Tweeters, measurements, thoughts . . .

Jeff Fritz

[Industry Expert]
Jun 7, 2010
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Hi guys,

There has been a lot of discussion on tweeters lately and I thought it might be helpful to look at how some measure, all under anechoic conditions at the NRC. My take is that there are good soft domes, good metal domes, and bad tweeters of all types and materials. It is very hard to generalize. However, there are a few things that should be taken into consideration. First, most designers that actually engineer their own drivers attempt to get pistonic operation within the driver's passband -- they want to avoid any nonlinearities. Basically, they aim for no break-up modes under 20kHz. And in fact they want to push them as far out of the passband as possible (30kHz, 40kHz, beyond). It has been done with a few soft domes, a higher number of exotic hard domes, and some ordinary metals that have advanced dome profiles.

Here is the Vivid G2, aluminum dome with a unique dome profile. Clean operation to 20kHz (refer to listening window):
http://www.soundstagenetwork.com/in...audio-giya-g2-loudspeakers&catid=77&Itemid=18

Here is a Magico V2 with a soft-dome ring-radiator, again with clean response to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/magico_v2/

Here is a WATT/Puppy 8. You can see the break-up starting at 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/wilson_wattpuppy8/

Focus FS8, with a soft-dome ring radiator, clean to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/focus_fs8/

Volent VL-2, with a ribbon tweeter, breaking up at 20kHz:
http://www.soundstagenetwork.com/in...ature-edition-loudspeakers&catid=77&Itemid=18

Audio Physic Virgo 25, ceramic-coated aluminum, breaking up at 20kHz:
http://www.soundstagenetwork.com/in...ysic-virgo-25-loudspeakers&catid=77&Itemid=18

The Revel Salon2, with a SOTA Be tweeter, clean to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/revel_ultima_salon2/

Some of the best speakers I've ever had here used soft domes -- the original Rockport Arrakis and Altair, which both used the Scan-Speak D30. Rockport has since moved on to what they claim performs better -- the S-S Be unit so popular today. The Magico Q7 also uses a Be unit with the same dome profile but different motor and voice coil. These are currently the state of the art in terms of pistonic operation, perhaps with the Accuton Diamond tweeter added in the discussion and Vivid's tweeter, too.

The point here is that great soft domes exist and SOTA hard domes are growing in number. But poor-performing soft domes are around and totally terrible metal domes can be found in many speakers. So, IMO, the generalizing is misleading. You really need to see some good anechoic measurements to know for sure what's going on. As others have said, the implementation is likely more important than the driver material, but SOTA sound comes from great drivers completely optimized in all facets of the design.
 

Phelonious Ponk

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Jun 30, 2010
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I've run into some notable exceptions, but more often than not, I prefer the sound of soft dome tweeters. I'm a subjectivist. :)

Tim
 

slowGEEZR

Member Sponsor
Sep 20, 2010
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Jeff, I don't read graphs like this often. Which graph shows the WP breaking up at 20khz? I did notice that since distortion was so low with the WP8 that they did extra graphs for it at a higher output than the other speakers.
 

amirm

Banned
Apr 2, 2010
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Jeff, I don't read graphs like this often. Which graph shows the WP breaking up at 20khz? I did notice that since distortion was so low with the WP8 that they did extra graphs for it at a higher output than the other speakers.
Before we talk about that, this speaker has pretty bad directivity. This is its far off-axis response (what you would get from side wall reflections):



That trough in the 1.2 Khz region shows that there is too much of a gap between the woofer and tweeter. The former becomes too directional before the latter picks up the load, causing that dip. This means that you likely need to absorb those side reflections as otherwise, you are going to have a trough in the area of most sensitivity for the ear. That would then take away some sense of spaciousness.

Back to the tweeter, this is the speaker's direct response:



I think Jeff is talking about the resonance that causes its level to peak at 20 Khz.
 

JackD201

WBF Founding Member
Apr 20, 2010
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Material is also only part of the story. Shape also determines the location of break-up on the diaphragm and break up also happens in the surrounds. Then there's the mechanical aspects which would include thermal distortion in the coils. Actually we'd need even more measurements to figure out what's going on. I know of some designers that use Laser-Interferometry to test cone flex distortions of the sound waves along with motor distortion and Time Delay Spectrometry and Cumulative Spectral Decay for the known remaining distortions of mechanical nature related to the suspension ringing.

In all yes, the generalizations can be misleading and I have made some generalizations myself. Like Jeff says there are good and bad examples of whatever material is out there.

In my case, I just find that the sins of a bad soft dome are more tolerable than a bad metal.
 

Steve Williams

Site Founder, Site Owner, Administrator
One interesting feature of the Aida silk dome tweeter was the presence of a curved thin piece of metal running from 12-6 o'clock postion. Mike at LMC said it is there to affect dispersion of the sound wave
 

JackD201

WBF Founding Member
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Revel Ultimas have two of them and I've seen such metal pieces elsewhere too. It is interesting. Some tweeters are even designed to perform with fixed mesh covers.
 

