Headroom: What it means, Why it's important - Examples - AVS Forum
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post #1 of 19 Old 01-07-2009, 10:07 PM - Thread Starter
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Hey Folks,

As we shop for speakers, amplifiers, and other audio equipment, the term "headroom" often arises. But what does this mean and why is it important? Put simply headroom is the amount of music above and beyond the average listening level that your system can play before it begins to clip the music. In the old days, music was mastered to have a large dynamic range, 20dB or more. Unfortunately, these days, music is mastered to have a very limited dynamic range, perhaps only 6-9dB. What this means is that much of our music today will sound louder when played over the radio, which is why it is mastered this way, but the cost of decreasing dynamic range for this purpose causes the music to be clipped off, or compressed.

I've attached some .mp3 examples that take a well mastered recording of ABBA's Take a Chance on Me and compressed them with various levels of compression. The original recording was mastered very, very well. None of the peaks were clipped and so the total dynamic range is about 24-27dB, which is HUGE, at least by our standards today. If this recording were mastered today, it would only have 6-9dB of dynamic range and wouldn't sound nearly as good.

The files can be interepreted this way:
1. 0db compress -> ~27dB dynamic range, no clipping
2. 6db compress -> ~21dB dynamic range, only tips of transients clipped
3. 12db compress -> ~15dB dynamic range, some clipping of music,
4. 15db compress -> ~12dB dynamic range, this is about how this would be mastered today (and that's being generous). after listening to the other clips, you can tell how bad it sounds.
5. 18db compress -> ~9dB dynamic range, sounds awful, severe clipping
6. 24db compress -> ~3dB dynamic range, massive clipping for demonstration*

* included just so you can hear how significant clipping distortion sounds

So how does this matter in choosing audio equipment? Well, to listen to ABBA at original 27dB of dynamic range, you need to have *a lot* of headroom in your system. If you like to listen to your music at around 80db, which is moderately loud, then you need to have about 90db coming out of your speakers, roughly speaking. Most "hi fi" type speakers will produce around 90db with one watt.

Now for the difficult part. In order to increase dB by 10, power must increase by TEN times. So, 27dB of headroom, translates to almost 1,000 times power. Of course, most people don't have 1,000 watts of power nor speakers that could handle that without introducing all kinds of other distortions. The advice therefore is buy as efficient of speakers as possible and as much amplifier as you can possibly afford. This will help minimize the clipping that your system is doing when playing well mastered recordings.

 

take_a_chance_18db_24db_compress.zip 459.0068359375k . file

 

take_a_chance_12db_15db_compress.zip 458.9677734375k . file

 

take_a_chance_0db_6db_compress.zip 459.060546875k . file

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post #2 of 19 Old 01-08-2009, 12:32 PM
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Originally Posted by LTD02 View Post

The advice therefore is buy as efficient of speakers as possible ...

Everything you worked on here is much appreciated, as I'm certain the community will agree. This one bit of advice I disagree with, since all that would be sold are Klipsch.

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post #3 of 19 Old 01-08-2009, 01:54 PM
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I co-own a small recording studio and I can tell you that the practice of "square waving" audio remains hotly debated among recording and mastering engineers. Personally I like dynamics in music and most of the gurus that I admire like Bob Katz, do as well, but it certainly doesn't seem to the norm for pop music these days.
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post #4 of 19 Old 01-08-2009, 03:43 PM
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Thanks for the samples. If you've got the money, buy triad platinum LCRs. They're rated at 94.5db/1w/1m. They can play louder than most can stand with negligible distortion I know that active studio monitors have great dynamic range. Meyer sound x10 for example can play exceedingly loud with very little distortion. Mind you they cost £40,000. More or less, you need good horned speakers to handle really big dynamics. I don't think tweeters can have really high sensitivity without a horn. Feel free to post examples though.

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post #5 of 19 Old 01-08-2009, 04:14 PM
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Paradigms are efficient speakers. Not quite as efficient as Klipsch, but plenty of models available at 93dB or higher. The Monitor 11 has a rating of 97dB. There are quite a few speakers out there with 90+dB efficiency ratings.

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post #6 of 19 Old 01-08-2009, 05:01 PM
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JTR Triple 12LF's. Around 100DB efficient. Will do a solid 130db with a kilowatt input. One of the few speakers that can actually meet the headroom requirements. Extraordinary resolution and sound quality too. Amazing what happens when you actually hear a speaker capable of true dynamics at reference levels without compression or going into rising distortion. Do a search here on the forum for user reviews.

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post #7 of 19 Old 01-08-2009, 05:48 PM
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Quote:
Originally Posted by CriticalListener View Post

Everything you worked on here is much appreciated, as I'm certain the community will agree. This one bit of advice I disagree with, since all that would be sold are Klipsch.

The situation is not quite that dire. In order to get 27 dB of dynamic range in the scenario described, one would actually need about 500 watts of peak power, which kind of sort of approximately requires a robust amp rated at 250 watts RMS. Adding 1 dB of efficiency to the speakers or subtracting 1 dB from the dynamic range or listening level would bring the requirement down to 200 watts RMS per channel, which is not a tall order. If one can afford to buy a fancy, relatively high-end receiver, as many people seem to do, then one can afford to buy this much amplifier power.
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post #8 of 19 Old 01-08-2009, 05:57 PM
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I understand the point is to get dB across, but why post MP3s? It's a lossy format. It clips frequencies to get a high compression ratio. You should instead rip it to FLAC, which is losses so no frequencies are dropped.
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post #9 of 19 Old 01-08-2009, 06:05 PM
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Quote:
Originally Posted by surma884 View Post

I understand the point is to get dB across, but why post MP3s? It's a lossy format. It clips frequencies to get a high compression ratio. You should instead rip it to FLAC, which is losses so no frequencies are dropped.

