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Loudspeaker compression (why a 200+ WPC amp doesn't help KHorns)


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Hi all,

The Klipschorns are rated at 105dB @ 1watt/1meter with a maximum acoustical output of 121dB.
Linearly, you could assume that the 121 dB limit should be reached at
40 Watts (1 Watt + 16 dB), yet the speakers are rated at 100 w max continuous (400 w
peak).

I still noticed an increase of about 3 dB going from a 50W receiver (set to 0dB theotical max) to a 100W external amp (still with the receiver at 0 dB and with the LED meters indicating 120W peaks), but swapping in a 300 WPC (again with meters) yielded no real further increse in peak SPL (maybe 1 dB...). So I guess using a 100 Watt is optimal for KHorns.

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This is why I primarily have amplifiers in the 30-60 WPC range for my Heritage. 60 good watts on KHorns/LaScala/Belle is PLENTY. I put my money into making those 30-60 watts as good as they can be, not for any additional power. My only 200+ WPC amp in house is for my HT subs - but for full range audio, I have three tube monoblock pairs and three 50WPC SS Mac stereo amps, which is all the power AND "flavors" I will ever need.

Many would argue even that 30 watts is too much for Heritage (in favor of the uber-close and seductive sounding single ended amps at 1.2 to 10 watts), but I prefer a little more power for the bass drive I prefer.

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The more powerful amp gives more headroom for musical transients. If you're listening to nothing but test tones, a few watts would give you all the volume you want, but if you want drumbeats, trumpet blasts, handclaps and the like (and gunshots and explosions for movies) to sound realistic, you need a lot more power, even if only for fractions of a second.

The more powerful amp will also reproduce subtle bass sounds more easily and give a more solid and authoritative (you could also say more realistic) sense of presence of certain instruments. Even if those hundreds of watts rarely come into play, you'll appreciate having them when needed, like passing power in a car is really appreciated when it's really needed.

Finally, with most amplifier companies, the more expensive amps tend to use better parts and better designs, with higher power thrown in to make them easier to sell. Accordingly, a company's more powerful amps are often their best-sounding amps. For example, the new Bryston 28B amp, with 1000Wpc, gets rave reviews for its sound quality. And the power is nice, too.

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I like to play this song at 121dBs

Now, the world don't move to the beat of just one drum,

What might be right for you, may not be right for some.

A man is born, he's a man of means.

Then along come two, they got nothing but their jeans.



But they got, Diff'rent Strokes.

It takes, Diff'rent Strokes.

It takes, Diff'rent Strokes to move the world.



Everybody's got a special kind of story

Everybody finds a way to shine,

It don't matter that you got not alot

So what,

They'll have theirs, and you'll have yours, and I'll have mine.

And together we'll be fine....



Because it takes, Diff'rent Strokes to move the world.

Yes it does.

It takes, Diff'rent Strokes to move the world.

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Hi all,

The Klipschorns are rated at 105dB @ 1watt/1meter with a maximum acoustical output of 121dB.
Linearly, you could assume that the 121 dB limit should be reached at
40 Watts (1 Watt + 16 dB), yet the speakers are rated at 100 w max continuous (400 w
peak).

I still noticed an increase of about 3 dB going from a 50W receiver (set to 0dB theotical max) to a 100W external amp (still with the receiver at 0 dB and with the LED meters indicating 120W peaks), but swapping in a 300 WPC (again with meters) yielded no real further increse in peak SPL (maybe 1 dB...). So I guess using a 100 Watt is optimal for KHorns.

How loud are you needing your speakers to go? [:o]

Once you get into the power compression region, distortion is going to shoot through the roof...not a place I'd wanna be running my speakers at all.

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this is a thread I've alwas wanted to start, and it begs the question:

The older Klipschorn's were rated for 124 db max at 104 db sensitivity. Makes perfect sense. But then, why are the new ones good for only 121 db. is the sensitivity 101 db, or is the powrer handling less than stated. Perhaps it has to do with the new , lower tweeter crossover freq of 4500 hz.

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this is a thread I've alwas wanted to start, and it begs the question:

The older Klipschorn's were rated for 124 db max at 104 db sensitivity. Makes perfect sense. But then, why are the new ones good for only 121 db. is the sensitivity 101 db, or is the powrer handling less than stated. Perhaps it has to do with the new , lower tweeter crossover freq of 4500 hz.

I don't recall ever seeing a max accoustic rating of 124 dB. As far as I am aware, they are both rated at 121dB max accoustic output, but the older ones are 104 dB at 1 watt at 1 meter, where as the newer ones have a sensitivity rating of 105 dB at 1 watt at 1 meter.

