RMS Power Question

[sgking]

Hello I'm new to the site, first time posting but have enjoyed reading the post over the last few weeks. I'm looking at buying a new sound system, but want to ensure that I don't damage the speakers. I have a Yamaha receiver that puts out 110w rms; do I need to make sure that the speakers I choose have the same rms rating? I'm looking for clarity as opposed to extreme loudness. Any input is greatly appreciated.

[wuzzzer]

Most Klipsch speakers have such high sensitivity ratings that the majority of people are using about 5 watts maximum, and that will usually give you decibel ratings of 100-110 depending on what model Klipsch you have.

As a general rule of thumb, its better to have an amplifier that delivers more power than the speakers can handle.

I know it may sound odd, but think of it as driving a Yugo at 80mph and a Corvette at 80mph. Which engine do you think is struggling between the two? Which engine do you think will last long at those speeds? In this case as well as the speakers, more power is better.

Your ears will usually give in long before the speakers do. []

[brennyE]

WRMS (the usable part of an AC wave shape) is the unit of measure for all klipsch speakers and most high end audio brands. It is best to have like wuzzer said an amplifier that is capable of overpowering your speakers than under powering them. In almost all scenarios if you approach a sound system and crank the volume towards full it will be the amplifier that will go into clipping before the speakers (causing danger for your speakers. This is evident in my bedroom system powering 2 rf-15's (100WRMS power handling) with a HK3480 rated at 120WRMS each channel (although apparently HK rate their amplifiers lower than they can cleanly deliver) and my amplifier will still give out before my speakers will on any material played (even very loud songs with big low bass lines) Although at this point the speakers are too loud to listen to comfortably and could probably run a fairly large party []

[Groomlakearea51]

The old 50% rule is also a good starting point. If you have a pair of speakers that are "rated" or it is suggested that the amp has a minimum of 35 watts, then look for an amp with 70 watts RMS. As you have seen on the forum, however, Klipsch are very, very efficient. Look at the SPL rating also. If a speaker, like a Klipschorn, produces 104 dB of sound at 1 watt/1 meter, then at 30+ watts it's probably going to get louder than a F-18 on takeoff... Klipschorn, as an example, is "max rated" at 100 watts (older ones anyways), I use an old 115 WRMS amp, but never have driven it past about 25-30 watts because the loudness simply becomes unbearable. Also, check your amp's specs, while it is rated at 110, what's it's "peak" power, or what does the manual or factory say it produces for transient peaks. Compare that number to the speaker's "peak" power handling capability. Lotta factors. I'm sure that when you've narrowed your search down to a couple of models, forum members with those types can help you make sure the amp you've got will either do the job, or give you suggestions for something that will drive them without any problems. Good luck.

[Islander]

Welcome to the forum, sgking!

With the sensitivity of Klipsch speakers, especially Heritage Series, an important factor in choosing your sources and amplification is low noise. Klipsches will let you know if your amp is putting out any hum or hiss.

For example, I'm using a Yamaha RX-V750, which is very quiet as well as clear, but with the La Scalas, I can hear a very faint "click" when switching inputs which was not audible with my previous speakers. Other than that really minor detail, the receiver and speakers seem to work fine together.

Clarity-wise, more power means more realistic transient sounds, even when you're listening at moderate volume levels. As others have pointed out, you won't have to turn up the volume very much to get plenty of sound, but it's good to have your amp running in its "comfort zone", without any stress or distortion. That's good for the amp and the speakers.

[sgking]

Thank you all for your input, it is very helpful, Mark great analogy that really makes a lot of sense!! I am looking at bookshelf speakers, RB61 and the RC52 or RC25 for a center channel, however after reading yall's replies I may need to rethink on the center as they are rated at 125w rms, 15w more than my receiver. Any suggestions that may work? Thanks again!!

[mas]

Thank you all for your input, it is very helpful, Mark great analogy that really makes a lot of sense!! I am looking at bookshelf speakers, RB61 and the RC52 or RC25 for a center channel, however after reading yall's replies I may need to rethink on the center as they are rated at 125w rms, 15w more than my receiver. Any suggestions that may work? Thanks again!!

