Maybe some car audio guys can give me a tip here...

I got some polk 5 1/4 components coming...they're rated at 100 rms. I've got basic pioneer 6x9's in the back, rated at 40 RMS. Ive got a 4 channel amp, 75x4. It also does 200x2. I heard the polks really love to suck down power.

Should I power all 4, front and rear, with 75x4? Or power the polk components up front with 200x2, and power the rear fills with the head unit?

What do you think?

12/14/2005 11:04:42 AM

wont you blow the rears>?

[Edited on December 14, 2005 at 11:08 AM. Reason : ]

12/14/2005 11:07:39 AM

I was figuring I could just tone down the gain on the rear? I don't know, what do you guys think? Im no expert at this...im sort of feeling my way through it.

12/14/2005 11:14:41 AM

nah, gain isnt the same as watts.

im thinking use it to power the fronts, and subs, and run the rears off the HU.

can you bridge just the rear channel?

12/14/2005 11:25:49 AM

choice B

12/14/2005 11:34:19 AM

Thanks for the input...i was figuring choice b myself. I've heard its better to overpower (200 rms to 100 rms components) than underpower (75 to 100 components).

12/14/2005 11:43:10 AM

Grape, ive got a seperate amp for the subs, if thats what you were asking about...

12/14/2005 11:45:23 AM

oh, then it seems a waste of a 4 channel amp to only power a pair. get some higher wattage 6x9s for the rear.

12/14/2005 12:10:13 PM

rears are lame. id take em out if i were you. but if were to keep them, id take the highs out (LP xover). if i were to keep them full range, id run the amp on the front stage where it counts, and fade mostly forward

[Edited on December 14, 2005 at 1:43 PM. Reason : afd]

12/14/2005 1:43:22 PM

i recomend you bridge the 4 channel to your fronts to make them happy and just run your rear 6x9s off the headunit. you may even want to fade it to the front a bit.people spend way too much time and $ on rear fill.

12/14/2005 1:48:30 PM

Yeah, thats what I keep hearing...most car audio people seem to all feel the rears are almost useless. I figure just running them off the head unit will be sufficient. thanks guys.

Now to begin drilling into my firewall...

12/14/2005 1:59:17 PM

It seems like he would have to do something special to keep the stereo image, no?

12/14/2005 2:15:46 PM

No. Essentially would be bridging the two lefts and the two rights into one of each...

12/14/2005 2:44:10 PM

Yep, choice B. The fronts off the amp, and the rears off the deck.

^^If I understand you correctly, here is the explanation. The HU powering the rears will have the left and right separated. The RCAs to the amp are left and right. The amp will have a left and right when it is bridged. Therefor, the front and rears will play left and right, and keep stereo.

12/14/2005 2:48:08 PM

I think you guys are wrong, but I am verfying this for myself.

12/14/2005 3:53:11 PM

^^ Is correct. If by "verifying" you mean you are going to ask some buddy of yours then don't bother.

12/14/2005 4:19:11 PM

lol

12/14/2005 4:24:23 PM

choice B will work fine. i know from experience

12/14/2005 4:25:31 PM

Can you guys describe the detailed connections regarding the amp and how this will keep the stereo image? That is, which RCAs are going to which inputs, and which bridged outputs are going to which speaker. His statement about it being in stereo is pretty vague so far, and your "backing" of his statement doesn't add anything. And my buddy is google thanks.

12/14/2005 4:25:51 PM

inputs (RCAs):
FL, FR, RL, RR
some amps will let you internally jumper front and rear inputs so you only need to run one set of RCAs. else use Y adapters

outputs (speaker wire, read your amp's manual for wiring):
(F+R)L, (F+R)R

12/14/2005 4:38:48 PM

preamp outputs of head unit into the amp, amp bridged still provides a L and R channel, so those are wired up to the correct front L and R speakers. The headunit amp will power the rear L and R speakers like normal.

or

take the front line level output from the head unit and run that to the amp, then the amp bridged to the front speakers and then the head unit straight to the rear. This will keep the fader function of the headunit working and you will keep the left and right channels separated.

Wire it up like this on the output to the speakers and you bridge 4 channels into 2 while keeping the L and R separate.

12/14/2005 4:40:15 PM

^ There, your diagram explains what needs to happen on the output, but I can't dope out if anyone has hit on a very key point about the input yet that needs to occur to maintain the correct image (^^ hard to understand with your "detailed" description).

12/14/2005 4:46:07 PM

^ok seriously.

