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In a 3 ways speaker you prefer a dome or a cone mid?

94.161.80.218
Posted on October 29, 2009 at 10:45:34
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
 Hello,

I have only two ways speakers.
I would like to try a 3 ways speakers.
I see that the mid comes or as a dome or a cone
Is it the same thing ?
I see that a lot of high end Manufacturers use a cone mid
Is that a rule ? which is the better way to reproduce mids ?
Thanks a lot and kind regards,
beppe

RE: In a 3 ways speaker you prefer a dome or a cone mid?, posted on November 1, 2009 at 19:46:08
Bill the K
Audiophile

Posts: 2324
Joined: June 3, 2006
 I havent seen too many dome mids used in speakers.The most interesting arrangement I saw was on a Coincident Victory speaker with two domes and a ribbon tweeter in a D'Appolito configuration and a few cones below and also side firing.I thought this made a lot of sense.I am yet to listen to this speaker though.

RE: In a 3 ways speaker you prefer a dome or a cone mid?, posted on November 2, 2009 at 10:32:41
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
Thanks a lot for yor kind reply.
Regards,
bg

RE: In a 3 ways speaker you prefer a dome or a cone mid?, posted on November 2, 2009 at 10:15:43
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
Thanks a lot for yor kind reply.
Regards,
bg

RE: In a 3 ways speaker you prefer a dome or a cone mid?, posted on October 30, 2009 at 09:02:54
Hornlover
Manufacturer

Posts: 1013
Joined: March 8, 2002
 There is some critisizm of dome mids because of positional problems (domes rocking side to side). Since they are using a single support at the edge of the dome, they are not as well controlled as a cone driver supported at the cone edge, and also with the spider at the voice coil. I dont remember now where I read a pretty good paper on the problem.
Aside from that problem, I agree with the others, that for best midrange performance, it is desirable to cross over at least by 300Hz, where the midrange starts. Reproducing the mids from a single driver is important, in my opinion, and not many domes can go that low.

RE: In a 3 ways speaker you prefer a dome or a cone mid?, posted on November 1, 2009 at 05:50:39
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
Please excuse my belated reply but I was out in the mountain for the weekend.
Thank you very much for your kind and very helpful reply.
Maybe the paper your are reffering at is the article of Lynn Olson on driver types ?
If I remember correctly the only dome mid of which he spoke well was the 3" ATC
Thanks again and kind regards,
bg
I've found better tonal balance with domes, posted on October 29, 2009 at 20:05:30
E-Stat
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Posts: 9840
Location: Central boonies
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Contributor
  Since: April 5, 2002
 The radiation pattern of cones narrows considerably as one goes up in frequency. I listened a pair of JBL L-110s at a friend's house which produced a fun house mirror kind of image. It runs a 5" midrange up to 4 kHz where its dispersion is quite narrow. While the lower and upper ends produced a reasonably wide stage, the lower highs were noticeably pinched. It was as though instruments in that range were playing on a far narrower stage.

Very strange.

rw

RE: I've found better tonal balance with domes, posted on October 31, 2009 at 17:00:27
Presto
Audiophile

Posts: 2947
Location: Canada
Joined: November 10, 2004
 "The radiation pattern of cones narrows considerably as one goes up in frequency."

Same with domes. There are small format mids out there from Vifa, Scanspeak, tangband and others that extend well beyond 10K on axis and almost to 10K 30 degrees off axis. And these drivers have Fs in the 80 to 120 range. Depending on Qts of the driver, they can even be used with an 12db electric/12db acoustic 4th order high-pass. With a moving mass under 5 grams, excellent dispersion and power handling, it's hard to know why anyone would fuss with domes anymore.

Scanspeak makes tweeters with an Fs of 450Hz to 500Hz nowadays. This is not much higher than the Fs of the typical dome.

Myself, I'd either go with small format mids in a WMTMW or stick with ScanSpeak or Seas tweets with a very low Fs, cross over low (around 1800Hz) and skip the mids altogether.

Sometimes the best mid is no mid.

