does preamp outputs have watts?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=104878
Printed Date: May 12, 2025 at 9:10 PM

Topic: does preamp outputs have watts?

Posted By: iwanttobang
Subject: does preamp outputs have watts?
Date Posted: May 20, 2008 at 9:57 PM

So would if my car stereo is 25x4 rms. So if I use the preamp out puts into a 25x4 amp will my total amps per speaker be 50 watts?
Basically when using the preamp outputs from the deck does the system still sees the deck power?

Replies:

Posted By: DYohn
Date Posted: May 20, 2008 at 10:07 PM

No. The power rating of an amplifier is what it can deliver into a speaker. A head unit is no different, the power rating is for the built-in amplifier.

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Posted By: stevdart
Date Posted: May 20, 2008 at 10:10 PM

No it doesn't. The deck acts as a preamp when the speakers are connected to a power amp. It amounts to this: an amplifier performs only when it is loaded with impedance at the input stage; no speakers to provide the load = no power output.

If a deck still had speakers loaded on it even when supplying a signal to a power amp, it would provide power to only those speakers. But it still wouldn't provide power to the amp.

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Posted By: iwanttobang
Date Posted: May 21, 2008 at 2:07 AM

stevdart wrote:

No it doesn't. The deck acts as a preamp when the speakers are connected to a power amp. It amounts to this: an amplifier performs only when it is loaded with impedance at the input stage; no speakers to provide the load = no power output.

If a deck still had speakers loaded on it even when supplying a signal to a power amp, it would provide power to only those speakers. But it still wouldn't provide power to the amp.

grrr..
I bought a Alpine MRPF240 4 Ch. 360 Watt Amplifier(which I just added . I swapped out my junk sound storm amp/ Alpine is much clearer). I was under the impression that the watts of my deck would add with the watts of the amp as well..

Well looks like when I buy a sub woofer I'm going to to to buy a more powerful amp for my highs right? The amp only dies 40x4 RMS @ 4 ohms
and 50x4 @2ohms

Posted By: jmelton86
Date Posted: May 21, 2008 at 2:25 AM

I have the exact same amp for my front stage. I doubt you'll need to upgrade from that. That is, if you have decent front speakers...

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Posted By: iwanttobang
Date Posted: May 21, 2008 at 3:04 PM

Yeah i have Kicker front and rear speakers. The front speakers have separate tweeters attached