"Headroom" - what does it sound like to you?

[sfogg]

Max,

"And the above does not mean a dynamic range of 30 dB. If the quiet parts of the recording were, for argument's sake 50 dB it would have a dynamic range of 60 dB."

Exactly.

"You can drop as much as 6 dB/meter in a typical room so if you are 5 meters away from the speakers you would need additional power over the"

Not quite. You drop 6dB (in free space) for every doubling of distance. So in free space moving from 1m to 2m does drop the level by 6dB. But for the next 6dB drop you have to move from 2m to 4m....then 4 to 8m...etc..etc. It is the inverse candle power rule.

However, in non-free space (listening room) the dropoff isn't that sharp because instead of the sound energy freely radiating in an ever expanding way it hits the walls of your room and some of it is reflected back.

Shawn

[Deang]

"Dean, I will add that if you're running a 20-watt amp at its full 20, you're clipping."

Sure, not doubt -- you have no "headroom" left.

"Gotta leave some very substantial room. So, that's where all you guys' figures are off. Your figures all assume playing a rated amp at its full open rating..."

None of us are doing or saying that. I'm not running the amp full out to get the 110dB peaks! The author of the article uses 10dB of headroom in his example. So, to get those peaks of 110dB my 20 watt amp is hovering around 2 watts (if that). Remember, 10dB = twice as loud = 10 X more power. Like Shawn said though, what's out there on a recording that has 10dB of dynamic range -- it sure isn't in the stuff I listen to!

[maxg]

"Not quite. You drop 6dB (in free space) for every doubling of distance. So in free space moving from 1m to 2m does drop the level by 6dB. But for the next 6dB drop you have to move from 2m to 4m....then 4 to 8m...etc..etc. It is the inverse candle power rule. "

Now that I did not know - thanks Shawn! Explains why the volume drop in my room (measured) was always less than I thought it ought to be.

[PrestonTom]

Although this thread has gone on, and on and on, no one has mentioned the issue of transient current capability (if it was mentioned, I missed it). This had been a popular issue with the "high current amps".

An amp can lack extra power (watts) to amplify the peaks without distortion (clipping). However, an amp can also fail to deliver the momentary amounts of high current that a speaker may require. While this is probably not a problem with a Kilpsch speaker since they are quite efficient and the impedance does not go all that low. It can be a problem with current loving speakers. That is one that is not very efficient and the impedance can drop to pretty low levels. Electrostatics and panel speakers are quite problematic in this regard.

It is a tricky issue to define a high current amp, since there are no agreed-upon specs. As I recall, the Harman Kardon line will have their own spec of how many amps (around 30-45 amps) will be sent over a short period of time (on the order of 10s of milliseconds).

Good luck,

-Tom

[MarkBK]

I just read this thread from beginning to end - Man! was that time consuming! From the 500 foot view - many valid points have been made. It all comes down to what works for you, your room, etc. Jeff, it's not about winning - it's about understanding dynamics and efficiency and the interaction of these and many other elements through out the music reproduction chain. Somewhere, many pages back the original thread turned left and never looked back....thank god my acoustic guitar doesn't get so loud that I lose the ability to hear it!!!!!

Dr. Who - where are going to test your hearing that actually test to 20k and above? Very few places offer that service that I'm aware of and it is one that I'm interested in finding!

[pauln]

My prediction is that there will come a time soon in the course of your persistense in the development of your inadequacy when you will need to push this overcompensation to the point of upgrading your gear to include a stereo pair of air raid sirens and jack hammers to get the dB levels of slam, punch, kick, pants flap, (insert aggressive/erotic descriptors here), needed to convince yourself and your peer group that you are a powerfull guy with a powerfull "sound system" to match.

Sadly, Jeff, it seems to be quite clear to some of us at this point that you are vainly searching for how to maintain sonic levels lost to your ears by just this same such said searching (cranking it up, and possibly from all the drumming), as you are certainly losing you hearing - as may be the case for some others here that are trying to see how dangerously insanely crazily absurdly rediculously perposterously loud their gear will play instead of employing their gear for normal enjoyment of music at human levels - those that don't destroy room furnishings, cook raw meat, or harm one's hearing. You are chasing an infantile and destructive course that has nothing to do with the reproduction of music and everthing to do with messing youself up.

