hey there just wondering if there is somewhere i can read about rms and amps. If i have 2 tens both rated at 200 rms each. does that mean i must have an amp with two channels, where one channel is rated at 200 rms, and the other rated at 200 rms?
thanks alot.
Replies (4)
ttocs on 06/17/2008 19:04:07
I just looked through our DIY articles and didn't see anything that covered it.
power ratings and RMS ratings are important numbers when you are looking at amps, I have never paid attention to a speakers rms or peak power rating. When I try to match an amp to a speaker I look at the impedences(ohms) ratings of the speaker/amp and just try to give the speaker as much power as I can. A speakers power rating will not really tell you much because you can blow a speaker easier with too little power then you can by over powering it. When an amp reaches its limit of amplification, the signal becomes so large that it "clips" to top of the signal off for a short amount of time. The more you turn it up, the more of the signal is clipped. When the signal is clipped it will sound like a popping noise to you but the speaker is actaully being fed DC(direct current) voltage rather then the AC(alternating current) that it is use to. when the signal is clipped it causes the speaker to drive to is mechanical limit and then holds it in that position. This is the same thing as flooring your gas while its in nuetral, it will do it for a little while but you would not want to do it for long. A smaller amp reaches is limit sooner then a larger amp does and will start to clip the signal much sooner as well.
The rms/peak power rating on speakers gives a good point to start but it is not the bible. If you have two 10's, both rated at 200 rms you will want to try and give them as close to 200 watts EACH(400 total) as you can but again, more is better usually....
swez on 06/17/2008 22:34:46
To piggy back on ttocs' information, (right on target) it's better to have an amp that has additional reserve power for rapid/sustained spikes in today's bass "juiced" music. Basically, having more "clean power", (Non-clipping signals) available is good for the speakers/subs and helps the amp last longer too. Here's a common analogy to think about.
Say we are driving along the road at say 40 MPH. (Low RMS power to speakers from amp) The engine is not working very hard once the car is rolling and up to speed. There's little strain on any part of the engine and drive train under these conditions.
Now, we want to enter a freeway that's moving along at 65-70 MPH. In order to merge into that faster flow of traffic, we need a spike in power demand to get the car up to merging speed. To do that, we get on the gas peddle and ask the engine and drivetrain for more power to merge. This is a momentary spike in power demand, (Peak Power demand) but once we reach the desired merging speed, we ease off on the gas and the load on the engine is reduced once we attain the cruising speed to keep up with traffic. The greater the reserve HP the car has, the sooner we attain the new cruising speed. (Higher power demand, but well within range of the drivetrain)
The same idea can be applied to audio. Sometimes we just want enough music to enjoy while driving, but not have to yell to passengers as we chat. The RMS power demand is low and both amp and speakers/subs are not working very hard at all.
Now, say we want to show off a bit and turn up the music levels and see what the system is able to deliver. OK, as we dial up the volume, the amp gets a higher demand request and responds with more voltage to the speakers/subs. If the amp and speakers are well matched in power ratings, all is well and the sound remains clean, strong and very clear too. The amp and speakers/subs are working harder, but not to a point where the amp is being strained. (High RMS voltage level demands, but not clipping)
If we are running a heavy bass track, when bass spikes hit, demand for power goes way up considerably during these peaks. This puts the amp and speaker/subs under more stress to meet that spike. If the amp has more reserve power to handle these spikes, the bass stays clean, strong and pure.
However, if the amp is not set up properly in the tuning process, or is too low in RMS power, the spikes come and the amp runs out of gas, we get lots of clipping and the subs sound terrible because the signal is beyond the amp's capability. It tries to meet demand, but it cannot do so and hence, we get heavy clipping and the bass clarity and sound quality falls apart too. (Bad for the subs and hard on the amp too) To avoid this scenario, it's better to have more reserve power in the amp then the speakers are rated for. (20-25% is a good rule of thumb) Some guys prefer even more "headroom". (50% + is not out of the question)
So, if the subs are rated at 200 watts RMS each, a good match would be using an amp that can supply more than 400 watts of RMS power. This allows the amp to deliver more clean power, will not clip and subs are happy as they are receiving plenty of clean power from the amp. (Subs love clean power)
Here, it would be good to use an amp that can supply a solid 500 watts RMS of power or a bit more, when bass spikes hit. As long as the amp gains are set properly, there is minimal or no clipping and that is safe for the subs and amp. The trick is setting the amp gain properly, use minimal bass boost and listen for rough sounding bass. (That indicates the amp is now clipping and hard on the subs)
Finally, our ears can detect amp clipping issues well. The trick is to get out of the car and listen at a distance of 10-20 feet away. If the bass sounds tight, clean and full, you have done a good job dialing things in. If the bass sounds muddy/mushy or we hear hear the cone pops or other strange noises, dial back on the amp gains until it sounds clear and strong again.
