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Multi-Way Conventional loudspeakers with crossovers

beryllium diaphragm VS titanium diaphragm
beryllium diaphragm VS titanium diaphragm
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Old 21st August 2018, 10:58 AM   #11
koutrou is offline koutrou  Greece
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Originally Posted by Scottmoose View Post
Are those drive units identical in every single respect other than the diaphragm material (including profile, thickness &c.)? If they aren't, your comparison is utterly worthless, since you have changed almost every single variable and haven't the first idea where and what causes the differences in performance.

Beryllium is technically superior to titanium for the reasons mentioned above: it has a higher stiffness / weight ratio, which when used optimally, allows a wider pistonic BW and potentially higher SPLs under otherwise identical conditions. So from that perspective, it doesn't make the slightest difference whether you think it is all marketing, because the laws of physics and engineering have rather obvious reasons for using it. Whether the implementation is of sufficient quality to exploit these potential advantages is another (separate) question: that is a matter of driver design.
Thank you Scottmoose so end of story beryllium is higher than titanium but it doesnt mean that a titanium driver is not better than a beryllium driver... Must be all parametres of a driver the same to say that a beryllium is better.
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Old 21st September 2018, 01:15 AM   #12
33Polkhigh is offline 33Polkhigh  United States
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Does Scottmoose or anyone understand why some metal dome tweeters are described as having a break up that is ultrasonic, such a this one

SEAS Prestige 27TBFC/G (H1212) Aluminum/Magnesium Dome Tweeter

Then what is the point of a beryllium tweeter if an aluminum dome can be made that breaks up outside our range? The FR of the aluminum dome doesn't look all that flat. Are there eariier mini break ups in the aluminum.

Will the aluminum dome still sound metallic. I associate a metallic sound with metal cone break up.
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Old 21st September 2018, 02:25 AM   #13
eriksquires is offline eriksquires  United States
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IMHO, the magic is in the waterfall plots, compression and FR

Regardless of technology, my ears prefer the smoothest FR and lowest stored energy in the audible range, along with a lack of compression throughout my listening range.
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Old 21st September 2018, 04:59 AM   #14
1audiohack is offline 1audiohack  United States
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Maybe there isnít much difference in a 26mm dome tweeter but at 100mm diaphragm diameter in a compression driver the difference is substantial.

Barry.
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Old 21st September 2018, 11:54 AM   #15
Scottmoose is offline Scottmoose  United Kingdom
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Originally Posted by 33Polkhigh View Post
Does Scottmoose or anyone understand why some metal dome tweeters are described as having a break up that is ultrasonic...
Yes, it's simply because the main bell mode is above the nominal maximum 20KHz HF limit of human hearing.

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Then what is the point of a beryllium tweeter if an aluminum dome can be made that breaks up outside our range? The FR of the aluminum dome doesn't look all that flat. Are there eariier mini break ups in the aluminum.
There are three points there. Last first: not unless there are. Not every aluminium dome tweeter of a given size behaves the same way. In the case of the Seas you link to, no. Again, using the 27TBFC/G, it looks pretty flat to me. Ruler flat from ~2KHz - c.14KHz. Not bad. The rolloff above that is due to the mass (the Seas is an aluminium / magnesium alloy BTW) until you hit its main resonant mode.

What is the point? Two reasons really. Firstly, lower mass, so potentially (note caveat: this is not a given) the Be dome can remain flatter at the top end of the nominal audio BW. Secondly, distortion. There is the potential for increased IM distortion in the audio band if a bell mode above it gets excited. Having a greater stiffness - weight ratio, Be can allow this bell mode to be shunted to a significantly higher frequecy, where it is less likely to be excited & amplify distortion lower down the range. The audibility of this is debated; for whatever my view is worth (nothing) I do not see it as a black / white matter but an interesting point worth keeping in mind, but which is likely to depend on circumstance (not least motor & suspension design, frequency, mode Q & other factors). Direct comparisons are difficult since there are few tweeters that are identical in all respects other than having, say, an alluminium or Be dome material.

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Will the aluminum dome still sound metallic. I associate a metallic sound with metal cone break up.
It also depends what you call a 'metallic sound'. If a driver is not in break up in the audio band (or it is heavily suppressed), you aren't hearing breakup. QED. You may however have distortion issues connected with it elsewhere. Depends on the driver. Most people love that Seas tweeter for e.g.; some hate it. I suspect a portion of those who hate it are listening with their eyes & are uneasy about that ~27KHz bell mode, but I wouldn't casually discount the potential for it to cause audible issues for some people either under certain conditions. YMMV.
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Old 21st September 2018, 03:07 PM   #16
ErnieM is offline ErnieM  United States
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Originally Posted by eriksquires View Post
IMHO, the magic is in the waterfall plots, compression and FR

Regardless of technology, my ears prefer the smoothest FR and lowest stored energy in the audible range, along with a lack of compression throughout my listening range.
I agree with this. In the same vein, the best overall non hornloaded tweeter I've heard is a compression driver with no horn. There are tweeters that are slightly smoother and extend higher but the headroom and low frequency capabilities can't be compared.
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Old 21st September 2018, 06:36 PM   #17
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by 33Polkhigh View Post
Does Scottmoose or anyone understand why some metal dome tweeters are described as having a break up that is ultrasonic, such a this one

SEAS Prestige 27TBFC/G (H1212) Aluminum/Magnesium Dome Tweeter

Then what is the point of a beryllium tweeter if an aluminum dome can be made that breaks up outside our range? The FR of the aluminum dome doesn't look all that flat. Are there eariier mini break ups in the aluminum.

Will the aluminum dome still sound metallic. I associate a metallic sound with metal cone break up.
A 3/4" or 1" aluminum dome can push the break up peak above 15khz.

The advantage of beryllium is that you can have a dome as large as 2-3" in diameter, and the peak is still ultrasonic.

That's why Be is popular in compression drivers, but not so much in HiFi dome tweeters.
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Old 21st September 2018, 11:38 PM   #18
33Polkhigh is offline 33Polkhigh  United States
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Thanks Scottmoose and everyone for all the replies. I've tried to equalize out metal cone break up in drivers (not tweeters though) and it seems like the metallic sound remains especially if you learn to identify it. I think its a bit like trying to hammer a dent out on a car. Its gets better but you can still see it.

It sounds like some metal tweeters might actually have the rigidity without the metal sound. Never heard a beryllium driver though.
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Old 22nd September 2018, 09:26 AM   #19
Scottmoose is offline Scottmoose  United Kingdom
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A tweeter is a rather different matter to a midbass or similar. EQing a major bell mode flat (or even applying a high Q notch alone) isn't going to help. The distortion lower down the range, which is what you are likely hearing, is still present. If you want to prevent that, you need to heavily suppress the bell / resonant modes, not just flatten them out. That really means high order crossovers well below the first mode (depending on order, 1 - 2 octaves below).
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