Stop the madness and TURN IT DOWN... it has become painfull to read your increasingly distressing and unfortunate posts. This thread reads like an intervention to save you from yourself.

[Deang]

So true so true.

I've found that since I've moved to different drivers I don't play as loud. 95 -100dB+ used to be common for me, where now I rarely if ever go over 90dB. The better the sound down low the less need to turn it up.

[jazman]

So true so true.

I've found that since I've moved to different drivers I don't play as loud. 95 -100dB+ used to be common for me, where now I rarely if ever go over 90dB. The better the sound down low the less need to turn it up.

Bingo for you Dean.

"The better the sound down low the less need to turn it up."

Klipsch out.

[Strabo]

You guys are still at it?

I'll have to rewind back to the beginning of this one. [<)]

[jpm]

After a 6 or 18 beers volume is very important. The louder the better!

[3dzapper]

[]

Rick

[NOSValves]

I personally prefer at least a 10 foot ceiling for proper headroom.

[MrMcGoo]

Ben, "When have I even implied that because I listen to movies (which can be quite loud) OTHERS should buy a big amp????? A big amp is needed only by folks that may listen to big transients for whatever reason. Folks that listen to chamber music on their Khorns at moderate levels clearly do not need a big amp." Even for those that listen to movies at Reference Level (which many consider is very loud) the *peak* output per channel is 105dB per speaker at the listening position with an average level of around 75-85dB. With a K'Horn or a LaScala 10 or 20 watts is more then enough to satisfy that requirement. One of the big problems many have with discussions such as this is what constitutes 'loud' varies depending upon who you are talking to. Few really have a reference for how loud they are listening at. Shawn

Shawn,

You are in the right ballpark, but I run RF-7s that produce 99 db/1w/1m, not 104 db Heritage speakers. The 99 db figure comes from S&V. The Klipsch number of 102 db is at 2.83 volts which is not 1 watt on RF-7s with an impedance way below 8 ohms.. The difference is significant when headroom is the topic, since you need nearly quadruple the amplifier power for the 5 db difference.

You have the reference levels right for the most part, but when you go from home reference of 75 db to commercial theater reference of 85 db the dynamic peaks on the full range speakers just moved up 10 db as well.

Most HT types, rightly or wrongly, seem to prefer DTS mixes over Dolby Digital mixes. The codecs are about the same quality IMO, but DTS is usually mixed hotter which accounts for the preference. Master and Commander was mixed so much hotter than I expected the first time through that my wife thought something had hit the house.

Headroom means that when you get hit with an unexpected transient all you have to do is turn it down; you do not have to buy new drivers for your speaker.

Room gain is only an issue when the system is calibrated to 75 db and when the master volume is set for a movie or music. At that point the system is committed, then wham, the unexpected 40 db transient from a broadside hits because some engineer is trying to sell DTS DVDs.

There are two choices to deal with this issue. You either get a big amp and/or turn the volume a bit lower on the first time through DTS mixes. I use both approaches.

Only one other person has commented on the headroom issue relative to impedance. On Heritage speakers the impedance is 8 ohms through the bass frequencies. On RF-7s that have to deal with the big dynamic peaks, the minimum impedance has been clocked as low as 2.8 ohms. I found out that a very solid 130 watt receiver does not have the high current capability to drive the Reference 7 to sound their best.

The bottom like is that one amplifier does not fit all Klipsch speakers or listeners. Yet the advice seems to always be the same. You allegedly do not need much power with any high sensitivity Klipsch speaker. Even Klipsch tech support takes a hit on this forum when they advise 200 wpc for the RF-7s used in a home theater. When people like myself advise setting the RF-7s as small, here come more flack nearly every time, because the RF-7s are being "wasted."

Then there is the crowd that implies that it is nearly impossible to find a high power amp that has a good first watt. While all amps are not created equally, there are good high power amps out there.

Bill

[Allan Songer]

I personally prefer at least a 10 foot ceiling for proper headroom.

But if you want the the experience to be more dynamic by adding a trampoline you will need more headroom.

[jpm]

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[sfogg]

Ben,

"but when you go from home reference of 75 db to commercial theater

reference of 85 db the dynamic peaks on the full range speakers

just moved up 10 db as well."

