It’s not about pistonic movement, but about directivity. Imho with a 3-way that is certainly possible with pistonic drivers by the way. A 2-way however…
Welcome to my world in the UK (other than for the largest companies etc.), although since my family happens to be Norwegian I suppose I have a foot in both camps. 😉
It's still not worth the money as far as I'm concerned -if it ever was, since there are units in Seas's own Prestige range, including the little H1283, that outperform it in most respects, despite the Millennium currently coming in at 6.8x the latter's price. It's a very nice tweeter, beautifully built, but it was always pricey for what you got, and it's currently extremely expensive for the performance on offer. And nobody can call me biased, since as I've said, Seas are one of my go-to / default suppliers of regular hi-fi drivers. I'm afraid I'm just calling that one as I see it.
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Mmm. In the case of the L15 with a rated Sd of 75cm^2, that nominal comes in at 1.122KHz [nearly]. Which, if we're going to use total Sd as the assumption rather than VC point source frequency, happens to be higher than the ER15, which is rated at 80cm^2 due to the lack of a solid polepiece extension. This is fairly moot of course, since the measured data (supplied) shows that the L15 holds up just as well as the ER15 out to 60 degrees off axis; being a piston the overall response trend is declining of course, so you can't cross as high -but as far as I'm concerned, I wouldn't cross any 5in higher than about 2.5KHz anyway -preferably lower.
Assuming a fairly normal box size & no severe diffraction etc. issues, then you should be able to hit LR4 around 2KHz with the L15 using roughly 3 components. Since, with its main bell mode at 8KHz, HD3 will be spiking around 700Hz higher than that (which is the main issue to watch for), you're on the H4 & it's already rolling off where H5 amplification spikes, I'm sure you'll forgive me not swooning with terror. 😉
That rather depends how you define a 'good sounding unit', since that's a bit of a nebulous criteria. It can indicate the general transition from piston to TL behaviour, but it's still an uncontrolled resonance / energy storage (i.e. colouration). Often benign, but not always, and that doesn't change the fact of it.
My understanding is that if you do not damp the cone breakup dissipatively somehow, then you are limited to what you can do by getting resonance modes to fall in frequencies where there is low coupling to the air, or to fall where the depth of the cone causes them to cancel at the listener. This means there would be a Q mismatch, so you end up with for instance a ring at 4KHz that starts 16db down but goes on forever.
Actually, you can formalise "good sounding" using DBLTs.
This is a huge topic but rest assured a DBLT is a measurement with all the requirements of any scientific measurement. Your instrument is your DBLT panel. It has an accuracy which needs checking and calibrating regularly.
But to each his own. For how much you need to drop yucky hard cone resonances with your xover, refer to our test results in the appendix of https://aes2.org/publications/elibrary-page/?id=2476. The paper isn't just about Intermod.
Da false prophets, Floyd & Olive, quote us so we must be pukka 😊
If you haven't attempted DBLTs on your stuff, feel free to ignore everything I say. All my prejudices are based on doing DBLTs for nearly 2 decades.
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Where did all this 'da false prophets' business come from? Perhaps you'd like to provide a detailed explanation, with clear referencing, about exactly what you mean, since Toole, Olive et al are some of the most distinguished researchers and authors in the industry and to the best of my knowledge have published rather more in the way of fully documented and referenced work than you have. A point-by-point analysis, with your documentary evidence supporting your critique would be of benefit to everybody.
Re the above, the 3 element filter I was referring to contains a bottomless (but for the minimal DCR of a roughly 0.01mH inductor) notch on the primary bell mode, so it's in effect suppressed to nothing, helps heavily attenuate the higher frequency modes too, and being a little over 2 octaves above the filter frequency with the driver tracking roughly an LR4 low pass until the notch increases that rate -I'm still not quivering in terror. 😉
Re the above, the 3 element filter I was referring to contains a bottomless (but for the minimal DCR of a roughly 0.01mH inductor) notch on the primary bell mode, so it's in effect suppressed to nothing, helps heavily attenuate the higher frequency modes too, and being a little over 2 octaves above the filter frequency with the driver tracking roughly an LR4 low pass until the notch increases that rate -I'm still not quivering in terror. 😉
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I think it’s a hyperbole… Toole and Olive deserve credits for collecting lots of insights, whereas quite some of their findings might not be that spectacular to the insider.
