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Why are all tweeters 1 inch in diameter ?

andreasmaaan

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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.

I had both the 44 and 66 at various times. Both excellent speakers for their day IMO. Never heard the Ditton 15, but there was good continuity between the performance/sound of the 44 and the 66, so I presume that was also the case for the 15.
 

MrPeabody

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The question seems to be why 1" in particular, rather than 2" or 1/2". The tradeoff is primarily dispersion vs. the driver's lowest usable frequency. The driver's lowest usable frequency depends on its ability displace air, which obviously depends on the diaphragm area. I think this is fairly apparent, and that the question isn't really what the tradeoffs are exactly, but why it is that 1" is apparently the optimal size? I think this is an interesting question. For 2-way speakers at least, 1" seems to be the diameter that strikes the balance that most speaker designers deem optimal. Dispersion isn't great enough for the off-axis response to remain flat all the way out to 20 kHz, but if the tweeter were any smaller, this would make it more difficult to integrate the tweeter with the woofer, without encountering an issue with either tweeter distortion or a directivity mismatch.

For 3-way speakers, it isn't so apparent that 1" is optimal in the same way that it apparently is for 2-way speakers. It depends on how large the woofer and the midrange are, and on how much directivity mismatch you are willing to tolerate. If the woofer in a 3-way speaker is on the small side for woofers found in 3-way speakers, for example if it is 7" or less, the optimal solution is probably for the midrange to be only about 2" and for the tweeter to be maybe 3/4". There are a number of 3/4" tweeters available to DIY speaker builders, but there's probably ten times as many 1" tweeters as 3/4" tweeters.

Something that I don't think has been mentioned is that as the diaphragm area is increased, the force that the motor must supply increases (relative to a given sound pressure), which is a direct consequence of the simple fact that force equates to the product of pressure and area. One way to increase the force is by increasing the total magnetic field strength in the gap, i.e., the integral of Bl. Another way is to increase the length of the voice coil in the gap. These are the same things that determine the electrical portion of the damping and the driver Q, which is the predominant part of total driver Q. It is apparent that driver design is a complex juggling act, and that nowadays no one would likely attempt it without the help of computer software. And with respect to computer software there is a fairly wide gamut of techniques to include execution of basic analytical formulas, numerical solutions to simple equations and to systems of equations, and of course sophisticated numerical simulations.
 

MetalDaze

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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.

Agreed. The tweeters in the speakers are new, as are the mid woofers. The subwoofers are original but have some electrical updates applied to them. The woofers are built in house by the manufacturer but the tweeters are outsourced. In the late 70's and early 80's Matsushita was the company I believe. Ohm Acoustics labels it the "low tweeter".

Aside from Scan-Speak, the only other company I know is wavecor which the new units in the cabinets are - http://www.wavecor.com/html/tw030wa13_14.html *edit linked the wrong tweeter. This is the correct one.*

It was rather hilarious when I removed the old 1.5'' tweeters which had - no joke - a 1.5lbs magnet structure attached.

I guess that's what was necessary to give them the power handling rating they have which is over 1,000 watts per speaker :oops:
 
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MetalDaze

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mhardy6647

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A bull's horn vs. an elephant's ear?
Trying to wind me up, Tuga? ;)

All righty then...
This oughta take you both right on over the edge! :cool:
1610907654777.png

https://worldradiohistory.com/hd2/I...OCR-Page-0033.pdf#search="yamaha ear speaker"
Yamaha ear speaker Audio 1969-09.jpg

https://worldradiohistory.com/hd2/I...o-IDX/IDX/60s/Audio-1969-09-OCR-Page-0085.pdf
Yamaha ear speaker Audio 1970-07.jpg

https://worldradiohistory.com/hd2/I...o-IDX/IDX/90s/Audio-1970-07-OCR-Page-0033.pdf
 

tuga

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dfuller

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It's a good balance in terms of size between HF directivity, LF (i.e. 2-3k) distortion performance, volume. Engineering is all compromise, and this is the best compromise for a 2-way system (and even some 3-way systems).
 

aasearles

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dorirod said:
@amirm sorry haven't read through this entire thread but it's listed under Reviews, which is probably a mistake.

Thread was a good read, but I agree with @dorirod. This thread feels out of place in Reviews, and may seem as an error in the long-term.
 

andreasmaaan

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Agreed. The tweeters in the speakers are new, as are the mid woofers. The subwoofers are original but have some electrical updates applied to them. The woofers are built in house by the manufacturer but the tweeters are outsourced. In the late 70's and early 80's Matsushita was the company I believe. Ohm Acoustics labels it the "low tweeter".

Aside from Scan-Speak, the only other company I know is wavecor which the new units in the cabinets are - http://www.wavecor.com/html/tw030wa13_14.html *edit linked the wrong tweeter. This is the correct one.*

It was rather hilarious when I removed the old 1.5'' tweeters which had - no joke - a 1.5lbs magnet structure attached.

I guess that's what was necessary to give them the power handling rating they have which is over 1,000 watts per speaker :oops:

Ah, so did I understand correctly that you've replaced the original 1.5" domes with Wavecor 30mm units? Was this a necessary repair or an upgrade? And did you redesign the crossovers?

