Leaving aside the number of times we've all witnessed people nodding away profoundly at shows and elsewhere to systems that have both the technical and sonic performance of shattering glass (to each their own and all that):
a/ A 'witch hunt' is not a synonym for fair critique. Pointing out wild, and very basic factual inaccuracies in data used by a company to advertise and sell their own product is very definitely not a 'witch hunt', just a statement of fact. Some people may well like the sound of them -so much the better. That isn't under dispute. But whether some people like what they do is no excuse for publishing outright nonsense.
b/ None of the 'shiny' drivers above appear to have a physical structure like the unit here, with a large flat mounting-plate, which is the item under design critique. Not that my opinion counts for much, I agree with GM's view that within the context of what it is, it's not likely to do any significant harm, although it's not an ideal configuration and very definitely better avoided for drivers that are shifting more air than the limited quantity this & similar units can do before running into obvious distortion issues.
a/ A 'witch hunt' is not a synonym for fair critique. Pointing out wild, and very basic factual inaccuracies in data used by a company to advertise and sell their own product is very definitely not a 'witch hunt', just a statement of fact. Some people may well like the sound of them -so much the better. That isn't under dispute. But whether some people like what they do is no excuse for publishing outright nonsense.
b/ None of the 'shiny' drivers above appear to have a physical structure like the unit here, with a large flat mounting-plate, which is the item under design critique. Not that my opinion counts for much, I agree with GM's view that within the context of what it is, it's not likely to do any significant harm, although it's not an ideal configuration and very definitely better avoided for drivers that are shifting more air than the limited quantity this & similar units can do before running into obvious distortion issues.
To play devil's advocate a little bit...
What's the effective surface area for a cone with a 'whizzer'? It seems to me that the whizzer can't be ignored because it helps push more air for a given displacement. Even in the bass the efficiency will be improved and the mms will be higher than expected with a regular cone without a whizzer. The other specs will be offset by that. Has anyone actually verified that their own T-S estimates are accurate before writing-off the published ones?
I haven't really seen any other manufacturers take good care of how the backwave behaves starting from the voice coil and the cone. No streamlined shape, just a big lump of magnet for diffraction and uneven loading of the cone. So a flat back-plate makes sense. So what what if it also happens to be shiny?
A high mass is not a bad idea. It means that the amplitude of vibrations transmitted to the box will be much lower, and they're less likely to be messed up by internal resonances.
That's all I can think of for now, but there may be other points that come to mind.
What's the effective surface area for a cone with a 'whizzer'? It seems to me that the whizzer can't be ignored because it helps push more air for a given displacement. Even in the bass the efficiency will be improved and the mms will be higher than expected with a regular cone without a whizzer. The other specs will be offset by that. Has anyone actually verified that their own T-S estimates are accurate before writing-off the published ones?
I haven't really seen any other manufacturers take good care of how the backwave behaves starting from the voice coil and the cone. No streamlined shape, just a big lump of magnet for diffraction and uneven loading of the cone. So a flat back-plate makes sense. So what what if it also happens to be shiny?
A high mass is not a bad idea. It means that the amplitude of vibrations transmitted to the box will be much lower, and they're less likely to be messed up by internal resonances.
That's all I can think of for now, but there may be other points that come to mind.
Left the system running all day today while working downstairs ….. Now I’m upstairs tonight and have had a bit of a listen bass has filled out and everything’s sounding bloody marvellous if you’ll excuse the French. Mind blowing. Hard to fathom it’s still early days with regards to break in. If there’s no change from here I’m happy camper. 🙂
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Basically equal to the unblanked CSA of the main cone structure.
Not really, any loading provided by a typical parasitic sub-cone is vanishingly small in the LF.
Mms = Mmd + Mmr where Mmd = the total mass of the moving components & Mmr = the air load on the effective LF radiating surface, which doesn't generally include sub-cones as an addition to the primary.
Yes. See above. They're drivel. Qts is not a matter of debate: it's a closed-form formula, period, which is derived solely from Qes and Qms.
