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post #1 of 24 Old 03-09-2012, 11:45 PM - Thread Starter
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I'm curious, I was watching this new movie Immortals on my system and many of the loud low noises sounded horrible. They were "scratchy" and noisy. Not like a clean low bass noise. If anyone has seen this movie, you may be aware it has a lot of LFE. I'm wondering if maybe my amp isn't up to the task.

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post #2 of 24 Old 03-10-2012, 12:01 AM
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The easiest way to explain clipping is when you reach the point where when you keep increasing the volume on your receiver you get no noticeable effect in the loudness from your speakers. Basically it is the point where your amp is playing the same loudness, no matter how much more gain you feed your speakers. At that point, "clipping" is introduced where as the signal has reached it's maximum output. At this point you will hear major distortion, as part of the sine wave is cut off or clipped. You will also typically hear part of the sound cut out, where all you get is distortion. Some amplifiers are able to deliver peak amplification in very short bursts, whereas others simply cannot, without introducing clipping.

Clipping normally occurs due to limitations in the power supply of the amp. The bigger the power supply and more stable the power supply usually the better. This is generally where separate amplifiers have an advantage over a/v receivers, because they have larger power supplies, that can deliver cleaner voltage at much lower harmonic distortion levels.

More than likely what is happening with your amp is that is having trouble with these very dynamic peaks in the movie your are playing. Big explosions, lots of low level bass, can cause a very taxing workout on any amp. More than likely, from what it sounds like, your receiver is cutting off a portion of this dynamic range, and is introducing distortion where you should be getting clean sound. What volume is the receiver set at when you hear this distortion?
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post #3 of 24 Old 03-10-2012, 05:16 AM
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The onkyo 809 has a pretty hefty power section. My guess is that your sub is not up to the task. What kind of sub are you using?

If distortion is with LFE, the sub is handling that which has its own power supply. I am assuming you are using a powered sub.

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post #4 of 24 Old 03-10-2012, 06:59 AM
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Quote:
Originally Posted by cjsiv View Post

The onkyo 809 has a pretty hefty power section. My guess is that your sub is not up to the task. What kind of sub are you using?

If distortion is with LFE, the sub is handling that which has its own power supply. I am assuming you are using a powered sub.

Pretty hefty power section, for a pair of RF-7 IIs?

Horn tweeters are super efficient, but he's asking his upper mid tier receiver to drive four 10" cones during a movie soundtrack that was mixed to torture dedicated subwoofers. I'm not an expert but my intuition says that, tweeter efficiency be damned, unless he's crossing over to a sub at like 100 Hz, the RF-7 IIs' impedance is plummeting and his speakers are drawing a huge current when the movie is playing.

Also, all the tech talk aside, how about his question: what does clipping sound like?

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post #5 of 24 Old 03-10-2012, 07:52 AM
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Originally Posted by cjsiv View Post

The onkyo 809 has a pretty hefty power section. My guess is that your sub is not up to the task. What kind of sub are you using?

And what size room (cubic feet)? Sub performance ability is related to room size.

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post #6 of 24 Old 03-10-2012, 08:04 AM
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Quote:
Originally Posted by theturtle View Post

I'm wondering if maybe my amp isn't up to the task.

That, or your sub. If the clipping is mainly heard in the tweeters chances are the amp is clipping, as that creates excess harmonic content that stresses the tweeters. If heard in the sub then it, or its amp, or both are probably at fault.

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post #7 of 24 Old 03-10-2012, 08:28 AM
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Clipping sounds seriously nasty; lots of distortion.

Since this is a low-frequency thing, it's probably due to an overdriven subwoofer.

You probably need to turn down the subwoofer's gain control, and you may need one with a larger power amplifier and/or overall size.



Quote:
Originally Posted by theturtle View Post

I'm curious, I was watching this new movie Immortals on my system and many of the loud low noises sounded horrible. They were "scratchy" and noisy. Not like a clean low bass noise. If anyone has seen this movie, you may be aware it has a lot of LFE. I'm wondering if maybe my amp isn't up to the task.

Onkyo 809 AVR
Klipsch RF-7 II speakers

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post #8 of 24 Old 03-10-2012, 08:56 AM
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Quote:
Originally Posted by commsysman View Post

Clipping sounds seriously nasty; lots of distortion.

Since this is a low-frequency thing, it's probably due to an overdriven subwoofer.

You probably need to turn down the subwoofer's gain control, and you may need one with a larger power amplifier and/or overall size.

Yes to the above statement. Also, for the OP, I have noticed some of my friends and family doing the wrong thing when it comes to setting controls for bass response. They simply crank up the bass when they don't hear much going on in the low end, when in fact that part of the movie or music, for those moments don't have any bass info present (the producer made it that way). What happens next when an explosion happens...distorted bass and clipping, or worse...damage to equipment.
So, If I can say this correctly, set the bass to the proper levels during the moments when the most LFE is present. Today's modern equipment will do this for you, but you can put some music on from your collection that you know has some of the deepest bass info that you will encounter, and set the bass levels to work for those moments.You are keeping the bass set within a given margin.