Cheers,
Presto

RE: I've found better tonal balance with domes, posted on November 1, 2009 at 06:39:03
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
 Thank you very much for your very interesting advice
I understand that not all drivers perform the same.
And I understand the importance on principle of using a driver in the range where its dispersione is good on at least +/- 30 degrees angle
Actually, in some cases at least, a wide dispersion is not a good thing
Riflections can be a problem, like with omnidirectional speakers, a nightmare to place in a normal listening room.
Nevrtheless I usually listen to music alone.
So a wide sweet spot is not an issue at all.
I can always get the speakers firing directly to me.
Thank you very much and kind regards,
bg
RE: I've found better tonal balance with domes, posted on October 30, 2009 at 02:38:06
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
Good morning !
You say
"I listened a pair of JBL L-110s at a friend's house which produced a fun house mirror kind of image. It runs a 5" midrange up to 4 kHz where its dispersion is quite narrow"

Maybe a wrong choice of upper crossover frequency for the mid ?
Maybe up to let's say 3kHz it dispersion would be better ?
Regards,
beppe

Wrong choice?, posted on October 30, 2009 at 06:21:00
E-Stat
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  Since: April 5, 2002
 Or a different set of compromises. I've read one source that suggests that dispersion drops significantly when the diameter of the cone is larger than the wavelength reproduced. For any given size, it is easy to calculate using this rule of thumb. In this case, the calculation would be: 13,200/5 = 2,640. Indeed, the crossover point should be nearly an octave lower to maintain optimum dispersion. Perhaps JBL chose a higher crossover point to ensure higher power handling for the tweeter. Having said that, it seems that a very common crossover point for tweeters today in a wide range of speakers from Polk to Magico is 2 kHz. You could then use a 6.5" midrange and still stay in the dispersion sweet spot.

rw

RE: Wrong choice?, posted on November 1, 2009 at 05:57:40
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004

Thank you very much again for your very interesting indications.
I think that the issue about the tweeter power handling can be quite critical.
I have a pair of Dynaudio speakers where the D28 tweeter is crossed at about 2kHz with a first order slope.
I heard them distort very badly when pushed a little.
Actually I am thinking of some changes in the crossover, on the basis of this bad behaviour.
Thanks and regards,
gb

RE: Wrong choice?, posted on October 31, 2009 at 00:13:21
djk
Manufacturer

Posts: 3888
Joined: June 17, 2000
 The cone is only 3.5", so the speed of sound is 1130*12=13560, and 13560/3.5=3.9Khz

Dispersion is generally specified as the ±angle that is -6dB from on-axis response. The 2105H (LE5-10) midrange driver has ±45° dispersion at 6Khz by this method.

The physical spacing between the drivers, as well as the 4.5Khz crossover, cause the dispersion to narrow at the crossover point. The biggest problems are the spacing (too wide) and the tweeter flange (too large). The cabinet can also get weak with close spacing.

With modern neo magnet tweeters, the existing tweeter could be replaced with a compact neo type mounted as close as possible to the mid (probably on an aluminum plate). This would require some work, including changing the tweeter attenuation resistors in the networks.

RE: Wrong choice?, posted on November 1, 2009 at 06:09:34
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
 Thank you very much for your kind explanation.
usually is easy to get the frequency response of this famous drivers in order to check their dispersion
Nevertheless I understand from your words that is of paramount importance to use a driver in its wide dispersion range
It can be calculated but also, and maybe more confidently, measured
I read that to get a full bandwidth with less than 4 ways is almost impossible.
Nevertheless there are cases like for instance Altec VOT where a ful bandwidth seems possible from just 2 drivers,
Other people swears even for full range single driver (!)
But I am convinced that these are exceptions more than rules,

Thank you very much for your kind advice,
bg
It would seem JBL learned their lesson, posted on October 31, 2009 at 07:07:30
E-Stat
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Posts: 9840
Location: Central boonies
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  Since: April 5, 2002
 Here's a current monitor with the 5" mid crossed over almost an octave lower in that 2 kHz range which seems to be the sweet spot used today.

rw

Bigger Midrange ?, posted on October 31, 2009 at 16:01:02
djk
Manufacturer

Posts: 3888
Joined: June 17, 2000
 That is a much larger midrange driver, about twice the cone area.

