XR100 opinions

[damacman]

Originally Posted by PHC1

Optimally you always want an amp with more power than the max handling of the speakers. It is not the dynamic peaks of music transients that can kill the speaker, many speakers can dissipate much more short bursts of wattage/power than they are rated for. It is the "clipping" or the amplifier reaching the limit of the dynamic headroom and sending a flat DC signal of some amplitude that will fry the speaker drivers if the amplifier does not have protection such as the McIntosh Power Guard. The following diagram should make more sense.

Oh good grief. If any part of that were true, a 3W SET driven into clipping would kill a pair of 1,000W speakers in seconds.

[PHC1]

Originally Posted by damacman

Oh good grief. If any part of that were true, a 3W SET driven into clipping would kill a pair of 1,000W speakers in seconds.

Think about it for a second... How can a 3W amplifier destroy 1000w speakers. Surely the components in such speakers are designed to handle much more than a 3W amplifier even in full clipping can ever put out. Besides, tubes clip "soft" vs transistor amps.

[PHC1]

Amplifier Clipping: How Do I Avoid It? https://www.mtx.com/library-clipping

[PHC1]

McIntosh crowd can rest easy. This is just a refresher.

POWER GUARD®
McIntosh designed and patented circuit that prevents speaker clipping. Photo-optics react in 1/1000th of a second to regulate power levels to speaker, protecting the speakers and the amplifier. A waveform comparison circuit continuously monitors both input and output signals. Power Guard dynamically adjusts the input level to avoid clipping while preventing harsh sounding distortion.

[markbodiford]

Aliens. You get the XR100 because they look like cool alien faces. Dark Cherry for the win.

[damacman]

Serge - I'll elaborate. For simplicity, assume all mentions of power are RMS values.

Originally Posted by PHC1

Optimally you always want an amp with more power than the max handling of the speakers.

This is where folks get into trouble. You take a 250wpc power amplifier and pair it up with a pair of speakers that are rated to handle 200wpc safely. More below.

Originally Posted by PHC1

It is not the dynamic peaks of music transients that can kill the speaker, many speakers can dissipate much more short bursts of wattage/power than they are rated for.

While this is true, and power over time is certainly a factor, it is still possible to damage speakers when exceeding their power ratings even for short bursts. It really all depends on the particular speakers and how much margin the manufacturer included in the power ratings.

Originally Posted by PHC1

It is the "clipping" or the amplifier reaching the limit of the dynamic headroom and sending a flat DC signal of some amplitude that will fry the speaker drivers if the amplifier does not have protection such as the McIntosh Power Guard.

This is where we get into trouble. First, amplifiers do not make DC when driven into clipping. Although the top of a clipped sine looks at first to be indistinguishable from Direct Current, it is in fact not Direct Current. Rather, it is simply the amplifier reaching the limits (rail voltage) trying to reproduce a signal when over-driven. In addition, even if an amplifier did produce DC when driven into clipping (it doesn't), the DC couldn't pass to the tweeter (and midrange) anyhow as the crossover network includes at least one series capacitor - which will not allow the passage of DC.

So, here's what really happens . . . speakers are damaged from overpowering. Plain and simple. A speaker can not differentiate a clean signal from a clipped signal. So, let's take our example above and say . . .

1) The manufacturer of the 250wpc power amplifier underrated it by 20%. So, the amp can really make 300wpc before the onset of clipping.
2) The manufacturer of the 200wpc speakers provides a 20% margin. So, they can really handle 240wpc before damage is an issue.

Now, the user drives the amplifier to clipping, where it can make as much as 200% of the power as it can make cleanly - that's 600wpc. 600wpc is 250% as much power as the speakers can really handle so they don't live though a single Judas Priest song . . .

The danger is just as real with McIntosh power amplifiers. (A year ago, a member here posted about his B&W speakers being damaged by his MC452 at the hand of his daughter during a party she threw while he was away.) Most McIntosh power amps can exceed their power ratings by 30% (or more even). An MC452 could easily damage the speakers I offer in the example above as it can make nearly 600wpc without a hint of strain.

Finally, we can't say blanket things like - amplifiers driven into clipping blow speakers up - without qualifying what we're actually saying. A 5wpc SS (I digress) amplifier driven into hard clipping could effectively make 10wpc. That's not blowing up even a single tweeter in a pair of XRT22s, no matter how crappy it sounds. However, if I swapped the 4A fuses in my XRT22s for 30A ones, I could easily kill a tweeter or few on Benny Benassi's Satisfaction without even flashing the Power Guard lamps on my bridged MC2600s.

[nalthien]

Thank you for a simple and effective explanation of one of the biggest misunderstandings in amplifier / speaker pairing!

[PHC1]

We say "DC" at clipping but that is an oversimplification really since it is still a sine wave technically but a sine wave with a flat top resembling a square wave....

A square wave or "clipped output wave with a flat top that persists" has twice as much energy as a since wave... Take a look at the description of the McIntosh Power guard again. What exactly is that circuit doing? Oh yeah, it is comparing the waveform from input to output to make sure THAT is not happening.

Bottom line is that if an amp is driven into clipping, it can damage a speaker faster than an amplifier that is capable of more power than a speaker can handle. Obviously common sense prevails and when the speaker is obviously playing way too loud, at some point one may run into a problem.

You can search google on this topic and come across many articles as I already posted one above. I think a speaker company and McIntosh should know what they are doing and recommending? Or are we going by hearsay?

[PHC1]

Perhaps we can put this argument to rest now. This video describes everything one needs to know about clipping and speaker damage. https://youtu.be/9PF32APSjrk

[PHC1]

Why is clipping so dangerous? Quick demonstration. https://youtu.be/2DHj_5cBZgU