Hello!
Here is some measurements on the Adire Maelstrom and Tumult
They are done in free air.
I really didnt think that the Maelstrom should look as good or even better then the Tumult when it comes to low distorsion but it did, I am anyhow really satisfied with the Tumult and think that it is an extreme Woofer, but the distorsion could have been a little lower. The measurement is done by a professional and with a microphone in the 15000 US$ range so I think theese numbers are all good.
Fig1. dB at the 4 stages of the Maelstrom
Fig2. 2nd and 3rd tone distorsion of the Maelstrom, blue is 2nd
Fig 3 dB at the 4 stages of the Tumult
Fig4. 2nd and 3rd tone distorsion of the Tumult, blue is 2nd
Here is some measurements on the Adire Maelstrom and Tumult
They are done in free air.
I really didnt think that the Maelstrom should look as good or even better then the Tumult when it comes to low distorsion but it did, I am anyhow really satisfied with the Tumult and think that it is an extreme Woofer, but the distorsion could have been a little lower. The measurement is done by a professional and with a microphone in the 15000 US$ range so I think theese numbers are all good.
Fig1. dB at the 4 stages of the Maelstrom
Fig2. 2nd and 3rd tone distorsion of the Maelstrom, blue is 2nd
Fig 3 dB at the 4 stages of the Tumult
Fig4. 2nd and 3rd tone distorsion of the Tumult, blue is 2nd
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Couple of thoughts...
Down in the deeper bass (below 40 Hz) the Tumult has significantly more output. Note at 20 Hz, the Tumult is generating approximately 7 dB more output than the Maelstrom.
The Maelstrom's THD curves look about right for low level SPLs; it won't do > 105 dB SPL @ 20 Hz with less than 5% THD.
The Maelstrom curves are correct in that they lower the THD around resonance - as expected. This does not show up in the Tumult, which is unexpected. THD in a free-air driver always drops around resonance. There's something not right in the THD measurements of the Tumult.
Dan Wiggins
Adire Audio
Down in the deeper bass (below 40 Hz) the Tumult has significantly more output. Note at 20 Hz, the Tumult is generating approximately 7 dB more output than the Maelstrom.
The Maelstrom's THD curves look about right for low level SPLs; it won't do > 105 dB SPL @ 20 Hz with less than 5% THD.
The Maelstrom curves are correct in that they lower the THD around resonance - as expected. This does not show up in the Tumult, which is unexpected. THD in a free-air driver always drops around resonance. There's something not right in the THD measurements of the Tumult.
Dan Wiggins
Adire Audio
ello Dan!
Nice to hear from you!
We did the measurments in the same room and on the same equipment.
We also thought that the curves looked strange especially since the 2nd tone distorsion didnt have that curved form.
We added the coils in series when we took the measurement of the Tumult cause the amplifier at the time couldnt take lower then 3ohm loads.
When it comes to the Maelstrom and Shiva (I assume that shiva have around the same distorsion curve as Malestrom)
we can see that they are very potent woofer but.... if people buy 2 of them and add in push/pull to lower the 2nd order distorsion they
are really mean little *******s and probbably have lower distorsion then anything else on the market from 15-80Hz
Nice to hear from you!
We did the measurments in the same room and on the same equipment.
We also thought that the curves looked strange especially since the 2nd tone distorsion didnt have that curved form.
We added the coils in series when we took the measurement of the Tumult cause the amplifier at the time couldnt take lower then 3ohm loads.
When it comes to the Maelstrom and Shiva (I assume that shiva have around the same distorsion curve as Malestrom)
we can see that they are very potent woofer but.... if people buy 2 of them and add in push/pull to lower the 2nd order distorsion they
are really mean little *******s and probbably have lower distorsion then anything else on the market from 15-80Hz
Isobaric loading does help to a certain extent, but a lot of the THD from BL - and especially from Cms - nonlinearities are odd order, so isobaric won't really help all that much.
We've seen a reduction in THD levels around 1.5 to 2 dB, when isobaric loading. You're better off running both drivers facing the room, and halve the excursion of each unit for a given SPL level. That does result in a bigger box, but definitely lowers the THD more than isobaric loading.
Dan Wiggins
Adire Audio
We've seen a reduction in THD levels around 1.5 to 2 dB, when isobaric loading. You're better off running both drivers facing the room, and halve the excursion of each unit for a given SPL level. That does result in a bigger box, but definitely lowers the THD more than isobaric loading.
Dan Wiggins
Adire Audio
DanWiggins said:
A third possibility would be to have both drivers in contact with the room, but inverting one, (magnet towards the room). Aesthetics aside, this would also contribute to cancellation of the second harmonic, as long as the wavelength produced is long compared to the distance between the drivers.
/Kranis
jdybnis said:
2nd-order distortion or harmonics exist when the positive and negative halves of the signal are not amplified by the same amount: there is an imbalance. Making the drivers work in opposite directions makes the sum of the halves equal, or at least more equal. If "a" is the positive half and "b" is the negative in a driver, the sums "a+b" and "b+a" using two drivers in opposite directions will be the same whether "a" and "b" are equal or not. This of course assumes identical drivers. Push-pull is not necessary: both drivers can face the room. Connecting drivers in a true push-pull is in my opinion primarily a way to get away with smaller enclosures. This may be a very valid reason in itself when space is premium. Cancellation of the second harmonic by a push-pull arrangement is not only seen in loudspeakers also in amplifers, whether solid state or valve.
/Kranis
"Why does push-pull driver configuration generally reduce even-order harmonics?"
A way of looking at the subject;
When a device distorts with 2nd order harmonics it means that the peak of the sinwave is made bigger, and the negative dip is made smaller. IOW the waveform is distorted in a non-symmetrical fashion (the positive and negative part of a sinewave is affected "differently").
If you have two identical drivers and turn one driver around the distortion is reduced due to cancellation.... the summed output becomes symmetric.
Or;
let´s say we put in a pure sinewave into the driver, with a voltage of +1V peak and -1V peak. An ideal driver will give an equivalent airpressure of let´s say +1Pa and -1Pa oscillating around the atmospheric airpressure.
If the driver has 2nd order harmonic distortion the +/-1V will not give +/-1Pa, but something like +1.1V and -0.9. Not only the peak values will differ but the whole waveform will lok slightly different
even closer to the zero crossing.
Now, by pure math we can see that adding a second identical driver facing the opposite way, the distortion will cancel; 1.1+0.9=2... 0.9+1.1=2. The peak and dips have the same value and the distortion dissapear.
/Peter
A way of looking at the subject;
When a device distorts with 2nd order harmonics it means that the peak of the sinwave is made bigger, and the negative dip is made smaller. IOW the waveform is distorted in a non-symmetrical fashion (the positive and negative part of a sinewave is affected "differently").
If you have two identical drivers and turn one driver around the distortion is reduced due to cancellation.... the summed output becomes symmetric.
Or;
let´s say we put in a pure sinewave into the driver, with a voltage of +1V peak and -1V peak. An ideal driver will give an equivalent airpressure of let´s say +1Pa and -1Pa oscillating around the atmospheric airpressure.
If the driver has 2nd order harmonic distortion the +/-1V will not give +/-1Pa, but something like +1.1V and -0.9. Not only the peak values will differ but the whole waveform will lok slightly different
even closer to the zero crossing.
Now, by pure math we can see that adding a second identical driver facing the opposite way, the distortion will cancel; 1.1+0.9=2... 0.9+1.1=2. The peak and dips have the same value and the distortion dissapear.
/Peter
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