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Old 23rd July 2003, 01:02 PM   #11
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Navin,

For subs? Nope.. You don't need some esoteric "high end" amp
to drive a sub woofer.. Any amplifiers distorsion figures will be
far better than a subwoofers distorsion. I'd stick with the elite,
expensive amps on the top end.. Use Pro or Plates for the subs.

But that is, as always just my opinion and YMMV
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Old 23rd July 2003, 01:04 PM   #12
navin is offline navin  India
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dont those plate amps have awfully small power supplies. i thoguth you need a lot of curent dumping capacity (read as big power supply) to feed subs. yes you might not need class A but a big power supply is certainly required. and these are expensive.
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Old 23rd July 2003, 01:07 PM   #13
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What Navin is trying to say, and I have had the same thoughts, is that when you take a look at some of these superheavyweights and see such low sensitivities, you have to wonder if you wouldn't be better off with a small excursioned driver and a smaller amp.

At some point, the sensitivity is so low that you never get to use the extra excursion because your maximum rated power has run out. When you have your amplifier having to play 500 watts to achieve the same SPL that a more efficient driver only has to play 125 watts to achieve, the SPL won't be that high when the maximum power input is achieved.

This is another argument in favor of ported subs, which cut cone excursion by 4 at the resonance point. This allows the use of a shorter voice coil, therefore makes for a more sensitive sub. However, ported is not necessarily the best choice in every subwoofer application.
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Old 23rd July 2003, 01:10 PM   #14
7V is offline 7V  United Kingdom
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Quote:
Originally posted by kelticwizard
Here is a link to a chart of Room Gain. This is an approximation-other charts will differ slightly.

It's all guesswork because of the room and it's modes anyway, but at least you can get an idea.

http://www.speakerbuilding.com/content/1020/rge.gif
So, roughly speaking you're 5dB down at 20Hz (relative to 30Hz). When you take into account the dramatic frequency peaks and troughs brought about by room resonances at bass frequencies I would say that this 5dB is, in practice, virtually insignificant.

Also, if you're planning to place a single subwoofer in a corner of the room in order to couple it to the room (a reasonable approach) then you can assume that the sub would be boosted by the room. You would probably need approximately 3dB less than the maximum SPL of your main speakers (+6dB for the room, -3db because there's only one sub but two mains).
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Old 23rd July 2003, 01:15 PM   #15
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Quote:
Originally posted by Brett D.
It's highly unlikely that a
driver with a robust suspension will have a short voice coil as that
goes against what it was designed for.


That being said, give me the large excursion driver any day, no
matter what the sensitivity is.. I don't even consider sensitivity
unless I am looking at midrange and tweeters.
Brett:

Actually, the example I gave of a 0.5" voice coil really wouldn't be adequate for any sub that anyone would want. What I meant was, when you have a choice between a 1" excursion, (midpoint-to-extreme) sub of 84 dB, and a 0.5" excursion, (midpoint-to-extreme) sub of 88 dB, you might be better off going with the more efficient sub in terms of maximum SPL's produced at the lowest frequency.

Everything is a balance.
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Old 23rd July 2003, 01:44 PM   #16
subwo1 is offline subwo1  United States
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Quote:
Originally posted by kelticwizard


Brett:

Actually, the example I gave of a 0.5" voice coil really wouldn't be adequate for any sub that anyone would want. What I meant was, when you have a choice between a 1" excursion, (midpoint-to-extreme) sub of 84 dB, and a 0.5" excursion, (midpoint-to-extreme) sub of 88 dB, you might be better off going with the more efficient sub in terms of maximum SPL's produced at the lowest frequency.

Everything is a balance.
Some woofers may get a boost in SPL rating by using tighter suspension, not more flux on the voice coil.
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Old 23rd July 2003, 06:15 PM   #17
navin is offline navin  India
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thanks kelticwizard
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Old 23rd July 2003, 07:58 PM   #18
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Quote:
Originally posted by navin

Ex: Driver with Xmax 27mm sens is 84db, Driver with Xmax 13mm Sens is 89db and Driver with Xmax 9mm Sens is 92db (all these 3 are well known 12" drivers).

Xmax=27mm?? You mean +/- 27mm?

I thought that +/-10mm was already a very high Xmax, like the Peerless XLS range.

Which drivers are you refering to Navin?
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Old 23rd July 2003, 08:17 PM   #19
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i saw them on the net. i guess one of the others will have a link. i dont use bookmarks.
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Old 23rd July 2003, 08:49 PM   #20
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Quote:
Originally posted by DIY_Peter



Xmax=27mm?? You mean +/- 27mm?

I thought that +/-10mm was already a very high Xmax, like the Peerless XLS range.

Which drivers are you refering to Navin?
I believe the Blueprint 1503 and 1203 had Xmax 25 mm, in fact a little over. Then there is the TC Sounds with linear excursions 1.5 inches. Adire has a huge subwoofer that is 1 inch as well.

I am not certain, but I think one of the models of Strykes is made by TC Sounds. It could be the very model this thread is about.

And yes, even 10 mm is very good. It used to be the best subwoofers around had excursions of 0.25", (6mm), until the Excursion Race started about a dozen years ago.

http://www.tcsounds.com/
http://www.adireaudio.com/diy_audio/...ire/tumult.htm
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