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Old 13th November 2007, 00:15   #1
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Default Calculating Sub Wattage

I read this article online that said that on an average you should provide 200W RMS to a 12" sub. That's okay when you are getting a separate monoblock / 2Ch amp for it. But how do you calculate what a 4Ch amp would give it?

For example, the Blaupunkt GTA 4 amp has a rating of RMS Power@4 ohms 4x60 / 2x180 watts. So how does that work? I am confused about how 4 channel means 240W RMS (4 x 60) but 2 channel means 360W RMS (2 x 180).

In the above example with this amp, is it fair to say that if I connected two component speakers in the front, and one sub in the rear, the components would get 60W each, and the Sub would get 180W? (so total 300W RMS?)
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Old 13th November 2007, 10:29   #2
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Originally Posted by vebmetal View Post
For example, the Blaupunkt GTA 4 amp has a rating of RMS Power@4 ohms 4x60 / 2x180 watts. So how does that work? I am confused about how 4 channel means 240W RMS (4 x 60) but 2 channel means 360W RMS (2 x 180).
In bridged mode, amps put out more power than in stereo mode. Thats why the latter number is higher in your example. If you want to get the full 360W, you have to use the amp in 2-ch mode, i.e. both channels bridged.
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Old 13th November 2007, 11:04   #3
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Originally Posted by vebmetal View Post
I read this article online that said that on an average you should provide 200W RMS to a 12" sub. That's okay when you are getting a separate monoblock / 2Ch amp for it. But how do you calculate what a 4Ch amp would give it?

For example, the Blaupunkt GTA 4 amp has a rating of RMS Power@4 ohms 4x60 / 2x180 watts. So how does that work? I am confused about how 4 channel means 240W RMS (4 x 60) but 2 channel means 360W RMS (2 x 180).

In the above example with this amp, is it fair to say that if I connected two component speakers in the front, and one sub in the rear, the components would get 60W each, and the Sub would get 180W? (so total 300W RMS?)
check the manual. they have break-ups.

a 4 channel amp usually will have:
4 x XYZw
2 x XYZw + 1 x XYZw
and
1 x XYZw

if its 100w @ 4 ohm
then 200w @ 2 ohm
and 400w @ 1 ohm

and yes, like B&T says, if you bridge, again you have different output.

however, it is wrong to presume "on an average you need 200w for a 12" sub". all subs have different power ratings.
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Old 13th November 2007, 15:56   #4
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Originally Posted by vebmetal View Post
I read this article online that said that on an average you should provide 200W RMS to a 12" sub. That's okay when you are getting a separate monoblock / 2Ch amp for it. But how do you calculate what a 4Ch amp would give it?

For example, the Blaupunkt GTA 4 amp has a rating of RMS Power@4 ohms 4x60 / 2x180 watts. So how does that work? I am confused about how 4 channel means 240W RMS (4 x 60) but 2 channel means 360W RMS (2 x 180).

In the above example with this amp, is it fair to say that if I connected two component speakers in the front, and one sub in the rear, the components would get 60W each, and the Sub would get 180W? (so total 300W RMS?)
hi,

there are subs which can take a lot more power. it is wrong to just take an average of 200w.

yes, that means your comps will get 60w each and the sub will get 180.
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Old 13th November 2007, 18:14   #5
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Originally Posted by Bass&Trouble View Post
If you want to get the full 360W, you have to use the amp in 2-ch mode, i.e. both channels bridged.
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Originally Posted by clipto333 View Post
yes, that means your comps will get 60w each and the sub will get 180.

So which one is right? For calculations sake, let's say I get the Blaupunkt GTA 480 which is rated RMS power (4 ohms) 4 x 75 W / 2 x 210 W. Would the config be #1 or #2?


#1) Front components: 75W each
Subwoofer: 210W

#2) Front Components: 75W each
Subwoofer: 150W (i.e. 75W x 2)
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Old 14th November 2007, 00:05   #6
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Originally Posted by vebmetal View Post
So which one is right? For calculations sake, let's say I get the Blaupunkt GTA 480 which is rated RMS power (4 ohms) 4 x 75 W / 2 x 210 W. Would the config be #1 or #2?


#1) Front components: 75W each
Subwoofer: 210W

#2) Front Components: 75W each
Subwoofer: 150W (i.e. 75W x 2)
if you use 2 channels for speakers and 1 for the sub, it should be:
2 channels: 2 x 75w (4ohms)
1 channel bridged: 1 x 150w. (4ohms)
or
1 channel bridged: 1 x 300w. (2ohms). if you want more go for a 4ohm DVC subwoofer rated for 300-400w @ 2 ohms.

i'm surprised. doesn't the manual or the tech sheet have this? please check.
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Old 14th November 2007, 12:52   #7
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So which one is right?
# 1

Quote:
Originally Posted by montyguru
1 channel bridged: 1 x 150w. (4ohms)
or
1 channel bridged: 1 x 300w. (2ohms).
Its a Blau 480 yaar. That would be a bit too much to ask.
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