Car Audio - Amp suggestions.

[pbkid]

ok, im gonna tune in on this one. sorry for the lengthy post, but for once, i consider myself somewhat of an experienced person on the subject.

everyone posting information- PLEASE for GODS SAKE use RMS ratings... "peak" or maximum ratings are completely useless and make no sense.
Beau was completely right on this one, RMS ratings are 'continual' power. So they are accurate ratings taken on each and every item when its made.

jharris-
one of the most important things for a good sounding and long lasting system is to match your RMS ratings on all your products. The best anology i've ever heard for matching your power is this- give a football player one cup of water and see how long he can perform at 100 percent, give him a whole jug of water and he will take however much of it he wants.
It works the same for 12v systems, overpowering is fine, underpowering is very bad.
first, subs-
the bazooka's you listed are 200w RMS. so, depending on whether they are single or dual voice coil, you theoretically need a 400w RMS amp.
so, first find out if they are single or dual voice coils (also find out if they are 2,4 or 8 ohms per voice coil)... any local shop can throw a DMM (digital multimeter) on them and tell you exactly what they are. Once you find that out, let me know what your shop tells you and i'll be happy to help you find an appropriate amp.

speakers-
90 percent of speakers are 4ohms each. (infinity and bose are good examples of exclusions, they are 2 ohms or 1 ohm)
and speakers can range 40-120w RMS (each).

factory decks are around 8-10w RMS and aftemarket ones range 12-20w RMS. so, your giving your speakers 10w, when they require 50w. they arent gonna last long. although, most people run speakers directly off the deck and work fine for years, they will definately last MUCH longer and SOUND 80 percent better with an amp giving them the proper power.

so, thats the over-analyzed, difficult answer to a relatively basic question

i honestly wouldnt worry much about amplifying your speakers, focus on your subs and you will probably be happy with the results.
go to the local shop and ask them to tell you the resistance per sub, and we'll find a good set up for you.

[Grif]

The problem with running lower powered amps with higher RMS speakers is that ppl tend to push the amps to try make the more power hungry speakers louder. Running the amps so high (overmodulating) introduces noise which manifests itself as wild fluctuations in audio frequencies that can damage both the amp and the speakers.

Using a speaker with an underpowered amp is not a hazard in and of itself. Its when humans try to turn up the volume to try make them sound good that can be a problem.

[tom4bren]

... overpowering is fine, underpowering is very bad.

Sometime when you have an hour or two, you'll have to 'splain that logic to me. From an Electronics Engineer perspective that is bass ackwards.

[pbkid]

The problem with running lower powered amps with higher RMS speakers is that ppl tend to push the amps to try make the more power hungry speakers louder. Running the amps so high (overmodulating) introduces noise which manifests itself as wild fluctuations in audio frequencies that can damage both the amp and the speakers.

Using a speaker with an underpowered amp is not a hazard in and of itself. Its when humans try to turn up the volume to try make them sound good that can be a problem.

yup. very correct grif. especially when referring to midrange and highrange speakers (any amplification is probably more power than the deck provides)

Sometime when you have an hour or two, you'll have to 'splain that logic to me. From an Electronics Engineer perspective that is bass ackwards.

well, i really only understand the basics of it, and the principles taught to me for functionality and longevity of car audio.
What I've always been told, by anyone who i consider an expert (people with 10+ years in the car electronics business) is that its always better to overpower speakers... Basically due to what Grif has said above, that it requires the gain's on the amplifiers to remain to a minimum and creates less distortion.
The best technical explanation that i've heard is that low power causes distortion, which causes 'wild flucuations' as grif said, which damage the voice coils and eventually blow speakers.

[etlsport]

tom I think the part of this theory you are missing is that your overpowered amp isn't used to its full potential. That is what I have always learned.. Use each of your components at 60-80% but never max out.

When setting up my audio in a car I set the amp to 25% or so, then turn the head unit to about 80% of its volume scale. With a song playing I slowly increase the gain on the amp until I hit the loudest volume I would potentially listen to. Any distortion what so ever and I back the amp down until distortion is completely gone.

An amp rated higher than the speakers gives a lot of room to adjust..

Some folks prefer to set their equipment up at normal listening level and 50% volume on the head unit, but I like making sure when doing a demo or just rocking out I won't be doing any damage with distortion

[JHarris1385]

This is some great information. Thanks a lot. I will take a pic of my set up tomorrow and try to post here. Is there any way around not pulling the door panels off for speaker info? I am not 100% sure they are infinity, but if I could verify that they are or that they are not is it safe to assume certain numbers and plan accordingly?