There is no difference there. Theaters are typically calibrated with

-20dB noise sources to 85dB, home theater equipment typically uses

-30dB noise to 75dB. End result is the same max SPL at 0dBFS

"The codecs are about the same quality IMO, but DTS is usually mixed hotter which accounts for the preference."

0dBFS is 0dBFS. That DTS is mixed hotter doesn't change the peak

levels... just the dynamics during the movie. If they raise average

level that simply means the peaks are going to be with less dynamic

range between peak and average.

"Room gain is only an issue when the system is calibrated to 75 db and when the master volume is set for a movie or music."

I'm not sure what you mean here. Room gain is typically referencing the

point where the room starts to show up to a 12dB/octave boost in the

bass response and it has nothing to do with the calibrated volume level.

"At that point the system is committed, then wham, the unexpected 40 db

transient from a broadside hits because some engineer is trying to sell

DTS DVDs."

With an average level of 75dB there is not 40dB of dynamic range

available for the main channels... they have 30dB available to hit

105dB max.

The LFE channel can have 40dB (max reference level is 115dB for the LFE

channel) but that is a problem for the subwoofer, not the mains. That

extra 10dB of output means the subwoofer needs the power, not the mains.

"The bottom like is that one amplifier does not fit all Klipsch speakers or listeners. "

Agreed. A 325w amp is pointless for many listeners with the big horns

at the levels they listen at. Similarly others with less

efficient speakers are going to need more power, esp. if they like to

listen louder. I hit reference level easily (and well beyond) on my

LaScala's with about 30w of power.... at the same time I have 3

channels of 1200w of power each channel available to each of my three

subwoofers. It is all about using the right tool for the job.

Shawn

[Fish]

I personally prefer at least a 10 foot ceiling for proper headroom.

But if you want the the experience to be more dynamic by adding a trampoline you will need more headroom.

Not to encourage you Allan but that's pretty funny.

[MrMcGoo]

Shawn,

Room gain is there, albeit a small amount, when you use pink noise from 20 Hz to 20 kHz to calibrate the channels.

Some of the other members seem to think room gain is important and that you need less amp as a result. My point is that you need enough headroom to handle the 30 db peaks and that room gain is not relevant if you want to avoid clipping.

You are right that 30 db peaks are the industry standard in movies. (30+75=105; 85+30=115.) However, the DVD medium has a dynamic range that is 144 decibels wide, which is 48 deicbels over the possible range on a CD. Hence the DVD medium was designed from day one to have a greater dynamic range than a CD. Please do not tell me that no one will ever utilize it. It's like saying that no onw will ever exceed the 70 mph speed limit on a car capable pf 150 mph.

I do not believe that the DTS mix in Master and Commander is within the 30 db industry standard. I lack the test gear to measure the dynamic peak, but it is in a different class than any other movie I have ever listened to or out of the 300+ movies that I own.

Bill

[Painful Reality]

Shawn,

You are in the right ballpark, but I run RF-7s that produce 99 db/1w/1m, not 104 db Heritage speakers. The 99 db figure comes from S&V. The Klipsch number of 102 db is at 2.83 volts which is not 1 watt on RF-7s with an impedance way below 8 ohms.. The difference is significant when headroom is the topic, since you need nearly quadruple the amplifier power for the 5 db difference.

You have the reference levels right for the most part, but when you go from home reference of 75 db to commercial theater reference of 85 db the dynamic peaks on the full range speakers just moved up 10 db as well.

Most HT types, rightly or wrongly, seem to prefer DTS mixes over Dolby Digital mixes. The codecs are about the same quality IMO, but DTS is usually mixed hotter which accounts for the preference. Master and Commander was mixed so much hotter than I expected the first time through that my wife thought something had hit the house.

Headroom means that when you get hit with an unexpected transient all you have to do is turn it down; you do not have to buy new drivers for your speaker.

Room gain is only an issue when the system is calibrated to 75 db and when the master volume is set for a movie or music. At that point the system is committed, then wham, the unexpected 40 db transient from a broadside hits because some engineer is trying to sell DTS DVDs.

There are two choices to deal with this issue. You either get a big amp and/or turn the volume a bit lower on the first time through DTS mixes. I use both approaches.

