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Why are all tweeters 1 inch in diameter ?

mhardy6647

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We talk about pistons of 1" having such and such characteristics, but in fact almost none of the tweeters fitted to commercial speakers are made in designs which could remain a piston for their whole pass band. This is mainly because of available materials and the ease (ie cost) of making complex shapes.
The reality of dispersion at highest frequency will depend on the break up modes of the tweeter at least as much as its diameter.
Oh.
As long as I am babbling...
Roy Allison (one of the stalwarts of AR, who had a long and pretty distinguished career on his own, too) had some interesting ideas for "dome" style drivers in the 1970s. The Allison loudspeakers were quite nice and very different compared to the monkey coffins of their time.

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source: http://www.classicspeakerpages.net/...ies_brochure_2/allison_one_series_brochure_2/

The unusual shape of the (paper) Allison tweeter and MR diaphragms remind some folks of nipples :rolleyes: Probably bottle babies. ;)

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bennybbbx

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i guess it is because the used tweeter is fast enough to produce a good step response for good tranients and frequency of 20 khz .slower speakers many people hear maybe. and lthey are large enough that the woofer (in 2 way system need not do too high frequency).on mid range speaker fast transient seem not so critical for sell but when use large woofers often crossover is lower. I have now a Eris 3.5 inch speaker pair around 99$ . this is lots faster as Kali with the 6,5 inch woofer. LP6 use crossover 1.5 khz and they do the trick that the tweeter do this low freq, that the tweeter is deeper in waveguide as other. so it is more simular to horn. The eris give very good stereo width and transients. i think the Eris sound in mids a little better as the MTM maybe because of Kevlar. but is not much only feeling when hear live Not hearable over headphone records. more about this in this thread https://www.audiosciencereview.com/...of-the-synth-sound-in-the-attached-mp3.18401/
step response eris 3.5.jpg
+
stepresponse Kali lp6.jpg
 

DonH56

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Ha ha theres always one isn't there don .

Of course, but he (she, it) makes a reasonable point. As @AudioSceptic said, only a few digits are significant, and there are a number of environmental factors that affect the speed of sound that I did not include. Engineers (speaking for myself; I have no idea his background) tend to look for flaws and correct them, often valuing accuracy (or in this case precision) over tact. Here at ASR we value science, but I feel a major goal is to teach, which means simplifying to reach an audience that is not all scientists and engineers, but that does not mean I should get too careless. It's worthwhile pointing out some of the factors that affect the sound we hear -- a lot of folk may know the speed of sound but not realize how dependent it is upon the medium and how variable it can be. Worthwhile pointing that out.

Now if I could just find that old acoustics text...

No worries, thanks for your support and common sense as always, Sir Thomas!
 

AudioSceptic

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Of course, but how detailed did you want? This was sea level, dry air, standard temp and pressure. Humidity is also a first-order effect. Feel free to provide the whole equation; I was too lazy to look it up in my old acoustics text so just spouted off what I remembered off-the-cuff. And of course you don't go from wide dispersion to beaming immediately, there's a transition period. And so forth. I just wanted to put some ballpark numbers out there for people to calculate on their own. The only one I remember is 1127'/s; the rest of the digits are from the calculator.
Only as detailed as is appropriate in the real world. Let's say 3 sig-fig. ;-)
 

AudioSceptic

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This is what's called a dome midrange. These work on the same principles as a dome tweeter, but are larger, being designed to cover upper midrange frequencies. Typically, they cross over from the woofer somewhere in the 400Hz-1000Hz range, and cross over to the tweeter somewhere in the 3kHz-5kHz range.
Isn't this what ATC make such a big thing of, their "famous" mid-range dome? <http://atcloudspeakers.co.uk/soft-dome-mid-range/> Most others use a cone in that range.
 

thewas

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I had a pair of Celestion Ditton 66 (first released late-60s IIRC) that used a similar large (3") midrange dome from 500-5000Hz:

View attachment 106660
I even have 4 pairs of vintage loudspeakers with a 2" mid dome in my collection (Braun L710, Braun SM 1002, MB Quart 590 MCS and Philips MFB 22AH587) and a new DIY one designed by me, it is a good combo for wide directivity without a waveguide especially combined with a 0,75" tweeter.
 

