Dynamic peaks in HT and music - are there typical frequencies? - AVS Forum | Home Theater Discussions And Reviews
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Old 04-18-2013, 01:21 PM - Thread Starter
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Everyone talks about how speakers need to be able to deal with dynamic peaks in movies and music.

I have read here that speakers should handle anywhere from 15 - 25 db peaks.

Are there frequency ranges that these peaks are most commonly in?

i.e. do all drivers need to be able to deal with the power that such a peak would represent?

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Old 04-18-2013, 08:16 PM
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Yes they do.

While the most common high-intensity peaks occur in the low bass in music (big bass drums and low organ notes are examples), there are also some pretty intense peaks in the midrange from a loud trumpet solo or similar.

Of course, if you are playing the overall volume very loud to start with, it takes relatively less of a peak in the music to add up to a very high level.

As far as driver FAILURE, however, tweeters usually are the weak link.

This is because they are physically smaller and therefore less able to dissipate heat.

The internal temperature of their voice coil can get very hot quickly and cause failure of the adhesives and insulating material.

Driver failures, in general, do not occur because of a brief peak, but because of too much continuous power producing too much heat faster than the drivers can radiate it, making them hotter and hotter until they fail.

Some speaker makers (Vandersteen for example), incorporate protection circuits that sense when too much power is being applied and switch in a limiting circuit and a warning LED or lamp.
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Old 04-19-2013, 02:25 AM
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As an example Reference volume of THX is 85 db continuous with 20 db of headroom. That is a massive jump in volume. This volume is actually quite loud. I find in music there arent as many peaks. I was listening to music to on my computer system and a very basic spl meter was reading 65-72 db. Once the meter shot up to 90 when the person started to scream but other than that I dont think I saw it pass 79 db.

Now in home theatre the peaks are intense. Sometimes you go from talk to a massive explosion which can create much more than a 20 db peak and probably approaching 40db. As commsysman said its usually the tweeter that does however thats more from constant power rather than peaks. A woofer is more likely to be damaged when the gain the increased too much and trying to make it do something it isnt supposed to. Drivers have an excursion limit exceeding that limit can flex the cone or cause damage to the voice coil. Either is very bad.

As far as which frequencies tend to peak the most, I would say the low frequencies in HT and Im not sure which in music.
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Old 04-19-2013, 02:34 AM
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^^ This depends on the speaker. For speakers using high efficiency compression drivers like JTR, Seaton Sound, Danley Sound Labs, and others, the lower frequency drivers or woofers are the limiting output component. Generally speaking, with these high efficiency designs, your ears will give out long before the speaker is close to audibly distorting.

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Old 04-19-2013, 04:50 AM
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Originally Posted by rick240 View Post

Everyone talks about how speakers need to be able to deal with dynamic peaks in movies and music.

Good set of questions.
I have read here that speakers should handle anywhere from 15 - 25 db peaks.

Something like that. 20 dB is commonly cited number and based on years of analysis of real world music, its a pretty good number.
Are there frequency ranges that these peaks are most commonly in?

I find that to be unpredictable. People write, perform, mix and master music in accordance with their preferences. Digital media can handle just about anything that someone can come up with.

What I can say for sure is that if the peak is in a low frequency band then it needs to be more intense for a desired perception of intensity because the ear's sensitivity is so much less in those ranges. I suspect that the 25 dB number may arise in situations involveing bass for this reason.
i.e. do all drivers need to be able to deal with the power that such a peak would represent?

I think so.

It is far easier to build highly efficient, high SPL high frequency speaker drivers than low frequency high SPL speaker drivers.

The efficiency of speakers for low frequencies is tightly constrained by some pretty rigid and oppressive laws of physics. Basically, size, efficiency, and low frequency extension are tightly connected and if you up one, you are forced to cut another. At medium and high frequencies the same physical laws are in force, but because the frequency is so much higher, the constraints are far less oppressive.

One of the evolutionary changes in loudspeaker system construction over the years has been the availability and use of drivers for high and low frequencies that have much larger power handling and SPL generating capabilities.

In the days of analog media subwoofers were relatively rare because they could cause feedback problems and really didn't have that much to do. Those kinds of frequencies weren't usually coming off of analog media in large quantities. They can't be recorded cleanly. Both analog tape and vinyl have severe limitations at very low frequencies.

In the days of analog media the dynamic range of the media significantly limited the low and high frequency dynamics that could be cleanly recorded and played back.

Digital media can generally handle all audible (and many inaudible ones as well!) signals with equal intensity, equally well.

The current problems with hypercompression are enabled by the more ideal characteristics of digital media.
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