Why don't you take the time to explain in detail about what yo uare talking about instead of telling everyone how they are wrong.

Better yet, explain this "key point" everyone is overlooking.



[Edited on December 14, 2005 at 5:11 PM. Reason : turn the obligation around]

12/14/2005 5:08:08 PM

Eh, everyone is so adamant on being correct. It seems to be the trend in every thread I have ever viewed. Why are you not confident now in your understanding of the material that you place the burden of proof with me? I want to give you a chance to be the thread hero, to show the whole site you know what you are talking about here.

12/14/2005 5:17:40 PM

No, everyone is on the same page EXCEPT for you. So instead of everyone trying to sway your opinion, why don't you enlighten us?

I personally think either you are very wrong and trolling or you are talking about something different. For the second case it would help if you used the proper terms because your question has been answered, but you don't seem to get it.

I could care less if I was right or wrong. I just want to know WTF you are talking about.

12/14/2005 5:23:40 PM

Nah, I'm on the same page as everyone. I know now that it can be done. I'm mostly interested to know who really knows car audio here and who doesn't so that everyone will know who to trust when it comes to advice giving. There is a pretty important detail being left out thus far and I want to know who knows it. Or don't mind me, when the new semester rolls around I'll go away again, but until then, you're stuck with me.

12/14/2005 5:49:57 PM

so you guys dont think running 200x2 to fronts rated for 100w rms will blow them?

12/14/2005 6:17:39 PM

i'm not familiar with this amp, but as long as this is "clean" power being run to the fronts, then the 200rms shouldnt blow them. It's distortion that will blow a sub...not purely being overpowered. You can run as much wattage to a speaker as you'd like, as long as it's not being distorted.

12/14/2005 6:26:16 PM

200 watts going to front 5 1/4 components, actually....Polk db5250 -- some of the reviews of read about it say they need really good power. I didnt wanna underpower them, so I was asking if 200 watts per channel up front would be too much...I've been told to "watch the volume" and it should be okay.

12/14/2005 6:32:29 PM

yeah, as long as you dont have the amp and volume maxed out so that it starts distorting, then you should be just fine.

Cobb Car Sterioran over 2000 watts RMS to a sony 12" sub...rated at 250RMS i believe....he pounded the hell out of the sub and it never skipped a beat. Didnt hurt the sub at all.

Anyone ever heard of Cobb Car Stereo...Located in Reidsville? These guys know what they're doing.

I have worked closely with these guys in the past, as well as a guy named Erik Reid that I worked with at Best Buy...he was sponsored by Memphis Audio and competed on a semi professional level for years. Here's his stats.
http://www.termpro.com/asp/competitorstats.asp?Competitor_ID=7

I take what he says to be money.



[Edited on December 14, 2005 at 6:45 PM. Reason : .]

[Edited on December 14, 2005 at 6:46 PM. Reason : .]

12/14/2005 6:39:47 PM

Depends on how retarded you are really. A low volumes the amp with be pushing out a low # of watts. Just because its rated for x number of watts doesn't mean it constantly outputs that much.

Personally I would overpower a speaker then underpower it. In the long run the chances of you damaging the speaker with it underpowered are much higher (unless you are trying to screw it up).

If you look at a lot of "audiophile" type home setups they are using floor standing speakers powered by 15 watt per channel tube amps. Now I know that sounds like it contradicts what I said above, but the tube amp guy will be in his house critically listeneing to music. He won't be trying to rock out the whole house or be trying to over power 80 db of road noise.

It can depend a lot on the music as well. Usually its not very constant and has high peaks in the music. This is partially what allows compression algorithms to save space over the uncompressed trac. Variable bit rate encoding takes this idea a step further and cranks up the bit rate when a lot of information in the track is present. When the levels die down so does the bit rate needed.

If you look at the people who compete in car audio, you'd be suprised how things are set up. For example Jay Lovelace who (I think) partialy owns Creative Acoustics in Raleigh at one point was the world record hold for the db drags. He hit 174.2 db with 4 15" subs. To power them however, he used 32 amps to produce 81,000 watts rms.

(I was taking time to look up the info for creative acoustics so my reply is a little late)

12/14/2005 6:47:37 PM

Quote :

"He hit 174.2 db with 4 15" subs. To power them however, he used 32 amps to produce 81,000 watts rms."

