Prius w/ JBL

The dash squakers are the most critical speaker. The rear speakers do very little. I used the polk 350i for my dash squakers.

Despite the claims of others, you really don't need a whole lot of power. I am doing fine with 6*20w
If you listed to uncompressed classical music, it has a bit more dynamic range than most music, and you might want a bit more power for the peaks.
This does not apply to classical music over the radio, as they need to limit the dynamic range to transmit it effectively.

For home use, I have an amp that puts out 350 w per channel (2 channels). That is the IEC rating. It also has a power meter. Only when playing pipe organ music at house shaking levels does the power level get close to 300w. My living room is significantly larger than a prius interior. That amount of power will cause hearing damage in a prius.

Now if you want to do competitive car audio, I have a friend who designs multi-kilowatt power supplies for big amps. But I suspect if you wanted that, you wouldn't be asking for advice here...

As for LOC's, they are not magic. If an amp has high level imputs, it is basically the same as built in LOCs. It is better to transmit signals inside a car at high voltage and low impedance. Look at that, the speaker outputs are high voltage and low impedance. This will minimize noise. A friend uses balanced line outputs, but that is real pro audio, not high end consumer stuff. You could also go optical digital to eliminate noise, but no consumer gear that I know of deals with that.

Just for info, a LOC is just a resistor divider. You can make a fixed one with just 2 resistors. This should cost about $0.25 at radio shack...

As for my qualifications, I took all the electronic engineering classes at my college (a 4 year engineering school). I have worked professionally as an electronic technician working my way through college. I have been doing audio stuff for many decades. I have built amplifiers and other audio electronic gear. And I installed my own system in my prius, because 90% of the 'professional' installers are not competent.

 

JordanC,
I am new to all this so any input is great. In your opinion, if my Apline amp has high level line inputs, should I use those or use two LOC to hook up to the amp via RCA lines? I am using the stock HU. Is the built in LOC on the amp better than the standard cheap LOCs?
Thanks. Sorry to high jack this thread for a bit.

 

I have installed plenty of amplifiers over the years utilizing line level inputs that are built into amplifiers with great results. At the end of the day you have options depending on what you are looking to get out of your system and what level of complexity you will be faced with when installing the system. The positive side of using line level in's on the Alpine is that you have less components to install which will make your system easier to integrate with the OEM head unit, the downside is that you are running 8 sets of speaker wire around your car which can be more difficult to manage if you are a novice. There won't be a noticeable difference between a cheap LOC and the Alpine amp's line level input. You will notice a difference if you are comparing a higher quality LOC like a JL Cleansweep, Audio Control LC2i or Soundgate LOCb.2 but then you are really in a different level of equipment altogether. I hope that helps and best of luck on your install.

 

MjThind, I am confident you will be happy going with the changes I recommended. I would make sure you are very comfortable with installing this equipment in your car otherwise you should seek out an experienced installer and especially one who knows how to properly tune an audio system. Proper tuning of your LOC and amplifier will make all the difference in the world. Best of luck and let me know how it comes out.

 

I looked up the specs on the JL HD500 amp. I didn't see any made by JBL, so all of my comments are specific to the JL.
The unit is rated at 4x100 + 1x500. The total is 900 w rms. According to their web page HD900/5 - Car Audio - Amplifiers - HD - JL Audio they recommend a 60 amp fuse. I find this very curious. Since they rate the unit to produce full power at 12.5v, multiplying 12.5*60 yields 750w. So if the amp is 100% efficient, it will produce 150w less than it is rated to produce. If the amp is 80% efficient (which is a more reasonable rating), it will produce 600w, which is 300w less than it is rated to produce.

My JBL ms-8 amp max rating is 30*8 (at 2 ohms). It has a 25 amp fuse. That implies an efficiency of 77%. Now I know fuses won't instantly blow at their rated current, but I think there is no possible way the JL amp can produce its rated power on all channels at the same time with a 60amp fuse. Since they call it a 900 w amp, it is reasonable to assume it can put out 900 w. This means either

1) for some reason they specify a tiny fuse, where they really should specify a 90amp or so fuse.
2) the amp simply can't produce full power on all channels at the same time
3) the amp is 120% efficient

Also the amp retains for $1000, which I find a bit spendy. Perhaps you should ask JL audio why they specify such a small fuse.

I recommend a different amp. I just bought some speakers for my camry frum crutchfield today. The person I spoke with seemd pretty clued in. Perhaps you should give them a call before spending so much on an amp.