Hi,
TC9 is a very nice driver that has been proven in lots of designs from sealed to dipole to cardioids.
https://www.parts-express.com/pedocs/specs/264-1062--tymphany-tc9fd18-08-spec-sheet.pdf
However, it beams too much in the treble to be used in a constant directivity design. Is there a way to widen the highs in a well controlled fashion with treatment or something else.
Thanks,
WA
TC9 is a very nice driver that has been proven in lots of designs from sealed to dipole to cardioids.
https://www.parts-express.com/pedocs/specs/264-1062--tymphany-tc9fd18-08-spec-sheet.pdf
However, it beams too much in the treble to be used in a constant directivity design. Is there a way to widen the highs in a well controlled fashion with treatment or something else.
Thanks,
WA
Hi there, there is absolutely no way to make an existing cone have a different dispersion unless you would make it perfectly rigid (pistonic) - imposible - and then you get a point source like dispersion - this is because the dispersion is related to the geometry of the cone.
Another thing - the TC9 is a very well behaved unit when it comes to offaxis response. The BMR type of fullrange drivers are the best.
The general way you take care of such a problem is by adding something to take care of the dispersion - an acoustic lens of a kind or another - example: DCT-1 | Parts Express Project Gallery ; the more popular thing is to make an Karlsonator type enclosure that has an acoustic lens build in.
Another thing - the TC9 is a very well behaved unit when it comes to offaxis response. The BMR type of fullrange drivers are the best.
The general way you take care of such a problem is by adding something to take care of the dispersion - an acoustic lens of a kind or another - example: DCT-1 | Parts Express Project Gallery ; the more popular thing is to make an Karlsonator type enclosure that has an acoustic lens build in.
yes, but, as a subspecies of horn, would the acoustic lens only have effect on a specific "three octave" band of frequencies? If so, yes, you could build one for the range above which the driver starts to beam, but to boost the high end freq. response in a driver already known for strident highs...
No free lunch in audio, I guess
Greets!
I can't find it when I need it, but in the '40s RCA had a huge folded BLH driven with an 'FR' driver with two different size flared waveguides suspended over it that worked pretty well since the BLH kept diaphragm excursion to around a mm max and somewhat later some DIY folks got decent results from using/DIYing JBL's 'potato masher' lens as already noted, but know of no treatment that will do this.
GM
You can try with a small whizzer cone, I tried it on a pair L-Cao 8 inch before. Before the whizzer cone mod, the mid-highs already sound very laid back.
After adding, it gave some attenuation to the mid-highs but it depends on the size of the whizzer cone you design for it. And from experiences with whizzer cone profile designs I would say they act like a small horn.
Playing around with several horns for high freq drivers, they do have attenuation which is called the horn flare freq similar from the Freq response behavior I measured on whizzer cone fullrange. This is from my understanding from the measurements and simulation using Hornresp.
I would say u can do up a small one and use some temporary removable glue to attached it.
Since it is a inexpensive method rather than keep spending on more drivers to enhance it. Otherwise, I rather spend more time designing multiway speakers than playing with fullrange.
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I don't know if you realized but the cone here is a 3 inch cone, and it does go all the way up but dispersion is not 100% of what it should be, I don't see how the wizzer helps with dispersion - that's why I asked; as far as an 8 inch driver is concerned it't probably incapable of playing on it's own that high so it's just not there (on axis or off axis), the wizzer starts playing the highest of frequencies for the 8 inch cone = more radiating surface for high frequencies.
I don't know if a wizzer can act as a waveguide / acoustic lens but if properly glued in place it will "buzz" highs.
I don't know if a wizzer can act as a waveguide / acoustic lens but if properly glued in place it will "buzz" highs.
IF cone were absolutely rigid, a whizzer cone would make no sense.
But it´s not.
Being thin and paper , it has significsnt flexibility.
Since cone has mass (inertia) and flexibility, it does not move "all at the same time) and in fact center area moves more than near edges, we are talking higher frequencies here, and it actually helps speaker produce more highs than it should.
Some speakers even have rings molded in its surface, so, say, a 12" speaker acts like a 12" one up to, say, 350Hz, then at higher frequencies it virtually becomes a 102 one, then an 8" one, and so on.
So eventually it will behave as if it were 4" or so.
That said, some clever guy noticed that the voice coil itself moves more than expected, because even the coil-to-cone-neck joint shows some flexibility ... but you are wasting bthat movement because once you got to the neck, "you have no more cone" to help you.
This clever guy attached a very light mini-cone to the voice coil itself, which should be slightly longer, and got some extra high extension.
Not perfect, but not bad at all.
A common mistake is to glue the VC to cone with a relatively heavy bead of adhesive and attach whizzer there, the proper way is to use a slightly longer voice coil , a few mm are enough, and attach whizzer to it with its own bead of lighter adhesive, otherwise you are negating its advantages.
JBL and a few others, attach a light but rigid aluminum dome straight to VC former, same considerations.
People who have no clue glue large aluminum domes to the cone itself, far away from VC ... obviously end result is cosmetic only.
Re
To ghemml:
You misquoted me there, the way I said it was - "the wizzer starts playing the highest of frequencies for the 8 inch cone = more radiating surface for high frequencies." = the wizzer plays highs for the 8 inch cone (because the 8 inch cone can't) - that's the extra radiating surface - the "more" = the wizzer.
To JMFahey:
I was aware of all that but the question of the day (not my thread here) was about modifying cones to achive better dispersion and my answer was that it's impossible (because you can't magically stiffen up the cone to perfection to make it pistonic al the way up) , the general solution is an acoustic lens but that is not attached to the cone so it's not a mod. By the way - if you got all that information from an article I (and many others) would be very interested to read it. I have difficulties assembling the puzzle of what is going on in a fullrange cone - just bits of information here and there it's pretty slow, the norm is to dismiss the fullrange cone in most articles because it's not perfect (pistonic mode all the way up) so they don't bother too much with it.
To ghemml:
You misquoted me there, the way I said it was - "the wizzer starts playing the highest of frequencies for the 8 inch cone = more radiating surface for high frequencies." = the wizzer plays highs for the 8 inch cone (because the 8 inch cone can't) - that's the extra radiating surface - the "more" = the wizzer.
To JMFahey:
I was aware of all that but the question of the day (not my thread here) was about modifying cones to achive better dispersion and my answer was that it's impossible (because you can't magically stiffen up the cone to perfection to make it pistonic al the way up) , the general solution is an acoustic lens but that is not attached to the cone so it's not a mod. By the way - if you got all that information from an article I (and many others) would be very interested to read it. I have difficulties assembling the puzzle of what is going on in a fullrange cone - just bits of information here and there it's pretty slow, the norm is to dismiss the fullrange cone in most articles because it's not perfect (pistonic mode all the way up) so they don't bother too much with it.
Mechanical Discontinuity
ADC used to make a mechanical transition on their tweeters. Higher frequencies used a smaller part of the cone than the lower frequencies. I have done the same mods on cheap tweeters, but I would not sacrifice an expensive driver for such experiments. haha
Jim
ADC used to make a mechanical transition on their tweeters. Higher frequencies used a smaller part of the cone than the lower frequencies. I have done the same mods on cheap tweeters, but I would not sacrifice an expensive driver for such experiments. haha
Jim
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