DaveyF

Well-Known Member
Jul 31, 2010
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A few years back, I got into an argument with Wslam ( remember he of the many Magico Mini posts on A'gon) wherein he was insisting that the tweeter in the Mini measured superior to the silk dome in my GH's and therefore sounded better.
As usual, I went by what my ears were telling me and not just by measurements and I didn't hear that at all. Today, I'm sure Wsalm has moved on from his beloved Magico Mini's to who knows where, and we are just now beginning to discover again the attributes of the good old fashioned silk dome. So, the next time someone assaults me with measurements and insists that they tell the whole story, I will say, like before....IF the speaker sounds better to my ears and measures great, then we're good, OTOH, If the speaker measures great and doesn't sound that great, then the measurements go out the window. Just IMHO;).
 

LL21

Well-Known Member
Dec 26, 2010
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One interesting feature of the Aida silk dome tweeter was the presence of a curved thin piece of metal running from 12-6 o'clock postion. Mike at LMC said it is there to affect dispersion of the sound wave

Hi Steve - 12-6 on both speakers? or 12-6 on time and 6-12 on the other? IOW, since there is left and right speaker, would the curved pieces mirror each other or both be on the right side of the tweeter when facing it?
 

treitz3

Super Moderator
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Dec 25, 2011
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Some of the best speakers I've ever had here used soft domes -- the original Rockport Arrakis and Altair, which both used the Scan-Speak D30
Hello, Jeff. I see that the D30 is part of the Revelator series and is apparently the newer version as well.
“AirCirc” D3004/6600. This is the latest and most advanced release from the famous Revelator tweeter line
Would you happen to know when these came out? I used to run with a Revelator tweeter but I'm not 100% sure these are the same as what I had. I'm currently running the Millennium tweeters [I believe it's the SEAS Excel T25CF-002]. I'll find out exactly what I have after I talk with Ty.

I ask because if the D30's are the same as what I've used, I'd be curious to see if the measurements match up to my preferences and observations.
 

andromedaaudio

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Jeff not only designers who design their own drivers attempt to achieve pistonic operation in the pass band of a unit
Unit manufacturers and the majority of LS designers attempt that also .
There are off course very good examples of manufacturers of doing so(make /modify their own ) , there are also who claim they do, but dont .
There are also specialized unitmanufacturers who do a damn good job at manufacturing a outstanding unit , if they didnt they would not be in business very long, and one chooses the design that fits in the overall freq band of the speaker you want to make .
Anonther thing is that a membrane material which does a very good job at the mid freq (paper composite )can be simply to soft for the bassmembrane , with a lot off different ingredients from specialized manufacturers its possible to make very good designs, without much distortion certainly till at least 20 khz
 

Phelonious Ponk

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Jun 30, 2010
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My B&W diamond tweeters are designed for use with the screen mesh covers.

Lee

Of course, Lee. They can cut glass. Surely they can make it through mesh. :)

Tim
 

rbbert

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Dec 12, 2010
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Revel Ultimas have two of them and I've seen such metal pieces elsewhere too. It is interesting. Some tweeters are even designed to perform with fixed mesh covers.

On the Revels, these are "waveguides", somewhat analogous to horns in the sense that they alter the directivity characteristics of the raw driver.
 

microstrip

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May 30, 2010
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Tim,

The mesh covers are there to preserve my kids' lives. If they poked a diamond tweeter with a nerf dart or something, child protectice services would be after me!

Lee

Lee,

Remember the old B&W Silver Signature's? My children grew in audiophile environment - since they started to walk they were used to go around turntables, cables or speakers laying anywhere. They never broke or damaged anything - except a B&W SS tweeter. When I found the metal tweeter dome pushed in I asked them who did - my 7 year old boy accused himself and explained - my finger get trapped and I could not take it out! If it was not for the protection maybe he would never have damaged it! Anyway B&W were very kind - they sent a new dome free of charge.
 

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treitz3

Super Moderator
Staff member
Dec 25, 2011
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A buddy of mine just had to replace a diamond tweeter who lives in Canada. Needless to say it wasn't cheap. Protect them and protect them dearly both upstream and downstream. That's all I have to say about that.
 

JackD201

WBF Founding Member
Apr 20, 2010
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Lee,

Remember the old B&W Silver Signature's? My children grew in audiophile environment - since they started to walk they were used to go around turntables, cables or speakers laying anywhere. They never broke or damaged anything - except a B&W SS tweeter. When I found the metal tweeter dome pushed in I asked them who did - my 7 year old boy accused himself and explained - my finger get trapped and I could not take it out! If it was not for the protection maybe he would never have damaged it! Anyway B&W were very kind - they sent a new dome free of charge.

One daughter was a serial tweeter poker. I went with Maggies for 3 years partly because there were no tempting little domes. LOL.

With the Revels I had to change the entire tweeters, with the B&W 604s just the domes. I will always love B&W for that. My main speakers have the really pointy ring radiators (2904). My littlest one took one look and didn't even try :LOL:

Worst poking I've ever seen was at a friends. All four tweeters of his Dynaudio Master Evidence speakers were poked in.

Worst poking story I've heard from a friend and fellow dealer. Some a-hole saboteur went to their shop and shattered a Focal Be tweeter. You'd have to poke it with something sharp to do that so they are pretty sure it was intentional. The perp was never caught.
 

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