Under-power Vs. Over-power (RMS)

[trf.architect]

This is my
first post; please forgive any errors in terminology or forum etiquette that I
have made.

My question
is in regard to supplied power (RMS) from my receiver to the speakers in my
system.

I am
running a 4.1 surround setup

(before you
ask, in the end my system will be 5.1, I started with the RB-81’s, then added the
subwoofer, and recently added the rb-51’s as JR audio made a mistake and sold them
to me for $249.99. The center channel
will be purchased within 6 months)

Receiver: Onkyo TX SR 705 (100watts RMS to 7
channels)

Front Speakers: Klipsch RB-81

Rear Speakers: Klipsch RB-51

Subwoofer: Outlaw Audio
LFM-1 EX



Back to the question. The RB 81’s are
rated at 150rms, while my receiver is only able to supply 100rms. What would be audible symptoms that I could listen
for that would suggest I was damaging the speakers. Better yet, would a 50rms difference be
reason for concern? Final question,
would it be better to under-power these speakers by 50rms, or over-power them
by 50rms (there is currently a 100watt x2 channel Onkyo amplifier for sale on
JR audio).



I have read many differing views about supplied RMS power on the internet. That being said, I have found no conclusive
answer to my questions and am hoping the audiophiles here on the Klipsch forums
can provide the advice I seek.

Appreciated

[TNRabbit]

What is your usual maximum listening level? 100 watts rms into Klipsch speakers is LOUD!

You would hear audible strain from the amp as you reach it's limits. Unless you're blasting it, you should be fine. THAT SAID, I personally prefer to have MORE power than the speakers will accept to allow for short, quick transients & avoid taxing the amp. An additional 50 watts in your setup would only account for less than 2 decibels additional output...

[trf.architect]

my reciever is set to display volume on a relative scale 0% being -82, 100% being +20.

i never exceed -20, which is approximately %60 volume.

[djk]

The difference between 100W and 150W is only 1.75dB, not very great as it can take as much as 10dB to sound twice as loud.

The markings on your volume control are relative, and give no indication of how much actual power is being used, or how much is left.

[trf.architect]

i have the option to display volume as an absolute instead of relative number... rewind, how would i go about determining how much power is used at any given volume?

[Islander]

It depends to a great degree on the level of the signal that the amp is receiving. Check out this discussion:

http://forums.klipsch.com/forums/t/114884.aspx

[InVeNtOr]

you'll be fine. there is plenty of people here who run different set ups with 50w receivers. i personally like to have head room because i don't want to have "clipping" problems. (hopefully i spelled that right).

just asking, what center channel did you decide on?

WELCOME TO THE BIGGEST SELF INFLICTED HEADACHE YOU WILL EVER HAVE!!!!!!!!!!!!

[sootshe]

I'll try to give you my opinion in general terms rather than technical terms. It's much better to have too much power than not enough. Most speaker blow outs are caused by the amplifier "clipping". That is, the amplifier runs out of power & the musical signal is no longer clean, but is introducing distortion. This will fry your tweeters. Bass drivers are much more robust & you will usually hear audible distortion before you blow them. Remember, you can never put the smoke back in once its come out!!

I have run La Scalas biamped with a 360 watt per channel on the bottom end & a 150 watt per channel on the top end without any problems whatsoever.

In general if you use a quality high powered amp you have less chance of blowing your speakers than an inferior low powered amp. I recall a quote from Paul where he mentioned that Klipschorns needed a quality distortion free amp (especially in the bottom end) rather than any sort of ultimate power rating.

Hope this helps.

[jacksonbart]

What would be audible symptoms that I could listen for that would suggest I was damaging the speakers.

Clipping sounds like very loud crackling. Typically this is preceeded by very edgy treble on loud passages. Most systems begin to loose their ability to image or produce smooth mid to upper treble when they start to clip. Clipping kills your tweeters and your ears.

[Coytee]

To draw a different analogy, but first... I'd say that after a point, you will have "enough" power... I don't propose to know that number though.

The other analogy would be... which would YOU rather be driving and which do you think would have more (or less) stress on the engine.

you have two cars... one is a Chevy Chevette and the other might be a Humvee.

You attach a trailer behind each one. Each trailer is equally loaded with stuff. Your job is to drive the trailer across the country on major highways.

When you are driving at 60 mph, the chevette has the throttle maxed, engine is screaming at 5,500 rpm and you're keeping up with traffic but don't have any headroom in the engine department to pass anyone. also, when you're at a stoplight (prior to getting on the highway of course!) even the blue haired lady driving the Oldsmobile is passing you because it takes you a while to accelerate from a dead stop with all that extra weight behind you.

Now, you can get into the Humvee... pulling the same amount of weight but has a 455 cubic engine with a 4bbl carb. Not only will this vehicle EASILY pull the load on the highway but if you need to accelerate up a hill to pass a semi, it will do so and not break a sweat. Even from a standing start, you could probablty keep up with most other cars that aren't pulling a trailer of any kind.