Hmmm.

Let me try a poor analogy and see if this helps...

You weigh 200 pounds. Your floor is rated at being able to support individuals weighing up to 500 pounds (ignoring mass per unit distribution).

Why would you need to re-evaluate your floor? You haven't exceeded its capacity? Why would you need to re-evaluate your speaker whose thermal capacity is rated greater than your amplifier?

Relax... []

[brennyE]

sgking:

Thank you all for your input, it is very helpful, Mark great analogy that really makes a lot of sense!! I am looking at bookshelf speakers, RB61 and the RC52 or RC25 for a center channel, however after reading yall's replies I may need to rethink on the center as they are rated at 125w rms, 15w more than my receiver. Any suggestions that may work? Thanks again!!

Wow, wow wow hold on! although the rule of having more power than your speakers still stands true, dont let 15W of difference completly make you rethink a speaker! especially when you factor in how efficient Klipsch speakers are you probably wont be using all that power any ways. Keep aiming for that centre channel it will sound great regardless!

[DrWho]

As a "better" rule of thumb - I would recommend leaving at least 10dB of headroom over your normal listening level peaks. So if you peak at say 100dB, then you need at minimum 10 watts. If you peak at 110dB, then you need at minimum 100 watts. But if you knew how loud you were listening, then you probably wouldn't be asking about the power requirements []

Just keep in mind that for every 3dB increase in volume, you need twice as much power from the amp. And you want to start with the sensitivity of your speakers, which is going to be around 97dB or so? I haven't looked it up for your speakers. But it'll only take 1 watt to reach loud levels.

Basically...all that to say that you're going to be just fine with your reciever.

[sgking]

Thanks for everyone's help, I can't wait to get them connected and enjoying the sound!!

[atleer]

Ok, I hate to hijack this thread, but now i'm concerned about my system after reading this thread.

I have an older yamaha RX-V630 that puts out a minimum RMS of 75 watts

per channel 6.1. It has a max power of 110 watts- 1 kHz, 10% THD, 8 O.

I have this receiver running rf-3II's for my mains, and an rc-3 center

and two ref bookshelf speakers. The mains say 150 w max continuous and

600 w peak. Center is the same but with 400w peak.

Am i doing something wrong?

Thanks for the help

[mas]

Are you doing something wrong? Perhaps...you are worrying yourself far too much! []

First regarding the Yamaha. I don't think that you really mean that it has a minimum wattage.

The speakers' wattage rating simply states how much heat (in watts) they can be subjected to before they enter a destructive mode. To put it very simplistically, a higher speaker wattage rating is good! You just want to avoid APPLYING more than this rating (in clean undistorted power) to the speakers. Anything less is fine! And please understand that simply because an amp has a higher rating than this, that it does not mean that the signal is exceeding the rating! That is what the gain control is for.

Additionally, as long as you observe the above condition of not exceeding the speakers power rating, you simply want to operate your amp - whatever its rating!!! - within its linear range of operation, thus insuring that it is not outputting a distorted signal which is distructive to the speaker.

Here is a very simple analogy:

A bridge is rated at 100 tons. A load of 100 tons or greater will cause it to collapse. (Think of this as your speaker)

You have a dump truck rated as being able to carry a load (including its own weight) of 200 tons. The empty truck weighs 10 tons. (Think of this as your amp)

Just don't load your truck up with more than 90 tons of 'stuff'. As long as you don't exceed the 100 ton limit of the bridge you are fine to drive across it.

Don't make this more difficult that it need be![][]

[Islander]

Just to make things clearer, or not, if a receiver is rated at 100 watts per channel and has 7 channels, that doesn't usually mean that the power amp can put out 700 watts, in spite of stickers on the unit that proclaim just that. In a comparison test, the Yamaha RX-V750 (rated at 100wpc x 7) produced 55 watts per channel when driving 5 channels, but 132 watts per channel when driving just 2 channels, i.e. in stereo.

