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So why do I need 1000s of watts to drive a subwoofer?
So why do I need 1000s of watts to drive a subwoofer?
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Old 5th July 2019, 03:19 PM   #1
grahamricho is offline grahamricho  United Kingdom
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Default So why do I need 1000s of watts to drive a subwoofer?

I'm building a 18 inch subwoofer with a dayton ultimax 18 inch driver, everybody tells me I need a inuke 6000 which outputs 2000 watts per channel? Why do I need that many watts?
My previous subs a pair of 12 inch sealed I ran from a Anthony gallo amp which had a built in crossover and was rated at 250 watts and seem to drive the 12 inch drivers fine ?
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Old 5th July 2019, 03:42 PM   #2
Cal Weldon is offline Cal Weldon  Canada
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So why do I need 1000s of watts to drive a subwoofer?
You don't but keep in mind that 10x the power is an increase of only 10 dB which translates to 2x perceived loudness. I think they are recommending the amp as it's hard to beat the price point and it will offer you a good amount of headroom.
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Old 5th July 2019, 03:50 PM   #3
tonskulus is offline tonskulus  Finland
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Big amp is only needed if you want to push your sub up to its limits.
Surely 18 inch sub will usually give lots of bass even at 50watts but as said, its not bad thing to have some headroom
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Old 5th July 2019, 03:59 PM   #4
Cal Weldon is offline Cal Weldon  Canada
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So why do I need 1000s of watts to drive a subwoofer?
You will need either a PLLXO or a bass control unit to low pass the signal but even so, it's hard to imagine trying to do this set up for this price even 10 years ago. I have paid more for plate amps with 1/10 the power.
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Old 5th July 2019, 04:30 PM   #5
chris661 is offline chris661  United Kingdom
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You only need large power inputs when efficiency is low and high SPLs are desired.

A lot of modern subs are very small sealed boxes, and Hoffman's Iron Law states that those subs must be very inefficient at low frequencies. As a result, if you want useful volume levels from such a subwoofer, you're going to have to dump lots of power in there.

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Old 5th July 2019, 04:53 PM   #6
bentoronto is offline bentoronto  Canada
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So why do I need 1000s of watts to drive a subwoofer?
I blame it on the scarcity of otherwise authoritative-sounding people owning oscilloscopes. Because that's the way you see how many volts are going into a speaker instead of all this hypothetical chit-chat.

Funny thing, nobody seems to mention that one acoustic watt will destroy your hearing. And work the efficiency formula from there. Assuming you could produce one acoustic watt at home.*

As far as sizing amps, the real criterion is instantaneous (or momentary) voltage peaks and how you feel about the audibility of flubbing an occasional peak, say once every 10 minutes while you are blasting you and your neighbours? There's no objective answer to that question (and the answer is different for tweeters). But in many spheres of design where rational people work, the thinking is sort of "OK to have floods every X years....".

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Old 5th July 2019, 05:19 PM   #7
wiseoldtech is offline wiseoldtech  United States
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A bit off topic, but WHY is there a need for such wattage and high DB thumping bass in a vehicle?
I'm sure the replies will be varied, but to me it's annoying and inconsiderate, to say the least.
To me, the resulting sonics inside the vehicle are pure vibration of everything that can rattle, not to mention damage due to hearing loss.
And it's not an enjoyment of music, particularly the vile lytics that I've heard quite clearly from hundreds of feet away while relaxing on my sofa.
What is the attraction?
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Old 5th July 2019, 05:37 PM   #8
freddi is offline freddi  United States
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So why do I need 1000s of watts to drive a subwoofer?
I once ran mono, one old beat Karlson K15 re-tuned to ~28Hz per Exemplar with a bit of boost at fb and Altec 416z(? - qts ~0.23) off one channel of a weak JC Penney receiver (maybe 20w/channel) with the receiver's other channel driving a Karlson 12 with vintage weak-motor Allied Knight coax (maybe Jensen) and 80Hz xover. The sound was fabulous on theater organ cds. Perhaps the old Altec's low mass and good linearity had something to do with the lack of muddiness or droning.

Last edited by freddi; 5th July 2019 at 05:43 PM.
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Old 5th July 2019, 05:58 PM   #9
chris661 is offline chris661  United Kingdom
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Quote:
Originally Posted by wiseoldtech View Post
What is the attraction?
Because it's fun!

A little while ago, I experienced a system with 16x horn-loaded 18" drivers, with kilowatts behind them.

I had earplugs in, of course. The thing was this - at that sort of level, the bass was as much felt as heard. The sensation is like nothing else, and can be very addictive - just as some people like rollercoasters or sky diving, some people like to seek the most intense bass they can find.

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Old 5th July 2019, 05:59 PM   #10
norman bates is offline norman bates  United States
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Car is a bit different.

Otherwise, I plan on 100 watts per driver, thats about it, +20db.

Even then, a 100 watt amp into 8ohms, that's tested into a resistor.
A speaker is more of an inductor, so there is a phase angle to the power.
100 watts really is more like 50 watts through the speaker.
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