[SouthJ1]

I have 2 12" subs and a 15" sub running off an old audiobahn amp I got for free and I have a 7" flip out monitor too

[Gussie2000]

The problem with running lower powered amps with higher RMS speakers is that ppl tend to push the amps to try make the more power hungry speakers louder. Running the amps so high (overmodulating) introduces noise which manifests itself as wild fluctuations in audio frequencies that can damage both the amp and the speakers.

Using a speaker with an underpowered amp is not a hazard in and of itself. Its when humans try to turn up the volume to try make them sound good that can be a problem.

X2

As i stated all goes down as how much you are willing to spend.

PBKID mentioned something very important..MATCH THE ENTIRE SET BY RMS not by peaks,although,electronics retailers usually use the peak value to impress customers that have no clue about RMS and PEAK values.

Personally i rather use amps with a lower RMS then the speakers just for some insurance, i hate to listen to a entire vehicule rattling all around,the key is tunning the music so you wouldn't need to be raise the volume in order to hear the music "better"

[Ascinder]

If you gonna replace the OEM speakers then aftermarket speakers ( 3-ways ).....

I had always heard 3 ways(speakers at least) were inferior to a component system(which we have). On 3 ways doesn't the tweeter get muddied by the midrange since it's sitting right on top of it? I thought that's why they came up with component(separated tweeter and mid) systems in the first place.

[Kenny]

I've been very happy with the JL 250W amp for my sub and the Alpine 400W for the F-R speakers.

I'm not an audiophile at all, but I like clear loud music. What I've found is that getting a decent brand amp ~$250 was good enough (previous year's model sales are awesome) - the real trick was to focus on your front speakers (components with aimed and calibrated tweeters in the A-pillar areas). Rear speakers should match in power but should only provide "fill" (some people even go mono) to make a nicer sound stage where you sit as a driver.

I've been experimenting a lot trying to figure out what people meant by "soundstage", "fill", "crossover freq" etc... and from my experience the vast improvements have come from upgrades and tweaking the front speakers.

Just my $0.02 from a neurotic layman's perspective.

From what I've seen on our site, most people are picking up nice head units so I'm assuming that issue is covered.


Sort of a work in progress pic.

[pbkid]

tom I think the part of this theory you are missing is that your overpowered amp isn't used to its full potential. That is what I have always learned.. Use each of your components at 60-80% but never max out.

When setting up my audio in a car I set the amp to 25% or so, then turn the head unit to about 80% of its volume scale. With a song playing I slowly increase the gain on the amp until I hit the loudest volume I would potentially listen to. Any distortion what so ever and I back the amp down until distortion is completely gone.

An amp rated higher than the speakers gives a lot of room to adjust..

Some folks prefer to set their equipment up at normal listening level and 50% volume on the head unit, but I like making sure when doing a demo or just rocking out I won't be doing any damage with distortion

Yes, etl is very correct. I couldnt of said it better myself.

I had always heard 3 ways(speakers at least) were inferior to a component system(which we have). On 3 ways doesn't the tweeter get muddied by the midrange since it's sitting right on top of it? I thought that's why they came up with component(separated tweeter and mid) systems in the first place.

and yes, once again. correct. 3 ways dont sound near as good as component speakers.
the difficult version is that higher frequencies are more directional than low frequencies. Therefore, the tweeters need to 'bounce' off something towards you (like the windshield or dash) or they need to be pointed straight at you. In the factory location (down by the feet) the sound of the tweeters get blocked by your legs.

the real trick was to focus on your front speakers (components with aimed and calibrated tweeters in the A-pillar areas). Rear speakers should match in power but should only provide "fill" (some people even go mono) to make a nicer sound stage where you sit as a driver.

ya, kenny also has a valid point. that the most important speakers in your car are the fronts. You dont go to a concert and stand backwards do you?

[tom4bren]

that it requires the gain's on the amplifiers to remain to a minimum and creates less distortion.

tom I think the part of this theory you are missing is that your overpowered amp isn't used to its full potential. That is what I have always learned.. Use each of your components at 60-80% but never max out.

... normal listening level and 50% volume on the head unit, but I like making sure when doing a demo or just rocking out I won't be doing any damage with distortion

OK, I'll buy off on that.

The way that you should look at it though is: The amp should be selected so that it is normally operating at approximately 1/2 of it's max power for the speakers being driven. This is done so that the amp is not being over driven into a level of distortion. Designing a system to intentionally over drive one of the components is asking for problems.

