Under what conditions would you need more than 100 Watts per channel with Khorns

[Guest " "]

a common question.....answer...if your listening position was 100ft away from speakers. http://myhometheater.homestead.com/splcalculator.html

[o0O Bill O0o]

Interesting :-)

Bill

[DrWho]

If you were listening to music with 30dB of crest factor at 88dB on speakers with 104dB sensitivity while sitting 2m away...

Btw, the boundary gain doesn't work for speakers with controlled directivity, nor for the Khorn which use the room corner as the final part of its flare.

[jacksonbart]

,.,

[Don Richard]

What Doc said, plus loss from power compression, maybe 3-4 dB additional loss.

[Guest " "]

I remember during my early school years, wondering what value algerbra had . In thinking about quadradic equations such as the difference of 2 perfect squares (a2 - b2 = c2), what real life purpose would it serve for the average joe. Later in life I need to tile a room that had a hot tube in it and i needed to know how mush tile I did not have to buy, since I did not need to tile under the hot tub. a2 -b2 = c2

"crest factor" is very useful to determine what value a slow blow fuse should be, if you wanted to use a slow blow fuse. "Crest factor" is used to identify the amount of "average power" within a peak power stream.

When we talk about sound pressure levels, the human ear can hear music peaks above the "crest factor" line. To say that "crest factor" is a transmission loss, is to say the human ear can not hear peak or program music and that the human ear can only hear average or contious music.

So sure, ideally, it should be clear what type of power (peak, average, continous, program, etc) SPL caculators, speakers, amps, takes into consideration to avoid folks from applying "average power" concepts to assumed peak or program power concepts.

So do we need to know how much "continous" or "average" power exist within "program" or "peak" music to determine the SPL level of "program" or "peak" music, of course not. SPL levels of "peak" and /or "program" music can be articulated with out reguard to "average" or "continuous music".

[Arkytype]

Btw, the boundary gain doesn't work for speakers with controlled directivity, nor for the Khorn which use the room corner as the final part of its flare.

While I agree (in general) with the first part of your statement, I disagree with the second. The fact that the Klipschorn uses the side walls as the final horn flare is a separate issue from boundary "loading" which does work for the Klipschorn and most any other type of loudspeaker.

Here's a link to a multiple boundary test done by Pat Brown of Syn-Aud-Con.

http://www.prosoundweb.com/article/print/tools_of_the_trade_how_boundaries_affect_loudspeakers

Lee

[Don Richard]

So do we need to know how much "continous" or "average" power exist within "program" or "peak" music to determine the SPL level of "program" or "peak" music, of course not. SPL levels of "peak" and /or "program" music can be articulated with out reguard to "average" or "continuous music".

All of that not withstanding, a Khorn will not output 104 dB SPL @ 100 feet with 100 watts input power. That is concert level SPL and would take something like a Turbosound or EAW pro rig with a lot more amplifier power to achieve that output @ 100 ft.

[DrWho]

"crest factor" is very useful to determine what value a slow blow fuse should be, if you wanted to use a slow blow fuse. "Crest factor" is used to identify the amount of "average power" within a peak power stream.

Are you understanding the significance of crest factor to this scenario? This has nothing to do with fuse ratings. I think most of the problem is that people talk in terms of power when really we're talking about amplifier output voltage. If you really want to talk power, then lets get into the nonlinear speaker impedance and the speaker's power factor.

If you want to listen to music at 88dB as often described by humans and measured on an SPL meter, then 30dB of crest puts your peak SPL's at 118dB. Sure, your average power level will be on the order of 0.1W in this scenario, but the point is that you need an amplifier capable of 100W to prevent transients from getting clipped.

This is why 90dB (or lower) direct radiator systems are so ineffective at producing transients...not because the average SPL levels are high, but because the transients require a lot of voltage swing. In this same scenario, if you need 100W with a 104dB speaker, then you would need over 2000W on the 90dB speaker...can you say thermal compression?

To be fair, 30dB would be extremely dynamic music. I'd say 20dB crest is more typical of the majority of music, so 10W would be just scraping by. A lot of the main stream pop crap is pushing 6-10dB of crest which would bring it down to 1W to just scrape by at 88dB, but I also own recordings that push the crest as far as 60dB. On the 60dB stuff you'll be clipping the crap out of everything while only listening to the low level details at a very quiet 70dB.

When we talk about sound pressure levels, the human ear can hear music peaks above the "crest factor" line. To say that "crest factor" is a transmission loss, is to say the human ear can not hear peak or program music and that the human ear can only hear average or contious music.

