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Crown XLI1500 a modern day staple?

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ClaudeJ1    650
On 5/7/2017 at 11:56 AM, John Warren said:

Need a sub however to handle the low stuff. 

It took the evolution of Home Theater Technology to get me to realize that a Klipschorn needed a subwoofer. I never realized that pipe organs could go down to 16 Hz., along with some extreme sub bass things in movies, until digital media became available, where vinyl failed to deliver. Having tried all the Danley TH HT worthy subwoofers, I'm convinced that going from 40 down to below 20 Hz. is a VERY expensive proposition, relative to the rest of the horn systems.

 

Having "botttomless" bass, so to speak, allowed me to discover all kinds of loose things in my house when doing pure sine wave testing a reasonable output levels. BUT having said that, it is quite a revelation to have this performance added to a system.  This is true even when it's rarely called upon to do it's thing for music, but mostly by Blue Ray movies with explosions. So having amplification specifically for those super low frequencies is a necessity and we all seek the best bang for the buck.

 

I personally prefer FANLESS Crown K2's available on the used market for about $500. They have a built-in 8 Hz. high pass filter. They cost about $1,600 New about 12 years ago and represent a very rugged, high quality build that is ideal for subwoofing in style. At between 800 to 1,200 watts per channel in the 4-2 ohm range with 12 AWG wiring, they never fail, or fail to please, while potentially pissing off the neighbors!!

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ClaudeJ1    650
On 6/4/2017 at 3:06 PM, John Warren said:

Note the response is +6dB in the passband because the model considers balanced inputs.  And yes, the output at that the Speakons is in-phase with the input!

Nice work. As a veteran PCB designer, I see your layout is not that critical. Are the op amps a dual variety?

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ClaudeJ1    650
On 6/29/2017 at 4:31 PM, John Warren said:

It would take a wheel-barrow of parts to make this in a passive, no thank you.  

This why I personally believe in an active/passive hybrid approach to Xovers. Being that our hearing sensitivity is much less in the bass area, we can also mess with PEQ's to flatten things out in a real room. It's easier to mess with film capacitor values from 1-50 uF in the midrange and tweeter passive sections. I my case I was using a single cap for highpass and relying on Audyssey to flatten things out in the room. The 3rd order high pass characteristic of horns, usually accompanied with a first order rolloff at the higher end, makes this ideal. Adding a single cap for the high pass on the bottom of a mid horn gave me a 4th order rollof. The huge K1133 drivers never saw more than 50 Milliwatts in normal operation, so operating the driver Bandwitdh to it's almost full natural state coupled with the horn bandpass characteristic yielded some very smooth and detailed midrange and tweeter sounds, but it took several trial and error sessions with different tweeters to get that right.

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ClaudeJ1    650

These days, however, I'm about to embark on 24/96 Khz. Xilica and Yamaha digital Xover controls that can simply be dialed in ahead of power amps. I can even listen to test music while tweaking the PEQ's, Xover points, and slopes. Using instruments and ears both, IMHO, yields the best sonic experience in any given space. Something the Klipsch engineers do every day.

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John Warren    128
3 hours ago, ClaudeJ1 said:

I'm assuming this bandpass filter could be implemented for a LaScala as well as a Khorn?

Yes, piece of cake. 

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John Warren    128
3 hours ago, ClaudeJ1 said:

I see your layout is not that critical. Are the op amps a dual variety?

Agreed, not critical but not trivial. 

 

Op-amp packages are Quads.  The topology is cascaded Sallen-Key, four op-amps/ch.

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John Warren    128
3 hours ago, ClaudeJ1 said:

It took the evolution of Home Theater Technology to get me to realize that a Klipschorn needed a subwoofer. I never realized that pipe organs could go down to 16 Hz., along with some extreme sub bass things in movies, 

 

I agree but must put the Klipschorn bass unit on a bandpass, all goodness then.

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ClaudeJ1    650
2 hours ago, John Warren said:

Yes, piece of cake. 

My comment was not how easy it is, but whether or not similar benefits exist for a shorter horn, more or less?

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John Warren    128
On ‎8‎/‎7‎/‎2017 at 6:29 PM, ClaudeJ1 said:

My comment was not how easy it is, but whether or not similar benefits exist for a shorter horn, more or less?

Yes.  For subwoofer integration, I'd recommend the bass horn be bandpass filtered.

 

 

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ClaudeJ1    650
On 8/9/2017 at 3:47 PM, John Warren said:

Yes.  For subwoofer integration, I'd recommend the bass horn be bandpass filtered.

 

 

Yes. It's not just for bass reflex and turntable subsonic anymore. A K-33 woofer produces WAY les IM distortion if the part below the horn's cutoff is filtered out and replace by a subwoofer "air pump."

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John Warren    128

Doing a bandpass using a passive means large capacitances so electrolytics are a way to keep the cost reasonable. 

 

Some time back I put an electrical equivalent model together of the Klipschorn bass unit using the Beranek approach shown in Acoustics (http://www.northreadingeng.com/Klipschorn_model/basshorn_model.htm ).

 

That model is useful as a simulated load for passive filter designs and it provides a way to predict a Klipschorn bass horn response for various filters. 

 

In the first plot the pink curve is the model output response (electrical equivalent) of the Klipschorn bass unit with no filter (raw).  The peak in radiation resistance is ~100Hz and below that the horn output drops. The output below 70Hz (or so) is not due to horn loading but due to the woofer working is a sealed enclosure and firing into a folded labyrinth.  That's shown in the dash line in the second plot, it's the seal woofer response.  This provides the "salami whacking the sofa" sound characteristic of the Klipschorn.   Combined is the measured Klipschorn response.  It's the sealed woofer response that needs to go.

 

Using the model as a simulated load, the blue plot is the model response with the AK4 network, the green is the AK3 and the light blue the AA.  The AK4 is the notch filtered net with the dipsy-doo in the range above 150Hz, the idea to attenuate the peaks that occur over that range. 

 

The red plot is the model with a passive band-pass filter, it will attenuate the seal woofer response.   

 

filter_responses.jpg

filter_responses_2.jpg

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John Warren    128

Getting a bit off topic.

 

Simulated impedance magnitudes from the model show why the AK-4 was revised to the AK-5.  The minimum is getting a bit too low. The AK-5 adds a little extra resistance to bring the level up to something closer to 4 Ohms over the range where the notch is dissipating.

 

Z-magnitude.jpg

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