Steve Deckert
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The problem with automotive acoustics is two fold... the noise floor is tilted heavily towards low frequencies, perhaps 10dB or in some cases 20dB higher than in your room. Back in the 1970's it was more like 40dB. The other issue is that the car is small, so you are having to create bass frequencies from a rather small box that is inside a large box, the car. You have to create 20dB more bass in the car than you do in your room just to sound and measure FLAT when the car is moving.
I put a Zen Triode amp in my Monte Carlo once. A pair of 12 inch full-range drivers were used, similar to the Lii Audio F12, around 98dB efficient. It sounded great. As soon as you started the car, it was over. God forbid you want to drive the car too... and if you want to drive with the windows down, you can turn the stereo on and off without hearing anything happen.
Yes, today's cars are better, but there is a serious heat issue with tube gear. To properly install anything larger than a zen amp (72 watts of dissipation) in a trunk would require liquid cooling with an external heat exchanger under the car. This is why you don't see any tube amps for cars.
Just to use a tube amp even like the ZMA in a car, you can't use car audio speakers because they're all low efficiency. You see in car audio, the 82dB woofer with a 6 mm air gap and 4 layer coil that handles/needs 400 watts to play reasonably loud, is what sells. Big sign - "500WATTS" - above the speakers. The 96dB woofer with a 1.5 mm air gap and 2 layer coil that handles 40 watts will actually play louder. But who will buy a woofer that says "40WATTS". Sad really.
So you see to do it right, you need non-caraudio drivers that work in small boxes and liquid cooling. It's all got to be custom. For every 3dB of noise floor you eliminate from the car body it is the same thing as doubling your power so before you even begin the stereo install, you disassemble the entire interior of the car, including dash, and triple the factory sound deadening so that 40 class A/B watts sounds like 160 class A/B watts. But since it's class A/B watts and we're comparing this to car audio watts, it would sound the same as 800 car audio watts. Then we go from 82dB drivers to 95dB drivers which translates to 12dB more, the 800 car audio watts are doubled 3 more times to 6400 car audio watts. Don't get too excited because car audio watts are like Styrofoam balls compared to real watts which would be more like lead weights. Nevertheless you now have a system that will hit harder and get louder than any 12Volt solid state car audio made. And you'll do it with 40 real watts.
It's way easier to make class N placebo power amplifiers with pulse-width modulated power supplies to create big dry sloppy power that just sounds like shit and pretend it's great which what the car audio industry has focused on as it's main money maker.
Steve
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