Largest Fused Amplifier I could add to a 750 Maxim?

Notes:
* New alternator brushes installed
* 100% LED lights on the bike
* New blade style fuse box already in place
* Only extra accessories are the current head unit & amp and cell phone charger.

I want to upgrade my cheap/weak head unit (radio) and amplifier I installed in my Windjammer Fairing. I have a total of 4 DB401 speakers installed on the bike (2 in fairing radio shell and 2 in rear hard saddlebags).

How large of an amp can I install BASED ON ITS FUSE SIZE used for the amp?

I know the MAIN fuse for our bikes is only 30 amp, but can I push it a little bit more for a separate relayed and fused line from the battery? How much before the alternator won't be able to keep up or I fry the system?

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On a seperate note, will a GOOD quality head unit make a big difference in total out put & quality vs. a cheap head unit that obviously lied about output power?

FYI: These are my speakers - listed as 45W RMS - 135 peak power.
http://www.crutchfield.com/S-nG8XYA8tVd ... db401.html

NO I DO NOT PLAN ON BUYING DIFFERENT SPEAKERS UNLESS I KILL MY CURRENT ONES. I NEED 4" for the fairing radio shell and 4" was about as large as I could mount in my saddle bags as well. The DB401 were afforable and marine grade when I purchased them. I just skimped on the head unit and amp while I had less funds to spend.

EDIT: If I have to buy new speakers I will, but buying 4 matching 4" marine grade ones will not be cheap if I need to UPGRADE from the DB401s.

 

You should not base anything on fuse size, its only a protection device and not an indication of current draw.

Check in the manual for your alternator spec, I bet its maximum output is 19 amps.
I would disconnect the alternator and check how many amps your bike currently draws when running. Once you exceed 19 amps you will be draining the battery as you ride.

Also amplifiers dont draw a constant load, they draw more with volume.

 

http://www.crutchfield.com/S-BkF3Fnm862 ... faq.html#2

 

It's been a long time since I was big in the audio scene, but I seem to remember some things
#1 look at the efficiency of the speakers, it should be related as decibels (dB) at 1 watt (you want the loudest speakers you can get at 1 watt)
#2 remember, every time you double your power output (wattage) you only go up 3 dB in volume
#3 make sure all four speakers are matched for Ohms...I don't remember exactly why this was so important, but I think it has something to do with how they draw from the amp

I can't imagine that sound quality is a major priority, what you want is maximum undistorted volume, so a "clean" signal will be very important. This will come from running your components well below their stated Max. (If your amp is rated at 100 watts, you don't want to run it at 100 watts..realistically running at or around 25 - 40 watts would yield the best results.

You might want to take your bike for a ride at different speeds and measure (actually have your passenger measure) sound levels...if you have a smartphone there are sound level meter apps available for free...this will give you an idea of what you're up against....let's say you're riding at 65 mph and you have about 95dB...you're going to need at least 105 - 110 dB to hear music clearly over the road noise...if you like to listen to "talk radio" you'll need to up the signal to noise ratio by another 5 - 10 dB...now let's say your speakers are pretty crappy and only put out 80dB at 1 watt...you'll need to overcome 30 - 40 dB of road noise...using our equation from above you'd need over 500 watts of power, way more power than those crappy speakers could handle...so what I'm saying is, measure first...then fit your system to your needs...you won't over or under build your system...

hope that helps.