Given my understanding, I'd say that is sort of the difference of having too much power. You don't ever have to USE it, but if you NEED it, it is certainly nice to have on top

I might add that the basic analogy is a true story and what happened to me many years ago however, instead of me driving a Humvee, I was driving my 1971 Oldsmobile 442 that was equipped with a 455cu and 4bbl carb. It was kind of cool leaving someone in the dust at a stoplight even though I had U-hauls largest trailer (loaded to the max) mated to the rear of the car.

[tommyboy]

I've always been told that too much power isn't necessarily bad and not enough power is how speakers blow...............

[trf.architect]

I appreciate all of the feedback.

It would seem that purchasing an amp for my front speakers would be a good investment for both audio fidelity and speaker longevity. I take it not all amps are created equal. Any particular manufactures i should focus on?

[Coytee]

I take it not all amps are created equal. Any particular manufactures i should focus on?

Where's the popcorn...this might get interesting! (many differing opinions)

Question: Where are you located?

also, what kind of listening do you do, what's your other equipment? how loud do you like it?

(perhaps you've answered these, I didn't look [:$])

[sootshe]

I appreciate all of the feedback.

It would seem that purchasing an amp for my front speakers would be a good investment for both audio fidelity and speaker longevity. I take it not all amps are created equal. Any particular manufactures i should focus on?

Well, I suppose I'll be the first guinea pig. Audio Research, Krell, Mark Levinson, VTL, Wavac, LAMM,Conrad-Johnson, McIntosh, & the list goes on.

[trf.architect]

My
listening habits cover a pretty broad range.



All of my digital media is played through either my PC or PS3. I have an HT Omega Claro+ soundcard in my computer
that outputs a range of digital signals [DTS, Dolby 7.1 included]. I run a
digital optical cable from the computer’s sound card to an Onkyo TX SR705 receiver. The PS3 is connected to the receiver using an
HDMI cable. The PS3 outputs an
uncompressed Dolby TrueHD signal.

With regard
to music, the more sophisticated end of my spectrum focuses on classical
music. I am always amazed at Klipsch’s
ability to accurately reproduce the highs and quick changes characteristic of
classical music [particularly violin concertos]. I have a fairly extensive collection of
classical music on vinyl as well as digital media. As old as it may be, I love the JVC QL Y66F I
use to play vinyl. This is connected
using the standard phono connector on the back of my receiver.



On the other end of my musical spectrum I listen to quite a bit of electronica. This is where my Outlaw Audio LFM-1 EX subwoofer
shines. Much of my electronic collection
requires the ability to produce solid accurate lows. The music would not be the same without it. If anyone wants a subwoofer recommendation,
OUTLAW is the way to go.



That being said, all of this is combined into the home entertainment system
which is used for both movies and video games.
Which was actually the source of my initial question…

Take a step back. When playing a PC game
called Crysis, [which is very processor and GPU intensive, and happens to be
encoded with Dolby Digital 5.1] during moments of intense loud action my front
speakers will occasionally pop. To be
honest I am not sure if this truly is an audio failure, or simply my processor
skipping a beat due to the enormous loads placed upon it by the video
game. [seriously, even if you look down
on video games, Google Crysis. The
graphics and audio are absolutely insane.]



Back to the setup…. Actually that’s about it.




I rarely blast my system. I will play it
loud when I am alone in the house or having a party. Usually the volume is at 50% or lower on my receiver,
but as mentioned above, this is not the most accurate gauge of sound
considering the volume on my computer [which often is the audio source] varies.

Oh and i live in Richmond VA

[trf.architect]

sootshe

damn... that is some serious equipment. i am a peon

[Guest " "]

I think I have enough power.

160X7 on one HT reciever. 130X7 on another.

1 400W active sub.

1 200W class A stereo amp

2 Marshall 100W stereo amps

1 Marshall 50W stereo amp

1 20W stereo amp

1 50W carvin Stereo amp

2 Peavey 120W stereo amps that can be bridged

1 Peavey 60W stereo amp that can be bridged

1 Shanglin 30W stereo amp

2 Mcintosh 130W stereo amps

.....any way....pretty much I use only .25Watts per channel at a time...so does an underpowered amp at .25Watts sound any different than an overpowered amp at .25watts....I think so....is my 30W amp underpowered if I only use .25W...wellno matter...it sounds different.

[sootshe]

I think I have enough power.

160X7 on one HT reciever. 130X7 on another.

1 400W active sub.

1 200W class A stereo amp

2 Marshall 100W stereo amps

1 Marshall 50W stereo amp

1 20W stereo amp

1 50W carvin Stereo amp

2 Peavey 120W stereo amps that can be bridged

1 Peavey 60W stereo amp that can be bridged

1 Shanglin 30W stereo amp

2 Mcintosh 130W stereo amps

.....any way....pretty much I use only .25Watts per channel at a time...so does an underpowered amp at .25Watts sound any different than an overpowered amp at .25watts....I think so....is my 30W amp underpowered if I only use .25W...wellno matter...it sounds different.

Way to go .....you can never have too much power! And you're right - they do sound different.

[colterphoto1]

this one goes to 11, it's one more, innit?