Mnyb

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I’ve had a large dynaudio contour with dome midrange and 8” inch bass driver and 8 inch pr , they where nice gave them to a friend , but sadly the foam surround has rotted currently.
 

AudioSceptic

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And Neumann ?
We're drifting away from tweeters, but didn't this come about because Neumann wanted a cheaper alternative to the ATC? <https://www.soundonsound.com/reviews/neumann-kh310a>
When the words 'mid-range' and 'special' are used in the same sentence, a lot of people will think of the well-known and much-loved ATC mid-range driver, and K+H actually used it in their O500C model. However, it was deemed too expensive for the new KH310A, so the Neumann/K+H designers designed their own 75mm mid-range dome driver, which they describe as being more cost-effective, more sensitive, having lower THD and intermodulation distortion, and better break-up behaviour.
 

MetalDaze

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Like to see those babies tested. Looks like an inverted lens. They were on to something.

Me too! They can be found for cheap on the second hand market. I ran them when I was in my late teens in a modest home theater set up I had with a Sony receiver and a Polk PSW10. Although at the time I had limited CD's and mostly used Itunes for the convenience, to my young and untrained ear they still sounded pretty good for what they were.
 

MetalDaze

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Oh.As long as I am babbling...
Roy Allison (one of the stalwarts of AR, who had a long and pretty distinguished career on his own, too) had some interesting ideas for "dome" style drivers in the 1970s. The Allison loudspeakers were quite nice and very different compared to the monkey coffins of their time.

I had a pair of Celestion Ditton 66 (first released late-60s IIRC) that used a similar large (3") midrange dome from 500-5000Hz

Those definitely were a thing! These are the speakers I currently use. The 8'' mid-woofer ranges from 100Hz - 1700Hz. Then the 1.5'' dome tweeter takes over up to 5000Hz (I think but maybe 7500 Hz?). And finally the two 1'' dome tweeters are in parallel and run up to 20k+ Hz.

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tuga

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The distinction between a "waveguide" (as it's often used in audio) and a "horn" is rather nebulous IMO.

All "horns" necessarily affect radiation pattern, and all "waveguides" necessarily affect acoustic impedance.

To stretch this just a touch further, the same is also true of all enclosures (especially baffles) - these affect both radiation pattern and acoustic impedance according to the same principles as horns/waveguides.

Maybe we could use horn for narrow directivity and waveguide for wide directivity control.

A bull's horn vs. an elephant's ear?
 

Frank Dernie

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I wasn't defending, merely reporting. :)
I wasn't criticising you, just pointing out that most discussions of tweeters centre round how people thing they work as opposed to what is actually going on in reality!
I always assumed the "poly-planar" drivers of the 1960s were based on the same concept(?).
I don't think there was much in the way of understanding or modal radiation back then, and they look pretty symmetrical and a symmetrical modal driver behaves poorly.
One of my best friends was used as a consultant by NXT to model the panel speakers, and then worked extensively on the BMR for them.
The biggest limitation in the BMR is that the superb theoretical performance potential at high frequencies with very wide dispersion is between very expensive and impossible to achieve in a real manufacturing environment, so it is probably most easily used as a mid driver.

I have a several of the NXT prototypes, including a super tweeter.
 

andreasmaaan

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Those definitely were a thing! These are the speakers I currently use. The 8'' mid-woofer ranges from 100Hz - 1700Hz. Then the 1.5'' dome tweeter takes over up to 5000Hz (I think but maybe 7500 Hz?). And finally the two 1'' dome tweeters are in parallel and run up to 20k+ Hz.

View attachment 106685





View attachment 106687

1.5" is a dimension you don't see very often these days, and places the dome somewhere between a midrange and a tweeter. The only one I can think of that's still in production today is the Scan-Speak D3806/820000, which is classified as a "tweeter", but really can't be used above c. 7 or 8kHz due to break-up and resultant beaming.
 

Frank Dernie

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I had a pair of Celestion Ditton 66 (first released late-60s IIRC) that used a similar large (3") midrange dome from 500-5000Hz:

View attachment 106660
I lusted after these massively when they came out, but couldn't afford them.
My mother had Ditton 15s at home which I always enjoyed when I visited.
 
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