So, are car audio devices also covered by the FCC/FTC (never can remember which it is) regs.?

A perusal of car deck specifications for a basic unit with 4 channels gives me 40w x 4 rms. No mention of how many channels driven. Something tells me it is not all 4.

FWIW, a couple of weeks of reading in a car audio site and a few visits to bb tells me that the quality of a speaker is determined by its overall diameter and its power handling.

If I start posting about how cables make a difference, I need an 'intervention'.

Fred, the FTC regs specifically apply to units sold for "home entertainment purposes" and therefore don't regulate automotive equipment. In 1998 the Commission took some evidence relating to expanding the coverage to include mobile units, but determined that there wasn't sufficient evidence presented to support the proposal.

There are no regulations which have the force of law, such as those which should make us confident of the accuracy of home audio amplification equipment power ratings , which would give similar assurance as to automotive equipment. There is a voluntary regulation(CEA-2006-B)for mobile equipment proposed by the Consumer Electronics Association which some manufacturers follow, but of course this isn't law. A brief discussion of this can be found here .

Thanks John. As always you seem to have the answer. Wow, so they can pretty much put whatever they want. 20w x 4 could mean one channel driven. Sigh.

Looking at a power calculator, an average of 3-7w should drive a set of speakers sufficiently, but how the heck do I know if a deck will deliver that? I guess 20w one channel will translate to roughly 10wpc 2 channels driven?

My car audio guy told me that a typical deck rated at 50wpc might actually deliver 15 wpc. I have no idea what lead him to say that (experience, just a guess, who knows.)

Hi fredk,

Yes, car audio "specs" are wildly misleading and inaccurate, especially for the in-dash head units. Power output is often quoted at 10% distortion levels in order to get bigger output numbers.

If you go to separate power amplifiers and more expensive head units that have pre-outs, you'll generally get much more complete and accurate specifications.

I'd agree with the figure of about 3.5 to perhaps 7 watts per channel maximum at a reasonable level of distortion (1% or less).

To get lots of clean power output in a car, you have to go to separate power amplifiers. With off-shore manufacturing, those are much less expensive now than they used to be.

Regards,
Alan

Thanks Alan. I hadn't even thought about distortion. Hmm... looks like I'm going to be doing this by the seat of my pants.

Looking at head units, its not going to be too expensive to get something with pre-outs.

The Alpine PDX amps are pretty kick a$$. I have a few of them and they come with birth sheets. They are all underated. My Alpine PDX-4.100 is rated at 4x100 watts and its actual measurement was 4x125 watts 2 0hms or 4 ohms doesnt matter. They are a class D, run super cool, super small, and super sweet.

MTX does the same thing. My amp (MTX Thunder 282) came with a test sheet with the actual wattage on it.

The question is which 'actual' wattage? I have yet to see a spec for a car amp the tells me how many channels were driven for that 4 X xxx watts.

Fred, did you pick out a head unit yet?

Not really. The plan is like this:

1. pull the door trim panels and do some treatments to dampen the door and to seal the inner (metal) panel to minimize the back-wave interference (create a proper infinite baffle).

This should clean up the sound a lot from what I have read so far. I may go so far as to install sound damping/barrier in other parts of the car to quiet it down on the highway as well. What the heck, I'm gonna be driving this thing for the next 15 years...

2. Replace the front door speakers with something a little better if I still feel I need it. The leading candidate here is Hybrid Audio, a small company that seems to deliver big sound (sound familiar?). I'm looking at speakers that can be run coax or as separates so I have sound quality upgrade possibilities in the future without changing speakers again.

3. Replace the head unit and pick up an amp fro the front speakers. I would do this only if the stock head unit does not have the power to drive the upgraded speakers. A mid-line head unit $100-$150 will give me the features I want. I won't ever need more than a pair of pre-outs.

As I posted above, I suspect that I won't need much more than 10wpc to get to a reasonable volume (with headroom) in the car.

Its pretty much the same as in home audio. Speakers first, then the room, and if that doesn't get you significantly better sound, look at other stuff. In this case I'm going to treat the 'room' first, then look at speakers...

I've never heard of, or come across Hybrid Audio, but I'm very new to this. I've been looking at Kicker and Kenwood speakers to replace the stock ones in my van.

I was going to suggest the same head unit that I just bought last week, but it is twice your budget on sale.

A website that I have found to have pretty decent deals is sonicelectronix.com .

Hybrid is a new kid on the block, but has been cleaning up in the car audio sound quality competition circuit.

I figure if I actually upgrade the speakers, I want it to be significant. The entry level convertable components from Hybrid are $200.

I wonder how warranties work for stuff bought out of the US? That looks like a good online site.

I would seriously check out the alpine pdx-4.100. Here in Canada theyre really expensive. I think visions sells them for $769. Sonicelectronix sells them for $349. The footprint is about 8x10 or the size of a sheet of paper. They really are that nice.