I'm guessing you like the sound of these, right? :) I've never actually heard a pair of Ohm speakers....
 

Mnyb

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Regarding low Tweeter + high Tweeter aka super tweeter .
Is xover at 8-10kHz deemed feasible with today’s knowledge, it’s been done in the past .
My limited understanding tells me that high xover frequency also demands that the drivers are in close proximity to make it work properly. Maybe even so that the closesnes required is not even physically possible.
 

andreasmaaan

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My limited understanding tells me that high xover frequency also demands that the drivers are in close proximity to make it work properly. Maybe even so that the closesnes required is not even physically possible.

Exactly. The wavelength of e.g. 10kHz is approximately 3.4cm/1.33". Keeping to any sensible rule of thumb regarding centre-to-centre spacing is just not going to be possible. If you were going to do a crossover this high in frequency, the best approach would be to make it a steep one so that at least the lobing is confined to a relatively narrow band of frequencies.
 

MRC01

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... Magnepan ribbon tweeter ...
Interesting comparison...

The tweeters in my 3.6/R are about 4mm or 1/6" wide and the active driving area is about 4' long. That width is roughly the wavelength of 70 kHz so it should provide uniform (line-source) dispersion well beyond 20 kHz. Its total area is 48 * (1/6) = 8 square inches. That big area means it's barely moving at any reasonable SPL, which promotes low distortion (REW measures it around 0.1%).

Compare that to a 1" dome tweeter, whose size equals the wavelength of about 13 kHz, and whose area is about 0.8 square inches.
 

MetalDaze

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Ah, so did I understand correctly that you've replaced the original 1.5" domes with Wavecor 30mm units? Was this a necessary repair or an upgrade? And did you redesign the crossovers?

I'm guessing you like the sound of these, right? :) I've never actually heard a pair of Ohm speakers....

It was sort of both. When I got them from the original owner, several tweeters were blown. One 1.5" tweeter being one of them. The other was functioning but it didn't make sense to just replace the one. I did not do any cross over work. I brought the cabinets into the manufacturer to be sure everything was in spec. The units which I linked are the one Ohm has chosen to use so I assume it's designed to work as a drop in for the existing crossover.

I do like the way they sound. It's an unconventional design & presents a semi omnidirectional sound. But with the 1'' tweeter on the front of the cabinet it still gives a lot of precision within the sound stage which normally gets lost in a fully omni directional design. The upper portion is separate internally from the lower portion of the cabinet, where the 12'' sub coupled with the vent moves the equivalent volume of an 18'' driver for the bass :)

I have a couple pairs of their large book shelf speakers which have been updated, an original pair of Walsh 2's and these "ayes". Their signature sound is very natural and realistic. Great extended bass and a rather airy upper register. They are I've found, very transparent to the upstream gear. And get along better with a fair amount of power if you really want the best out of them.
 

Frank Dernie

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where the 12'' sub coupled with the vent moves the equivalent volume of an 18'' driver for the bass :)
I am puzzled by what you mean here, in a reflex enclosure the port output is low above resonance and the driver movement is low at resonance, so it is only a slight over simplification to say when one is radiating the other is not.
So adding a port does not increase the apparent area of the bass radiator in a normal reflex speaker.
 

mhardy6647

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Sad to say I remember that speaker being announced and the adverts well. Never seen or heard one though.
I had a single NS-15 (dump find, of course!) -- a rather curious open-baffle two-way design with a cast metal baffle and a horn tweeter to go with the ear-woofer.
It actually didn't sound bad. It would've been interesting to have had/heard a pair.

P1030013 by Mark Hardy, on Flickr
P1030011 by Mark Hardy, on Flickr
P1030008 by Mark Hardy, on Flickr

I did not remember them from their "heyday", and only "discovered" them in the 1990s. I was kind of shocked -- perhaps the response a latecomer to the Grateful Dead (thinking they were a good timey, shuffling, roots-Americana kind of outfit) might be if he/she/they were suddenly confronted with, say, Anthem of the Sun. ;)

1610977454786.png

1610977496722.png


Some of Yamaha's marketing for their weird woofers was sort of... suspect. Most of the ads I've seen stressed the "ear shape"*, others stressed the similarity to the innards of a pianoforte. :)


______________
* I must say that I thought that a lot of the magic in the ear was in its crenellations convolutions, whereas the ear-ness of the Yamaha driver is pretty much two-dimensional.
 

MetalDaze

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I am puzzled by what you mean here, in a reflex enclosure the port output is low above resonance and the driver movement is low at resonance, so it is only a slight over simplification to say when one is radiating the other is not.
So adding a port does not increase the apparent area of the bass radiator in a normal reflex speaker.

I lifted that bit of information from the 1979 July/August edition of Hi-Fi Stereo Buyers Guide. Which has a review of these speakers.

"What kind of structure does it take to create this sound? Pull off the front and top grilles and you see the answer. Front bottom is a 12 -inch subwoofer with a massive 72 -ounce magnet that has its own resonating cavity vented through a 5 -inch diameter duct, ample enough to prevent the audible "breathing" sometimes heard from smaller bass vents. We poked into the
hole and found that the duct extends nearly all the way to the rear wall before opening into the resonating space. A configuration that creates the effective equivalent of an 18 -inch woofer."
 
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