Correct the upper peaks marked in orange are around -22 dB and -25dB down and rather inaudible.
As for the bandwidth of the tweeter only -10 dB down.
The contribution to overall signal is more of course, and is visible in overall SPL how it sums with the Mid.
Good enough as many would say. The issue is that the tweeter is reproducing more frequencies closer to its physical
capabilities for low frequency. As noted the resonant frequency being a big hint.
At low listening levels likely little issues, At higher SPL likely where typical tweeter distortion is found. Though reduced by the filter
its still producing lower frequency. So you simply use a higher order filter like 3rd or 4th order which will bring the -10 dB portion down lower.
Of course the Mid being second order and now asymmetric filter. It is very important their absolute positions are modeled
So any phase issue will be visible for summing. Simplified You will get dips or peaks in final SPL and use the model to flatten it like any other. Not only is phase determined by its physical location to other drivers .The filter order also changes the phase response. Which can actually be helpful.
As far as center to center spacing. The actual physical mounting distances from each other based on the driver center.
Or simply how far apart they are mounted Vertically or Horizontally. likely helpful displayed graphically.
The driver phase response is what it is of course. But the phase response changes according to its physical location
to other drivers. This is why the Model includes XYZ coordinates. So your modeling the actual true phase relations.
And not making a model where drivers are physically impossible to even be mounted as so. Being they have physical size of
course and the actual physical mounting area make it physically impossible to be mounted closer. Hence very important
in the model.
Before I do a Crossover Model I create a Cad drawing and mark the actual physical locations. So the model is correct
and make sure it is even physically possible to mount them as modeled. Example drawing to just show tweeter and mid
center to center location on X and Y axis and how - negative and positive coordinates relate to VirtuixCad
( click to enlarge)
Anyone that publishes driver measurements and consistent distortion measurements in particular has earned sainthood in my opinion. A true hero around here. I rely heavily on distortion data and Xmax values to do speaker design. It's a drag to have to buy five different drivers, test them and then return the losers. So any published reliable test data is total gold.
I like to use drivers where the distortion is 0.1% at my relatively modest listening level. The lower rated soft dome driver distortion is clearly higher than the others, so I would pass on that driver. None of these have distortion down -60 dB ( ie 0.1% ), but I have not looked to see the SPL that these were tested at.
I like to use drivers where the distortion is 0.1% at my relatively modest listening level. The lower rated soft dome driver distortion is clearly higher than the others, so I would pass on that driver. None of these have distortion down -60 dB ( ie 0.1% ), but I have not looked to see the SPL that these were tested at.
SPL would match the data sheet being tested as shown 2.83 volts.
Taking Dayton Aluminum in mind 90 dB
Rather good for a 2" dome mid.
Even if you found some amazing low distortion 2" cone driver. Sensitivity would be nowhere close try 80 to 85 dB at best
So applying enough power to even match 90 dB the distortion ratings = No where close.
The Aluminum dome mid at 90 dB is already well within your needs H2 H3 within -60 to - 52
Keeping in mind the test high pass filters range from 200 to 400 Hz 2nd order
300 Hz respectively for Aluminum dayton.
Being some recent designs planned for the Dayton Mid was using approx. 700 Hz 3rd Order Highpass
And also 3rd order lowpass.
To even match the SPL with a " low distortion" cone mid and highly likely 2x to 3x the price.
Again = No where close
And if the designers incorporates well chosen high order crossover points to extend performance.
Expect the same as always. Dam good for way less money, usually better than 2x or 3x cost drivers.
Excluding the fact the 2" cone allows extremely small tweeters for high frequency performance
and extremely low center to center spacing.
Taking Dayton Aluminum in mind 90 dB
Rather good for a 2" dome mid.
Even if you found some amazing low distortion 2" cone driver. Sensitivity would be nowhere close try 80 to 85 dB at best
So applying enough power to even match 90 dB the distortion ratings = No where close.
The Aluminum dome mid at 90 dB is already well within your needs H2 H3 within -60 to - 52
Keeping in mind the test high pass filters range from 200 to 400 Hz 2nd order
300 Hz respectively for Aluminum dayton.
Being some recent designs planned for the Dayton Mid was using approx. 700 Hz 3rd Order Highpass
And also 3rd order lowpass.
To even match the SPL with a " low distortion" cone mid and highly likely 2x to 3x the price.
Again = No where close
And if the designers incorporates well chosen high order crossover points to extend performance.
Expect the same as always. Dam good for way less money, usually better than 2x or 3x cost drivers.
Excluding the fact the 2" cone allows extremely small tweeters for high frequency performance
and extremely low center to center spacing.
Last edited:
I now better understand the situation. In the end, it's a very long tweeter for your application, which detracts from its objective performance at higher frequencies. From the simulations, it seems quite clear that it can produce a reasonable-looking on-axis response. However, you may find that, at higher frequencies, the response in the vertical plane is characterized by the presence of several off-axis lobes. That is a less-than-ideal situation regarding the sound radiation pattern.
You will need to enclose the back of them, otherwise they will be affected by the pressures generated by the lower-frequency driver. In any case, the filter cut-off frequency needs to be increased.
