1 Watt@1meter?

[jtubbs6117]

This may be a rookie question but i am going to ask anyway. This might bring up some good information. If I understand this one watt of power applied to a speaker will result in x number of db or sound at 3 feet or one meter. Is this right? Ok if we only need one watt why do we buy huge amps? Me included. I have always gone with the theory run at least the RMS wattage to the speaker cab. I hope this will start some great disscusion.

[Youthman]

For me, its about Headroom and dynamic peaks. Realize testing does not invoke a kick drum, a gunshot or an explosion.

If you have a 1 watt amp, and the soundtrack goes from dead silence to a huge explosion, it will not be near as impact fil as if you had say a 200 w/ch amp.

It's the difference between driving a VW bug and a Lamborghini. Sure they both can reach 80mph....but amp will take much longer and will be approaching its max while the other will get there quicker and will be doing so effortlessly

[Youthman]

I have always heard to try to run two times the RMS to help avoid clipping your amp

[derrickdj1]

The key is looking at what frequency the 1 watt at 1 meter is for a given spl. The higher frequencies like 1 kHz can produce a 70 db sound level using very little wattage. A LF like 40 Hz may take 100x more power to produce the same spl. Youthman is correct, that 2x the RMS of a speaker is commonly recommended but, most of us don't do that with our Klipsch speakers due to the sensitivity of the speakers. The clipping mention in the other post can happen but most times it is so transient, that it goes undetected and does not put the amp or speakers at risk.

Because of LF demands, that is a common reason for setting speakers to small in a HT setup and letting subs take the load off the system. IMHO how an amp handels these transient clips may be a factor why people say that some amps sound better than others.

For example,
to sound as loud as a 1 kHz tone at 70 dB SPL, a 40 Hz tone must be
at 90 dB. That extra 20 dB is 100 times the power! So if your
speakers only need 1 W to produce that 70 dB, 1 kHz tone, then a 40
Hz tone requires 100 W to sound as loud

[SuBXeRo]

its just a benchmark number to use when testing to set apples to apples when comparing drivers/speakers. Each speaker can have a different sensitivity rating so to achieve the same amplitude, some speakers may require more or less power. Its just saying the driver is x efficient at 1 watt of power at 3 feet away from the driver. To go off what youthman said, you may only need half a watt of power and a whole watt may cover the peak of an explosion but you may have to be listening at a very low volume. Music and home theater are both very dynamic. One second you need 1 watt and the next you could need 50, it all depends. To further this, you bring in your RMS rating which more or less is the nominal consistent wattage a driver is capable of handling without failing mechanically. Realistically, with movies and music, you wont maintain a consistent wattage ever but theoretically if the driver were to handle a consistent wattage, the RMS is the number it would be. The RMS isn't linked to the peak power a driver can handle which is known as peak wattage which is the power handling of a driver for a very short time for instance the loudest part of an explosion. If you were to feed peak power to a driver for a consistent time, it would most likely fail within a few seconds. Headroom is a great thing to have when it comes to any amplifier class other than Class A because it ensures that you wont clip your speakers. Class A doesn't suffer from clipping because of its design, its also the purest and most inefficient way of producing amplifier power. Having power on tap more than RMS is just a rule of thumb and its nice to have but not a requirement. I have my RF-7's powered by 125 watts a channel and I have 0 issues. Larger amplifiers (larger amounts of power per channel) can often suffer from higher ground floor noise which can be heard through your speakers. I had an emo xpa-5 and i thought the noise floor was horrendous. I switched amps, brands and went with less power and haven't had any issues. I bought the Emo mini-x amp for my computer and that amp is quiet as a whistle but its only like 50 watts a channel.

[jtubbs6117]

Thanks guys for all the information. That really helps in explaining that concept.

[RRFL]

When I bought my LaScala in 1976 the rating was 1w@4feet 104db. From memory, the continuous power handling was 100w and transient power handling was 10 times that provided 100w was the average power over 1 second intervals.

Currently the LaScala II is 105db with 1 w @ 1 meter handling 100w continuous 400w peak.

If you give the LaScala II 10w you would get a technical 115db and for 100w a technical 125db. An issue called power compression reduces this increase to be less than the technical.

10 times the power, sounds twice as loud to your hearing, which is a 10db increase.

So that's "either" 1 speaker supplied with 1w and then increased to 10w "or" 1 speaker with 1w increased to 10 speakers with 1w each.

Double the power gives a 3db increase which you can only tell the difference if the change is made in front of you. If you leave the room and a second speaker is turned on and then return you cannot determine the difference, provided the speakers are positioned together.

So double 1 is 2 gives 3db increase, then double 2 is 4 gives a 3db increase, then double 4 is 8 gives a 3db increase, therefore you now have 9db increase going from 1 - 8 increase. Add 2 more and you get the 10db.

Hornloading, generally gives 10db increase. Then the floor against the speaker cabinet gives 3db. Then the floor plus add a wall behind the speaker gives 6db. Then the corner of the room with it's 3 surfaces gives 9db.

So consider this with a Klipschorn or LaScala or Jubilee in the corner and you can really piss off the neighbours.

Someone else may be able to explain this better, but the end result is having a system with a lot of headroom makes it sound cleaner.

I found that most of the time my LaScala were using 0.2w.

[Quiet_Hollow]

If people actually measured what they used...

[RRFL]

If people actually measured what they used...

[]

[derrickdj1]

If people actually measured what they used...

Are you implying that a lot of us look for more power than we need, lol.

[Islander]

This may be a rookie question but i am going to ask anyway. This might bring up some good information.

Don't worry about asking rookie questions here. We all started somewhere, and I don't mind admitting that I learned much of what I know about audio from participating in this forum.

That said, it's a good idea to do lots of your own research as well. That way, you may be able to confirm or disprove what you see here, plus you'll be better able to contribute to the discussions.

[Quiet_Hollow]

Are you implying that a lot of us look for more power than we need, lol.

I'm implying that a lot of us typically don't know what we need....myself included. I enjoy pouring over big, gnarly amps as much as the next guy. [H] [:$]..but

power is only one metric....and with respect to home audio amplifiers, it's just about the most useless one at that because it's so difficult to measure in real-time. In addition, as others have mentioned, it bears little practical significance so long as sufficient quantity is available for maximum listening levels.

For that, we need to measure SPL, determine how loud is "Loud enough for me" [:|] and at which frequencies [8], then figure back into the speaker(s), then figure even further back into the power amp(s). [li]

If all the system will ever use is 10V, then there's no point in lusting after something that'll do 50. Especially at the expense of other desirable features like cost or topology etc.