Got all that?
Swez
PS It may be difficult to detect clipping issues inside the vehicle. Loud music blunts our normal hearing abilities. That's why I suggest getting out of the car and do a good walk around and listen from a distance. If the amp is clipping, you'll hear it easily while outside the vehicle and can adjust volume/gain settings until the bass is clean, tight and full sounding again.
swez on 06/17/2008 23:00:06
Ah, there is an article in our DIY about clipping. It's an older one and needs updating, but the basics are there and easy to understand.
http://www.clubknowledge.com/Car_Audio_FAQ/?t20
Forgot to answer one of your questions. Depending on the subs used, you can easily find a Class D sub amp to power both subs to full potential and more. A 2-channel amp will work in most cases too. But these are Class A/B amps and are not as efficient with power.
Class D amps that are normally made for sub applications. The offer about 80% eff and easy to find at reasonable prices too.
Class A/B amps are oftem multi-channel amps, (2,4, 5 or 6 channels) and are best used for mids and highs. Class A/B amps are about 60-65% eff. Fine for full range use, but they waste power in sub applications.
What subs are you considering here? (Brand & model #) Knowing that, we can show you several good amp options to meet their needs. Knowing the budget you have in mind will help too. No need to break the bank as you plan this system upgrade.
Swez
MrBrownstone on 06/23/2008 05:31:09
http://caraudioknowledge.yuku.com/forums/2?page=1
I don't know what's the thin with FAQs but here's a few pages of interesting notes
thanks alot.
Replies (4)
ttocs on 06/17/2008 19:04:07
I just looked through our DIY articles and didn't see anything that covered it.
power ratings and RMS ratings are important numbers when you are looking at amps, I have never paid attention to a speakers rms or peak power rating. When I try to match an amp to a speaker I look at the impedences(ohms) ratings of the speaker/amp and just try to give the speaker as much power as I can. A speakers power rating will not really tell you much because you can blow a speaker easier with too little power then you can by over powering it. When an amp reaches its limit of amplification, the signal becomes so large that it "clips" to top of the signal off for a short amount of time. The more you turn it up, the more of the signal is clipped. When the signal is clipped it will sound like a popping noise to you but the speaker is actaully being fed DC(direct current) voltage rather then the AC(alternating current) that it is use to. when the signal is clipped it causes the speaker to drive to is mechanical limit and then holds it in that position. This is the same thing as flooring your gas while its in nuetral, it will do it for a little while but you would not want to do it for long. A smaller amp reaches is limit sooner then a larger amp does and will start to clip the signal much sooner as well.
The rms/peak power rating on speakers gives a good point to start but it is not the bible. If you have two 10's, both rated at 200 rms you will want to try and give them as close to 200 watts EACH(400 total) as you can but again, more is better usually....
swez on 06/17/2008 22:34:46
To piggy back on ttocs' information, (right on target) it's better to have an amp that has additional reserve power for rapid/sustained spikes in today's bass "juiced" music. Basically, having more "clean power", (Non-clipping signals) available is good for the speakers/subs and helps the amp last longer too. Here's a common analogy to think about.
Say we are driving along the road at say 40 MPH. (Low RMS power to speakers from amp) The engine is not working very hard once the car is rolling and up to speed. There's little strain on any part of the engine and drive train under these conditions.