Qts = (Qes*Qms)/(Qes+Qms). If Qts is stated as being dramatically different from what you obtain from those Qe and Qm values using that formula, then either it, or the Qe and Qm values are wrong. End of story. Which is rather underlined by the fact that a Canadian distributor (?) has published totally different Qe, Qm and Qt values for the same drive unit -which are also completely inconsistent with themselves, let alone the other (incorrect) values. A small amount of variation might be understandable if, for e.g., the various Q values are batch averages, but with any reasonable production QA / QC tolerance they should still be fairly close.
You might want to look at the work put in by Scan, SB, Seas and many others (especially pro-audio manufacturers) in minimising motor structures, open & highly profiled baskets and shaped magnet structures, vented coil formers, vented motor structures etc., plus attempts by others to eliminate traditional rear suspensions. Since form follows function there's a limit to what can be done with regular moving coil designs of course, but plenty have put work into reducing interference as far as practicable -especially important / useful in high power pro-audio.
It makes sense from a construction and potentially aesthetic perspective in cases where it will have minimal effect (which probably includes this one). That doesn't mean it's a good idea in general, just an acceptable tradeoff (or at least one where the inherent compromises are unlikely to cause issues) under a given set of conditions.
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Hi,
The effective surface is mutually defined by the diameter of the cone and half of the surround, in a flat circle, of course any phase plugs need to be substracted. So, Sd of a whizzered driver is not larger than the same unwhizzered, and it can´t "push more air" in pistonic movement. Otherwise, Cube Audios 3- or 4-times whizzered drivers would have an enormous Sd...
I may be allowed to show a picture of what I regard as an open back speaker, trying to maintain a maximally open area near the rear side of the cone. But oh ****, it´s shiny as well...
A high mass of a driver is not a bad idea, sure. A high Mms is a bad idea for fullrange drivers.
All the best
Mattes
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Cheap they are not. OTOH, inflation-adjusted, it's in-line (arguably better) than their historical ancestors of the '50s, '60s etc.
I still can't afford them, obviously. 😉
I still can't afford them, obviously. 😉
You guys are way off topic of the speaker build here.
Interestingly, the Lii Song Canada distributor made a mistake and uploaded the data for the Silver-10 against the Platinum-10. It will be corrected to mirror the global site.
Interestingly, the Lii Song Canada distributor made a mistake and uploaded the data for the Silver-10 against the Platinum-10. It will be corrected to mirror the global site.
Well, that's a result. 🙂 Except that means that the data (such as it is) for both the Platinum-10, and the Silver-10 is utter nonsense. Which unfortunately isn't much of a step forward. 
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...........and here I was 'sitting on my hands' trying not to inflame further! 
No less accurate than Fostex data….. I assume you’re getting your knickers in a twist like this over every Fostex build thread? Plenty of happy Fostex users out there I believe.Well, that's a result. 🙂 Except that means that the data (such as it is) for both the Platinum-10, and the Silver-10 is utter nonsense. Which unfortunately isn't much of a step forward.
Really? I don't generally see Fostex publishing Qt values that have zero relationship to the Qe and Qm values on the self-same data-sheet. 
They tend to provide a trifle more information too. 😉
Variations in data from independent measurements taken at different voltage drives (for example) is one thing. You'd expect that. Utter nonsense in a manufacturer's own published information is another thing entirely.
They tend to provide a trifle more information too. 😉Variations in data from independent measurements taken at different voltage drives (for example) is one thing. You'd expect that. Utter nonsense in a manufacturer's own published information is another thing entirely.
Really?! News to me, though assuming you're referring to basic Fs, Vas, Qts, whereas its efficiency we historically want to decide if the specs 'in toto' are accurate enough for accurate cab design based on the original Altec Lansing which AFAIK only using it for specs quality assurance (QA), which IOW meant = < +/- 10%.
Will try find time to do a little recording of my system today.... Sounding lovely. Course the recording itself is next to useless though it can give a sense of the system thats about it. My Samsung Galaxy A70 phone + Rode NT1A mic are just not up to the task.
What I can hear are the only things matter to me. Music sounding just stunning irrespective of gentre..... I don't listen to heavy metal or prog rock mind you.
EDIT: Not sure if recording worth the effort. Never sounds anything like being there anyway.
What I can hear are the only things matter to me. Music sounding just stunning irrespective of gentre..... I don't listen to heavy metal or prog rock mind you.
EDIT: Not sure if recording worth the effort. Never sounds anything like being there anyway.
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