I'm afraid your logic doesn't quite work here ... Power isn't the problem with my unit ... distortion at higher volume is, because the four inch speakers simply can't handle the volume necessary to overcome the road noise at speed without distorting. My stereo has more than enough power to provide the volume (as your Alpine also does), but the little speakers are just that ... little.
You MIGHT get better results with more expensive four inchers than what I have (I bought what I consider to be a mid-level pair of four inchers) and there's a chance that the Alpine will put out slightly cleaner sound at volume, but in the end I believe the small size of the speakers will ultimately prove to be the weak link in your system (as it is in mine). Simply going with larger speakers (like the five inchers I'd like to try to make fit someday) would make a world of difference, simply because they can handle the higher volume level without distorting as soon as the smaller speakers do.
Good luck with it, though, and
Regards,
Unfortunately, and I don't mean this to be rude at all, but your logic is the logic that is flawed.
Power supply is of utmost importance when it comes to stereo equipment. Especially when you're talking about smaller speakers. Anything smaller than a six inch speaker is basically going to be useless for providing adequate bass response. So unless you can manage to fit 6.5 inch drivers into the space, bass response is going to be virtually indistinguishable between a 4 inch driver and a 5.25 inch driver. Not to mention, the quality of the plastic that is enclosing these drivers isn't going to be very good for providing adequate bass response anyways.
A typical pair of 4" drivers is going to provide roughly 26 inches of surface area. That surface area is what delivers bass. Remember, bass is nothing more than movement of air. Of course, larger diameter drivers move more air. A typical pair of 5.25" drivers is going to provide roughly 40 inches of surface area. To be quite honest with you, that extra 14" of square surface area is going to make absolutely no difference...especially with the non-acoustic enclosure that is the fairing's mounting spots. Now, when you get to the 6" drivers, you MAY be able to actually start tinkering to some extent with actual midrange bass response. At this size you are pushing nearly 60 inches of air...enough to actually start to tinker with some of the higher frequencies that are considered "lows," but still not enough to adequately provide any true bass response.
Now, where your logic is truly beginning to waiver is on the issue of power. MOST speakers will put out good sound at any volume provided that the power source is a good, clean power source. To get technical, what is the THD, or total harmonic distortion, and the RMS power rating of the head unit that you are using?? THD is basically a measurement of what kind of distortion you are going to get out of your speakers when you turn the volume up quite a bit. A deck with a lower THD will sound better at the same volume than a deck with a higher THD. In essence, that $750 Alpine head unit at, say, 90 db is going to sound cleaner than the $49 Walmart special will. Humans attribute clean sound to louder sound. When something sounds clean without much distortion, it will tend to sound louder.
Now, this is when the difference comes into play with a deck with more power. A deck with more power will produce cleaner sounds at louder volumes. Say you have two decks that both have a THD of .01 at 1khz. Those two decks have matching specs in the THD department. Now, say that one of those decks puts out an RMS power rating of 20 watts per channel. The other deck puts out an RMS power rating of 30 watts per channel. I won't do the actual math and figures, but let's just say that at 80db (the "loudness" of a typical vacuum cleaner) that the 20 watt deck is at it's "THD" threshold. Anything over that will cause distortion and bad sound. Go much higher, and it starts to sound REALLY bad. However, the 30 watt deck would still have room to go louder without hitting it's "THD" threshold. It's got 50% more power, so let's just say that it can get an extra 20db. That's only 25% more loudness with 50% more power. That extra 20db will put it at 100db. Doesn't really seem like a ton...but keep in mind that decibels increase exponentially. 100db gets you to a rating that is like being in the front row of an orchestra concert. That's quite a bit louder than a vacuum cleaner. All of that was achieved by having a head unit that has an RMS rating of 10 watts more per channel than the other deck. This, of course, is in no way an absolutely accurate example. It has just been used to show the difference in a REALLY quick way that's pretty easy to understand.
Also, keep in mind that MOST speakers can handle quite a bit more power than what they recommend...provided that the power being fed to the driver is a pure, clean, undistorted power. So, with that said, smaller speakers with a cleaner power source will dound better than larger speakers with a less clean power source.
Take my current car as an example. I have an Alpine CDA-98something or other. It's a few years old, but it's got one of the most powerful in-unit amplifiers that's ever been marketed. It's powerful enough to require an actual 12 gauge wire run directly from the battery to provide it with power, instead of the skinny power wire that's in the factory vehicle wiring harness. It also required a separate stand alone ground, instead of the factory ground. It is rated at 60 watts max power, and got reviewed with an RMS of about 36 watts per channel. In the rear of the vehicle I have some Polk DB 6.5 inch two way drivers. In the front of the vehicle, in the doors, I have two stock paper 5.25 inch two way drivers. They are stock because I have always been too lazy to pull the door panels off to replace them. At volume, the two different types of speakers are nearly indistinguisable. Anyone other than an absolute audiphile will not be able to tell any difference between the two different sizes, brands, or material makeup of the speakers. However, when I get the deck turned up loud enough to hit it's THD levels, that's when the speakers become "different" sounding. The Polks sound slightly cleaner than the stockers when the deck is passed it's THD levels. However, for spending nearly $300 on the Polks a good amount of years ago, it's really hard to justify the price compared to the stock ones when you hear them together like that.
So, in short, a deck with more power will produce cleaner power at a louder volume, thus limiting distortion. I would be willing to be that it's not your speakers that are actually distorting at that high volume so much as it is the head unit itself. Providing a head unit with a higher power rating will reduce the distortion which will make the speakers sound better. What it also does is allow you to turn the volume up more until you get to the level of distortion that you feel comfortable with. The higher powered deck will raise that level significantly...and as such you would be able to get by with the same speakers probably fairly well. For this same exact reason, an extrenal amplifier will almost ALWAYS sound better than a head unit...even if the two are rated at nearly the same power. For example, if a head unit puts out an RMS of 25 watts per channel, I woudl prefer to run an external four channel amp that puts out an RMS of 25 watts per channel. That external amp is going to provide cleaner power, allowing you to use more of those 25 watts before you run into distortion.
I worked in car audio for years. Sold stereos, installed stereos, competed in sound quality AND dB contests. I was one of the first people in the country to figure out how to run a video signal to an Alpine CVA-1000 in dash monitor (had to fabricate a plug and a switch system to do it). I ran an SQ setup in a Dodge Intrepid that had 16 speakers in it...including the subwoofers. Four in the dash. Four in the doors. Four in the rear deck. Two in the ceiling above the front seats. Two subs in the trunk. Before I did the SQ stuff, I was running 6 Soundstream SPL 12" subwoofers in the trunk of that same Intrepid. I had them bridged down running off of three Soundstream Class A 10.2 Rubicon amplifiers. Those amps ran about $2k each at the time I had them. Even after seven years a solid working 10.2 amp runs around $500 or so.
I've installed a stereo system of some kind in every vehicle that I've ever owned. Car audio is something that I don't even consider a hobby...it's more like a necessity to me.
Trust me...when it comes to car audio, more power is ALWAYS better than less power. It provides cleaner, louder sound with less distortion. That less distortion is the biggest thing...because it allows you to get more volume until you hit your accepted level of distortion. Am I saying that speakers never make a difference?? Not at all. But at the small sizes that will easily fit into the fairing, there won't be much of a discernable difference. The 4" driver will produce the same mids and highs as the 5.25" driver. Bass response is really something that will be lacking in this no matter what. There simply is no way to get "good" bass response out of ANYTHING smalelr than a 6.5" driver. And I believe that a 6.5" driver would be too large to fit in the fairing at all.
Regards!!