Adding a horn to adjust the radiation pattern may be helpful. However, there may be some peaks and dips added to the response as a result of the horn loading, which may detract from the natural smooth response of the driver.
The smaller planar tweeter is the best option overall. It will have a more "traditional" radiation pattern and will be able to blend in quite nicely with the low-pass filtered output from the dome midrange unit.
Most mid domes can't go low enough to cross to a sub, like at all. Even the ATC SM75 needs 400hz; forget this for the Dayton. Midbass will be horrible like $5 computer sub sats of the 1990s. You want/need a 4-way! 😉 Or a cone. 😢
Last edited:
It's important to keep in mind that a driver-inherent resonance may be attenuated for frequency response by chosing appropriate crossover parameters, but usually the distortion also follows the response curve.
So e.g. a steep 3 kHz resonance peak may be attenuated by crossover to get a smooth response, but there will usually also be a strong h3 peak for a 1 kHz tone, still in the driver passband.
This can be adressed by a notch filter, see purify publication.
Yeah audibility threshold of those breakup peaks could vary depending how the system is implemented. Simple thought experiment between passive and active systems as an example: think your amplifier is bad and has lots of noise. Passive filter for a woofer would low pass the noise, while active doesn't. Even if both systems could measure about same for an input signal, the active system would have much more apparent audible noise as it's not low passed, and even has the peak sticking out like sore thumb. Well yeah the tweeter would also have the noise, but now imagine the noise barely audible and you'd likely hear the peak fade out last.
More over, a cone resonance peak in on-axis response is often a dip off-axis the noisy version might not sound too bad listened off-axis, but if you happen to pass on-axis, like walk around the room, the on-axis would likely reveal itself. This means it is one aspect on speakers that make sound vary through out the room. Whether this matters or not is everyone to try out, audibility of stuff like this depends.
More over, a cone resonance peak in on-axis response is often a dip off-axis the noisy version might not sound too bad listened off-axis, but if you happen to pass on-axis, like walk around the room, the on-axis would likely reveal itself. This means it is one aspect on speakers that make sound vary through out the room. Whether this matters or not is everyone to try out, audibility of stuff like this depends.
White,
This is what I have been doing
I know a dome would be more optimal here but as STV said, they won't cross down to a sub. This turns the whole thing into a 4 way. It still might be worth it as I spend most of my days at work and probably listen to my desk unit more than any others.
I have also considered using both the mid/tweeter planar AND the planar tweeter. Bandpass the mid and it would cross to the sub and tweeter making it a 3 way again. The advantage here is a very small horizontal footprint between my 3 monitors. I could then run the sub underneath the monitors somehow. I haven't quite worked it all out yet.
This is what I have been doing
I did plan to model up an enclosure for the back in a sort of enclosed folded horn. This would be packed with wool to dampen the rear reflections.
I know a dome would be more optimal here but as STV said, they won't cross down to a sub. This turns the whole thing into a 4 way. It still might be worth it as I spend most of my days at work and probably listen to my desk unit more than any others.
I have also considered using both the mid/tweeter planar AND the planar tweeter. Bandpass the mid and it would cross to the sub and tweeter making it a 3 way again. The advantage here is a very small horizontal footprint between my 3 monitors. I could then run the sub underneath the monitors somehow. I haven't quite worked it all out yet.
^only if the filter makes high series impedance with teh driver at the resonance. The peak is mechanical resonance of the cone itself, so it happens regadless of any crossovers since the crossovers do not modify the cone physically, right, no matter what the excitation the cone boosts it as the peak indicates. This also means the amplifier noise, or any anomaly in current like driver motor distortion gets amplified by the resonance. The purifi article shows how a filter can notch all currents in circuit including driver motor distortion generated, and the distortion is effectively equalized just like the main input signal. If you do this any other way than with series impedance the resonance peak amplifies the motor distortion. Sometimes you'll get high impedance in series with the driver just with the low pass network, sometimes you might not, depending on which frequency things are at. If the resonance peak is big you might want to notch it, like in the Purifi doc. Two peaks, perhaps two notches.
If this feel silly explanation you must read the article again and perhaps consider reading about "current drive", which has same distortion reduction mechanism, high series impedance for the driver 🙂
If this feel silly explanation you must read the article again and perhaps consider reading about "current drive", which has same distortion reduction mechanism, high series impedance for the driver 🙂
I understand it now. Impendence is the only real way to tame breakup distortion. You cannot actively dumb down the signal at a line level and get the same effect
A simpler approach, albeit not as accurate, is to use an elliptical LP filter to attenuate a HF woofer cone resonance. With a 2nd order LP, add a capacitor across the inductor. Effectiveness of this approach depends on many factors. I've had much success with it when applied to 2W, XO at 2KHz designs with metal cone woofers.
In the case of the 2" AL dome mid, a diffuser can also quite effectively reduce the amplitude of the HF dome resonance just as it does on a metal dome tweeter. Nothing new here... you'll see it on the classic Yamaha NS1000 Be mid (and tweeter).
In the case of the 2" AL dome mid, a diffuser can also quite effectively reduce the amplitude of the HF dome resonance just as it does on a metal dome tweeter. Nothing new here... you'll see it on the classic Yamaha NS1000 Be mid (and tweeter).