Peaks above the crest factor are absolutely audible - nobody is denying that. Nobody is calling crest factor a "transmission loss" either...I don't understand how that even makes sense to say.

[DrWho]

Btw, the boundary gain doesn't work for speakers with controlled directivity, nor for the Khorn which use the room corner as the final part of its flare.

While I agree (in general) with the first part of your statement, I disagree with the second. The fact that the Klipschorn uses the side walls as the final horn flare is a separate issue from boundary "loading" which does work for the Klipschorn and most any other type of loudspeaker.

Here's a link to a multiple boundary test done by Pat Brown of Syn-Aud-Con.

http://www.prosoundweb.com/article/print/tools_of_the_trade_how_boundaries_affect_loudspeakers

Lee

The problem with the Khorn is that you can't separate the "boundary gain" from the horn DI gain....so discussion of the Khorn LF DI gain becomes a semantic argument. Someone like Pat Brown with a proper understanding of both boundary gain and DI gain would have no problem with my statement.

The reason I brought it up and stated it the way I did is because the calculator referenced at the start of this thread shows 6dB of "boundary gain", which isn't going to be applicable to the Khorn LF since its sensitivity is already measured in an "anechoic 1/8 space" environment. In other words, the advertized sensitivity of the Khorn LF includes the boundary gain and the horn gain because they are effectively the same thing depending on your perspective. The horn gain is effectively the DI gain plus the compression ratio of the throat (assuming a "good" horn). If you want to call the DI gain the boundary gain, then I have no problem there...in the far-field they are two ways of describing the same thing.

[Guest " "]

"All of that not withstanding, a Khorn will not output 104 dB SPL @ 100 feet with 100 watts input power. That is concert level SPL and would take something like a Turbosound or EAW pro rig with a lot more amplifier power to achieve that output @ 100 ft. "

Actually, the Khorn sensitivity is 105 @ 1 W. In the calculated senerio, at point source, it would be putting out about 112db's. The max spl of the khorn at point source is 121db. Way above what is needed to deleiver 104dbs at 100ft.

[Chris A]

I'm a little surprised that no one here has discussion dynamic headroom on amplifiers [:|]

Back to the subject of boundary (room) gain--from the link provided by Lee (Arkytype):

"Boundary loading is often touted as being desirable for subwoofers. While some impressive gains were seen at very low frequencies, it’s not likely that the boundaries available for such placements are sufficiently large and rigid to realize these benefits.

Room modes will also dominate the subwoofer response in most applications. So, the ear remains the final authority on benefits of boundary-loading subs."

This is an interesting subtopic on the "how many Watts for..." discussion, which, to me is interesting, but not wholly useful. I believe that instrumented in-room readings are most desirable to install speakers into rooms (small, medium and large rooms) and the effects of doing in-room EQ really can't be overemphasized, IMHO.

But what about corner horns - like the Khorn and the Jubilee? What is the deal about room gain? Well--it's frequency-dependent--isn't it? There is a pretty good AES article that discusses the same subject with regard to subwoofers (T. Salava, "Subwoofers in Small Listening Rooms", 4940 (N5), 1999, JAES) except that the discussion is limited to that region where we typically want to have "room gain" -- the lowest-lf performance of loudspeakers and subwoofers. I don't think that I personally need room gain above the bottom lf region--do you? (I.e., in small rooms--the type that we all own unless we live in a large high-bay warehouse or a gymnasium.) What was his "surprising results"? Do what most acoustics "experts tell you NOT to do - put the subs into the corners to couple to the room modes:

The reason why to place subwoofers in corners especially in small listening room seems quite simple. In this case all the room modes are fully excited, and can be transfer-active."

Counterintuitive? Not for the guy that designed the Khorn.

So what is the deal with room gain above, well let's say, 100 Hz? Placing your speakers into the corners will result in undesirable effects if the following is true: using "nondirectional" speakers. For instance, the problem with Bose 901s is that they sound bigger than they are but the sound image is very confusing to the ear, and they are taking advantage of the boundary gain effect in ways that many here in this forum abhor due to their "nondirectional" behavior.

Many small-box loudspeaker aficionados like their speakers placed out into the room. Why? Nondirectionality of direct radiating drivers above about 400-600 Hz. This is a big deal. If you like direct-radiating loudspeakers above about 400 Hz, then--more power to you. However, it's definitely not my cup of tea.

I have learned more about corner horn placement and room boundaries recently: it's really nice to be able to get the top horns (~400 Hz and higher) slightly away from the closest room boundaries and furnishings between stereo pairs of cornerhorns. How? By placing your horn-loaded subs behind your cornerhorns to form a false corner behind them (...notice how I slipped that one in).

