calculating what amp i need

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=129087
Printed Date: May 09, 2025 at 11:08 AM

Topic: calculating what amp i need

Posted By: fiat1980spyder
Subject: calculating what amp i need
Date Posted: November 03, 2011 at 8:37 PM

I have a 1980 Fiat spider convertible. While the top was down I always had a a problem hearing the speakers since they were placed on the corners near my feet so i made a custom box and installed Alpine type R components in the box and the tweeters a bit higher, Initially i had a Boss 800Watt amp from a friend but that eneded up burning out so now I need to get another amp and wanted to know that size amp to get.

The deck is a Sony CDX-S2000-Specs.
https://www......com/item_1929_Sony-CDX-S2000.html

Speakers Alpine Type-R SPR-17LP-Specs.
https://www.crutchfield.com/S-ZC4Gq8qOnvq/p_500SPR17LP/Alpine-Type-R-SPR-17LP.html

Car had a 65Amp alternator

Is there some type of calculation?

Replies:

Posted By: DYohn
Date Posted: November 05, 2011 at 11:26 AM

Here's the method I use. First, calculate how much money you can spend. Decide how many output channels you require (if it's for subs, usually that means mono.) Decide how low a load it must handle (how are you wiring the subs?) Then, ignore all the low-end brands (like Boss. Crunch, etc) and purchase the best amp you can possibly afford from a good quality manufacturer (like Alpine, JBL, JL Audio, etc.) ignoring things like power rating. Install it properly. Rock and roll.

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Posted By: fiat1980spyder
Date Posted: November 06, 2011 at 10:14 AM

In terms of load how would I find that? This is for component speakers no subs.

Saids
RMS range is 2-50watts
RMS max is 250

Posted By: DYohn
Date Posted: November 06, 2011 at 11:08 PM

What's the impedance of each set? 4-ohms? 2-ohms? That's the load it places on the amp.

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Posted By: fiat1980spyder
Date Posted: November 07, 2011 at 3:02 PM

4 ohms

Sensitivity: 87 dB at 1 watt

Frequency Response: 35 - 30k Hz

RMS Power Range (Watts):2-50

Peak Power Handling (Watts):250

Impedance (Ohms):4

Posted By: DYohn
Date Posted: November 07, 2011 at 7:42 PM

50 watts per channel @ 4-ohms.

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Posted By: fiat1980spyder
Date Posted: November 08, 2011 at 1:51 PM

you figured that by the range??

Posted By: DYohn
Date Posted: November 08, 2011 at 4:30 PM

You said the speakers are 4-ohms and are rated at 50 watts RMS. That's all you need to know.

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