Car Audio Anyone????

[xl1200r]

I'm looking at getting a CD player for my car. I know what the signal to noise ratio is and what it means, but I don't know how to judge it. The decks I've been looking at range from 86db to 120db. The one I really want is 92db. Am I going to hear anything in the background? Will a higher rating really make that much difference? I will most likely be using the stock speakers and wires.

[Broncodog]

To test system noise, turn on an audio system and turn the volume all the way down so no signal is being output. Place your ear close to the speaker and listen closely. The hissing, incoherent sound you hear is noise in your system. High-quality systems will have less noise and others may have great deals of noise. The lower the noise, the better. 92DB is a good ratio you shouldn't have any problems, you weak link would be the speakers. :D

[xl1200r]

Thanks...that's what I was figuring. I just want a cd-player for the new car. The reason I'm picking the one I am is because of the looks mostly. Is has a folding face, and there only red lights when it's folded so there isn't any intesne light comming from the deck. My friend just put a stereo in his car with blue lights and it makes driving a pain.

[Broncodog]

I know what you mean, some of the new decks have some crazy lights on them! Good luck with the new deck! :D

[missyd]

I have a Sony Tuner/Tape unit with a 10CD charger. 4x Small high quality speaker and a high-end boombox ... all driven by a Kenwood amplifier. The system has some 1500W output.
Wiring is topclass ..... I suggest to use only matching (good quality) speakers/wires/amp/tuner etc. ... the weakest part will not stand up to high quality output.
BTW my car system is way too loud!!!! :D :D :D

[Broncodog]

"Power ratings in speakers refer to the manufacturer’s estimates of the maximum rated power amplifier that should be connected to the speaker. A speaker’s power rating is generally only an estimate of the size amplifier that should be connected. In fact, amplifier distortion is what generally creates speaker problems and causes speaker failure, not too much power. High power amplifiers tend to have less distortion than their lower power siblings enabling speakers to play louder and cleaner. An increase in clean, undistorted power benefits speakers by enabling them to generate clean, high output levels. Speakers’ power ratings, or recommended power, can be generally ignored. It is more important that the amplifier is clean and high quality with high power helping to ensure speakers will not distort and have problems." :D

[xl1200r]

There's no amp on the way. I'm not into the whole "car audio" scene. I just want a CD player that isn't a piece of junk.

[Narley]

the suggestion about listening to the system while volume is low is a good one...and a common one...too common. some decks to remove all hisses incorporate a zero bit mute circuit. meaning ,when there is nothing playing in the cd slot there is no noise . so when doing the test...keep the volume down but ensure there is a disc in there playing.

[Narley]

also...dont buy the entry level model even if you recognize the brand...most higher quality brands are farnming out their entry level models to brands you have never heard of and just rebadge them.

[XLFREAK]

I worked in car audio for 5 years (8 years ago) and still have a pretty good ear. I recently went to buy a cd player for my wife and couldn't believe the horrible sound quality of current name brand head units, I bought and returned 3 played, Sony, Pioneer and Kenwood before paying an extra $20 and buying an Alpine.

I've only owned Alpines for my car but was trying to save a few $$$ on wifes ride, but I could live with the sound quality and at $169 it wasn't priced too bad.

My two cents worth.

[Narley]

Alpine owner....20 years in the business

[Mainstreet1200c]

ive always had good luck with pioneer head units- If you are into MP3 audio at all, I would strongly suggest this one (http://www.pioneerelectronics.com/pna/product/detail/0,,2076_4039_63891888,00.html)

I put this head unit in when I upgraded my whole sound system in my 01 Monte Carlo, works great with the amp, subs and speakers I have now. Would sound good in a stock setup as well, put the same unit in my old pickup truck and sounds way better than I could have imagined 1988 stock chevrolet speakers could sound. Pics of the head unit etc here (http://www.cardomain.com/memberpage/525642/2) - No I didnt leave the power cord running through the door jam, just wanted to test out the setup before drilling holes in my Harleys garage mate...

spend the extra $ and get a good mid level model, dont cheap out, you will regret it- I agree with Narley, good lower end models are gettting hard to find. just my .02

good luck on the install

[Myke]

Geez, I don't want to rain on this parade but the explanations of power and signal to noise ratios aren't even close.

