Yes, that's so true. Pay attention to what the manufacturer says for box size. Wayne, how about subs for SPL? Bigger is better might work here, right?
Wayne: Well, it's complicated, there's a direct relationship between size, excursion and SPL. If you cut the cone diameter in half, then you need four times the excursion at the same frequency to achieve the same SPL. But if you double the cone area, the excursion is one-quarter. So up to a point, more cone area, or more cones will get you more SPL. The problem comes in getting cones that are so big, they can't be driven effectively with the size voice coil they have. But that would maybe only happen in a general-use woofer that someone was trying to use for competition or extreme SPL. Most of the true competition woofers have well-matched magnets, voice coils and cones. But from what I've seen, the most competitive size seems to be a 15.
So a wall of 15s and you're breaking world records?
Wayne: Yeah maybe, but there's another myth for you. The SPL difference between one woofer and five or more in my Extreme class is 1.2dB. What I'm saying is that since you have to build a much larger space for those woofers, they have more air to compress, but a single woofer doesn't need as much cabin space so it can efficiently compress the air.
Amazing! Another myth busted. But how about for the average consumer looking at a prefab box with a pair of 12s or a pair of 10s? You would get more SPL from a pair of 12s?
Wayne: Yeah, you would. You'd get at least 3dB more and possible up to 6dB because the two speakers really act like a single larger one. I actually think a person could build a 140dB+ system for around $500 with just a pair of 12s and a 1,000-watt amp - the technology and materials have moved up so much.
CablesThat would rock. Next topic: speaker cables. I think that for power into amps it's clear, the current demands and the length of the run determine the cable size. But from the amp to the speaker, how about that?
Garry: The quality of the wire is the most important. Having said that, quality equal, bigger can be better just to have a cushion.
What about these super sub amps that let you connect 8- and 4-gauge wire to drive the subs? Is that needed, or is it overkill?
Garry: Yeah, most of that is marketing. You need an awful lot of power at a very low impedance to require 8-gauge speaker cable. I mean for goodness sake, let me get my calculator here. Let's take a 2,500-watt amp, at a 1-ohm load, that's still only going to be about 50 amps of current. Fifty amps doesn't require an 8-gauge cable. Ten or 12-gauge is probably as heavy as anyone is going to need in a car and quite honestly, the amount of resistance in a cable is so negligible; there's more difference in the resistance in the voice coil of the speaker.
Wayne, you must have something to say about this?
Wayne: No, not really, I can't argue with any of that logic.
AmplifiersMoving up the chain, let's talk about amplifiers. Some are so huge and others fit nicely under your seat but can have the same power ratings. Is someone lying?
Garry: I think "bigger is better" will always be a marketing thing, but way back in the '80s the Japanese amp guys would make a heatsink way bigger than the circuit board just for that reason. But now aluminum is very expensive and can contribute a lot to an amp's price, so a bigger amp doesn't really mean it's any better. What it most likely means is that it has a lot of thermal capacity. Take for example Rockford Fosgate's Power Series. The goal on those amps was that they could never shut down because of thermal load. In the summer, in a boat, in direct sunlight, this amp can't shut down. That's why it's physically so large. Alpine, Pioneer and others that are using the new, very efficient ICE [power] chipset can build amps that are much smaller because they don't have to dissipate as much heat due to the higher efficiency of the ICE [power] design; and the design doesn't have the same objectives as the Rockford amp.