Distorsion on Maelstrom VS Tumult! - diyAudio
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Old 16th December 2004, 08:48 PM   #1
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Default Distorsion on Maelstrom VS Tumult!

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

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Old 16th December 2004, 11:14 PM   #2
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Harmnoic distortion isnt everything. the distortion curves are flatter on the tumult too
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Old 16th December 2004, 11:18 PM   #3
morbo is offline morbo  Canada
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thanks for posting the results of your testing, very interesting!
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Old 17th December 2004, 05:46 AM   #4
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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
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Old 17th December 2004, 10:35 AM   #5
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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
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Old 17th December 2004, 03:31 PM   #6
morbo is offline morbo  Canada
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That is an interesting idea.. I've always wondered how much an isobaric loading really lowers distortion. Because like you said, the subs that are now 'mid-price' like Shiva, tempest, maelstrom, titanic etc., are cheap enough that you could use them isobaric if it really helped that much.
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Old 17th December 2004, 04:24 PM   #7
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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
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Old 19th December 2004, 05:11 PM   #8
Kranis is offline Kranis  Sweden
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Quote:
Originally posted by DanWiggins
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
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
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Old 19th December 2004, 05:56 PM   #9
jdybnis is offline jdybnis  United States
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Why does push-pull driver configuration generally reduce even-order harmonics?
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Old 19th December 2004, 09:09 PM   #10
morbo is offline morbo  Canada
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good to know, thanks for the info!
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