The background noise that you hear is just that, background noise. If you get too much try filtering the power input. The source usually isn’t in the device, it’s in the power source.

Signal to noise is a ratio that defines the ability of the input (first stage amplifier) to reject common mode noise versus signal, aka the ability to discern source induced noise versus usable signal. The cmrr (common mode rejection ratio) is measured in decibels, and yes 92 is pretty good.

Now power.. Most of what you read is for peak power (a sales technique to make things look better than they are). You really want to focus on the RMS number. The discussion of distortion is, well distorted. Distortion is no different to the speaker than the cleanest high or the lowest low. It’s all about frequency response and power levels…….
Myke

[dabronco]

Like Myke said, Don't ignore the power rating of a speaker. If you don't, they make great fuses! You want the speakers to be able to handle more than the amp is capable of producing. Distortion is often a misused term. What most people are calling distortion is actually clipping. It happens when the amp is asked to produce a signal higher than the power supply can accommidate. For instance, a one volt signal goes into an amp with a gain factor of ten. Power supply is capable of eight volts. The audio signal climbs until it hits that 8 volt peak and stays there until the sine wave comes back down to the point where the input signal is 1/10th of the available voltage of the power supply. That period of time that the output signal is flat or "clipped" is what you hear as distortion. Also alot of people assume that the info on the back of their stereo that says " 120 volts, 60hz, 250 watts means they have a 250 watt amp. NOT SO! That 250 watts is the consumed power or required power from the outlet. The actual output to the speakers will say "output 80 watts into 8 ohms" or something like that If it says nothing, output power will be roughly 1/3 of the consumed power. Higher end amps will be more efficient than that but are also more likely to tell you what the output actually is.

[Narley]

Unsure of their US marketing, but in Canada Alpine has returned to a more honest rms output for claimed power on head units...versus the inflated peak power ratings too common today!

[Narley]

Geez, I don't want to rain on this parade but the explanations of power and signal to noise ratios aren't even close.

The background noise that you hear is just that, background noise. If you get too much try filtering the power input. The source usually isn’t in the device, it’s in the power source.

Signal to noise is a ratio that defines the ability of the input (first stage amplifier) to reject common mode noise versus signal, aka the ability to discern source induced noise versus usable signal. The cmrr (common mode rejection ratio) is measured in decibels, and yes 92 is pretty good.

Now power.. Most of what you read is for peak power (a sales technique to make things look better than they are). You really want to focus on the RMS number. The discussion of distortion is, well distorted. Distortion is no different to the speaker than the cleanest high or the lowest low. It’s all about frequency response and power levels…….
Myke
The explanations of signal to noise are no good to consumer ears. Thet hear hiss and need an explantion firstly of why and secondly of how to cure it. With the engine off car audio systems do produce a noise floor of their own. Noticeable in lousy models and something you have to listen hard for on better models. internal motors creating a a rumbly sound and poor dacs creating a hiss. Now...the noises that arent from within the headunit...things like engine noise are not so common anymore, and when they are ...they are tough to troubleshhot.
I have found the couple distortion comments here are fine. The distortion or square wave signal is what damages most quality speakers. A decent speaker can play loud and clear on an amp that is rated for more power than the speaker is rated for.
Conversely a small amp can play to volumes beyond what it should. its the industries vicious cycle of trying to outdo each others BS marketing claims. Play a small amp or deck power to a loud volume and the siganl which is being sent to the speaker CLIPS...meaning the nice smooth forward and back movements of the speaker (you can see these movements on a woofer but they are too minute on a tweeter) anyways, the back and forth movement caused by the signal from the amplifier gets clipped. This means the back and froth movement is interrupted for a fraction of a second and the wooffer or tweeter remains staionary during this clipped signal. The normal airflow and cooling of the normal back and forth movements is halted...its only for a fraction of a second, but imagine 100 movements forward and back in a second...then imagine at the start and stop of each back and forth movement the woofer remians stationary...the motor (voicecoil) of the speakers gets less cooling..it heats up and melts ,smokes, burns , fries....etc. Dont clip the signal...dont run the amp too hard....get enough power to run the ssytem cleanily....realize that deck power is only about 15 watts per speaker and to play truly loud you need an outboard amp to drive 40 watts...decks rated at 40-50 watts are full of marketing hype....you bought it didnt you....thats the vicious cyle...they makret it ...we buy it...they keep on doing it.
Hats off to Alpine for taking the high road with legit ratings even though they loose sales cause their cd players are only 16 watts per channel!

