Dayton reference 2in Dome Midrange

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angsuman

Member
Joined 2005
Hello everyone, I am thinking of doing a 3 way project a few months down the road. I want to try out a dome midrange because of its better dispersion.

I'm curious how the new Dayton reference dome midrange
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=285-020

Performs. Is there anything wrong with this driver or if anyone has experience with this driver?

Also, could someone give advantages/disadvantages of using dome midranges compared to cone midranges.
 
Cloth Ears

Cloth Ears

Member
Joined 2001
from Lynn Olsen's "Looking over my shoulder" (1994)
Soft Dome Midranges
These things are dogs! I've listened to the AR-3, AR LST, ADS systems, Audax 2", and the Dynaudio D-52 soft dome midranges, and they barked, they snarled, they chewed the rug, and made a mess on any loudspeaker they approached! They measure flat, all right, but they sound opaque, fatiguing, strongly colored, and 2-dimensional.

The first problem is that soft-dome midranges have a limited bandwidth resulting from restricted linear excursion (1-2 mm typical) and do not gracefully tolerate even a 500 Hz crossover, operating best over a limited 800 Hz to 3200 Hz range.

A second problem is that they are quite prone to side-to-side rocking modes, since there is no spider combined with the surround to force the movement into a linear back-and-forth motion.

A third problem is that the doped silk dome is just, well, too soft for the job it has to do in the power band of the midrange.

The newer class of cone-domes, such as the 5" Scan-Speak 13M/8636 and 13M/8640, and the 5" Dynaudio 15W-75, are another story. These 3 drivers are actually constructed as high-precision cone drivers, not midrange domes. The only thing they have in common with the soft domes is a large dustcap, which does act as a dome at high frequencies.

This class of driver has much more excursion, much lower distortion, and much wider frequency response than the older soft-dome midranges. The cone-dome drivers are capable of realistic and transparent sound. They are described in more detail in the other sections, since they use Kevlar, paper, and polypropylene respectively.

Another "special case" is the professional-grade ATC 3" dome with an integral short horn. This driver uses a dual spider to eliminate the rocking problem that plagues most soft-domes, reducing the IM distortion very significantly. Ron Nelson (of Nelson-Reed) recommended this driver as one of the very best midranges around, and I take his recommendation seriously. This is a very expensive driver (around US$300/each) and needs to be hand-selected so the resonant frequencies of the left and right channels match.

Strengths are: None. Metal-dome midranges have some potential, but they require sharp crossovers on both ends with an additional sharp notch filter at high frequencies to remove the first (and worst) HF breakup mode. Note: This does not apply to the ATC driver or the cone-domes.

Weaknesses are: High distortion, fatiguing sound, high crossover frequency, limited bandwidth, limited power-handling, and misleading frequency response measurements. It takes a detailed swept IM distortion measurement and laser holography to get the goods on these drivers. Note: This does not apply to the ATC driver or the cone-domes.

Best Examples are: ATC 3" professional-series - a totally different animal than the usual soft-domes. About 4 times as expensive, though. The Dynaudio D-54 in a Edgarhorn is reputed by the "Sound Practices" group to be the finest midrange in the world ... yours truly has a pair on order, so I'll let you know.
Click to expand...
 
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dwk123

Member
Joined 2002
I'm actually very intrigued by this driver as well. It'll be interesting to see whether the key points make it different from other dome mids:
- metal dome
- 2" vs 3 or 4"

My idea is to put these guys in a Geddes OS Waveguide. Should be able to cover maybe ~500-5k+. Augment with a good 15 on the bottom, and fill in the treble and it chould be a very interesting and relatively inexpensive system. Making the 2" throat waveguide would be a challenge, though.

Oh, well, put it on the list of projects I probably won't get to.....
 
A

angsuman

Member
Joined 2005
Thanks, for all your help. The complexity of a 3 way project is really getting to me. That and the steep learning curve for speaker workshop.
One more thing, i'm curious on bandpass gain.
What is one supposed to do to correct for bandpass gain.
Let's say there will be 2.84dB in bandpass gain, would i simply attenuate the midrange driver by the same amount?
 
Cloth Ears

Cloth Ears

Member
Joined 2001
Without knowing exactly what "bandpass gain" is (but assuming it's the amount which the midrange is 'louder' than both the bass AND treble) then yes, you would "simply attenuate the midrange driver by the same amount".

Rod Elliot has the basic calculations in here: http://sound.westhost.com/lr-passive.htm#6.0 (and no matter whether you disagree with his opinions, his formulae are mostly correct).

Originally posted by angsuman
The complexity of a 3 way project is really getting to me.
Click to expand...
You are not wrong about the complexity. A lot of people never end up tackling a 3-way passive speaker, going more for a 2-way with an added active bass module (2-way subwoofers) or a '2.5-way' with 2 mid-basses crossed over at different points (generally one to the tweeter and one at the Baffle step point).
 
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angsuman

Member
Joined 2005
Sounds interesting making a veritas from reference drivers.
My plan is a TMW bookshelf. I have no woodworking skills so i'm thinking of using a partsexpress 1.0 cubic foot MTM enclosure.
There will be a vifa xt19 tweeter with a dome midrange for its dispersion characteristics and perhaps a 7 or 8 inch dayton reference woofer depending on how large a woofer i can jam in that enclosure.
 
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