There is a drawback to this approach however, with this set up, you could easily end up with blown speakers if some Gomer cranks the volume too high and overpowers your speakers.

Keep in mind as well that initial transients can be as high as 150% of max normal operation. What I mean here is that if you leave your sound system turned on to a high volume when you turn off your car, when you turn it back on, you could get short duration spikes that could damage your system. A lot of systems (but not all) avoid this by having a short delay in powering up your amp after the head unit gets power.

Sorry if I'm coming across as anal retentive about this ... rekin it's one of my pet peeves. I H8 pulling up next to a car and hearing their stereo cranked so high that the the distortion causes physical pain in each and every one of my fillings.

[pbkid]

yup tom. thats why i tune amplifiers the same as etl explained.
i turn everything all the way down on each amp, turn all the settings up on the deck (EQ's, volume, etc) then turn the amp up until the speakers distort, then turn it back....
that way, even if the gomer who own the car turns their bass all the way up on the EQ on the deck and crank the volume, it doesnt damage the speakers.

in fact, we have stickers at our best buy store that we would put over the knobs on the amp, so that if someone tries to screw with it themselves, their warranties on everything is void.

also, regarding overpowering speakers. New spakers have filters on them that they only take the amount of current that they need to operate at full capacity. so its virtually impossible to overpower speakers nowadays.

[Junster]

Two main amp killers are too small power wires going to them and improper speaker wiring. DC voltage gets huge drops over short distances. Use fat 6ga. on a 200watt amp, 4 or 2 gauge on a 1000w. 1ga or 0ga on a 2000w. Don't forget the ground wire has to be at least half the size of the power wire or bigger. If you have a big sub and at idle when the sub hits hard you see the headlights dim that is bad. To low of a power pulse can turn your dc to ac and blow the amp that why ppl install a big capacitor in the + side of the power wire. Fuses are critical when the wires are this big. A short can set your car on fire. The other killer is wiring the speakers so you inadvertently drop the OHM load down to 1 or less. The less OHM loading the more power that gets returned to the amp on the - side. This is why a 1 OHM rated amp is so costly cause the internal components have to be much larger and heavy duty to dissipate the returning power that gets turned to heat. A "dual coil" sub is a good example. it's usually rated at 4 OHMs. Each coil is 4 OHM. If you jump + on one terminal to - on the other, then + on the amp to one and - on the amp to the other it's now a 8 OHM speaker (easy on the amp but not as loud). Hook both + together then to the amp, both - together then to the amp now it's a 2 OHM speaker. Louder by far but hard on the amp. Do the 2 OHM thing then "bridge" the amp? Now it's a 1 OHM load, crank it up and you better have a expensive amp or it will melt it. Parallel connections (+ to+) half the OHM. Series connections (+ to -) double the OHM. As far as power of the amp? to get a 10" sub to make good thump takes about 250watts. To get twice what 250 delivers takes 1200watts. Good box design makes a sub thump. Good wiring keeps your stuff working.

[Junster]

Sry if I'm ranting. My personal choice for speakers? It's hard to beat the sound from Infinity. If you search the web you can find free speaker box design programs. I built a bass box for my best friends wifes Toyota truck, It's 18" x 9" x 9" has a forward firing folded port that is 8" x 2" x 18". It has a 8" kicker sub in it and it will drive you right out of the truck. It's run by a bridged 66w planet audio amp wired to 2 OHMs. Thats not a typo it's a 33 watt old 2 channel amp bridged to 66 watts she's been using it for over a year now and she cranks it all the time. Tons of power can overcome poor design. But it isn't necessary. Separates do sound better. But if you get them to far apart you lose the stereo imaging. It's all about wavelength. The higher the frequency the shorter the wavelength. The short wavelength the more easily it's absorbed. That's why your neighbor cranks his stereo all you hear is the thump thump. Long waves (bass) penetrate things, short ones don't. The best things about separates are the better quality crossovers that usually come with them and that the separate singles are usually better made. The newer plate speakers, mid and tweeter mounted together on a flat plate really sound good. One of the easiest ways to make small speakers sound better is to get a set of chokes or blocks. It's a single capacitor sized to block the bass out of the signal and let the higher frequency thru. So your 5 or 6" mid isn't trying to play the low stuff. They make a huge difference if you have a sub in your car and your door speakers are running off the head unit. They are cheap and easy. You just pull the + wire off the speaker hook it to the cap then the other end of the cap to the speaker.