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post #9 of 24 Old 03-10-2012, 08:58 AM
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I would want a 250 watt amp to drive those RF-7.
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post #10 of 24 Old 03-10-2012, 08:59 AM
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Quote:
Originally Posted by SaviorMachine View Post

Pretty hefty power section, for a pair of RF-7 IIs?

Horn tweeters are super efficient, but he's asking his upper mid tier receiver to drive four 10" cones during a movie soundtrack that was mixed to torture dedicated subwoofers. I'm not an expert but my intuition says that, tweeter efficiency be damned, unless he's crossing over to a sub at like 100 Hz, the RF-7 IIs' impedance is plummeting and his speakers are drawing a huge current when the movie is playing.

Also, all the tech talk aside, how about his question: what does clipping sound like?

I don't know about the RF-7 II's, but the RF-7's had some low impedance dips, making them hard to drive at high levels using an AVR.

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post #11 of 24 Old 03-10-2012, 11:25 AM
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What I would do is play the movie again with either the speakers or the sub disconnected/turned off and see if I got the same result. Then at least you'll know where the issue is.
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post #12 of 24 Old 03-10-2012, 12:42 PM
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I don't know why you guys keep referring to these speakers as hard to drive? In the Audioholics review it was stated that those speakers are so efficient that "they could be driven with a clock radio" if it had to right connections. The Onkyo 809 is one of the better amp sections in its price range. Numerous people on this forum drive 4 ohm less efficient speakers with it no problem. That movie is heavy on LFE.. He more than likely has a sub issue.

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post #13 of 24 Old 03-10-2012, 06:24 PM - Thread Starter
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Actually I don't have a sub at all. I have a Rythmik fv15 on order. The movie overall had several places where the speakers were just booming, but there were many parts where the booming became staticy ugliness. Which I believe is what everyone refers to as clipping. I'm hoping I didn't damage the speakers, but I'm going to at least try it again with a sub and a new separate amp. Probably an Emotiva XPA-2.

The loud distortion that I was hearing is what is considered clipping?
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post #14 of 24 Old 03-10-2012, 06:38 PM
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Different amplifiers behave differently when encountering clipping. Disastrously, one very bad behavior is loss of all damping factor/control of cone movement.

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post #15 of 24 Old 03-10-2012, 07:42 PM
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Quote:
Originally Posted by theturtle View Post

Actually I don't have a sub at all. I have a Rythmik fv15 on order. The movie overall had several places where the speakers were just booming, but there were many parts where the booming became staticy ugliness. Which I believe is what everyone refers to as clipping. I'm hoping I didn't damage the speakers, but I'm going to at least try it again with a sub and a new separate amp. Probably an Emotiva XPA-2.

The loud distortion that I was hearing is what is considered clipping?

That is what I think it is.
Also a HUGE reason why powered subs are a must for Movies with LFE.
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post #16 of 24 Old 03-10-2012, 10:08 PM
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Quote:
Originally Posted by theturtle View Post

Actually I don't have a sub at all. I have a Rythmik fv15 on order.

Shoots my theory. Guess I shouldn't have assumed there was a sub.

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post #17 of 24 Old 03-10-2012, 11:06 PM
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I've heard what I ASSUMED was clipping at high volumes when sometimes watching movies. It sounded like a loud and short TICK sound that would start coming from random speakers in my setup. As soon as I would quickly turn it down it would stop. Am I right?
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post #18 of 24 Old 03-11-2012, 12:26 AM
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Originally Posted by ambesolman View Post

I've heard what I ASSUMED was clipping at high volumes when sometimes watching movies. It sounded like a loud and short TICK sound that would start coming from random speakers in my setup. As soon as I would quickly turn it down it would stop. Am I right?

It's hard to say. Clipping is simply driving an amplifier beyond it's maximum stated current output. Some people intentionally over drive their amps to get a desired sound level. In the very simplest terms clipping only really refers to driving a signal, or current beyond what the amplifier is rated at. For example if an amplifier is rated at a max current of 100 watts x 2 channel at .01% distortion, you can bet that at 90% gain you will get a slightly altered waveform. This is a lot of gain for signal attenuation, but not really enough to notice too much distortion. A good power supply will have enough clean voltage in it's stored reserves that it will not produce much of any noticeable clipping or signal cut off, as long as the peaks in the waveform are short term. But if you have an amplifier that is rated at 100 watts x 2 channels rated at 1% distortion, then at 90% gain you can also bet that you will exceed what that power supply is capable of producing with noticeable distortion.