Perhaps someone more knowledgeable can jump in, but it sounds to me like there may be a limiting factor, perhaps the power supply, limiting the overall power. Based on the two figures above, maybe only 45 watts or so are available when driving 7 channels. It's a good thing subwoofers have their own amps, or it would get even more confusing.

There are a few higher-end receivers (yes, there are such things) that will put out their full rated power to all channels at the same time, but most of the affordable units perform as described above, including the SONY and JVC that were tested along with the Yamaha.

The bright side is that there's plenty of power available when listening in stereo.

Pat on the Island

[Colin]

In both situations, the receiver has plenty of power to drive the efficient Klipsch bookshelf speakers, the question might be how well will it do it?

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

The answer is pretty well. Could something else do better? Yes. I would look for better bass control, such as amps that double their power as the impedance decreases, for example, the Unit delivers 50 watts into 8-ohms, all channels driven, but 100-watts into 4-ohms. In my opinion, such a receiver would have great bass control.

The other thing I would look at is THD, which on a solid-state receiver, can be an ear splitter. The lower the better. You also want extremely low THD in the first few watts rare for all but the most expensive units.

In general, the older the receiver and the heavier its construction, the better the quality (NOT quantity) of the sound. Want even more sound? Get a sub-woofer.

[Islander]

Colin posted: In general, the older the receiver and the heavier its construction, the better the quality (NOT quantity) of the sound.

Not so sure about that. I've had 4 Yamaha receivers, a CR-600 (1975), CR-1020 (1978), RX-V392 (1998, still have it) and an RX-V750 (2005, still have it), and found that the newer ones, although they are lighter in weight, have much cleaner and more transparent sound.

At high volume, the CR-1020 would often cause the tweeter protection breakers to trip on my pre-Klipsch speakers, but that never happened with the 392 or 750. I'm not sure if that means the new ones don't start clipping at any volume I'd want to listen to, but they seem to have audibly less distortion than the '70s units. Just my experience.

Pat on the Island

[DrWho]

Ya, the rule of thumb for "heavier is better" for amps is kinda out the window with the advent of much more efficient power supply topologies. Older amps are so heavy because they need big heatsinks to handle all the wasted energy being turned into heat. And a heatsink is generally just a huge chunk of metal.

[mas]

Mr Who sir:

I will be travelling to the Denver area over the holidays, and I want to take my .00001 mw amplifier that I just purchased on Audiogon for $18,683.29 just so that I can impress my friends who think they are so cool as they have a new Bose theater in a box system. I figured that I could just use my auto jumper cables as inteconnects as they have the high performance red insulation - unlike those cheap cables that still use the yellow insulation.

I may even take my extra special copy of the 1912 Overture to which I made reference in an earlier post! I figure that that will really show off the system!

But, here is my question: Since the gravity will be less at the higher elevation, will I need a new heavier amplifier to achieve comparable performance to that of the lower altitudes?

Would one of those acoustic bricks that used to be so common for transformers help?

This hobby is sure getting expensive quick!

Why does this have to be sooo complicated?

Thank you in advance, MrWho sir.

Signed,

I'll sure show them Denver dudes who knows what!

Oh oh! I just remembered, the Denver airport has 'them' converyors...At least I will have my amplifier and cables with me, as we may never get off the ground & out of there!

PS Doc, I hope you had a wonderful Thanksgiving!

[Arkytype]

One of my pet peeves is the use (or misuse) of the term "RMS power". There is no such quantity as "RMS power".

Here's a good article which addresses the fallacy of using this over used expression.

http://www.hifi-writer.com/he/misc/rmspower.htm

[DrWho]

One of my pet peeves is the use (or misuse) of the term "RMS power". There is no such quantity as "RMS power".

Here's a good article which addresses the fallacy of using this over used expression.

http://www.hifi-writer.com/he/misc/rmspower.htm

He's just arguing symantecs...

[ricktate]

My Harmon Kardon 430 reciever with just 24 watts going to Klipschorns or RB35s is darn loud believe me even at 9AM position on the volume dial.Just to add this the HK with 24 watts beats my Yammy reciever with 8o watts.So not everything is as it seems. Rick