| Amplifier Compatability - Click HERE for Original Thread |
| Ken_D |
| hi i've just installed new speakers to my car, and now i need an amplifier for it, which someone has recommended 4ch. The speakers i just installed are two tweeters which are 35watts rms 105watts peak and 4ohms, four 61/2" which are 60watts rms 180watts peak and 4 ohms. my question is how powerful of an amp must i install in order for me to get the best out of these speakers? |
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| kevito_ |
When considering the power requirements of the speakers, you want to first look at RMS (root-mean-squared) which is the average amount of power per cycle the speakers will use. At the very least you need a power supply that can deliever that RMS rating for all the speakers. After that, you can look at the peak power and determine, from your musical tastes and price range, what type of capacitor system you may need (or if you even need one) to run the speakers without underdriving them (and causing them to break).
Big bass kicks are mainly the maximum power usage for the speakers. Loud constant bass is mainly the RMS power of the speakers.
So for you... the minimum power you need:
Pmin_RMS = (2 * 35 W) + (4 * 60 W) = 310 W
Just to run them at their full capacity without underdriving them.
Now, if you like super massive bass kicks, you'll need to consider the peak power. Massive constant vibrating bass PLUS massive bass kicks will use all the power your speakers can take.
So for maximum power you will need:
Pmax = (2 * 105 W) + (4 * 108 W) = 642 W
But very rarely will any song be putting out constant bass and massive kicks at all times... you you will probably need a happy medium somewhere between 310 W and 642 W using a capacitor (or a bank of them).
I'd probably get a 400/450W (RMS) power amp with a 1 farad capacitor to drive the system without worrying about breaking it. The capacitor should give you decent amount of extra power when 'the music gets heavy'. IF you get a 650W RMS amp, you won't need a capacitor at all... but you might need a new alternator!
The entire time the system is not using the maximum power of the amplifier, the amplifier is charging the capacitor to use when the system can't deliever the required power. As long as you never 'use up all the capacitor' you will be fine.
Cheers |
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| Ken_D |
| ahh alrights i see thanks man |
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| Ravendarat |
quote:
Originally posted by kevito_
When considering the power requirements of the speakers, you want to first look at RMS (root-mean-squared) which is the average amount of power per cycle the speakers will use. At the very least you need a power supply that can deliever that RMS rating for all the speakers. After that, you can look at the peak power and determine, from your musical tastes and price range, what type of capacitor system you may need (or if you even need one) to run the speakers without underdriving them (and causing them to break).
Big bass kicks are mainly the maximum power usage for the speakers. Loud constant bass is mainly the RMS power of the speakers.
So for you... the minimum power you need:
Pmin_RMS = (2 * 35 W) + (4 * 60 W) = 310 W
Just to run them at their full capacity without underdriving them.
Now, if you like super massive bass kicks, you'll need to consider the peak power. Massive constant vibrating bass PLUS massive bass kicks will use all the power your speakers can take.
So for maximum power you will need:
Pmax = (2 * 105 W) + (4 * 108 W) = 642 W
But very rarely will any song be putting out constant bass and massive kicks at all times... you you will probably need a happy medium somewhere between 310 W and 642 W using a capacitor (or a bank of them).
I'd probably get a 400/450W (RMS) power amp with a 1 farad capacitor to drive the system without worrying about breaking it. The capacitor should give you decent amount of extra power when 'the music gets heavy'. IF you get a 650W RMS amp, you won't need a capacitor at all... but you might need a new alternator!
The entire time the system is not using the maximum power of the amplifier, the amplifier is charging the capacitor to use when the system can't deliever the required power. As long as you never 'use up all the capacitor' you will be fine.
Cheers
Did you need to go to school to learn to spout out that much bullshit or does it come naturally to you. |
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| AudiInProgress |
quote:
Originally posted by Ravendarat
Did you need to go to school to learn to spout out that much bullshit or does it come naturally to you.
It was good solid advice, and he didn't say anything that ANYONE who does their own car stereo wouldn't understand, pretty fucking simple if you ask me. |
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| kevito_ |
Just remember that the key is to supply enough power to the speakers for the given volume you want to listen to them at. Not enough power will distort the signal and damage the speakers because the signal wont be 'smooth', it will be distorted andover-driven.
Also, with the temperature and weather we have in the winter, high power rating speakers take a longer time to warm up than factory speakers. Make sure you have the system on low for a minute or two before you blast the music or you can blow the cones (glue might not be warm enough and not strong enough) or you could damage the coil (uneven heating/hotspots caused by condensation induced shorts in the coil windings).