Only info I could find around these numbers is 24 mmatts and 12 Cerwin Vega 15s. When you typed that out, did you honestly think to yourself, a sub that can handle 20,000W surely exists, right?
Here -
http://atomicsound.net/fin/ice/mm/dclass.htm

12/14/2005 7:31:07 PM

buckojackson - Can you post some links where you are reading people are claiming these are power hungry? I can't find much, and with a sensitivity at 91db, these shouldn't be really power hungry compared to any other speaker out there.

12/14/2005 7:39:03 PM

If you know so much, and know something that we are all missing, then why don't you tell us and be the savior of your own thread. A lot of us know what we are talking about, so don't try and at like you are trying to weed out the knowledgable. We already know eachother.

200W RMS will not hurt your speakers. just keep the gain away from all the way up, and be cautious of distortion.

Is that basic enough for you? Since you ask questions about simple stuff, but say we aren't giving you answers.

12/14/2005 7:42:15 PM

I agree that at sensitivity of 91db, these should not be very power hungry at all...however, I dont have any personal experience with these speakers though, so I will not claim to know this beyond the shadow of a doubt.

p.s., I think 1CYPHER is a jackass.

[Edited on December 14, 2005 at 7:53 PM. Reason : jackass]

12/14/2005 7:50:46 PM

You don't want to step up to the plate either Maxima? This isn't my thread for one thing. And I don't care if you know each other, I don't know you, and I am certainly not going to rely on the "scratch your buddies back" method for proving credibility. It seems to me that tnezami and dannydigital might know whats up, but I am a little skeptical of you and gephelps right now based on the language and terminology you have used in this thread so far.

12/14/2005 7:54:47 PM

Jackass? Harsh. Come on now, don't you think this is fun? See who has more knowledge? This isn't about being an ass at all, just a fun little game to see who the authority is, thats all. Someone here should be able to take what bucko has told us, combined with a little googling, and give some bonafide quality advice based on the situation. I actually have a no scenario that you non "think outside the boxers" haven't considered yet that might be the best one of all.

12/14/2005 7:56:52 PM

I know my stuff. Just because I try and explain things as simple as possible does not mean I am pulling stuff out of my ass.

And not to have a pissing contest, but still, why don't you step up yourself?

12/14/2005 7:58:05 PM

Quote :

"The RCAs to the amp are left and right. The amp will have a left and right when it is bridged."

Your initial comment. Just explain how the amp will have a left and right stereo image. Phelps gave you the diagram. But I'd like to know how R and L from his diagram (R attached to 4/3, and L attached to 2/1) have a different signal to create the stereo pair. Just because that diagram has L and R labeled as such doesn't mean anything to me, especially when I don't know what the input was.

I did the calling out here, not the other way around.

You say you know your stuff, but even after someone making this statement:

Quote :

"A low volumes the amp with be pushing out a low # of watts. Just because its rated for x number of watts doesn't mean it constantly outputs that much."

A correct one
you said this:

Quote :

"200W RMS will not hurt your speakers. just keep the gain away from all the way up, and be cautious of distortion."

which contains 1 correct statement, one "not always statement" (almost a semantic argument), and a misleading almost lack of knowledge statement (at the very least, careless word choice). So you have to see where I am coming from when I say you don't give me a warm fuzzy in the car stereo knowledge department.

12/14/2005 8:10:59 PM

ok,

4 channel amps are labeled with a positive and negative such as:
A(front) L+- R-+
B(rear) L+- R-+

When Bridged, you then have
A +-
B +-

When the RCA are plugged in, the amp is labbeled A, B. Amps may also have L, R labbeled. The amps circuitry will change the AB from front rear to LR. That is the way it has worked on the amps that I have handled. I am positive that there are exceptions, so don't try and call me out on that. Specifiacally, my kenwood amp is handled this way.



As far as the rest of what I said, which you quoted, I told you, I dumb down what I say when explaining to people who know nothing. You claim to know your stuff as well, so you can understand that there is a lot of play in what I say. I know that what I typed has a lot of innacuracy, but I works for someone who knows nothing. I can go into the power produced by amps, matching voltages when setting gain, and specifics on distortion and "clean" signal, but that didn't seem neccesary(sp).

12/14/2005 8:33:52 PM

Quote :

"When the RCA are plugged in, the amp is labbeled A, B. Amps may also have L, R labbeled. The amps circuitry will change the AB from front rear to LR. That is the way it has worked on the amps that I have handled. I am positive that there are exceptions, so don't try and call me out on that. Specifiacally, my kenwood amp is handled this way."

