Who makes the lowest distortion pro-sound subwoofers? - Page 2 - diyAudio
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Old 20th February 2008, 05:58 PM   #11
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JBL at least quote distortion data for their prosound woofers.

Sufficient multiples of their 18" devices (e.g. 2241) would move lots of air with low distortion.
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Old 20th February 2008, 10:54 PM   #12
MaVo is offline MaVo  Germany
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beyma and bms also show distortion measurements
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Old 21st February 2008, 01:19 PM   #13
iand is offline iand  United Kingdom
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If you're looking for a pro-audio subwoofer -- one that won't run out of linear Xmax at full power down to (say) 30Hz or below -- there are few choices.

Taking linear Xmax as (Hvc-Hg) and mathematical Xmax as Hvc-3Hg/4 (estimated to agree with DUMAX or Klippel Xmax), we have in order of descending mathematical Xmax (which is what most manufacturers quote):

1. Aura 1808/Seismic 8196 : 100mm underhung 25mm Al coil in 50mm gap
-- linear Xmax 13mm, mathematical Xmax 19mm
-- replaced the 6174 (see below), has lasted me for several years now
-- extremely expensive

2. McCauley 6174 : 100mm overhung 40mm Al coil in 10mm gap
-- linear Xmax 15mm, mathematical Xmax 17.5mm
-- relatively low BL, I fried one of these with repetitive 25Hz bass
-- very expensive, needs huge box

3. BMS 18N850V2 : 100mm overhung 38mm Cu coil in 12mm gap
-- linear Xmax 13mm, mathematical Xmax 16mm
-- just plain expensive, I will use this next time (since I need 4 drivers)

4. Ciare 12.00SW / 15.00SW : 100mm overhung 33mm Cu coil in 10mm gap
-- linear Xmax 11.5mm, mathematical Xmax 14mm
-- not much margin past Xmax before damage?

5. B&C 21SW150: 150mm overhung 32mm Cu coil in 12mm gap
-- linear Xmax 10mm, mathematical Xmax 13mm (B&C quote 15mm...)
-- extremely expensive 21" driver

6. B&C 18SW115 : 115mm overhung 29mm Cu coil in 11mm gap
-- linear Xmax 9mm, mathematical Xmax 12mm (B&C quote 14mm...)

7. Ciare NDH 15-4S : 100mm overhung 30mm Cu coil in 14mm gap
-- linear Xmax 8mm, mathematical Xmax 11.5mm

8. PD 2150 : 150mm overhung 30mm Cu coil in 15mm gap
-- linear Xmax 7.5mm, mathematical Xmax 11.5mm (PD quote 12mm)

Below these there are a lot of drivers with 25mm or shorter coils which shouldn't really call themselves *sub*woofers...

Out of all these the Aura/Seismic driver is probably the most linear, especially because there's very little flux or inductance modulation due to the underhung radial neo magnet structure. However it's not suitable for many enclosure types due to very low Qes, and is *very* expensive.

The McCauley needs a huge box and is (in my experience) a bit fragile, and it costs almost as much as the Aura (if you can find one).

The BMS is probably the best choice overall, it's pretty linear and quiet at high amplitudes, and works well in relatively small reflex boxes e.g. 140l tuned to 32Hz is close to ideal. It's about half the price of the Aura/Seismic driver.

The Ciare drivers are good and quite cheap but don't have as much displacement because the diameter is smaller.

The B&C and PD 21" look good at first, until you realise that they cost more than a pair of BMS18N850 and have lower power handling, efficiency and displacement.

Overall I'd say the BMS18N850V2 is the best bet -- the V1 has higher BL and Mmd which again makes it less useful except in a very big horn.

Ian
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Old 21st February 2008, 04:00 PM   #14
MaVo is offline MaVo  Germany
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Why limit yourself to linkwitz transformed IB? In comparison with more efficient designs, you loose alot of linear spl on this route, which you have to compensate with lots of drivers, which is like throwing money out of the window. If your goal is high spl and clean sound, nothing beats horns. And since the invention of tapped horns, they can also have a moderate size.
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Old 21st February 2008, 06:08 PM   #15
iand is offline iand  United Kingdom
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Quote:
Originally posted by MaVo
Why limit yourself to linkwitz transformed IB? In comparison with more efficient designs, you loose alot of linear spl on this route, which you have to compensate with lots of drivers, which is like throwing money out of the window. If your goal is high spl and clean sound, nothing beats horns. And since the invention of tapped horns, they can also have a moderate size.
Tapped horns aren't necessarily more efficient, lower distortion or have higher maximum output tha a reflex of the same size -- I'm just going to post an interesting comparison to the "Collaborative tapped horn project" thread...

Full-size horns are impossible to beat by definition, but oh boy are they big :-)

Ian
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Old 21st February 2008, 06:18 PM   #16
Eva is offline Eva  Spain
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Quote:
Originally posted by iand


Tapped horns aren't necessarily more efficient, lower distortion or have higher maximum output tha a reflex of the same size -- I'm just going to post an interesting comparison to the "Collaborative tapped horn project" thread...

Full-size horns are impossible to beat by definition, but oh boy are they big :-)

Ian
This is a risky statement. Remember that in a tapped horn the radiation from both sides of the driver is used and this already produces some gain by itself. Then you have the gain due to horn loading.

A bass reflex box has only one resonant mode (subject to vent "choking" non-linear effects at high SPL) and one corresponding frequency zone where cone displacement is reduced, but in a tapped horn you have several resonant modes and cone displacement nulls across the passband.
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Old 21st February 2008, 07:44 PM   #17
iand is offline iand  United Kingdom
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Quote:
Originally posted by Eva


This is a risky statement. Remember that in a tapped horn the radiation from both sides of the driver is used and this already produces some gain by itself. Then you have the gain due to horn loading.

A bass reflex box has only one resonant mode (subject to vent "choking" non-linear effects at high SPL) and one corresponding frequency zone where cone displacement is reduced, but in a tapped horn you have several resonant modes and cone displacement nulls across the passband.
True indeed, *if* you compare one driver in a tapped horn with one driver in a reflex, which is what Tom Danley did in his white paper when he concluded that a tapped horn was much superior. But he was really comparing it to the wrong thing (which is why I don't think my statement is risky)...

It turns out that if you compare one (expensive) driver in a tapped horn with two (cheaper) drivers in a reflex you end up with the same box size, efficiency, maximum output, cone travel, and cost -- see my (rather long) post to the tapped horn thread. If you don't believe me plug the numbers into Hornresp and you'll get the same answers.

Vent choking is only a problem if they're too small; each BMS18N850 needs a 200mm diameter port 500mm long, which is over 10% of the box volume but will not suffer this problem.

Ian
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Old 21st February 2008, 09:34 PM   #18
thadman is offline thadman  United States
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No love for 18sound drivers? They weren't even mentioned in your analysis.
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Old 21st February 2008, 10:11 PM   #19
iand is offline iand  United Kingdom
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Quote:
Originally posted by thadman
No love for 18sound drivers? They weren't even mentioned in your analysis.
18sound make some excellent drivers, but not for this purpose -- along with Beyma, DAC, RCF they fall into the category of "drivers with 25mm or shorter coils which shouldn't really call themselves *sub*woofers"... :-)

Ian

P.S. All the above are OK down to 40Hz or so without running out of Xmax, but not lower which is where I'd say a subwoofer should go.
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Old 22nd February 2008, 03:41 PM   #20
thadman is offline thadman  United States
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How reasonable would a 30-40hz horn be?
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