Stereo Question

[SCWDP911]

Hey, I have a general stereo question. I know there is a guy here that is the stereo guru, but cannot for the life of me remember their ID. The question is open for anyone though:

I have a choice between a 35x4 and a 45x4 deck with cd changer to install. I also had a set of infinity 5.25 and 6.5 sitting here that I decided I will put in the 911. Do you think I will need to amp it? If so, any rec's to make the system "complete"? I do not need something to impress the teenagers with... just want a good sounding stereo, even with top down!

Thanks

[kees]

Originally posted by v8_ranch
Hey, I have a general stereo question. I know there is a guy here that is the stereo guru, but cannot for the life of me remember their ID.

Bell

Kees.

[SCWDP911]

Yeah, Bell. Thanks!

[RoninLB]

bell is the stereo man.

the 6.5 will give much better bass. Each 6.5 should have 75w. Actually bell is selling an amp as of last week. Not sure of output but I'm sure it's more than enough.

You may not need the rear speakers for fill. If you must have rear speakers bell has a solution to prevent the rear from screwing up your clairity.

There is a noticable difference between 5.25 and 6.5. External amp is necessary for nice.

[quattrorunner]

Good sound is easier with an amp even for small speakers. It makes a differance. Don't worry about the stereos output, just use an amp even a small one is better than the head unit's output.

[Jay H]

Originally posted by v8_ranch
I have a choice between a 35x4 and a 45x4 deck with cd changer to install. I also had a set of infinity 5.25 and 6.5 sitting here that I decided I will put in the 911. Do you think I will need to amp it? If so, any rec's to make the system "complete"? I do not need something to impress the teenagers with... just want a good sounding stereo, even with top down!

Thanks

Those 35 watt and 45 watt head unit ratings are peak power ratings. These power output ratings are obtained in a lab with 1 frequency (such as 1000 hertz) at a high distortion level such as 10% (you can start to hear 3% and greater distortion levels).

So, most head units have about 3.5 watts to 18 watts RMS (root means square) output for a larger freqency response (such as 40 hertz to 20k hertz) and a much less distortion rating (such as 1%). Those types of power output levels are more meaningful and many manufactures bury these rating in small print on the box or back of the owner's manual.

Another part of the equation is sensitivity of the speaker itself. For every 3 db increase in a speaker's sensitivity, the speaker will sound twice as loud with the same rated power. For example, a speaker with a 92 db sensitivity rating (at the standard measurement of 1 watt of power at 1 meter distance) will sound twice as loud as an 89 db rated speaker with 10 watts of power driving each speaker. Look carefully at the manufacturer's specifications. I know Polk used to rate their speakers at a 1 watt and HALF meter distance to get a higher sensitivity rating which makes it hard to compare apples to apples. Not sure if Polk is still doing this...

Higher sensitivity is good for car audio, but you do give up some detail and clarity. Many good home speakers are not all that sensitive due to the manufacturers wanting higher detail out of their speakers verses overall output level. So, with car audio, you have to find a nice balance between sensitivity and audio quality. All that being said, I typically look at speakers such as 6.5's or 5.25's that have at least a 90 db sensitivity rating so I don't need a 200 watt amp to get at least some volume out of them.

If your budget allows, I agree with everyone else in that you need an amp to get decent output levels in a car environment. The noise floor is so high in autos... A good rule of thumb is to take the RMS wattage rating of a speaker and double it (within reason). Then get an amp with that doubled rating of the speaker and you're doing well. For example, if a speaker is rated at 40 watts RMS, driving it with an amp that produces 60-80 watts RMS is a good match.

I have had some good sounding systems in cars with just 6.5 speakers, but they tend to be working very hard and need a high output amp (along with a good sensitivity rating!) to produce any meaningful bass in a moving car. Subs are really almost mandatory in most car audio systems to get a full spectrum of sound reproduced. Most 5.25" speakers just won't cut it and 6.5's even have a hard time in the car at full range.

If you ad a sub or two, you then need a crossover to separate the low frequencies from the mid/hi drivers and remove higher frequencies from the sub(s). A dedicated sub amp is needed as well. Many times, amps have the needed crossovers built in.

I do have a system in a car with two 6.5" subs in a proper enclosure (and proper amp) along with two 6.5" separates running full range (as well as other crossed over mid/hi speakers). That system has good bass output even with the small cone sizes, but there are two dedicated subs helping out the full range 6.5" speakers. It's all about how much cone area you have in a car when it comes to bass response.

Also, by adding a sub and crossing over all the drivers correctly, you actually "clean up" your mid hi drivers because they no longer need to reproduce the lowest frequencies. That cone in the mid hi speaker no longer has to flap around wildly while it reproduces kick drum, bass guitar, etc and is allowed to be more accurate while it reproduces the critical mid range frequencies.

Sorry for the extended length of this post!

Jay
90 964, 84 3.2

[jbrinkley]

that 500 he's got for sale is sweet. He'd be a great guy to buy from as he would probably hook you up with wire and fuses and such.
I like the JL300/4 because it fits under the pass seat perfect. But his would be plenty to do what you want.

[randywebb]

Jay posted a good explanation -- and there are other good comments above also. Ask about any specific questions you have and I'm sure someone can fill you in.

Remember that the law of diminishing returns applies to your wallet...

[SCWDP911]

Yeah, at this point, this is down the priority list, but I am trying to get the best bang for the buck. I do not want to spend much on it right now, just mayube enhance what I have a bit. I have wheels and exhaust to worry about first on the big moiney list. Wife is already telling me that I have spent enmough money on hobbies this year. Gonna be in trouble when she finds out about the wheels!

Anway, I can usually find 200-400w amps for next to nothing. Most are usually 2 channel, but occaionally find a 4. Is there a brand any of you stereo guys would recommend over others, as far as inexpensive amps go?

Thanks

[Jay H]

Originally posted by v8_ranch
Anway, I can usually find 200-400w amps for next to nothing. Most are usually 2 channel, but occaionally find a 4. Is there a brand any of you stereo guys would recommend over others, as far as inexpensive amps go?

Thanks

I think most of these inexpensive amps are pretty comparible now days. I bet everyone is copying everyone in amp design to remain competitive and lots of stuff is now made in China, evening out the manufacturing aspect.

You typically get what you pay for though and big power in car audio is just like big power in autos. It costs money for the high wattage, solid gear.

[quattrorunner]

I did my car on the cheep using Evilbay and buying quality name brands. Sony head unit with XM radio, alpine 6X9(guy who stole my car cut the holes!), alpine 6.5 two ways in the doors, and JL audio 8" in two seperate boxes behind the seats. Sony 4 channel with one channel bridged for the subs and no amp for the fronts. Sounds nice for what I spent.

[imcarthur]

Other than amplifier power (current is what's really important but that's another story) . . .

Remember that your door becomes a speaker enclosure. So, just like any acoustic suspension enclosure, it has to be solid, damped & no air leaks. So prepare to add some weight (Dynamat or equivalent) to do it right. I will report as I do mine in the spring.

Ian

Amazing: Up to 11 replies & we haven't gotten any posts from the rip-it-out-flat-6-music brigade.