I wholeheartedly retreat from being a bit of a dick in this thread. I haven't had any new equipment in awhile and my old stuff (probably 5 years old now maybe?) you couldn't do it like this. So for fairness sake to both of us being "right" for different reasons, this bucko has to be sure that his amp will work like this. If not, the way around it would be to give one pair of channels the same signal (left, for example) to both RCA inputs and the other channel right, because if you give both L and R, then thats how you lose the stereo image...unless, like you say, the amp makers were smart enough to think about this and handle it "behind the curtains" for you.

12/14/2005 8:40:33 PM

Here's the link to 5 reviews, that mention its power intake:

http://www.cardomain.com/reviews/list.pl?reviewed_sku=POLDB5250

[Edited on December 14, 2005 at 8:45 PM. Reason : .]

12/14/2005 8:45:33 PM

I think that was stated before. If there are 4 RCA input, then you will use 'y' splitters and run two lefts to the 'A' side and two rights to the 'B' side.
This would still leave you with a separate signal for left and right.

12/14/2005 8:48:01 PM

well....i assume it would work...im using one set of R-L RCA outs from the headunit, going to one set of R-L inputs on the amp. Then, the R speaker output to the right speaker, the L speaker output to the left speaker. I mean, am I totally missing something here or is this theory of this easy?

12/14/2005 8:57:31 PM

what amp do you have?

12/14/2005 8:58:56 PM

It's an old amp a friend gave me...a JBL GTQ400.

12/14/2005 9:00:40 PM

forgive me, im now learning stuff i thought i knew.

how are rms ratings on speakers determined, and what do they mean, if you can overdrive his front speakers by twice (maybe more) what is a safe overdrive, what speakers can take it, etc?

12/14/2005 10:19:49 PM

You are far more likely to blow a speaker with too little power than too much.

And honestly many of the ratings for both speakers and amps aren't very accurate, or too important to be honest. Your 100watt RMS amp is only putting out 5-10 watts 90% of the time, even when its turned up. The high RMS rating allows for headroom and for the amp, and speaker, to actually reporduce the dynamic portions of the music source.

With the exception of multiple, by which I mean 4 or more, large subwoofers and competition specific cars I have never seen a speaker blown by too much clean power.

12/14/2005 10:41:31 PM

exactly. When a speaker is underpowered, you're usually maxing your amp out...creating distortion...which fucks up your speaker.

12/14/2005 10:50:16 PM

^^
An RMS rating, or root mean square, is a way to talk about an AC signal in DC terms. We treat the speaker like a DC load (a resistor essentially, even though it isn't) and this lets us talk about how much equivalent DC power it could handle over time. There are a lot of other variables that are left out that under any other electro/mechanical circuit specification(say an IC heatsink combo) you would need. In general, a good manufacturer is going to rate theirs fairly accurately, a great mfg. will underrate, and a shitty mfg. will overrate.

Quote :

"You are far more likely to blow a speaker with too little power than too much."

Lets educate people here because across the average case, your typical uninformed user could blow up any speaker with any amp combo if he really wanted to. Where this comment is originating from is when you drive an amp harder than it wants to go, the nice round sine waves we want our music to be turns into square waves. When the speaker is being driven by the flat part of the wave, it is essentially DC, and instead of a nice harmonius charging and discharging of that inductor that is the voice coil, it becomes a short circuit through the wires, causing them to heat up and eventually kills the voice coil. Most modern speakers are made such that their mechnical power handling (comprised of the surround, spider, some cases the voice coil collar, the pole peice, even the cone) is much greater than their electrical. For the electrical to be on par with the mechanical, you would need some sort of heat sink and fan on the voice coil to guard against clipping (the flattened waves I mentioned earlier).

Quote :

"And honestly many of the ratings for both speakers and amps aren't very accurate, or too important to be honest."

Too important? Come on now, lets not be that critical. I'd like to know if my sub can take a 1000W class D amp I am about to throw at it.

Quote :

"Your 100watt RMS amp is only putting out 5-10 watts 90% of the time, even when its turned up. The high RMS rating allows for headroom and for the amp, and speaker, to actually reporduce the dynamic portions of the music source."

This isn't really correct. If you run a fairly clean audio signal through your amp and take a strong enough speaker you can drive close to full RMS power that the amp will put out. RMS is an average already, how robust the resevior caps and the feeback loops in the amp will determine how much headroom you actually have.

Quote :

"With the exception of multiple, by which I mean 4 or more, large subwoofers and competition specific cars I have never seen a speaker blown by too much clean power."

It's relatively easy to burn a tweeter up, especially a silk dome, with too much power.

12/14/2005 11:03:15 PM