AVS Forum banner
Status
Not open for further replies.
1 - 16 of 16 Posts

·
Registered
Joined
·
62 Posts
Discussion Starter · #1 ·
okey another question. I'm shopping for a subwoofer and want to know what it means when it says 100W rms/150W dynamic. what is this "rms" and "dynamic" stuff? thanks
 

·
Registered
Joined
·
5,605 Posts
RMS is constant power handling. Dynamic is transient peak or maximum power handling expressed by mill-seconds. That was my thought on it, but here is what www.audiovideo101.com saids:


"RMS (Root Mean Square): Generally, the average continuous power output an amplifier is capable of producing; power output an amplifier can produce consistently over extended lengths of time."


"Dynamic Headroom: The ability of an amplifier to put out more power than its average power output for a short time in order to faithfully reproduce sudden, loud sounds without distorting or clipping."


"Dynamic Range: Difference between the highest and lowest sound levels a sound system reproduces; also the difference between the overload level (the highest possible output) and the noise floor (point where output is at a minimum if output goes lower it is obscured by distortions or noise making it unusable)."



"Dynamics: Term used to describe how well a particular sound system can accurately portray sound from the lowest amplitude (lowest volume) signals to those of very high amplitude or volume."


A speaker may handle 100 watts for a short RMS period, but only handle 1000 watts at peak dynamic power. So if you feed 1000 watts continuously into a driver that handles 100 watts continuous you will damage the driver.
 

·
Registered
Joined
·
62 Posts
Discussion Starter · #3 ·
so basically if the highest it goes is 200W and I leave it at 3/4 power it will be fine? or as long as it isn't at its max for more than a couple seconds its okey? thanks (if this isn't right please tell me!
 

·
Registered
Joined
·
5,605 Posts
The volume knob has nothing to do with the power in watts the speaker receives. If a speaker can handle 200 watts max than the amplifier power going to it should be no more than 200 watts. You need to find a speaker that is power matched with the amplifier or receiver. If you buy a powered sub, the guess work is taken away for you as it is matched.
 

·
Banned
Joined
·
20,735 Posts
Quote:
If a speaker can handle 200 watts max than the amplifier power going to it should be no more than 200 watts
Not so!! The best thing for a speaker is clean, unclipped power that is well within the range of the amplifier to provide. A much better combination is an amp that exceeds the max capability of the speaker. This means that if you turn up the volume to a point where the speaker is reaching its limits, you are still *well* within the capability of the power amp to send out very clean unclipped signals. The other way around, the amp will stress and clip, you'll lose dynamic range capabilities, and the clipping is what threatens speakers (especially tweeters) more. It is very difficult usually to overdrive a speaker with an amp that exceends the capabilities of the speaker. Usually it's damage because of an *underpowered* amp.


An amplifier can provide something like an "average" power (loosely what RMS is, you can consider it that for conceptualization purposes and simplicity). This is continuous power over a period of time, that is the limits of the amp. However, it can provide more power than that from it's reservoirs, for very brief signals like transients, and other very quick bursts.


In any case, the wattage ratings on many a product are notoriously misleading in terms of performance, "real" watts, etc. But that's the idea behind it anyway, but I would caution anyone to be very wary at looking at wattage numbers as meaning much of anything, until you've acertained the honesty of the numbers. Usually this is hard to do.
 

·
Registered
Joined
·
5,605 Posts
I have known that more power (clean power) is safer than less power since 1985. A clipped amp will destroy a speaker. But, there is such a thing as overpowering a speaker and damaging it.
 

·
Banned
Joined
·
20,735 Posts
I didn't say there wasn't such a thing as overpowering a speaker, just that it's usually not the problem. Suggesting that an amp that matches, or is lower than the power handling capability of the speaker supports a common misconception that leads to fried speakers just the same. You seem to be contradicting yourself, because more power capability is ALWAYS better. I think we agree on that. The key is that you should keep the volume to a reasonable level to not overdrive the speakers with too big an amp. At the same time, an underpowered amp is more likely to damage the speakers sooner, at lower volumes.
 

·
Registered
Joined
·
5,605 Posts
I agree completely. More power is better. What I originally tried to help him with was power matching a speaker with a receiver or amplifier. If a speaker has a spec of 200RMS/400max and the receiver should match that range. Very true about drivers blowing if given too little power.
 

·
Registered
Joined
·
62 Posts
Discussion Starter · #10 ·
okey thanks so far but now that leads to another question...I havn't seen a receiver yet that gives out more than 120W per channel... what do I do if my speaker is 200W because you said its better have more watts going to the speaker than its at. and another thing... what exactly is watts? thanks again guys
 

·
Registered
Joined
·
62 Posts
Discussion Starter · #12 ·
so if I get a 6.1 600W sony receiver and 2 front 150W sony speakers, 120W center speaker sony, 2 rear 100W speakers sonyand a 250W sony sub I'll be okey? that's what its looking like... sound good? any changes?
 

·
Registered
Joined
·
62 Posts
Discussion Starter · #14 ·
well thanks so far guys but everyone is telling me to make sure I have 150W going to 150W speakers or more... I havn't seen a receiver yet that gives out more than 130W/channel... where do I find one or what do I do?? thanks
 

·
Registered
Joined
·
7,656 Posts
The speaker rating is just a max. You've gotten some good advice above. As long as you operate the receiver within it's capability to deliver clean power, you'll be OK. Also, if the sub is powered, forget that all together. It is not tied in any way to the receiver rating.


The output of the speaker is measured in decibels (db). A speaker has an efficiency rating which will tell you how loud it will play with 1W continuous input measured from 1 meter away. Usually those numbers fall in the 80's and 90's. You'd be amazed at how loud 1W CONTINUOUS is on a pair of relatively efficient speakers. For every 3db of additional loudness you want, you need to double the power of the amplifier output. 3db is generally accepted as the amount of increase required for a human to sense it. So, if a speaker is rated at 87db efficiency, it will take 2 watts from the amp to drive it to 90db, 4 watts to 93db, etc.


In general, the reason people say more is better is that you are much more likely to blow a speaker with DISTORTION that you are with power. I can run 300W speakers all day long with 5W. Depending on their efficiency, I might not get the VOLUME I want but as long as I don't ask the amp to do more than it's rating, I'm OK. By the same token, I've had speakers rated at 100W that I drove with a 200W amp all day long. I'll guarantee you that I've NEVER used 200W CONTINUOUS. BUT I always run the amp within it's design parameters. Never blown a driver. Everything is relative. I wouldn't think of putting a 200W amp on a pair of 5W speakers! I also wouldn't think of putting a 30W receiver on a pair of speakers rated at 80db efficiency.


A good general rule of thumb is that if you look at a receiver volume control as a clock, never turn it up past say 1:00 or maybe 1:30 to really push it. Every brand is different so your mileage may vary. You'll just usually stay out of trouble that way.


I'd agree with the Sony advice too but that's just me. Take a look at Denon or Outlaw if you're going to do a receiver. There are also a lot of other brands of speakers at reasonable prices that will smoke the Sony's. Sony makes user friendly and relatively reliable stuff. It's just not the best performance out there for the $$$.
 
1 - 16 of 16 Posts
Status
Not open for further replies.
Top