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Welcome to the teamROCS Frequently Asked Questions of Audio. This is a compilation of the most commonly asked questions as they relate to audio and 12 volt electronics. If you have more questions, you can refer to our technical section or e-mail the Team.

What is phase?
Can window tint affect my radar detector?
Can my steering wheel controls operate my aftermarket radio?
My Honda radio has a CD button on it. Can I add a changer?
How do you measure your amps output wattage?
What does RMS mean?
What is "oversampling"?
What is "Transfer Function"
What is "Dispersion"




What is Phase? 
Phase is defined as a fraction of a complete cycle, and is usually expressed in degrees. Sound travels in waves, and waves are divided into degrees. The total number of degrees in a wave is 360 (just like in a circle). When you talk about the phase of a wave, you often refer to the number of degrees a wave has already fluctuated. This is important in sound, since many things can go wrong with phase and make a speaker system sound bad.

The most common thing that goes wrong, is that some doofus hooks up one or more speakers out of phase. Most commonly, a subwoofer is hooked up backwards compared to its mate. Then, it is 180 degrees out of phase. The result is that the one woofer is moving out, while the other is going in, and you get piss poor bass performance. Phase can also affect performance between subs, mids, and highs. 


Can window tint affect my radar detector? 
This depends greatly on what type of tint you have. Normally, tint is a plastic film with a dye painted on to it. This will have no effect on the ability of the unit to detect X, K, and Ka, or Safety Radar. This will affect the rearward laser detection, since laser is still light. 

Other types of tint include metallic film tint. This type of tint is a very fine layer of aluminum, gold, titanium, or other metal. This will affect your rearward and side radar and laser detection. Gold tinting is used on the windows of the F-117 Stealth Fighter to keep the pilots helmet from returning a radar signal, so I'm sure it'll deflect the radar guns signals. 


Can my steering wheel controls operate my aftermarket radio? 
No, you putz, of course not. Aftermarket steering wheel controls differ from car to car. In GM, there is an 8 pin harness that plugs into the back of the factory radio. Sony, PIE, and others make an adapter that will allow these controls to work with the Sony stereos which use the wired rotary controls. Many companies also make adapters which will translate the steering wheel controls of most cars to the programmed pulses of the remote, but you have to program them. 

Ford's system uses a single wire and different voltages to signal the radio. This is very easily adapted to work with Sony's rotary commander wired input. See the white papers section at for the R values for specific functions. You can either make your own adapter, or just build your own separate control panel. 

My Honda radio has a CD button on it. Can I add a CD changer? 
Yes, you can. Several different companies manufacture an adapter which allows the Alpine CHMS-601, 602, 603, and 611 changers to be directly controlled by the Honda factory radio. 

By the same token, if you have a factory CD slave unit, or factory changer, you can control it from an Alpine cassette or CD head unit by putting the same adapter inline with the alpine M-Bus output. The adapter simply reverses the phase on the right side pre-amp signal. The factory Honda radio uses Alpine's protocols. 

How do you measure your amps output wattage? 
For a pretty close guestimate, it can be as simple as hooking your voltmeter in parallel with your speaker leads while the amp is playing. Set your meter to AC Volts. If you have a meter which can measure RMS, then select that option. Take whatever reading you got, and using Ohm's Law, you can calculate the wattage. The formula is "power equals voltage squared, then divided by resistance (P=E^2/R). The resistance you will use is the resistance of your speaker. While this will get you in the neighborhood, there are many factors which affect the amplifiers output power, and much more equipment is needed to accurately test for this. For more information, Eddie Runner has authored a Technical Paper on the subject. 


What does RMS mean?
RMS means Root Mean Square.  RMS is basically a way to calculate the actual power of an AC wave. Since a wave goes from peak to peak, it's apparent power is often more than the actual power of the entire signal.


What is oversampling?
Oversampling is a way to remove digital noise from the signal of a digital media player. Typically, there is a slight distortion introduced because of the way a digital player (CD, DAT, or MD player) decodes the information. Oversampling does not actually take this distortion out, but it makes it inaudible to humans (your dog will probably bitch about it though). You may wish to check out the article on Oversampling in the technical section.


What is "Transfer Function"?
Transfer Function, simply put, is the difference between a sound or signal before it enters a system, and while it is in that system. Most often, when we talk about a cars transfer function, we talk about how the car itself affects sound. Some cars, like hatchbacks, tend to amplify bass, making them sound boomy, while other cars sound great. Transfer function most often has to do with the size and shape of the cabin. A hatchback is shaped like a horn, and tends to bring out bass, while a convertible has almost infinite volume (since it is not contained), so bass is often harder to reproduce. Transfer function can also describe what a signal processor or amplifier does to a signal in terms of adding distortion.


What is "Dispersion"?
Dispersion, quite simply, is the way a speaker sounds when it's not pointed at you. When you are off axis, meaning, you are not directly in front of a speaker, it often will sound different. A speaker with good dispersion will sound pretty much the same even if it's pointing slightly away from you, while a speaker with poor dispersion will change drastically when directed away from you.



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