So, what tweeter-or type of tweeter would you use if your priority were to have a dispersion at 10K that is similar to that of an Allison?
The specs for the old Dynaudio D21AF show dispersion holding up pretty well that high. Any contemporary tweeters come to mind, or would you use a lens of some sort?
The specs for the old Dynaudio D21AF show dispersion holding up pretty well that high. Any contemporary tweeters come to mind, or would you use a lens of some sort?
Vifa XT 19.
Have a look at Zaphs site on tweetr off axis measurements. Although the off axis is unfortunately measured only up to 30 degrees, its behaviour around 10 kHz seems for 30 degrees off axis similar to the RA tweeter. Additionally you get a ruler flat on axis and 15 degree off axis response from 1 kHz upwards at approx 87/88 dB.
Interestingly the 19 mm domes in the Zaphs measurements seem indeed to be a bit more directional at 10kHz.
Good luck,
Eelco
Have a look at Zaphs site on tweetr off axis measurements. Although the off axis is unfortunately measured only up to 30 degrees, its behaviour around 10 kHz seems for 30 degrees off axis similar to the RA tweeter. Additionally you get a ruler flat on axis and 15 degree off axis response from 1 kHz upwards at approx 87/88 dB.
Interestingly the 19 mm domes in the Zaphs measurements seem indeed to be a bit more directional at 10kHz.
Good luck,
Eelco
Allison was right: Power response is what matters most in room. Regarding tweeters the problem is that most units have a definitely dull power response. Basically the question is that flat on axis is not enough: on axis should be rising and flat around 30º off axis. This can be obtained listening off axis and applying eq. No need for any special tweeter, any model can work if correctly used.
GDO - "with all due respect", even with current EQ and room correction software, I think it'd be fair to say that not all tweeters are created equal.
There may or not be something very special about the in room sonic performance of the Allisons, even if the "patented technology" appears to be less than revolutionary 40-ish years later.
There may or not be something very special about the in room sonic performance of the Allisons, even if the "patented technology" appears to be less than revolutionary 40-ish years later.
There are two:
Seas 27TBCD/GB-DXT aluminium dome with diffraction lens / short horn
SB Acoustics SB26ADC aluminium dome with phase cap
Both offers remarkable directivity, exceptionally low THD, low crossover frequency and almost no stored energy problems despite their affordable non-audiophile price... Both sound clean and transparent.
No idea about why Allison tweeters might be so special. One thing at least is clear for me: Allison built loudspeakers designed to deliver a decent response in the guy next door's room, without ranting about boundary effects nor requiring any room positionning nor treatment: he designed pre-equed speakers for normal rooms. Nice guy and a real pionneer, but i think any speaker can be equed like this and even better even if designed for pure ( nonsense) anechoical conditions, and i really am no DRC freak, quite the other way...
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This Seas DXT offers rather narrow dispersion and requires huge eq for decent flat response. Nothing in common with a 21 Dynaudio...
Impossible?
-you probably mean something else. Obviously, if you apply some eq, this eq will be applied to any direction,and will also impact the power response, that is the total amount of trebble energy radiated to the room.What cannot be changed by eq is the radiation pattern, but by carefully chosing an off axis listenning angle and apply eq based on the corresponding response, you can make one tweeter sound in very different ways, whatever the radiation pattern. This can be done with the DXT above too, the only penalty being loss of sensitivity due to eq. Imho, this tweeter is only ok in a loudspeaker of max 85dbs sensitivity.
Obviously this Morel ET448 delivers more trebble energy:
An externally hosted image should be here but it was not working when we last tested it.
Some guys have serious concerns about dispersing energy out of the listening position. I personnaly have a different one: poor power response owing to pattern narrowing. That's why i also prefer wide dispersion patterns.
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Impossible?
Clarification: it is impossible to EQ both on-axis and off-axis to be flat (or same).
Morel IDR (Improved Dispersion Recess) provides good, above average dispersion (tweeter E338), but tweeter E448 is not a particulary good representative of the IDR technology because there is a pronounced "hot spot" at 10 kHz.
Severe off axis roll off is common place. Do you know any device free of this?
http://www.gattiweb.com/images/dynaudio/esotarT330d_data.pdf
http://www.gattiweb.com/images/dynaudio/esotarT330d_data.pdf
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Sorry for posting to an old thread, but I am interested in the Allison tweeter - and now in the Linn tweeter. My memory of the Allison design is slightly different from the drawing (I think) - I thought the whole fabric diaphragm was one piece, and the voice coil attached to it a bit farther down the side of the dome? I could be wrong.
The Linn tweeter is new to me, and I like how it appears to work. It, like the Allison (and the Peerless dual ring radiator tweeter) produce concentric rings of sound, and therefore they have much wider dispersion at higher frequencies, because they approach acting like point sources.
The Linn tweeter is new to me, and I like how it appears to work. It, like the Allison (and the Peerless dual ring radiator tweeter) produce concentric rings of sound, and therefore they have much wider dispersion at higher frequencies, because they approach acting like point sources.
No fabric, paper.
Roy said many times that he made the mids and tweeters int that way because he could not afford to buy then-current drivers with appropriate behavior and still sell a reasonably priced product.
There are midranges today that will give excellent off-axis response from 350-3500hz.
And plenty of tweeters that will keep it together well up to the last octave. The3.5k for the three-ways is easy, the 1.8-2.2 for the twosies will narrow the choices somewhat.
One thing Roy never was, was full of himself.
Roy said many times that he made the mids and tweeters int that way because he could not afford to buy then-current drivers with appropriate behavior and still sell a reasonably priced product.
There are midranges today that will give excellent off-axis response from 350-3500hz.
And plenty of tweeters that will keep it together well up to the last octave. The3.5k for the three-ways is easy, the 1.8-2.2 for the twosies will narrow the choices somewhat.
One thing Roy never was, was full of himself.
Okay, I had the pleasure of hearing a big prototype he was designing in the RA Labs shop, that appeared to be a fabric version, of his tweeter. The drawing doesn't look like either - it has two pieces to the diaphragm.
By the way, the Linaeum TLS tweeter (6" high version) plays down to about 400Hz, and still maintains very wide dispersion, because it acts closer and closer to a line source as the frequency rises.
By the way, the Linaeum TLS tweeter (6" high version) plays down to about 400Hz, and still maintains very wide dispersion, because it acts closer and closer to a line source as the frequency rises.
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