And yes, Ravendarat, I went to school. Did you? |
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| AudiInProgress |
This guy is giving some really solid advice...
The worst thing you can do is underpower a speaker (speaker is a relative term I'm going to use to describe anything from a tweeter, a speaker, a subwoofer, coaxials) and pushing unclean power into a speaker is going to ruin it. You can have an amplifier rated for 150WRMS x4 and hook up 4 speakers with a RMS rating of 100W... And you're not going to hurt it, because you're pushing clean power. I mean, mind you, you wouldn't want to blast 100% volume through it 24/7... But in general speaking, most people couldn't handle that much volume anyways. |
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| Ravendarat |
OK Ill be nice. There are many inacuracies in this thread, and some things that I think you have right but have worded funny. Ill start at the top and go from there.
"At the very least you need a power supply that can deliever that RMS rating for all the speakers" This statement is not correct. You do not NEED to supply a speaker with this much power, you CAN supply a speaker with UP TO that much power from a source without risk of overpowering. In that I mean that if you have a speaker that is rated for 50 wrms and an amp that has a rated output of 50 wrms than you are set, however if the amp has 100 wrms of rated output per channel than you can deliver more than enough clean power nessasary to toast the speaker. On the flip side I can have a speaker that is capable of handling 200 wrms and only put 15 wrms to it and so long as the system levels are set properly than I will never do damage to the speaker provided I use the system properly.
"After that, you can look at the peak power and determine, from your musical tastes and price range, what type of capacitor system you may need (or if you even need one) to run the speakers without underdriving them (and causing them to break).
" This really makes no sense whatsoever. Your musical tastes have basically nothing to do with whether or not you need a cap, nor is a cap going to help you not underdrive a speaker, and as I said above underdriving a speaker is fine and perfectly safe provided the levels are set correctly. Also underdriving a speaker doesnt cause damage, improper use does. A capacitor is simply a shitty bandaid for all but 2% of the vehicles on the road. The common misconception is that if your lights are dimming than you should add a cap so that you have an additional power source to draw from that is fast reacting. This is a BS line of thought. A cap actually adds a strain on an everyday electrical system as it is giving the alternator another component to recharge. Lack of power in a car is fixed by adding a bigger alternator, period. You can add batteries for more reserve, or caps can be effectivly used in systems that need bursts of power for such things as SPL competitons but for everyday drivers they generally do more harm than good. Alot of people say that they added a cap and things got better or their subs hit harder or whatever, but realisticly it is generally that persons mind playing tricks on them and giving them a false perception as they want to believe that they didnt waste their money on a shiney paper weight so they see and hear differences that simply arent there. Show me an every day driver with a stock alt that actually had a real improvement by adding a cap and back it up with number proof and Ill resind my statements but in almost ten years of doing this no one has been able to do it yet.
Your math is correct in theory but not in reality. You have not taken into acount any of the other nessasary parameters such as voltage or efficency or sensitivity, so your numbers for a real world application are scewed.
"But very rarely will any song be putting out constant bass and massive kicks at all times... you you will probably need a happy medium somewhere between 310 W and 642 W using a capacitor (or a bank of them). " Once again I fail to see where you make the connection between his needs and adding capacitors.
"The entire time the system is not using the maximum power of the amplifier, the amplifier is charging the capacitor to use when the system can't deliever the required power. As long as you never 'use up all the capacitor' you will be fine." Amplifiers dont charge caps, the altenator does via way of the battery, also caps dont get "used up" they can discharge but the recharge in the same second, in fact caps in a proper electrical system can discharge and recharge several times a second.
"Just remember that the key is to supply enough power to the speakers for the given volume you want to listen to them at. Not enough power will distort the signal and damage the speakers because the signal wont be 'smooth', it will be distorted andover-driven." Well you are definatly correct in that you need to supply enough power to the speakers in relation to the volume level you hope to achieve. However distortion doesnt cause a speaker to be overdriven nor does a lack of power. Overpower causes a speaker to be overdriven.
"Also, with the temperature and weather we have in the winter, high power rating speakers take a longer time to warm up than factory speakers. Make sure you have the system on low for a minute or two before you blast the music or you can blow the cones (glue might not be warm enough and not strong enough) or you could damage the coil (uneven heating/hotspots caused by condensation induced shorts in the coil windings)." A higher end speaker doesnt require more time to "Warm Up". Condensation builds up on a speaker no matter whether its stock or aftermarket. The glue is actually less likly to let go on a higher end speaker as it SHOULD have a better build quality than the stock speakers.