[Myke]

“The explanations of signal to noise are no good to consumer ears. Thet hear hiss and need an explantion firstly of why and secondly of how to cure it. With the engine off car audio systems do produce a noise floor of their own”

Tell them the truth, if a unit has systemic noise don’t buy it. Telling someone that the background noise level is somehow defined through the signal to noise ratio is just plain false. I can take the best unit available and do a crappy job with the wiring and induce background noise.

“The distortion or square wave signal is what damages most quality speakers.”

I’ve got to call you on this one too. Distortion is not always clipping, in fact it’s usually harmonic based. Harmonics (think THD, it stands for Total Harmonic Distortion) have nothing to do with clipping, nor does clipping produce a square wave as defined. While clipping does flatten the top of the wave form when the amplification stage reaches saturation, the rise time for audio based signals aren’t short enough to cause true square waves.

Clipping is built into most low end systems as a compromise for gain in a single stage of amplification. The “Q” (a measured curve of bandwidth to amplification) is the next “compromise” point

The discussion of speakers blowing, well I don’t even know where to start. It has nothing to do with “cooling”, “clipping”, cones in motion or not or any of the other stuff mentioned. It’s all about volts, ohms, and frequency…..

One other point to consider, there is a difference between speaker induced distortion (generally a mechanical compromise) and head unit based distortion. Both count in the quest for accurate signal reproduction.

As for the power of an amplifier, think decibels. Twice the power does NOT mean twice the noise. Your gain would be measured with something like 20LogV1/V2 or 10LogP1/P2. Neither will give you twice the db for twice the power, but that’s a story for another day….
Myke

[xl1200r]

Geez...I just wanted to know if a 92 dbl Noise Ratio was good....

[Broncodog]

Geez...I just wanted to know if a 92 dbl Noise Ratio was good....
:laugh :laugh YES

[Myke]

xl1200r,
I think the moral of the story is, buy whatever sounds good to you. Don’t put two cents into the marketing babble and various specifications. Don’t believe that more power is always good either. Remember a basic rule of thumb is 10 times the power to get twice the db level.

Audio is a subjective thing, and all the science in the world won’t make something sound good to you that you don’t like.

Myke

[dabronco]

Hey Myke, I just didn't want to try and explain Ohm's law and the relationship w/ the inductive reactive component of a speaker coil and all that stuff. I just wanted to toss out some stuff that the average person could understand and possibly make use of. You and I understand what d.c. does to a speaker coil,(the clipped portion of an audio signal fer instance) But I saw the subject of speaker distortion brought up and wanted to try and correct the misunderstanding that the SPEAKER is distorting. I've seen way too many perfectly good speakers go in the trash because the signal was bad. Of course I you apply too much power to the speaker it can open or warp the voice coil and a dragging coil will sound like crap.

[Broncodog]

OHM'S LAW


V = I x R

V = voltage
I = current
R = resistance

:laugh :D

[dabronco]

Ok if you wanna be accurate, it's E=IR

E= electromotive force or voltage
I= current
R= resistance

:p