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Here is the deal. I own a pair of Klipsch KLF 20s, hooked up through a Pioneer SX 1280. The amp is Rated a 180 watts. Speakers are rated at 200 watts(Sensitivity 100db/1 WATT). Just for fun, I wanted to see what 180watts sounds like(not that Im going to listen to music at this level). Turns out, I can only turn the volume nob about three quarters of the way before the protection circut kicks in. The thing is, I hear no clipping when this happens. Ive checked all cables/wires are ok.

Whats the deal here? For certain, Im not pushing these speakers to their potential?. OR am I??? With the vol nob turned up between Half and 3/4 way?.

The amp has power meters for each channel in Watts&db. It cuts out between 100 and 150 watts. Should I be worried about what it reads?..Am I really pushing 180watts when it says 100-150watts? With the speakers switched off, I can crank the volume nob and it pushes and pegs the power meters past the 180 watt reading.

Im just wonding, if those speakers can really handle 200 watts(like it says), or if the power rating circa late seventies(The amp) is different to the power rating these present


Should I even worry about this, since its so damn loud anyway? Im curious though?


I would appreciate any feedback.

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i had a pioneer QX-747(quad) in the early 70's & set off it's protection circuits on a regular basis. is that receiver rated 180 rms or peak?

klipsch are loud speaks. & those klf can handle 600 watts peak. but the receiver distorts so much at that level that it breaks.

u want loud, get a new receiver/amp w/ less distortion.

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Going out on a limb here, and posting a hypothesis (rather than an answer) and seeking confirmation.

Hypothesis: Protection will kick in when the resistance (impedance) on the amp is too great. It is possible that the music you were playing at those levels caused the impedance of the speakers to rise to a point that, combined with the wattage you were asking the amp to produce, caused it to protect itself.

Ok, teachers, you can grade my answer now.


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Doug, I think you are heading in the correct direction, but most likely there is a point in the bass where the impedance gets too LOW and the amp is asked for too much current. The protection circuit kicks in to prevent heat damage from overcurrent.

This is a likely situation. Pioneers of that age were not designed with much excess capacity either in the power supply or the heat sinks.


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The amp is rated at 180 WAtts RMS..That is also, from what I heard, is on the conservative side.

What could be the problem.? COuld it be possible that the speaks are too efficient for that amp. Remember, I can only turn the nob just over halfway. I hear no distortion. I also had seen the amp run some less efficent speaks, and you could crank it up higher...

Also Im using banana plugs..does it matter which terminals I plug into? I dont think it should.

And John. What do you mean when you say?:

"This is a likely situation. Pioneers of that age were not designed with much excess capacity either in the power supply or the heat sinks." ..I dont quite understand what you mean.

Thank you all for your responses..

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My guess is that the amp is dropping out because the low impedance of the speakers is drawing too much current at high voltages. As Albright says.

The meters are probably only measuring voltage. The "calculation" is that "IF there is an 8 ohm load, then I'm putting out so many watts." This is why they are reporting so many watts when there is no speaker connected at all.

This must be very loud when the speakers are connected. No?

You may well be exceeding the power, and specifically current, output of the amp.


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In my experience the amplifier will protect itself right at or before clipping. This may or may not be audible. The amp clips when the power supply runs out of current. On musical peaks I found that a little extra capacitance helps the power supply. Clipping kills speakers not power unless its for extended period of time. My rule of thumb is buy an amp at twice the power of speaker.

I am running 250wpc on 100wpc speaker and in 15 years never blew a speaker. Even had a 450wpc pro amp at one time.

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Power is voltage x amperage. Your amp is spec'd at 180 into an 8 ohm resistor. It might do a little more. More than likely its power supply amd cooling capacity are designed for just that and have little "reserve". The protection circuits are designed to prevent exceeding the amperage that equals 180 watts to prevent overheating. Also the speakers probably dip to 6 ohms in the bass, drawing 50% more current at that point than they would at 8 ohms. That is more current than you amp's cooling and power supply can tolerate. Shutdown.

BTW, 3/4 "throttle" on every amp is well beyond clipping with most sources. 10 to 12 o'clock in normally full output

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