"The worst thing you can do is underpower a speaker (speaker is a relative term I'm going to use to describe anything from a tweeter, a speaker, a subwoofer, coaxials) and pushing unclean power into a speaker is going to ruin it. You can have an amplifier rated for 150WRMS x4 and hook up 4 speakers with a RMS rating of 100W... And you're not going to hurt it, because you're pushing clean power. I mean, mind you, you wouldn't want to blast 100% volume through it 24/7... But in general speaking, most people couldn't handle that much volume anyways." Myth plain and simple. Underpowering a speaker CAN NOT CAUSE IT TO BLOW. Plain and simple, and any acoutic engineer will tell you the exact same thing. For further info on this I can sit here and explain it till my fingers are sore from typing but I will instead post a link to a discusion on another board about this very topic including links to some very well respected experts that tested this very myth.
Underpowering myth
So there ya go, its my two cents on the whole thing so you can take it for what its worth. And BTW the school comment wasnt really suposed to be an insult, just a joke. Sorry if it came off as anything but. |
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| kevito_ |
This is quite a long reply and I probably won't write something this long for a while... lol
My original post was just to give Ken_D a general overview of how to choose a decent sound system setup. Anyways, it's always good to discuss the specifics of any topic, and I agree with you that some of the things I mentioned may sound strange of funny- but please remember it was just a general overview of the subject.
If you really want to get into the specifics of signal amplification, the main concept regarding the differences between RMS power and peak power is flawed. The difference is just used to highlight some slight behavioral differences of an amplifier's ability to supply power when the input signal voltage is a pulsed wave packet (a big bass 'kick') versus a solid sine input (a consistent 'solid bass tone'). The main power of an amplifier is rated on its ability to put current through a resistive load at different voltages (ie: the power rating of the amp itself, not the signal load). So as long as we are going to use the terms RMS power and peak power to explain amplifier and speaker ratings, we must accept that we are just estimating or generalizing our understanding of the amplifiers true specifications.
If you want the full explanation, please read http://www.hifi-writer.com/he/misc/rmspower.htm, as the article is written by a very experienced and technically proficient author on the subject.
>You do not NEED to supply a speaker with this much power, you CAN supply a speaker with UP TO that much power from a source without risk of overpowering. In that I mean that if you have a speaker that is rated for 50 wrms and an amp that has a rated output of 50 wrms than you are set, however if the amp has 100 wrms of rated output per channel than you can deliver more than enough clean power nessasary to toast the speaker. On the flip side I can have a speaker that is capable of handling 200 wrms and only put 15 wrms to it and so long as the system levels are set properly than I will never do damage to the speaker provided I use the system properly.
Of course you do not need to supply a speaker with its peak power, that is precisely what the volume control is for. You want to have 100% volume to get as close to your peak power rating of the speaker without going over. However, when you crank the amplifier to maximum output, you don't want the signal reaching the speaker to be distorted and amplified in a weird way, causing damage through under-driving. Also, it's pretty obvious that putting more power through a speaker that it is currently rated for will over-drive and ruin the speaker. I've seen a lot of stereos ruined by being underpowered, but very few ruined by overpowering. It costs a lot more money to purchase and set up a amplifier system that provides excessive power to the speakers its paired up with. Usually if someone is going to drop two thousand dollars on an amplifier, they also get speakers that are rated to a extremely high power rating (very high quality and expensive speakers).
"After that, you can look at the peak power and determine, from your musical tastes and price range, what type of capacitor system you may need (or if you even need one) to run the speakers without underdriving them (and causing them to break)."
I'm sure you can agree with me that Dvorak's Symphony Number 9 would require an amplifier to output a significantly different output signal that if it were playing a Jonathen Peter's remix track. The instantaneous power and continuous power requirements for an amplifier to provide for these signals are completely different. There won't really ever be long periods of extended bass with huge bass kicks (unless you play around with the equalizer) in the classical piece... so you can assume you will be needing an amplifier system that needs to generally provide a constant level of power. For the electronica piece, you're going to expect some phat bass and most likely big kicks at the same time as the bass, requiring a completely different power requirement (there is a completely different signal) than the classical piece.
A capacitor is not a band aid solution: it is a piece of electronic equipment with a specific response under specific conditions. If it provides the desired output on the specific conditions, it is not a 'band-aid' fix. You don't call the capacitors on your computer's motherboard that sit near the CPU a band aid fix? If you want to get extremely high sound levels, you're going to need them, regardless. I don't know of any amplifiers that can push out 20,000W of power for a big, fast bass kick.