It's best to use an amplifiers gain with in common sense boundaries. Using more efficient speakers will allow you to reach a desired sound level without having to push an amplifier to these limits.

Still though clipping in and of itself is not really enough to damage a speaker. A lot of this depends on what your speakers are rated for power handling. For example, a speaker rated at 200 watts max, being driven by an amplifier with a maximum signal current of 40 watts per channel @ .01% distortion levels will produce clipping if you exceed 90% gain or even 100% gain @ 1% distortion. Those 40 watts can easily double to 80 watts with that much gain, and you are already at high levels of distortion and well beyond normal clipping and cut outs. Still though even 80 watts of clipped programe is not going to produce enough thermal heat to do any damage to speakers rated at 200 watts unclipped programe.

Heat is the real destroyer of speakers and voice coils. You are far more likely to damage speakers rated at 200 watts max unclipped programe by using an amplifier that is rated at say 150 watts at 1% distortion levels and pushing that amplifier beyond is current limitations, because the power supply is going to produce a lot more heat, especially if that amp begins to oscillate. Once oscillation starts your speakers will be damaged. Basically oscillation produces way too much heat that causes bad distortion, and can also destroy an amplifier by causing thermal decay to the power supply. Still though I would put my money on the amp being destroyed, long before the speakers.

It has been my experience that all these things are very hard to do, unless a person intentionally sets out to do it. As long as you use some common sense and stay within the boundaries of both your amps maximum ratings and your speakers maximum acceptable current, even if you do have peaks of distortion, the heat will not be enough to damage your speakers.

The tick that you heard or are hearing, may be as much from the source as the amp. Even the lossless audio formats we listen to are still prone to sampling errors and all kinds of other inherit flaws. I wouldn't worry too much. In most cases severe clipping will destroy the power supply in your receiver long before it destroys your speakers. And you will know it when your hear it. Lots of signal cut outs and major distortion to the point where you are no longer hearing normal sine waves and hearing nothing but distortion.
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post #19 of 24 Old 03-11-2012, 12:38 AM
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Quote:
Originally Posted by theturtle View Post

I'm curious, I was watching this new movie Immortals on my system and many of the loud low noises sounded horrible. They were "scratchy" and noisy. Not like a clean low bass noise. If anyone has seen this movie, you may be aware it has a lot of LFE. I'm wondering if maybe my amp isn't up to the task.

Onkyo 809 AVR
Klipsch RF-7 II speakers

IMO bass levels, and perhaps the phase switch needs adjusted.

1.) Subwoofer phase switch
2.) Speaker level adjustment (I believe this can be boosted as much as 12 DB)

Read your manual about #1 above. adjust it to sound convincing to your ears. You might need to switch this in your settings from 0 to 180...one will sound better than the other.

Regarding #2 above: If you currently have this boosted up somewhere close to the 12 DB max for the low end, reduce it way back down to a much smaller number...start out at 1,2,or3, not 12DB.
My advice is to play those extra heavy bass scenes that you mention. Most DVD/Blu-Ray players have a setting that allows one to continuously repeat segments of the disc for adjustment purpose's.
Your goal, IMO is to have all of the low end level settings boosted/adjusted/equalized, just enough to handle those heaviest scenes.
Basically, If your bass is set high to boost those scenes that are purposely weaker in bass (set that way by the producer), the obvious overload/distortion is inevitable when those heavy bass scenes arrive.

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post #20 of 24 Old 03-11-2012, 08:13 AM
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Originally Posted by theturtle View Post

Actually I don't have a sub at all.

That's your problem.

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post #21 of 24 Old 03-11-2012, 08:19 AM
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I've heard car stereos clipping. It sounded like loud pops. Ugly.
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post #22 of 24 Old 03-12-2012, 02:55 PM
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Quote:
Originally Posted by theturtle View Post

I'm curious, I was watching this new movie Immortals on my system and many of the loud low noises sounded horrible. They were "scratchy" and noisy. Not like a clean low bass noise. If anyone has seen this movie, you may be aware it has a lot of LFE. I'm wondering if maybe my amp isn't up to the task.

Onkyo 809 AVR
Klipsch RF-7 II speakers

Clipping sounds like, if you were in a night club and the music was playing rather loudly, and one of your friends cups his hands up near his mouth, and leans over very close to your ears and yells something.

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post #23 of 24 Old 03-12-2012, 03:22 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

That's your problem.

+1..... You get a sub and set the Xover on the RF-7s to 40 or 60hz and everything will sound so much better. It will even open up the midrange and highs.

You were simply trying to get the amp to send too much low freq power to those speakers. It was working the amp too hard. You xover them at 60 hz and that amp should power them til your ears give out.

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post #24 of 24 Old 03-19-2012, 04:36 PM
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The dts track of that movie clips like hell anyway. Mastering an audio track is hard nowadays it seems..
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