Only one other person has commented on the headroom issue relative to impedance. On Heritage speakers the impedance is 8 ohms through the bass frequencies. On RF-7s that have to deal with the big dynamic peaks, the minimum impedance has been clocked as low as 2.8 ohms. I found out that a very solid 130 watt receiver does not have the high current capability to drive the Reference 7 to sound their best.

The bottom like is that one amplifier does not fit all Klipsch speakers or listeners. Yet the advice seems to always be the same. You allegedly do not need much power with any high sensitivity Klipsch speaker. Even Klipsch tech support takes a hit on this forum when they advise 200 wpc for the RF-7s used in a home theater. When people like myself advise setting the RF-7s as small, here come more flack nearly every time, because the RF-7s are being "wasted."

Then there is the crowd that implies that it is nearly impossible to find a high power amp that has a good first watt. While all amps are not created equally, there are good high power amps out there.

Bill

I think I'm going to post on the Home Theater Forum about low power SET amps...

[sfogg]

"Room gain is there, albeit a small amount, when you use pink noise from 20 Hz to 20 kHz to calibrate the channels. "

Actually the bigger problem there is room modes artificially boosting

the reading. That is also why most controllers don't use pink noise for

calibration.

The high frequency noise is band limited with little bass response for

the mains while the sub(s) are calibrated using a different frequency

noise.

"However, the DVD medium has a dynamic range that is 144 decibels wide, which is 48 deicbels over the possible range on a CD. "

And that number is theory only and doesn't apply to *20* bit lossy

compressions format anyway. The best 24bit D/As are at about 120dB SNR.

Every piece of gear beyond that DAC would have to at least match that

number as far as SNR or dynamic range is going to be lost in the

equipment itself.

Even if you could get 144dB of dynamic range in a DAC and the rest of

the supporting electronics (which is *extremely* difficult if you

consider the noise floor of even a 100 ohm resistor is about -144dB)

there isn't a system on the planet that could take advantage of that

dynamic range.

Since we can't hear below 0dB that means to fully take advantage of

that dynamic range the peak playback level is 144dB... otherwise we are

loosing dynamic range because the level is lower then we can hear.

Ever stand next to a jet engine at takeoff? That is about how loud

144dB is. For a K'Horn to hit 144dB 1meter away it would literally need

10,000 watts of power which of course it can't even remotely handle.

And that 144dB level is *if* the rest of the system, including the room

had a 0dB noise floor. If you have a room with a typical 50dB noise

floor to fully use that dynamic range would mean max playback level

would have to be 144dB above the noise floor..... 194dB... which is

within a couple of dB of the highest SPL level (about 198dB) the

atmosphere itself can support.

"Please do not tell me that no one will ever utilize it. "

No one will ever utilize 144dB of dynamic range in a system in their home.

Anyone that says otherwise doesn't understand what it means to fully utilize that dynamic range

" do not believe that the DTS mix in Master and Commander is within the 30 db industry standard. "

Don't believe it all you want. The fact is digital has a hard and fast

limit to maximum signal. That is 0dBFS. Unlike analog tape on digital

you CAN NOT run a signal higher then 0dBFS. If you try all you do is

clip the signal and cause large amounts of distortion yet the signal

goes no higher in level. Therefor... in a system calibrated to

reference level the max playback level per speaker in the main channels

is 105dB. The LFE channel has 10dB of additional headroom so it can hit

115dB. That is how it works.

"I lack the test gear to measure the dynamic peak,"

If you calibrate to Reference Level properly the max possible dynamic

peaks are 105dB per main channel at the listening position with the LFE

possible to hit 115dB.

Doesn't matter what movie you play... those maximum possibles are the

same. That is what happens when you calibrate a -30dB signal to 75dB at

the listening position. The loudest the system can go is 0dBFS. 0dBFS

is 30dB above a -30dB signal. Which means you will play back 30dB above

whatever you calibrated level was.... 75+30 = 105dB.

BTW... if you want to see how 'Master and Commander' compares to *many* other movies check out this very long thread:

http://www.hometheaterforum.com/htforum/showthread.php?s=&threadid=144887&perpage=30&display=&pagenumber=1

The direct link to the post on 'Master and Commander' is at:

http://www.hometheaterforum.com/htforum/showthread.php?postid=2205921#post2205921

Shawn