Car Insurance

A lot of people think that they can just buy whatever size amplifier and electronics they want to, and stuff in in the car, and it will all work out.

not true

well, for example, you just put a 1200 watt amplifier into your car, your car’s charging system has to be able to power it.
To find out how much power(or current) is required, divide the RMS of the amplifier by the voltage of the electrical system(with efficiency factored in) which would be about 12v. 1200/12 would be an extra 100 amps of current that your alternator needs to accomodate for on top of the every day electrical needs of the car.
To find out if your alternator is adequate for your system, look at the hot rating on the alternator, if you can find it. if you cannot find it, contact the dealer and find out.

a common mistake in this area is buying a 50 farad or whatever cap, this will not help if you are underpowered.

If you find out that you only need about 10-12 extra amps of current and do not want to buy a new alternator, you could get a new, larger battery(optima yellow top) and a stiffening cap (1 or 2 farad) this should get the job done, but that will not solve everyones problems.

a proper charging system makes all the difference

I see your point and have taken the same approach. I now have a USX-4065 and a JBL 2 channel that develops 300 RMS when bridged MONO to a 4 ohm load. (2 x 20A., fuses here) My goal is above average SQ and some degree of SPL. My target is a clean, pure, realistic mix of SQ and ~120dB of clean SPL. Plenty for me.

The JBL MONOVALVE series is 1 or 2 ohm stable. There is no power output differential between 1 or 2 ohms… just capability. Its Class D mode operation nets very efficient use of power VS power to drive the subs. Last time I calculated that, was very close top 90% efficient. Ie: 100 watts consumed, nets almost 90 watts output. The only drawback, class D will not do well above 500 Hz. Not bad huh?

Compare that to a classic 2/4 channel Class A/B amp. These are cleaner and more suited for high frequency reproduction. The are not as efficient as Class D models, but do the mid/highs well. The efficiency rating of most typical Class A/B amps is/are between 50-60%. That’s not a big problem in modest 2/4 channel amps as far as power consumption goes… only when using larger 2 channel amps for subs, does the power efficiency come into the game. (500 RMS and higher)

NOTE: Amp efficiencies vary from one maker to another. Different designs and component choices play a part in this. Some amps just loaf along very nicely at rated power and stay cool. Some amps really puff hard at rated output and may generate a fair amount of heat. Indication of how close to the limits the amp design is to internal components. A cooler running amp is working less hard and will usually last longer than a hot running amp. ELECTRONIC DEVICE HATE HEAT !!!

The last major aspect to the system are the speakers. This is the soul of any good system. Here, the old addage… ya get what ya paid for is generally most notable. Efficiency ratings on drivers can be very deceptive by design. Some speakers tout a 92% efficiency rating, while others may be in the low 80’s. Which is better? Without a frequency plot at 1 watt/1 meter over a wide range of usable frequencies, the numbers are meaningless, if not outright deceptive.

Better speaker makers have these LEAP plots on their web sites. The ones who don’t want you to know them, do not. There’s usually a good reason not as well.

First off, let’s define CLIPPING distortion…

This is when an amplifier has reached its maximum output capacity yet tries to keep up with the input signal gain ratio between the signal source “HU” and Amp. The amp hits an imaginary wall whereby the output signal is no longer a symetrical replication of the input signal. The wave form in, does not match the wave form out in shape or amplitude. (you can see this easily if you had a A/B channel oscilloscope; channel A connected to the amp input, channel B to amp output) The only difference you should see between channel A & B are signal amplitude values. If the signal shape varies considerably in channel B, you have a problem with clipping.

So.. what’s wrong with this picture? The amp tries to put out the appropriate power, but runs out of voltage from the supply rails and we get a flat spot at the upper and lower peaks of the wave form. In an extreme case, “severe clipping”, there is so much additional energy buildup (heat) into the voice coil(s), but the cone does not move (motivate) enough to cool the voice coil and former adequately. Hense, the voice coil over heats and either seizes in the gap or burns the voice coil windings. RESULT: OPEN CIRCUIT and a blown speaker!

OK, what happens to the speakers when they are underpowered? Under normal listening conditions… NOTHING! There is adequate signal voltage from the amplifier to motivate the speaker. This moves the speaker cone and draws/expells air to cool the voice coil adequately. No problems here… just modest output from the speaker. This happens all the time when we ride with the tunes playing low enough to hear our buddy in the co-pilot seat chattering on his/her cell phone.

SO WE CAN USE LOW POWER SAFELY ON SPEAKERS?

Yes… When we use a small amp to drive a high powered speaker, the speaker can take all the “clean power” the amp can deliver and more. But it’s when we push the amplifer into high distortion (”clipping”) mode, the speaker cannot move (motivate) in and out adequately to cool the voice coil. Eventually, this will even fry a very expensive speaker in this manner.

WELL THEN WISE GUY… WHAT CAUSES THIS “CLIPPING” THING?

Glad you asked! The amp will try to meet the power demand placed upon it, but it cannot exceed its design capabilities. This in turn, produces the deadly “square wave” output to the speaker. The speaker sees this severely clipped signal as something similar to DC current. Speakers cannot deal well with DC inputs. The cone goes in or out and stays there. No motivation to cool the voilce coil and sooner or later, the speaker will fail.

YEAH… YEAH… SO WHAT CAN I DO TO PREVENT THIS?

Alright, we know what clipping is, how it affects amps and speakers. What do we do to keep this problem from destroying our expensive drivers? Easy deal:

1. Use amps that closely match or modestly exceed the power rating of the speaker. A 100 watt speaker will love getting 125 watts of “clean power” vs a 100 watt speaker getting 25 watts of badly clipped (distorted) power.

2. Know what distortion sounds like and prevent it by proper amp setup procedures. (HU/amp gain matching, limited bass boost usage)

3. If you are not sure your system is clipping, best thing to do is get out
of the vehicle, open the doors and step to the rear of the vehicle about 10 feet and listen…

a. Are the highs and mids clear and natural sounding or harsh, shrill and very poor SQ? You are clipping the amp if you hear the latter!

b. Does the bass sound full, tight, have a definite thump and smooth transitions from one note to another? If not, good chance the sub amp is clipping or your enclosure design is not optimal for the subs.

If you ask us, a car stereo system is much more than a stereo and a pair of speakers. Adding components like satellite radios, subwoofers, amplifiers, navigation units, and video systems can transform the time you spend in your car from a boring daily routine to a highlight of your day. A well-designed system will allow you to catch up on the music you’ve been missing out on, keep up with the latest news, follow your favorite sporting events, entertain your kids with a backseat movie, or simply turn some heads in the parking lot.

In 1892 Rudolf Diesel developed and obtained the German patent for the diesel engine. His goal was to create an engine that was highly efficient. Much more efficient than the gasoline engine that was invented in 1876 and was not very efficient at all. Especially at that point in time.

There are two main differences between a diesel engine and a gasoline engine.

* A gasoline engine intakes a mixture of gas and air, compresses it and ignites the mixture with a spark. A diesel engine takes in just air, compresses it and then injects fuel into the compressed air. The heat of the compressed air lights the fuel spontaneously.
* A gasoline engine compresses at a ratio of 8:1 to 12:1, while a diesel engine compresses at a ratio of 14:1 to as high as 25:1.