When it comes to the problem of dimming headlights while listening to music...
Consider when the headlights are dimming: when there is a big bass kick or long constant bass tones (they dim more as the tone continues with time). Now consider the physics of an alternator: an alternator provides a constant AC to DC electrical power generation depending on the efficiency, size and running speed of the generator. This power supply is relatively constant (as long as the RPMS are constant).
Consider the following example: You are listening to a piece of music that is using a pretty constant amount of power, causing your alternator (along with all the vital car functions) to use 50% of its maximumsupply-able output. Suddenly the song changes pace and fast, loud bass kicks come up. Now say that the alternator is spiking to 120% power usage during the big kicks to supply enough instantaneous power to run the amplifier. Your available power is being exceeded, causing the battery to act like a capacitor, but since a battery isn't an ideal capacitor, it can't make up for all the power drain and the headlights dim. You also get clipping, sound distortion and a headache. How can you fix the problem of the amplifier draining all the current of the charging system? Since the bass isn't occurring all the time, the average power demand on the system isn't really much higher than the 50%, because a short big signal averaged over a long low signal is still a low signal. You can add an energy storage device, ie: a capacitor, and use any extra alternator power to charge it so that extra power is available upon demand. With an appropriate capacitor installed, the alternator is running at say 85% power generation all the time in order to keep the capacitor in a state that can be charged. Any time the alternator reaches its maximum 100% power, the exceed demand of power will come from the capacitor, so the battery isn't used and the headlights will not dim. The capacitor will drain quickly and refill when the bass isn't kicking hard. The net drain on the alternator now is higher and may induce more wear and tear on the alternator. Either way, you're not running the alternator beyond what it can deliver. Sometimes you simply cannot choose a capacitor/amplifier combination that will provide you with the desired results and you must replace your alternator with something stronger. Such are the laws of the physical world...
When the amplifier attempts to draw too much power, the effective power supply voltage will drop below 12V and the capacitor will discharge at a rate that power is needed (up to a maximum speed) to feed the amplifier. A good capacitor will discharge quickly and a big capacitor will charge slowly.
The ideal design choices for alternators, batteries, capacitors, amplifiers, cables and speakers are quite complicated if you want to completely maximize the audio experience (its also expensive and takes a long time to calculate out), which is why I chose to estimate things in the first place. That's why people into hardcore audio pay the professionals to calculate and work out what would be the best possible combination as its not simple. But if you want to just get a decent amp and speaker setup and have them run properly without burning anything out, what I said is a decent procedure to follow.
> Your math is correct in theory but not in reality. You have not taken into acount any of the other nessasary parameters such as voltage or efficency or sensitivity, so your numbers for a real world application are scewed.
My math is actually quite oversimplified and isn't really all that correct for reality, since power RMS really doesn't actually mean anything useful. Anyone who tells themselves that RMS power has any real specific meaning does not understand physics nor mathematics: amplifiers aren't asked to output solid sine waves for long periods of time. However, it is a good way to estimate things without getting into some pretty nitty gritty details of electronics and engineering.
> "But very rarely will any song be putting out constant bass and massive kicks at all times... you you will probably need a happy medium somewhere between 310 W and 642 W using a capacitor (or a bank of them). " Once again I fail to see where you make the connection between his needs and adding capacitors.
It has to do with the RMS voltage signal vs. the available power supply from the amplifier which comes from the original battery/alternator supply. They are all linked as they all play a role in the power transfer process. If he decides on a low power amplifier and doesn't listen to music too loud, he won't need one. If he picks an amp close to the RMS rating of the speakers, he might need a capacitor to moderate any problems with power supply (without having to change a battery or alternator). |
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| kevito_ |
> "The entire time the system is not using the maximum power of the amplifier, the amplifier is charging the capacitor to use when the system can't deliever the required power. As long as you never 'use up all the capacitor' you will be fine." Amplifiers dont charge caps, the altenator does via way of the battery, also caps dont get "used up" they can discharge but the recharge in the same second, in fact caps in a proper electrical system can discharge and recharge several times a second.
Capacitors charge slowly and discharge quickly (relatively speaking). Since they do this over time, if you discharge the capacitor and can't charge it fast enough before it is required to discharge again, they are 'used up.' The storage becomes ineffective and the available power reserve is depleted. The battery(ies) can make up for this sometimes, if the system is designed well.
