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Al Klappenberger

A time-aligned top end - Part II

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"That limits how much you can cut down the extra efficiency (above that of the woofer) of the high section."

It only limits it if you aren't willing to lower the overall system efficiency. Like you said if you have a woofer that is 104 dB/w/m and a high frequency driver that is 111 dB/w/m you have 7 dB difference you can use as EQ.

If you are willing to drop overall efficency to say 98dB (by padding down the woofer) you have 13dB difference to use in EQ.

Shawn

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Exactly. The recording will already have the big hall acoustics on the disc. The goal of your room should be to make sure that sound gets to your ears and creates that convincing hologram that transforms you to that particular hall. Then if you go to another album recorded somewhere else, then your room should transform you there...instead of having you in the same hall for every recording...

That has been my goal, not the 'they are here' I am going for 'I am there.'

The problem is this is extremely difficult to achieve in a 2 channel system. The halls sound is originating from the completely wrong direction.

Shawn

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Exactly. The recording will already have the big hall acoustics on the disc. The goal of your room should be to make sure that sound gets to your ears and creates that convincing hologram that transforms you to that particular hall. Then if you go to another album recorded somewhere else, then your room should transform you there...instead of having you in the same hall for every recording...

That has been my goal, not the 'they are here' I am going for 'I am there.'

The problem is this is extremely difficult to achieve in a 2 channel system. The halls sound is originating from the completely wrong direction.

Shawn

Exactly..!

I have found that if one uses well controlled horns with proper placement of absorption and diffusion in the room one can have very good imaging, clarity, tonal balance and a very pleasurable sense of envelopment with a 2 channel system.

mike tn

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Guest David H

How would you compare the sound of the Eliptrac vs Stock horn with the K-55 driver?

This would depend on which stock horn you are referring to ? The Fastrac K and Eliptrac sound almost identical to me with the K-55.

I have a Faital Pro HF-200 here I got from Crites last week, but I am clearly the wrong person to ask. The Eliptrac's sound needs to be evaluated by those who do not have a vested interest.

I could have done the measurements in house, but ALK and Lee Clinton have much better equipment, and far more experinence.

Dave

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Shawn,

Lowering the efficiency of the woofer would do it, but how is it normally done? Resistive pads are bad news and a transformer would be the same size as the output transformers used in tube type power amps. It would be exactly like the autoformers used in the output stage of McIntosh SS amps. Besides, aren't we all proud of the efficiency of out horn speakers? It seems a crime to cut it back. I always assumed the woofer to be the thing that dictates everyting else.

Al K.

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Are these plots reflecting the K-69-A drivers or TADs?

bnc 75

Th K69-A should be close to this also.

Hmm...

I was thinking those 402 polars were with the K1132

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Al,

"aren't we all proud of the efficiency of out horn speakers? It seems a crime to cut it back."

It is a trade off, like everything else. If you want to do it passive you loose some system efficency but in its place you make big gains in the power response of the system. Some are willing to make that trade off, others aren't. If you want both you go active.

Shawn

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Shawn,

I agree. I'm just not clear how you would cut back the efficiency of a woofer like the Jube. Is there an alternitive set of drivers that are just less efficienct?

Al K.

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Run the woofers in series, the efficiency stays the same, but the sensitivity goes down 6dB.

Or:

Use an autoformer in the network like Klipsch does in some of the pro models to boost HF drive (lowering the impedance at very high frequencies).

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Run the woofers in series, the efficiency stays the same, but the sensitivity goes down 6dB.

This looks like a good solution.

Use an autoformer in the network like Klipsch does in some of the pro models to boost HF drive (lowering the impedance at very high frequencies).

I thought there was a dicscussion about using the autoformer inverse recently, and although worked, had it own set of issues.

Craig.

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I wasn't able to locate the Autoformer thread, and it's not important, but it had some good info.

I thought ALK ran some simulations and Bob Crites has some input as well, was a good read.

Craig 73

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Guys,

I don't think the sidewall obscuring the throat is a problem at all for a simple driver with a single diaphragm used as a mid-range. It just seems to mess things up when the two drivers of a coaxial need to work together. Notice the green plot on the K2 horn goes west right at the 9 KHz crossover. That's where the two drivers are both operating and must sum together cleanly. Earlier tests with the DCM50 driver showed good off axis response all the way to 10 KHz, Dr. Edgar expected his type of horn to be crossed over far lower than that anyhow! I'm not sure what would happen to the off axis response with a wide range driver. I don't have one here to try. For use in the Khorn, it would need to extend all the way down to 400 Hz without distortion too. That's a tall order! That's why PWK couldn't do a 2-way. This is really the reason for doing a coaxial. It's to get as close to a 2-way as possible.

Al K.

The tweeter needs 2 notch filters and the midrange needs a zobel network in order for the passive crossover to function correctly.

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Al,

"aren't we all proud of the efficiency of out horn speakers? It seems a crime to cut it back."

It is a trade off, like everything else. If you want to do it passive you loose some system efficency but in its place you make big gains in the power response of the system. Some are willing to make that trade off, others aren't. If you want both you go active.

Shawn

A couple thoughts here...

1) Depending on the topology, amplifier behavior near 0V can be worse, or at least is usually different from the middle band of its operation. If nothing else, you have more dynamic range at higher drive levels.

2) The dominant reason for using horns is due to the decreased mechanical related distortions - in other words, even though the efficiency might be reduced, the mechanical distortion isn't changing. And really, if the energy being dissipated in the xover isn't causing more distortion, then the total system distortion isn't changing.

3) Combining 1 and 2 above, you might end up with less total system distortion because you can run your amplifiers in their sweet range of operation. This is actually one advantage to passive xovers over going active.

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2) The dominant reason for using horns is due to the decreased mechanical related distortions - in other words, even though the efficiency might be reduced, the mechanical distortion isn't changing. And really, if the energy being dissipated in the xover isn't causing more distortion, then the total system distortion isn't changing.

INteresting revival of an old thread............try passive bi-amping. I use the little Tripath 2020 amps, which have a gain control at the front. Keep the 100W amps for the woofer section.

On the series vs. parallel wiring of the twin 12" woofers of the Jubiliee.........I have 6 ohm corner horns with their own amp/gain control. On the top of the stack, all drivers are driven by the receiver amp section and have the following impedances: 8 ohms on the midbass horn, 16 ohms on the midrange horn, and 4 ohms on the twin parallel 8 ohm/107 db/W super tweets..............all trying to match up the different sensitivities reasonably well. Audyssey EQ takes care of the rest. So I use a combination of these tricks to get each section as close to the rest. In my case, I'm trying to get about 109-110 db/2.83Volts sensitivity on top and boosting the 104 db/W efficiency of the corner horn to catch up with the rest.

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