Part 6
Speakers:
Importance: Frequency response. Efficiency, Impedance, Power handling; Rolloff; Q (subwoofer); Size
Without a doubt this is singularly the most important aspect within the system. This is what makes or break a good system. As I’ve indicate in the preface of how sounds are produce, many specifications company champion are not really that important. The most important are frequency response and efficiency. Tweeter cannot produce thumping bass nor midbass produce decent cymbals. With that in mind, most company will provide the frequency response specification with a +/-3 DB deviation. That specification is absolutely useless without a graph. A swing of 2 db all over the place can be worst than one with a single 6 db difference which is still with the +/- 3DB spec . What’s more difficult to determine is the response off center. Variations of responses are typical on mid to high frequency drivers and are more pronounced. Some have cliff like roll off that only sound good if faced directly at the listener. Knowing this deviation would allow some predictions as how it will respond given the mounting location and angle.
Often when people think about speaker they’d ask “how much power can it take” which they perceive it to be how loud it can play. This is half correct, the determination of “loudness” apply to how efficient the speaker can produce in terms of db given 1 watt of power measured at a distance of one meter. This is standard measurement in terms of speaker efficiency. Some don’t follow this rule but all reputable company will. Given that any 3 db drop will require doubling the power to achieve the same level of loudness and it takes ten times the power to double the volume (6db), one can see how efficiency is so important. Bare in mind the human ear and how we perceive volume is not linear, “perceived loudness” ratio is even worst as the volume increases.
Power rating is meant as a guide to determine what the speaker can safely handle in term of clean wattage. This does not mean that a 50 watt amplifier cannot fry a 500w rating speaker. As noted above, the worst thing can happen to a speaker is when an amplifier clip. When an amplifier is driven past it’s maximum a sine wave become a distorted square-wave-type waveform causing the speaker to overheat.
What to look for:
Selecting your speakers really comes down to 4 things with one being above all else and that cannot be measured with specifications. The first being physical size of the speaker given the space available. The majority mid/midbass speakers are mounted in the doors and as such the depth and physical size available dictate what can go in there. The rule of thumb is that you try to put the biggest drivers since bigger driver usually means the ability to produce a lower frequency given the same volume. This is not absolute but general rule. The theory is always put as much frequency bands in front rather relying on the sub to fill in the sound. Rear fill and reasoning can be discuss later but any good system would put as much as possible up front. You don't go to a concert facing backwards do you?
Which leads to frequency response. For the front one look for roll off in the low end. This determine where x-over frequency would need to be set. For example if the speaker begins to roll off around 100HZ, your X-over would be set around this band to start and your subwoofer would have the low pass point around this point as well. Tuning will be done later but this will give you a general guideline. In general, if a graph is provided, look for a smooth and linear line with as little deviations as possible. Again industry standard typically quote +/- 3db. Without one, I would suspect it's validity.
Impedance is something to consider since most car amps are designed to work with a 4 ohms load. Keep in mind that should you run any speakers with a different load, make sure the amp is capable of delivering the power cleanly. Not all amps are rated nor designed to power speakers below 4 ohms nominal. A word on efficiency, as stated above, it determine 'how loud' the speaker can play given a set power so selecting a efficient speaker allow your amp to be more efficient.
The last and most important things to look for in any speaker is...using your ears. No specifications can determine what truly sound good except your own ears. Keeping in mind that what you hear in the typical booth would sound slightly different in your car. That may be but you can't start with a bad ingredient and make it into a gourmet meal. So whatever sounds good to you will likely to sound good to you in the car as well. Trust your ears and don't rely on what people TELL you what sounds good and what doesn't. Everything else being equal, it is you that must live with it. I would often start when someone asks me for advice is to first ask what type of music they listen to, how loud and then give suggestions as some type of speaker tend to perform better than others. I would recommend that you visit your dealers and ask them for their recommendations base on your music types and just listens to each recommendation and come to your own conclusions
In the Z34 (pre-2012):
Base Audio/Nismo: 4 Speakers system
2”x2 tweeter - on dash
6.5x2 woofers - doors
Bose and NAV system: 8 Speakers system
2”x2 tweeter - on dash
6x9x2 woofers - doors
3.5x2 - at the back fill
3.5X2 Subwoofers for coupe; 6x9x2 Subwoofers for Roadster
I have no affinity for brands of gear as everyone has their own preference. One can however be assured that typically brand name will likely carry a longer warranty have better features and likely quality which will unlikely to be inexpensive. One thing that one needs to remember is that this is a system and like any system, it is only as good as the weakest link. It would be like planning a track session with a GTM TT and have balding snow tires. My suggestion is to set your budget and plan accordingly. Avoid putting excessive budget in one area while neglecting others.
Installation has a huge effect both cosmetically and sound quality and in particularly on higher end systems, sometimes as much as 70% of the total cost. That said, the majority do not need to spend that percentage on a typical instal to get great sound as there are many great companies out there that produce great gears.. What’s important is to select ones that fits your budgetary needs and ones that will reproduce the music that you listen to in ways that sounds good to YOU unless you want to do it to satisfy someone else’s tastes.
Again, this is not a comprehensive thread dedicated to every little detail. It is an overview with some background information that hopefully will give you some perspective and knowledge when dealing with car audio. In the future with time permitting, I will add to this with related posts and updates as necessary and the practical side of things. I hope to discuss further in the future on other aspects including; accessories; cabling, power distribution, alternator, grounding and installation.
Last edited by zakimak; 11-28-2013 at 05:33 PM.
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