I have made a generalization of the location of the capacitor in the charging system. There are preferred locations for the capacitor in the system depending on the required behaviors. It can be placed in such as way as to be charged through the battery/alternator system or they can also be charged by an amplifier with the appropriate feed throughs. So thanks for pointing that out.
"Just remember that the key is to supply enough power to the speakers for the given volume you want to listen to them at. Not enough power will distort the signal and damage the speakers because the signal wont be 'smooth', it will be distorted andover-driven." Well you are definatly correct in that you need to supply enough power to the speakers in relation to the volume level you hope to achieve. However distortion doesnt cause a speaker to be overdriven nor does a lack of power. Overpower causes a speaker to be overdriven.
You are correct... on second thought I should have said: "Not enough power will distort the signal. Under high volume conditions, the signal may be distorted enough to cause over-driving (amplifier behaving strangely) or damage the speaker through distortions."
>"Also, with the temperature and weather we have in the winter, high power rating speakers take a longer time to warm up than factory speakers. Make sure you have the system on low for a minute or two before you blast the music or you can blow the cones (glue might not be warm enough and not strong enough) or you could damage the coil (uneven heating/hotspots caused by condensation induced shorts in the coil windings)." A higher end speaker doesnt require more time to "Warm Up". Condensation builds up on a speaker no matter whether its stock or aftermarket. The glue is actually less likly to let go on a higher end speaker as it SHOULD have a better build quality than the stock speakers.
Anything electronic that has current passing through it will generate a heat since it is a resistive load. More expensive devices that are usually more efficient and heat up slower. Even if the speakers were designed with quick warm up time in mind (which I doubt many are), I'd still air on the side of caution since I don't want my investment to 'go up in smoke'. High end speakers will most likely have higher end glues. Just think about the operating temperature range of a high end speaker: a high end speaker will be loud and clear, meaning they use tons of electricity. This means the manufacturer will choose glue that stays strong at higher temperatures. There are very few glues that are good at very high and very low temperatures. The more you drive up one performance in one extreme, the more it goes down in the other. So if anything, I'd wait even longer for high end speakers to warm up because I'm pretty confident -20C isn't the standard operating temperature that they were designed for.
> "The worst thing you can do is underpower a speaker (speaker is a relative term I'm going to use to describe anything from a tweeter, a speaker, a subwoofer, coaxials) and pushing unclean power into a speaker is going to ruin it. You can have an amplifier rated for 150WRMS x4 and hook up 4 speakers with a RMS rating of 100W... And you're not going to hurt it, because you're pushing clean power. I mean, mind you, you wouldn't want to blast 100% volume through it 24/7... But in general speaking, most people couldn't handle that much volume anyways." Myth plain and simple. Underpowering a speaker CAN NOT CAUSE IT TO BLOW. Plain and simple, and any acoutic engineer will tell you the exact same thing. For further info on this I can sit here and explain it till my fingers are sore from typing but I will instead post a link to a discusion on another board about this very topic including links to some very well respected experts that tested this very myth.
Underpowering myth
Under-powering a signal sent to a speaker (which is under-powering the speaker) can cause it to blow if the characteristics of such signal induces clipping or saturation for the amplifier (because it maybe running out of specifications). It actually mentioned in your Under-powering Myth Link:
This is the origin of the "under-power myth." If your speakers are rated for 150 watts and you use a 100 watt amplifier then drive it into full clipping, it is actually delivering more like 200 watts of effective power to the speaker when the speaker blows. "Oh," you say, "I used a smaller amplifier than the speaker rating and it blew. Therefore under-powering must blow speakers." No, what happened was idiotic amplifier setup blew the speaker.
The amp may be delivering well above the expected power through a clipping problem with is generated routed in poor hardware design or bad power supply setup. So you can blow a speaker by under-powering, that's why it is usually suggested to keep speakers' maximum power rating above the amp power rating: Which is what I suggested (without explaining it, though). But it should be noted that indeed the speakers should never have their maximum power levels exceeded as they will be damaged, but its pretty obvious that you shouldn't overdrive a speaker.
> So there ya go, its my two cents on the whole thing so you can take it for what its worth. And BTW the school comment wasnt really suposed to be an insult, just a joke. Sorry if it came off as anything but.
You should maybe work on the way your personality is represented online, because I'm sure I'm not the only one who thought a comment like that was weak and unprofessional, especially since your profile indicates that you are a car audio installation manager. |
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| Ken_D |
| Wow i've been reading all of these and tried some of them and you guys all have different ideas O_O |
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