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The Advantages of a Ring Radiator vs. Conventional Domes? (Concave/Convex)
The Advantages of a Ring Radiator vs. Conventional Domes? (Concave/Convex)
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Old 9th October 2015, 06:21 PM   #1
ReDress is offline ReDress  Canada
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Default The Advantages of a Ring Radiator vs. Conventional Domes? (Concave/Convex)

Hey guys,

I've been interested in trying out some ring radiators lately (Due to the fact that they are a variation on the conventional dome design and are said to offer some advantages when compared to them), however, I've been having a hard time trying to find out what the advantages of them are when placed against the more traditional concave/convex type of designs.

Other than the fact that they've have got an integrated phase plug (which, for whatever reason, seems to have worse off-axis response than your usual dome...) I haven't been able to find out their advantages.

If you guys could help me figure this out, it would be greatly appreciated

Much love/Many thanks in advance for your guys' help.
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Old 9th October 2015, 06:38 PM   #2
weltersys is offline weltersys  United States
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Quote:
Originally Posted by ReDress View Post
Hey guys,

I've been interested in trying out some ring radiators lately (Due to the fact that they are a variation on the conventional dome design and are said to offer some advantages when compared to them), however, I've been having a hard time trying to find out what the advantages of them are when placed against the more traditional concave/convex type of designs.

Other than the fact that they've have got an integrated phase plug (which, for whatever reason, seems to have worse off-axis response than your usual dome...) I haven't been able to find out their advantages.
The ring allows a large voice coil with a diaphragm that can use less area than a dome shape diaphragm of the same diameter. Less area =less mass, less mass is better for HF response and transients.
Though the JBL 075/2402 "bullet" has narrowing HF response, there are ring radiator tweeters using various horns that have excellent dispersion.

Last edited by weltersys; 9th October 2015 at 06:42 PM.
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Old 9th October 2015, 06:57 PM   #3
dragonweed is offline dragonweed  Hungary
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Besides the "integrated" phase plug , their main advantage vs. (any type) dome tweeters is the lack of the bell resonance mode (dome breakup) which is present on ALL dome types regardless of material and shape used. With standard 3/4 and 1" tweeters it is happening somewhere between 22 and 40 kHz with a magnitude of 3-12 dB (the harder the dome material, the higher the resonance peak is) so basically it is inaudible, but its subharmonics and the related distortions are definitely yes.
Ring radiators are almost completely free of that kind of problem, and while they are not perfect either, their uppermost range is definitely cleaner and more extended than most dome tweeter's. Nice example is the SB29RDC from SB acoustics (or the XT series from Vifa, Scan Speak also has a range of them)
Below are two examples, the first one is a high-end dome, the other is the excellent Satori tweeter of SB.
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File Type: jpg f_seas_prestige_loudspeaker_tweeter_h1212_27tbfc_g.jpg (85.1 KB, 1045 views)
File Type: gif SATORI-TW29R-chart.gif (41.1 KB, 1043 views)

Last edited by dragonweed; 9th October 2015 at 07:04 PM.
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Old 9th October 2015, 07:13 PM   #4
TBTL is offline TBTL  Germany
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Originally Posted by weltersys View Post
Less area =less mass, less mass is better for HF response and transients.
Agree on HF response, but less mass does not necessarily mean better transients. Transient response is primarily determined by whether there are resonances within the pass band and how they are damped.

A disadvantage of ring radiators is that they start to beam at a lower frequency than hard convex domes.
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Old 9th October 2015, 07:46 PM   #5
twinter is offline twinter  United States
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The center of the soft dome tweeter moves in antiphase relative to the rest of the dome, somewhere in the 12 to 15 kHz range for a 1" dome, and 15 to 20 kHz for a 3/4 inch dome.

The Vifa XT19, a 3/4" ring radiator, has a high frequency dispersion similar to a one inch dome tweeter.
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Old 9th October 2015, 08:26 PM   #6
weltersys is offline weltersys  United States
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Originally Posted by TBTL View Post
A disadvantage of ring radiators is that they start to beam at a lower frequency than hard convex domes.
An advantage of a compression driver (whether the diaphragm is a ring or a dome)is a horn or waveguide of the desired pattern can be used.

Another example of a ring radiator that does not beam is a JBL 2402, it has a 100 degree uniform pattern out to 20 kHz.
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Old 9th October 2015, 08:55 PM   #7
mondogenerator is offline mondogenerator  England
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I don't classify the SB29 as a ring radiator (may be misconception on my part)

But the fixed dome 'cap' eliminates the antiphase breakup - I see this as a far more pronounced problem in soft domes.

The Vifa rings seem like completely different animals (to me) they don't seem like a dome with a fixed centre (maybe they are, haven't held.one in my hand...)
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Old 10th October 2015, 06:00 PM   #8
ReDress is offline ReDress  Canada
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Thanks for the responses everyone
(Based on what I've read - the advantages are less mass, and as such, extended HF response. The downside is that, perhaps counter-intuitively (at least to myself) they'll begin to beam earlier/have worse off axis response)

As an abstract question, do you guys think we'll ever see a ring radiator midrange (2-3" type of deal - kind of like 2-3" dome midranges)
If so, why/why not?

Thanks for the thoughts everyone.
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Old 18th October 2015, 05:47 AM   #9
whgeiger is offline whgeiger  United States
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Quote:
Originally Posted by ReDress View Post
Hey guys,

I've been interested in trying out some ring radiators lately (Due to the fact that they are a variation on the conventional dome design and are said to offer some advantages when compared to them), however, I've been having a hard time trying to find out what the advantages of them are when placed against the more traditional concave/convex type of designs.

Other than the fact that they've have got an integrated phase plug (which, for whatever reason, seems to have worse off-axis response than your usual dome...) I haven't been able to find out their advantages.

If you guys could help me figure this out, it would be greatly appreciated

Much love/Many thanks in advance for your guys' help.
Firstly, the ring radiator does not exhibit the break up modes of a dome diaphragm of otherwise comparable performance.

Note, however; that the [Sd] of a ring radiator will always be smaller than that of a dome radiator of the same moving mass when that of the suspension, voice coil and former are included.

Secondly, a ring diaphragm has two compliances controlling its movement instead of just one for the dome design. This feature suppresses the occurrence of diaphragm rocking modes at lower frequencies inherent in single suspension moving systems.

The challenge here is getting a balanced elasticity between the two compliance rings as the outer ring is necessarily larger than the inner ring.

The third advantage is that ring geometry permits two such rings to occupy the same compression chamber where they may be operated in opposition to each other using separate voice coils.

This feature has been successfully exploited in JBL D2 Compression Driver designed by Alex Voishvillo.

The issue here, is getting air tight seals between the many rings that are joined to form the driver compression chamber and phase plug. If an air seal fails here, driver output is all but lost.

WHG
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Old 18th October 2015, 07:06 PM   #10
gedlee is offline gedlee  United States
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To be clear here, I see no reason why the directivity of a ring diaphragm would have to be any different than that of a dome. Its all in how the phase plug and the waveguide are designed.

The ring - supported at both its inner and outer edges is far more rigid structurally than a dome. But it also has less radiating area for a given outside radius, and since it has two compliances, it will have a higher fundamental resonance than the dome. If one is seeking a good LF response from the driver then a dome is likely to have the advantage. If one wants to extend the HF response then the ring will have an advantage. I prefer a single driver for the upper range and the rings just can't get down low enough to cover the range I seek. If you can live with the higher crossover point then the rings work fine.
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