MP3 is more than adequate to get this particular point across and it uses less bandwidth. My puny, cheap computer speakers were likewise more than adequate for this purpose, as well.
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post #10 of 19 Old 01-08-2009, 08:18 PM
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the question is, why do you think people want to hear six different versions of the same ABBA song ?!

no amount of education/edification is worth that horrific price...

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post #11 of 19 Old 01-08-2009, 09:17 PM - Thread Starter
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Quote:
Originally Posted by CriticalListener View Post

Everything you worked on here is much appreciated, as I'm certain the community will agree. This one bit of advice I disagree with, since all that would be sold are Klipsch.

thanks. obviously there are tradeoffs and i didn't mean to imply that efficiency is the only, or even the most important, aspect of speakers that matters. it is often overlooked however.

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post #12 of 19 Old 01-08-2009, 09:24 PM - Thread Starter
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Quote:
Originally Posted by Dbuudo07 View Post

Thanks for the samples. If you've got the money, buy triad platinum LCRs. They're rated at 94.5db/1w/1m. They can play louder than most can stand with negligible distortion I know that active studio monitors have great dynamic range. Meyer sound x10 for example can play exceedingly loud with very little distortion. Mind you they cost £40,000. More or less, you need good horned speakers to handle really big dynamics. I don't think tweeters can have really high sensitivity without a horn. Feel free to post examples though.

the meyer x10's are definitely heading in the right direction. i bet they sound really nice. that said, zero waf factor.

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post #13 of 19 Old 01-08-2009, 09:26 PM - Thread Starter
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Originally Posted by fireman325 View Post

Paradigms are efficient speakers. Not quite as efficient as Klipsch, but plenty of models available at 93dB or higher. The Monitor 11 has a rating of 97dB. There are quite a few speakers out there with 90+dB efficiency ratings.

i've owned some paradigm stuff in past. they use phony sensitivity ratings because they add room effects. not that they are bad or anything, just that they are not an apples to apples comparison.

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post #14 of 19 Old 01-08-2009, 09:39 PM - Thread Starter
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Quote:
Originally Posted by Robert Cook View Post

The situation is not quite that dire. In order to get 27 dB of dynamic range in the scenario described, one would actually need about 500 watts of peak power, which kind of sort of approximately requires a robust amp rated at 250 watts RMS. Adding 1 dB of efficiency to the speakers or subtracting 1 dB from the dynamic range or listening level would bring the requirement down to 200 watts RMS per channel, which is not a tall order. If one can afford to buy a fancy, relatively high-end receiver, as many people seem to do, then one can afford to buy this much amplifier power.

good points. there are other effects that i left out for simplicity of the original post. power compression is a big one. most 90 db sensitive speakers are not built to handle even 500 watts of power for any duration. the passive crossover components aren't typically built to handle that kind of power either, so there are going to be major shifts in the crossover if that power is pumped through which is going to throw tonal balance all out of whack. the likelihood of burning up the tweeter would also become a real risk.

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post #15 of 19 Old 01-08-2009, 11:06 PM - Thread Starter
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Originally Posted by Soundood View Post

JTR Triple 12LF's. Around 100DB efficient. Will do a solid 130db with a kilowatt input. One of the few speakers that can actually meet the headroom requirements. Extraordinary resolution and sound quality too. Amazing what happens when you actually hear a speaker capable of true dynamics at reference levels without compression or going into rising distortion. Do a search here on the forum for user reviews.


LL

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post #16 of 19 Old 01-10-2009, 11:28 PM
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Originally Posted by LTD02 View Post

the meyer x10's are definitely heading in the right direction. i bet they sound really nice. that said, zero waf factor.

If she can't appreciate the x10, she's not worth my time. Actually I'm hearing that the price is around $15,000. That is pretty incredible considering what you get. There should be a comparo between the jtr triple 12lf and the x10. The jtr is nowhere close to the x10 in bass extension, but they both use compression drivers, and the jtr only costs $1500-$1000(not sure). So if its close to the x10, that would be amazing. They both have the ability to give you more spl than almost any speaker ever made.

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post #17 of 19 Old 01-11-2009, 01:58 AM
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Not canned meat, good sounding speakers.
Others that meet the grade...

Several models of Danley Sound Labs.
The two larger PMC monitors in active mode.
Mark Seaton's Active monitors.
Dynaudio AIR monitors...the M4U.
Several Westlake Monitors
ADAM SA-6's and SA-7's.

Most of these are well outside the budget range of most ordinary people. All of them are designed with VERY high output and power handling capabilities as all are designed with 1st generation and live musical reproduction in mind. Not second, third, etc. as found on most consumer recordings. The Danley, Seaton and JTR are within what some folks can afford to do and fully meet the headroom and power handling requirements. The JTR comes closest to what the average person can afford to put into their system.

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post #18 of 19 Old 01-11-2009, 10:43 AM
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What this means is that much of our music today will sound louder when played over the radio, which is why it is mastered this way, but the cost of decreasing dynamic range for this purpose causes the music to be clipped off, or compressed.

I only question whether compression and clipping are one and the same. To me clipping means actually removing the tops of the waveforms due to lack of power output in the amplifier during playback. Compression, OTOH, means decreasing the dynamic range without actually altering the frequencies and is done at the production level. It may seem trivial, but the differences are significant.

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post #19 of 19 Old 01-12-2009, 04:13 AM
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I don't think that compression automatically results in clipping of the signal (only if it done poorly). You should be able to compress the volume range of music without "clipping" the signal.

In fact a recording with high dynamic range is more likely to be clipped during playback as pointed out by LTD. Hmmm, maybe that is the reason some people publish compressed music - so that it does not get clipped on low quality/power playback equipment . . .

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