This way, decoupling the issue of room gain to get lf-only and allowing you to place your cornerhorns out into the room very slightly is a big deal in imaging since, IMHO, you don't want boundary room gain to couple to the hf above about 400 Hz. But your hf horns must control their polars down below their crossover point - in the vertical and horizontal directions if you want to decouple from those "undesirable boundary couplings".

Chris [8-|]

[DrWho]

Actually, the Khorn sensitivity is 105 @ 1 W.

Based on what data?

[jacksonbart]

hold on its gonna be a rough ride, you probably should take your shorts off first.

[Guest " "]

Actually, the Khorn sensitivity is 105 @ 1 W.

Based on what data?

How about Klipsch, the manufacture of the system. see attached snap shot. Go down to where is say's sensitivity, read across to the right.

I know that we could probally conceptulize a senerio in which the manufactures claims would not be ture, like for example, if we say lets operate the system on the planet Mars, since the atmosphere is thinner, SPL would be lower, or if we say lets operate the system on the planet Venus, the air is thicker and....etc, etc..

[Arkytype]

speakerfritz:

Actually, the Khorn sensitivity is 105 @ 1 W.

DrWho: Based on what data?

Is that a trick question? According to the Klipsch website the Klipschorn sensitivity is rated at 105 dB SPL 1 watt/1m.

To be more precise, speakerfritz should have included the measurement distance which is currently "standardized" at 1 meter. Before standardization, Klipsch sensitivity ratings were given in terms of voltage and imperial distances e.g. 4 feet. The old Klipschorn rating was 104 dB SPL @ 2.83V @ 4 feet.

In actual practice neither Klipsch nor most manufacturers measure their products at one meter with 2.83 volts of a single tone applied to the loudspeaker's input terminals.

Lee

[Don Richard]

"All of that not withstanding, a Khorn will not output 104 dB SPL @ 100 feet with 100 watts input power. That is concert level SPL and would take something like a Turbosound or EAW pro rig with a lot more amplifier power to achieve that output @ 100 ft. "

Actually, the Khorn sensitivity is 105 @ 1 W. In the calculated senerio, at point source, it would be putting out about 112db's. The max spl of the khorn at point source is 121db. Way above what is needed to deleiver 104dbs at 100ft.

Due to power compression a stock Khorn will not do 121 dB continuous, but we will assume that it can to give your argument a best case scenario.

Per the inverse square law, 6 dB loss per doubling of distance:

4 ft. 121 dB

8 ft. 115 dB

16 ft. 109 dB

32 ft. 103 dB

64 ft. 97 dB

128 ft. 91 dB

For 2 Khorns, add 3 dB.

In the late 60s a friend and I hauled a Khorn to a gymnasium and put it into a corner on the floor. Powered by 60 watts of tube amplification (Golden Ear Laboratory Amplifier) we measured 90 dB with sine tones at an approximate 100 ft. distance. Past a certain distance the SPL did not follow the inverse square law (critical distance). Considering these measurements, and Pat Brown's article, I would conclude that the calculator you used would work better with less directional speakers. As the quoted article shows and as Pat Brown says, " Horns are immune from boundary effects"

[Chris A]

This is an interesting subtopic on the "how many Watts for..." discussion, which, to me is interesting, but not wholly useful.

Apparently it is important to others...[8-)] Okay, I'll get with it...

So how much power are you running and do you ever run out of headroom in your setup? [*-)]

I'm biamping using Crown D-75As (~45 W/channel into 8 Ohms at rated distortion) and have never seen any hint of a clipping light, and I regularly run well above WAF loudness levels (~100+ dB© on the "fast scale" using very dynamic recordings. No hint of running out of headroom. We must be talking about a totally different regime of operation unknown to my ears.

Or am I missing something? [*-)]

Chris

[Islander]

Past a certain distance the SPL did not follow the inverse square law (critical distance).

That occurred to me, too. In the real world, rather than a testing lab, everything around the speaker would cause variations from the calculated sound level, such as whether the speaker is indoors or out, is the ceiling high or low, does it have a hard floor or carpet or concrete or grass in front of it?

If it's a windy day or the air is extra dry or extra humid, that would make a difference also. All those possibilities become more important factors as you get farther from the speaker.

I agree with Don that the only way to find out the useable or possible sound level at a distance much longer than you'd use in a typical home setting is to try it and measure it for yourself.

[jheis]

What's "need" got to do with anything?