Despite the large area, by using a plate to mount the mids and highs together they are able to get a tighter center-to-center spacing. The 'waveguide' (horn) molded into the mounting plate also gives some time off-set correction, and allows the tweeter to load to a lower crossover point.

How expensive are these? I notice that the replacement cost on the mid is about $300 (not that you would burn out a 2" coil mid driver).

They are both specified as 5" drivers, posted on October 31, 2009 at 22:20:30
E-Stat
Audiophile

Posts: 9840
Location: Central boonies
Joined: May 12, 2000
Contributor
  Since: April 5, 2002
 I understand that the piston area of any cone is smaller than the nominal size, but otherwise they are measured the same by JBL.

rw

RE: Bigger Midrange ?, posted on October 31, 2009 at 16:59:35
andy_c
Audiophile

Posts: 963
Joined: June 2, 2007
 Last I checked, you can get them online for $2500 per pair.

RE: In a 3 ways speaker you prefer a dome or a cone mid?, posted on October 29, 2009 at 19:43:21
caspian@peak.org
Audiophile

Posts: 389
Location: Oregon
Joined: January 12, 2008
 Hoo boy, that's one of those "theoretical" questions with as many answers as there are speaker designers and enthusiasts!

A 4" to 7" cone midrange driver has the advantage of being able to play (depending on size) down into the upper bass/lower mid frequencies -- 150 to 350Hz region. It can play (again depending on size) up to maybe 2 to 5kHz. Above its size-determined upper limit, its radiation pattern will narrow (beam) and the cone may go into breakup distortions. Still, it can cover most of the range of most human voices, to which range the human ear is most sensitive. It may in this sense sound more "coherent" than a design with a crossover in this broad frequency region.

Dome mids cannot play as low: they must usually (depending on size) be crossed in from 500 to 800Hz. But they can play higher with good off-axis dispersion, allowing them to cross higher to a smaller tweeter, which also has good off-axis dispersion.

In a 3-way system, a dome mid therefore requires a woofer with good midrange quality up to the higher crosspoint. This USUALLY means a smaller woofer that cannot play as low, so bass is compromised.

A number of systems employing dome mids are 4-ways (or more-ways), with a real woofer, a lower mid cone, an upper mid dome, and a tweeter. The classic Dahlquist DQ-10 used this configuration, along with a supertweeter. Dynaudio has offered several 4-ways with this driver complement over the years.

RE: In a 3 ways speaker you prefer a dome or a cone mid?, posted on October 30, 2009 at 02:34:27
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
 Thank you very much for your kind and valuable reply.
Now the all issue is clearer to me.
If the speaker must be a 3 ways it must have a cone mid.
Kind regards,
beppe

I want my midrange driver to go as low as possible, posted on October 29, 2009 at 16:18:42
Jon L
Audiophile

Posts: 4839
Joined: April 6, 2000
 To me, this way sounds much more coherent in that critical low-midrange to upper-bass transition. I currently cross over my midrange cone at 140 Hz via electronic crossover.

There's always tradeoffs, of course, and smaller midranges will do higher frequencies better. This is why I use pretty large ribbons to reach down a bit lower as well..

RE: I want my midrange driver to go as low as possible, posted on October 30, 2009 at 02:27:45
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
 Good morning,

Actually I read something about the woofer distortion obtained when the woofer must reproduce a low bass (under 100) and a mid-low bass (above 200) frequencies at the same time.
I saw a plot showing high level of intermodulation distortion (please excuse my poor knowledge of english and terms)
RE: The Important Thing Is The 'Total' Synergy Of The Sound:, posted on October 29, 2009 at 12:02:06
Vinylly
 It probably doesn't make any difference if it's cone or dome. It's the engineering of the speakers and the parts that make up the speaker and the sound of it's output that's important.

RE: The Important Thing Is The 'Total' Synergy Of The Sound:, posted on October 29, 2009 at 15:10:33
beppe61
Audiophile

Posts: 1452
Joined: January 29, 2004
Thank you very much for your kind and helpful reply.
Actually I notice that drivers of both types are used.
In the audiophile and the pro sector.
Kind regards,
beppe

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