Now, we want to enter a freeway that's moving along at 65-70 MPH. In order to merge into that faster flow of traffic, we need a spike in power demand to get the car up to merging speed. To do that, we get on the gas peddle and ask the engine and drivetrain for more power to merge. This is a momentary spike in power demand, (Peak Power demand) but once we reach the desired merging speed, we ease off on the gas and the load on the engine is reduced once we attain the cruising speed to keep up with traffic. The greater the reserve HP the car has, the sooner we attain the new cruising speed. (Higher power demand, but well within range of the drivetrain)
The same idea can be applied to audio. Sometimes we just want enough music to enjoy while driving, but not have to yell to passengers as we chat. The RMS power demand is low and both amp and speakers/subs are not working very hard at all.
Now, say we want to show off a bit and turn up the music levels and see what the system is able to deliver. OK, as we dial up the volume, the amp gets a higher demand request and responds with more voltage to the speakers/subs. If the amp and speakers are well matched in power ratings, all is well and the sound remains clean, strong and very clear too. The amp and speakers/subs are working harder, but not to a point where the amp is being strained. (High RMS voltage level demands, but not clipping)
If we are running a heavy bass track, when bass spikes hit, demand for power goes way up considerably during these peaks. This puts the amp and speaker/subs under more stress to meet that spike. If the amp has more reserve power to handle these spikes, the bass stays clean, strong and pure.
However, if the amp is not set up properly in the tuning process, or is too low in RMS power, the spikes come and the amp runs out of gas, we get lots of clipping and the subs sound terrible because the signal is beyond the amp's capability. It tries to meet demand, but it cannot do so and hence, we get heavy clipping and the bass clarity and sound quality falls apart too. (Bad for the subs and hard on the amp too) To avoid this scenario, it's better to have more reserve power in the amp then the speakers are rated for. (20-25% is a good rule of thumb) Some guys prefer even more "headroom". (50% + is not out of the question)
So, if the subs are rated at 200 watts RMS each, a good match would be using an amp that can supply more than 400 watts of RMS power. This allows the amp to deliver more clean power, will not clip and subs are happy as they are receiving plenty of clean power from the amp. (Subs love clean power)
Here, it would be good to use an amp that can supply a solid 500 watts RMS of power or a bit more, when bass spikes hit. As long as the amp gains are set properly, there is minimal or no clipping and that is safe for the subs and amp. The trick is setting the amp gain properly, use minimal bass boost and listen for rough sounding bass. (That indicates the amp is now clipping and hard on the subs)
Finally, our ears can detect amp clipping issues well. The trick is to get out of the car and listen at a distance of 10-20 feet away. If the bass sounds tight, clean and full, you have done a good job dialing things in. If the bass sounds muddy/mushy or we hear hear the cone pops or other strange noises, dial back on the amp gains until it sounds clear and strong again.
Got all that?
Swez
PS It may be difficult to detect clipping issues inside the vehicle. Loud music blunts our normal hearing abilities. That's why I suggest getting out of the car and do a good walk around and listen from a distance. If the amp is clipping, you'll hear it easily while outside the vehicle and can adjust volume/gain settings until the bass is clean, tight and full sounding again.
swez on 06/17/2008 23:00:06
Ah, there is an article in our DIY about clipping. It's an older one and needs updating, but the basics are there and easy to understand.
http://www.clubknowledge.com/Car_Audio_FAQ/?t20
Forgot to answer one of your questions. Depending on the subs used, you can easily find a Class D sub amp to power both subs to full potential and more. A 2-channel amp will work in most cases too. But these are Class A/B amps and are not as efficient with power.
Class D amps that are normally made for sub applications. The offer about 80% eff and easy to find at reasonable prices too.
Class A/B amps are oftem multi-channel amps, (2,4, 5 or 6 channels) and are best used for mids and highs. Class A/B amps are about 60-65% eff. Fine for full range use, but they waste power in sub applications.
What subs are you considering here? (Brand & model #) Knowing that, we can show you several good amp options to meet their needs. Knowing the budget you have in mind will help too. No need to break the bank as you plan this system upgrade.
Swez
MrBrownstone on 06/23/2008 05:31:09
http://caraudioknowledge.yuku.com/forums/2?page=1
I don't know what's the thin with FAQs but here's a few pages of interesting notes
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