Since Toole & Olive quote & reference us, they must be pukka too 😊
No. I haven't published as much as they have but I have probably done as much original work on the subject. You'll have to look at their references to check up on this.
The most important point is correlating dem fancy measurements to DBLTs which IIRC, dem False Prophets also attempt to do.
As a REAL beach bum dis Millenium, I no longer have a horse in this race so won't go into the issues I have with their DBLTs. Their stuff is mostly OK .. but not all. 😊
Quite; the point is they actually bother to do it, and reference it properly, so there is some benefit to the community in general. It's very easy for others (general comment, not personal) to sit and make snide little remarks about people who have the temerity to write generalised textbooks (novel idea -might catch on, that), or anybody else who dares to publish a properly written and cited text for that matter -I see it all the time in academia. It's another thing, if a person has a critique they are so very concerned about, to get off their backside and do something useful, even if it is as minimal as writing a review with clearly cited data demonstrating why a xyz is disagreed with. If they can't be bothered, or want to try wriggling out of it: Thumper's Mother's advice remains as valid today as it ever was. 😉
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May I suggest to steer this discussion in a somewhat different direction? The research referred to in this thread is -for most part- not unfamiliar to me. For many here the same will apply.
But for me the million dollar question is how -e.g. Fryers- research has been operationalized and applied in new driver developments back in the day, say between 1978 and 1988-1990
The work by Arie Kayzer is a classic exemple of research that was globally recognized, but within Philips, the company A.K. worked for, hardly lead to any driver developments: the product range of Philips drivers did change very little between say 1978 and 1988. Some cosmetic modernizations were done, but for most part Philips remained faithful - until around 1990- to fairly thin straight sided paper cones. Tweeters and mids were updated, but I can hardly relate that to Kayzers work.
For the UK, from the outside it looks as if only B&W and to a lesser degree Celestion, applied some of the research done. Kevlar cones and copper domes are all that I can think of, but there must have been much more.
I would to learn from Richard Lee how these findings were applied.
What techniques were practically applied and which drivers were newly developed?
But for me the million dollar question is how -e.g. Fryers- research has been operationalized and applied in new driver developments back in the day, say between 1978 and 1988-1990
The work by Arie Kayzer is a classic exemple of research that was globally recognized, but within Philips, the company A.K. worked for, hardly lead to any driver developments: the product range of Philips drivers did change very little between say 1978 and 1988. Some cosmetic modernizations were done, but for most part Philips remained faithful - until around 1990- to fairly thin straight sided paper cones. Tweeters and mids were updated, but I can hardly relate that to Kayzers work.
For the UK, from the outside it looks as if only B&W and to a lesser degree Celestion, applied some of the research done. Kevlar cones and copper domes are all that I can think of, but there must have been much more.
I would to learn from Richard Lee how these findings were applied.
What techniques were practically applied and which drivers were newly developed?
Something you learn from lesser fullrange drivers, they tend to have problems at the breakup frequencies for the size. Anyone who applies filters to tame the issue will know that filtering them is not usually enough.
This indicates that there's more than simple resonance going on.
This indicates that there's more than simple resonance going on.
@Juhazi @wchang using a piece of felt as pictured. Naked tweeter only of coaxial TB W6 2313. 1/12 smoothing.
Comparing the baffle not properly aligned with the monitor surface without felt vs. properly aligned with felt:
For some reason making the felt thicker by folding is worse.
The large peak 4.5 kHz is when the wave gets out of the waveguide and is jumping on the rubber suspension. This must be notch filtered, it's not really a distortion. The same frequency for the woofer also 7 cm length at the rubber band is a distortion and must be squashed.
... surprisingly, an immediate improvement of imaging after 1 hour of listening. So it's not about 2 Db smoothing but about small reflections confusing my brain from locating the source. That was really good.
The felt was $7: https://www.amazon.com/dp/B07DX7HLNQ?ref=ppx_yo2ov_dt_b_fed_asin_title
The felt was $7: https://www.amazon.com/dp/B07DX7HLNQ?ref=ppx_yo2ov_dt_b_fed_asin_title
I am surprised to see any kind of effect on tweeter response... by using felt that way.
May I suggest that you cover the monitor with felt, or with a thick pillow. Or even bettr caryy the monitor away and replace it with a pillow.
Seriously, if that is the setting that you measure, 95% of wiggles in the response come from the table, monitor etc.
May I suggest that you cover the monitor with felt, or with a thick pillow. Or even bettr caryy the monitor away and replace it with a pillow.
