What exactly is clipping?

[N.Cotman]

Hi everyone,

I am using a NAD 7100 with Paradigm 7se MKiis. I believe the receiver outputs 50 watts per channel, while the Paradigms can each handle 100 watts.

When I crank the receiver to about 60%, the speakers start to make a clipping noise (which I believe is "clipping"? haha, sorry, still kind of new to this!).

I was wondering: is this a result of the receiver working too hard, or the speakers be unable to handle the power? Also, if I am listening to my iPod through the receiver, if a song with a louder/deeper recording is being played, does this affect the wattage? I'm assuming not, just thought I'd ask.

Any input appreciated!

Thanks,
Nick

 

[j_garcia]

1) The wattage rating on your speakers is a maximum UNCLIPPED rating, not how much they require.

2) yes bass dramatically affects the wattage requirement because lower frequencies require more power to properly reproduce

3) Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its published ratings.

So it is sort of a backwards thing - the result ends up being too much power sent to the speaker, but the reason for it is because the amp didn't have sufficient power to cleanly reproduce the signal in the first place. That distortion is literally the peaks of the sound waves being "clipped off", thus the term clipping. Notice the flats here:

Here is the key takeaway: if you hear this distortion in your speakers, turn it down immediately. The risk will be damaging the speaker because distortion results in the drivers heating up and can physically damage them.

 

[ski2xblack]

Recent re-capping and bench test of an NAD 2100 (same amp as within your 7100)...it can crank out much more than it's continuous 50 watt rating, at least for a few cycles. You could simply be over-driving your speakers, from how you describe things.

 

[TLS Guy]

Recent re-capping and bench test of an NAD 2100 (same amp as within your 7100)...it can crank out much more than it's continuous 50 watt rating, at least for a few cycles. You could simply be over-driving your speakers, from how you describe things.

I doubt it. He is clipping the amp and needs to be careful. For clean reproduction, you actually need much more power than people realize.

 

[N.Cotman]

Thanks for all the input guys!

My other speakers are rated at 90 watts and didnt do this. (Though I know that ratings arent always relevant).

Cheers,
nick

 

[Goliath]

was wondering: is this a result of the receiver working too hard, or the speakers be unable to handle the power? Also, if I am listening to my iPod through the receiver, if a song with a louder/deeper recording is being played, does this affect the wattage? I'm assuming not, just thought I'd ask.

It's possible you exceeded the speakers mechanical limits (too much woofer excursion) and consequently experienced distortion.

 

[TLS Guy]

It's possible you exceeded the speakers mechanical limits (too much woofer excursion) and consequently experienced distortion.

You have asked a complex problem. The power drawn form an amp depends on the speakers sensitivity, its impedance and especially its impedance curve. Another important factor is the phase angle which is the phase relationship between current and voltage. Speakers are all over the map in all these parameters, and few manufacturers specify these important details. When they do they are frequently known to tell big fish stories!

So you can't compare speakers like you are. My bet is one set of speakers puts far more demand on the amp than the other. Unless you have the bass turned up high, I doubt you are exceeding the mechanical limits of the drivers. For a lot of receivers for many speakers, the amps can not even give their rated power without clipping, because a combination of factors I outline, often stack up against the amp.

Amps which deliver their rated power under a variety of complex loads are spendy formidable units.

 

[mtrycrafts]

...

Amps which deliver their rated power under a variety of complex loads are spendy formidable units.

To bad no one is doing the power cubed testing anymore with published data unlike The Audio Critic has in the past. Not all amps that can perform well +/- 60 deg need to be spendy and some that are cannot perform well on the power cube test, at least what TAC has published in the past.

 

[mtrycrafts]

Hi everyone,

I am using a NAD 7100 with Paradigm 7se MKiis. I believe the receiver outputs 50 watts per channel, while the Paradigms can each handle 100 watts.

When I crank the receiver to about 60%, the speakers start to make a clipping noise (which I believe is "clipping"? haha, sorry, still kind of new to this!).

I was wondering: is this a result of the receiver working too hard, or the speakers be unable to handle the power? Also, if I am listening to my iPod through the receiver, if a song with a louder/deeper recording is being played, does this affect the wattage? I'm assuming not, just thought I'd ask.

Any input appreciated!

Thanks,
Nick

How did you arrive at that 60%? The volume dial has no such scale on it that I know of.

The spec on the speaker shows 89 dB in room sensitivity. And nothing shows at what point it might be in compression operation and badly distorting.
What is your other speaker? Perhaps it has a better sensitivity? Impedance is better? Who knows.