As for running a larger amp, as previously stated, more Bass authority, even at lower volumes, more headroom, better build quality. Your 100 watt RMS amp may be capable of pushing it up to the continuous wattage rating, but where does that 100 watt RMS amp begin to CLIP at?? Further, that 100 watt amp will probably never ever be capable of reaching peak power threshold.

Finally, ad a second set of K-Horns, or step up to TSCMs, MCM-1900s, or KP-600s if 121 dB just isn't enough anymore!! [6] [6] [6]

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The older Klipschorn's were rated for 124 db max at 104 db sensitivity. Makes perfect sense. But then, why are the new ones good for only 121 db. is the sensitivity 101 db, or is the powrer handling less than stated. Perhaps it has to do with the new , lower tweeter crossover freq of 4500 hz.


I don't think any of those figures are absolutes, like size or weight measurements. In some cases, they're a judgement call on the part of the engineer. Maybe running the older Khorns at a continuous 124dB caused them to fail earlier than the engineer liked, so he lowered the rating to give a bit more margin of safety, or some similar consideration. It doesn't imply that the newer speakers are not as good as the older ones.

As for sensitivity, it may be that the method of measurement has changed since the earlier models. Also, just as horsepower comparisons are only valid if measured with the same equipment on the same day, speaker performance measurements are precise only to a certain degree, so debating about a decibel or two this way or that way is sort of pointless.
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I'm searching my archives for the 124 db figure right now, I know I've seen it. Found the 127 for the pro la Scala, and the 130 for the theatre version. La scala's are now rated at 121, also

stereohermit,

Post any of these that you can find...

Islander,

"that this is only a few dB", 121 dB compared to 130 db is eight times the sound level.

stereohermit,

Our ears are inefficient, and it takes about 10 dB for it to sound twice as loud to us, but you have to double the wattage or speakers to go up 3 dB. There is no way that Pro LaScalas or LSIs will put out that kind of output. As stated prior above, (If 121 dB = 1 speakers total maximum output, then two speakers total output would be 124 dB, it would take four speakers to reach 127 dB, and eight speakers to reah 130 dB) this is eight times the physical output!! The only difference in a home La Scala and a Pro La Scala is the K-43E woofer rated at 200 watts, instead of the K-33E, and the K-33E puts out more Bass at lower volumes. When you are talking 130dB, you are up into the big Klipsch Pro arena, NOT La Scalas of any kind. My guess is probably a misprint in the Data. 121 dB to 124 dB could easily be explained as one speaker vs: a pair, as people in the advetizing department could easily misunderstand these figgeres, but 130 dB... not possible and clearly a misprint if it does exist!

Roger

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Factory claims 130 for the TLSI

I see these ratings are from when WWR owned the Klipsch Pro Line, and I will hazzard that as a guess to the reason for the misinformation.

Further still, I have owned LSI before, and presntly own 9 of those TSCM Bass Bins and 5 of the TSCM top sections. I used to have eleven of the TSCM Bass Bins, but I sold a pair of them to "Indy Roger". The LSI, just like a regular La Scala, has a single K-77 tweeter, a single K-55 driver on a K-400 horn that has a 5/8 inch throat, and the LSI has a K-43 woofer rated at 200 watts RMS, this is the same K-43 woofer that is found in an MWM Bass Bin, but the MWM Bass Bin has two of them instead of only one. Now the TSCM top section has a tweeter that Y's out in back and mounts a pair of K-77 tweeters, the K-400 horn in the TSCM has an X manifold attached to it's larger 2 inch throat and it mounts four K-55 drivers to a single K-400 horn. The TSCM Woofer is a K-44 that is rated at 250 Watts RMS, so there is no way that an LSI is going to outperform a TSCM. You can see the 400 horn of the TSCM is mounted on the outside instead of inside like on the LSI. The TSCM K-400 horn also has the word klipsch molded into it on the bottom of the front of it. You can also see that the larger double tweeter throat is mounted on the outside of the box. If you do a search in the Forums for TSCM, you will find a thread with pictures from when Colter came over to my barn to pick up Indy Rogers TSCM Bass Bins, and there are pictures of the double tweeter and the Quad K-55 K-400 horn. Clearly, there is no way that an LSI could compete in Max SPL with the TSCM or MCM-1900 system, or the KP-600 system which is the arena we are discussing at 130dB... [;)]

Roger

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I definitely agree with you on the 130 db spec.

Original Scalas were always rated for 124 db standard and127 db pro on paper., which is why the new 121 db spec is curious, although probably closer to the truth, considering power compression.

i thought I saw an extra theatre catalog in my stuff, I'd be happy to make it yours, if thats the case. I'll look later today. you can email me at.... stereohermit@yahoo.com.....Dave

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