Seriously, if that is the setting that you measure, 95% of wiggles in the response come from the table, monitor etc.
@Juhazi indeed on the desktop the monitor dominates. In the past I already measured the optimal position, just a little wiggle makes a difference. But conveniently, the best position is when the baffle is the exact extension of the monitor aligned as accurate as possible. Also you can see my baffle is rugged, everything is asymmetrical, stepped and curved. I listen and measure 12 degrees off axis, the larger part of the baffle is beaming outward from me. So the measurements from the felt are consistent - just covering the small flat area below the speaker with 1/8 inch felt is audible. I think I came with a shape that is not too bad as a computer speaker.
I have direct experience and contact with the Wharfedale, Celestion & KEF people & stuff. I worked closely with Peter Fryer when he was at Wharfedale but had much less contact with him when he went to B&W. A good move for him BTW.
My impression is that he had a much less hands on role at B&W especially compared with what he did at Wharfedale. There are people who worked with him at B&W who might enlighten us.
My feeling with B&W is 'not much' and the evidence is their Kevlar units. You gotta have done SCAnned Laser Plots of Kevlar units to unnerstan dis.
Nearly all Wharfedale drive units from circa 1978 and Celestion units from 1980 benefited from da laser juju. I was the one attempting to correlate dis wid DBLTs.
KEF didn't use this stuff until GPI bought both KEF & Celestion and some ex Wharfedale people joined them too.
Today, GPI/Celestion/KEF probably lead the world in integrating laser juju with FEA/BEA bla bla and using this to design units.
Speakers were never really important to Philips. Arie used to moan a lot about this. But I'm not sure it's fair to say they remained faithful "to fairly thin straight sided paper cones".
BTW, us Jurassic speaker designers have all tried sticking bits of felt etc too.
as for da False Prophets, Floyd & Olive, I plead "guilty". As I'm no longer associated with a commercial company, I'm often just sh*t stirring but not always. You have to figure out which bits are pukka. Most of Floyd & Olive's stuff is OK, especially when they quote us 😊
I have some issues with their DBLTs but dis beach bum no longer has access to their august work this Millenium.
If some kind soul will send me copies of their stuff, I might tear myself away from da Great Barrier Reef and attempt a detailed academic critique that might meet Scottmoose's approval ... but don't hold your breathe.
Some good stuff but also loadsa liquid BS. The next video is sorta better. Actually there's loadsa liquid BS on the next video too but not so much as the first.
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@ Wharfedale and Celestion: did W and C make all of their drivers, including the cones and surrounds in house anno 1978, or was Kurt Muller supplier of the soft parts?
@ vid D.R. is so full of c..p I do not even bother to watch his stuff any more. Time and again these vids end with the recommendation of buying his overpriced boutique components to turn a "decent, but...." design into SOTA......
But I must admit: this is a clever, yet fully deceiving marketing strategy.
@ vid D.R. is so full of c..p I do not even bother to watch his stuff any more. Time and again these vids end with the recommendation of buying his overpriced boutique components to turn a "decent, but...." design into SOTA......
But I must admit: this is a clever, yet fully deceiving marketing strategy.
Wharfedale, Celestion & KEF certainly made all their drivers in house, especially the plastic cone units. Surrounds were mostly bought in, not always from KM. There were some surrounds which we made ourselves but not the best ones, IIRC. I specified two important cone formulations. This was always a big risk cos you had to order a huge batch from ICI and there was always the fear that a subsequent batch wasn't exactly the same as the previous.
Paper cones were much more specialised and KM cones were 'usually' the preferred ones though we made successful speakers with cones from one or two other suppliers too.
Cone 'felting' was very much black magic and so was 'rubber' manufacture. Surrounds for speakers were always limited to formulations that were popular in current tyre manufacture.
At the end of the Millenium, when I was already secretly planning my life as a beach bum, we were trialing an injection molded cone with integral surround which came out of our FEA/BEA & laser work.
Paper cones were much more specialised and KM cones were 'usually' the preferred ones though we made successful speakers with cones from one or two other suppliers too.
Cone 'felting' was very much black magic and so was 'rubber' manufacture. Surrounds for speakers were always limited to formulations that were popular in current tyre manufacture.
At the end of the Millenium, when I was already secretly planning my life as a beach bum, we were trialing an injection molded cone with integral surround which came out of our FEA/BEA & laser work.