So I'm wondering why you never see two, say, 4" drivers stacked vertically in a cabinet design, in an attempt to virtualize a larger diameter speaker?
Is this a radiation pattern issue that everyone understands and therefore is never done? Larger "line-array" speakers are attempted, but in these the driver count is >> 2.
It seems the full range driver cost goes up "exponentially" with diameter, but things like the off-axis performance not so - with dips so awful, you'd have to aim the driver at your sweet spot - like a gun.
Just curious if something starts to happen in the 1 - 10K Hz decade with such an arrangement that I'm unaware of. Thanks!
Is this a radiation pattern issue that everyone understands and therefore is never done? Larger "line-array" speakers are attempted, but in these the driver count is >> 2.
It seems the full range driver cost goes up "exponentially" with diameter, but things like the off-axis performance not so - with dips so awful, you'd have to aim the driver at your sweet spot - like a gun.
Just curious if something starts to happen in the 1 - 10K Hz decade with such an arrangement that I'm unaware of. Thanks!
What Jim said, with 2 4” you probably want to roll one off (electrically or acoustically)so that you get 1/4 the excursion in the bass, but only one driver up high for best dispersion and no combing.
The main reasoning for not using 2 FRs is that at high frequencies the distance between the drivers becomes greater than the wavelength being reproduced and you get coming… a string of eaks & dips dependent on where your head is in relation to the speaker.
This becomes less & less as the distance from the speaker increases, Toole has shown that it looks worse than it sounds (our brains have evolved to deal w it). In practise many having been happy with 2 small FRs working together.
Now as a generalization a larger driver goes lower, but particularily when discussing FR that goes out the window. For instance the largest Mark Audio (FR) is hard to get as low as either of the 5.25” drivers and some of the 4” drivers.
Here are generalized outline of the options when wiring 2 drivers.
http://www.planet10-hifi.com/downloads/Dual-Driver-Wiring.pdf
An acoustic solution would be a bipole (back & front), castle (top & front), ot 1 driver on the side,
Note that the moving part of 2 4” is closer to that of a 5.25”.
dave
The main reasoning for not using 2 FRs is that at high frequencies the distance between the drivers becomes greater than the wavelength being reproduced and you get coming… a string of eaks & dips dependent on where your head is in relation to the speaker.
This becomes less & less as the distance from the speaker increases, Toole has shown that it looks worse than it sounds (our brains have evolved to deal w it). In practise many having been happy with 2 small FRs working together.
Now as a generalization a larger driver goes lower, but particularily when discussing FR that goes out the window. For instance the largest Mark Audio (FR) is hard to get as low as either of the 5.25” drivers and some of the 4” drivers.
Here are generalized outline of the options when wiring 2 drivers.
http://www.planet10-hifi.com/downloads/Dual-Driver-Wiring.pdf
An acoustic solution would be a bipole (back & front), castle (top & front), ot 1 driver on the side,
Note that the moving part of 2 4” is closer to that of a 5.25”.
dave
Each has its pluses and minuses. It depends on the amp and whether you need maximum baffle step. I rarely have issues w BS so i tend toward series connection.
With parallel connection you do need to be below baffle step, with series XO point is much more flexible. I can then push it down to less than a quarterlength of the C-C and most of th eissues with XOs go away.
dave
Another of the acoustic roll-off tricks. If you took the pair of side/front mounted drivers and rotated the box 45° you have a servere splay. Same with the castle but in the vertical direction (i like the spash from the ceiling)
dave
I was looking at the Mark Audio drivers and their nice responses. Admiring the 12P @$157, the 10P @$110 with data showing off-axis response without the wild 20 db dips of some other designs. Then I stumbled upon the CHN-70 and thought this one has a pretty nice looking response too - but at just $27 - so I wondered if I could use two per cabinet?
From the responses here, it looks like I could - thanks, appreciate the input; gives me some encouragement to explore this idea more! Fortunately (or unfortunately) I'm now the proud owner of a pair of 6.5" Daytons I scored off ebay, so I'll be playing with those first. $150 to see if I can knock my beloved FE103ens off the stands by meeting up with my sub an octave lower - than 120. We'll see what happens!
From the responses here, it looks like I could - thanks, appreciate the input; gives me some encouragement to explore this idea more! Fortunately (or unfortunately) I'm now the proud owner of a pair of 6.5" Daytons I scored off ebay, so I'll be playing with those first. $150 to see if I can knock my beloved FE103ens off the stands by meeting up with my sub an octave lower - than 120. We'll see what happens!
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The CHN has a response shaped for the Japanese market. Otherwise a nice driver. But the Alpairs are in a different class.
The A10p goes higher, lower and resolves more in the midrange. The A12p moves more air.
A12p is 6.5”, A10p is 5.25”, A7.3 or A7ms are the 4”. The A6p has the same MA paper cone signature sound as the larger A10/12p — i always wanted to try to in Frugel-Horn Mk3.
WAWs have a lot of pluses. The FE103 don’t go overly low, how high can the daytons go? Do you have 2 amps?
dave
The A10p goes higher, lower and resolves more in the midrange. The A12p moves more air.
A12p is 6.5”, A10p is 5.25”, A7.3 or A7ms are the 4”. The A6p has the same MA paper cone signature sound as the larger A10/12p — i always wanted to try to in Frugel-Horn Mk3.
WAWs have a lot of pluses. The FE103 don’t go overly low, how high can the daytons go? Do you have 2 amps?
dave
We have done exactly this in a couple of our designs. Have a look at the Eikona DCR, for example. The same principle applies to other matched drivers.
Trouble with severe splay is that you start to rely on reflections for the higher frequencies, and your room therefore needs to account for that. you probably also want to at least double the reflecting drivers if you have one direct sound driver.
With only slight amounts of splay, like on the Bozaks you get wider high frequency coverage (if that is desired), with only a little spatial and temporal combing.
Without having to deal with reflections.
I'm not against reflecting speakers, but they can be problematic, and you have to "design" your listening room to a greater degree.
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I've done plenty of such designs. A variety are on threads on this forum, although I would not term it 'an attempt to virtualise a larger diameter speaker'. Many others also; Colin refers to his Jordan designs, Omega sell commercial models to name but a couple of examples. They're not as common as some, but they exist.
Well, since it is done, we've mostly covered that.
They're more directional in the vertical axis within the Fresnel zone. In the Fraunhofer (farfield) they revert to point source behaviour, just as a line array does if you're sufficiently far from it & the upper / lower boundaries allow. They also start to suffer from more in the way of output lobing on the vertical axis. The destructive interference pattern (comb lines) aren't particularly audible due to the precidence / Haas effect, but the HF attenuation can (as in 'can', not 'invariably' -depends on specifics) be. On the horizontal axis, less in the way of this. Well, there are plenty of relatively expensive 3in & 4in drivers & plenty of relatively cheap large units. Relative quality being equal, larger drivers cost more, and most of the very high priced ones are larger for obvious reasons, but a quantifiable definition for that relative quality is also necessary.
Again, not an invariable and design dependent. All other things being equal, a smaller unit should have an advantage, but they're rarely (never) equal. In the same vein it depends how you define quality or lack thereof. With a fixed definition, you can make some meaningful comparisons. Without criteria, it's just a bald and essentially meaningless statement of opinion. Many wideband drivers of 5in or > size tend to have a rising on-axis response in order to provide a little more off-axis gain, so listening directly on that axis is not necessarily a good idea unless you happen to like said balance.
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