Hi.
My name is Dave and i am the UK Distributor for US Amps. I would like to just allay a couple of fears and dispel a couple of myths about the products.
Beasty Jay does to some extent make a very valid point about amplifier effeciency and one that we should discuss, as it affects ALL amplifiers.
Hoffmans iron law says that Power(Watts) = Voltage(V) x Current(I). It also states that Voltage (V)/ Current (I)= Impedance (R)
Now this may seem very pointless and not at all relavent - but bear with me for a moment. Consider the fact that Voltage is over 5 times more effecient to produce than Current. This is why the national grid produces power at 11,000 volts or more. Effeciency.
OK - so what the hell does this have to do with car audio - well quite a lot as it goes.
At 4 ohms if your amp produces 50 volts and 12.5 amps you get 625 watts.
At 2 ohms if your amp produces 25 volts and 25 amps you get 625 watts.
At 1 ohms if your amp produces 12.5 volts and 50 amps you get 625 watts.
As impedance drops effeciecy also drops. At 4 ohms and a class a/b amp expect 65% effeciency, 50% at 2 ohms and 40% 1 ohm.
This means the amplifier turns that percentage of battery DC into Speaker AC. So looking at the 2 ohm load - the amplifier needs 1250 watts input from the power source. Using the iron law above 1250 watts @ 11.5 volts (cars float at 14 volts but as load is increased voltage drops considerably - i.e. when the bass hits.) equals 110 amperes current. Which is more than the alternator provides so therefore it is pulling it from the battery.
Now that is a relatively small amplifier - so the next thing to look at to determine if your amplifier meets its specifications is the fuse rating.......
Anyway the thing is that the reason US Amps has a bad rep for being a power hog is because they have consistently made the most powerful amps in the world. They made a "2400 watt" amp that made 4000 w back in 1996. Now in 1996 you couldnt get 2000 watt subs like you can today (remember RMS not music or "peak" kiddies) so you had to use lots of 300 watt subs. 12 for example would be the right amount in this application. 12 8 ohm subs results in a 0.66 ohm load.
At 0.66 ohms expect an amplifier to be about 35% effecient - so 4000 x 3 = 12000 watts - at 12 volts = 1000 amps. Hence you need power supply. GOOD power supply - 2 optimas say and a big alternator.
Class D changes the rules but that is for a different day.
The next point i would like to move onto is the quality of the product. Our "AX" line which is going to be hitting shops imminently is the only amplifier still 100% made in the USA. I dont care what your PG or RF says on it - it is a korean amplfier that is assembled in the USA. Open it up.
Below there are a few images of our new product though - the Double D. This amplifier produces 7200 W RMS into a 0.5 ohm load (it is class D so effeciency is different to the above). It has 8 x 8AWG power wires direct to the board, 8 x 8AWG ground wires direct to the board and 4 x 8AWG speaker wires direct to the board. Next to it is a DE3000 - which is half a Double D, so you can see the board (all AX amps have perspex bottoms so you can see where the money goes)...... check the warning on the amp
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Pic5
IS is an offshore product however it is producing over 20% more than its CES2006 spec RMS rating - and doing it all day long. And its cheap.......
A few more nuggets. Power caps are bad and lower the output of the system. Fact. If you want to stop lights dimming then 2 x 0.25 caps in series with the + on your lights works better
Gel batteries are the way forward.
6*9's and subs reduces your amount of bass.
Ported boxes can give better SQ than sealed if correctly designed.
Speakers should be round not square.
I could go on.....hehehe
Have fun guys.
EDITED TO LINK PICCIES
ALSO feel free to ask ANY ICE question - i am here to help
P.S. - my fave small car of all time is a Strada 130TC Abarth - can i be in your gang?