 

[ski2xblack]

No idea what 60% is either, but if Nick's NAD is in proper working order, a big "if" given it's age, it's no slouch. It's "50 watt" rating is highly misleading. It underestimates is actual continuous power, and on top of that it's a dual rail supply type. The rails don't commute until >60 watts, and the power supply trickery allows short term dynamic power of several hundred watts into any load down to two ohms. Also, unless I'm missing something, Nick is not using any sort of bass management, so his 'Digms are getting everything, and they're ported speakers. We all know what happens with ported speakers trying to reproduce frequencies where the woofs and ports are out of phase. Lots of excessive cone motion. And he's cranking it to eleven, er, 60%. I still suspect what he heard were cries for mercy from woofs trying to go beyond their limits.

 

[Goliath]

So you can't compare speakers like you are. My bet is one set of speakers puts far more demand on the amp than the other. Unless you have the bass turned up high, I doubt you are exceeding the mechanical limits of the drivers. For a lot of receivers for many speakers, the amps can not even give their rated power without clipping, because a combination of factors I outline, often stack up against the amp.

Comparing speakers? What are you talking about?

It's more than possible that he exceeded the mechanical limits of his speaker long before reaching the thermal limits. You can exceed the excursion limits of a speaker even at half thermal rating, and since he has not described the actual distortion in any depth leaves it as a distinct possible option.

At a minimum, he has not ruled it out. People often blame the distortion they hear on amplifier clipping but never consider the alternative.

 

[AcuDefTechGuy]

No idea what 60% is either, but if Nick's NAD is in proper working order, a big "if" given it's age, it's no slouch.

I tend to agree based on my experience with AVR and all the speakers I've used. The NAD is possibly defective.

IMO most AVRs (including my 50WPC HK AVR powering speakers w/ 2.7 ohm min impedance) have no trouble at all driving most speakers and producing great sound (assuming the speakers are great).

Time for a new AVR.

 

[cpp]

Hi everyone,

I am using a NAD 7100 with Paradigm 7se MKiis. I believe the receiver outputs 50 watts per channel, while the Paradigms can each handle 100 watts.

When I crank the receiver to about 60%, the speakers start to make a clipping noise (which I believe is "clipping"? haha, sorry, still kind of new to this!).

I was wondering: is this a result of the receiver working too hard, or the speakers be unable to handle the power? Also, if I am listening to my iPod through the receiver, if a song with a louder/deeper recording is being played, does this affect the wattage? I'm assuming not, just thought I'd ask.

Any input appreciated!

Thanks,
Nick

I was doing some reading about your NAD. IN your manual page 8 #17 the is a circuit call Soft Clipping. It is supposed to be switched on for high levels. Also according to your manual there is a impedance switch ( page 9 & 10 item 19) on the rear of the unit which is screwed down for 8 ohms.

And your speakers are noted in the manual as normal 6 ohms speakers with a min impedance of 4 ohms.

A good read on impedance http://www.audioholics.com/audio-amplifier/impedance-selector-switch-1

 

[AcuDefTechGuy]

Do we know the approximate measured SPL when this is happening?

Is it 100dB?

Or 85dB?

 

[markw]

From what you've described it could be either the amp or the speakers, or possibly both.

What Paradigms? from that 100 watt limit, they don't sound too big and you may be asking too much out of them.

Just because a speaker is rated to be able to withstand so many watts safely doesn't mean you can't ask it to (try to) produce too much bass and exceed its physical limits, which is a form of clipping, albeit a physical one. Likewise, if your source material is hot (too high a level), it could overdrive the emp and force it into electrical clipping.

so, if you want more answers you need to specify which paradigms you're listening to, what source hardware you're using, and what music you're playing. All these factor into the equation.

 

[mtrycrafts]

...
What Paradigms? f...

1st post: Paradigm 7se MKiis

 

[markw]

1st post: Paradigm 7se MKiis

Thanks. They ain't no powerhouses and can be overdriven with that amp if his expectations are too high. IMNSHO, it could still be both, ot either depending on how hard he's actually driving them.

 

[mtrycrafts]

... depending on how hard he's actually driving them.

Which we don't know. 60% of something.

 

[markw]

Which we don't know. 60% of something.

And that could well be 120% of their, or the amps, capabilities.

But, if he's talking about 1:00 - 2:00 or so on the volume pot, he's pushing something beyond it's limits.