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Klipsch KPT456 High Frequency Range


MAGRF7

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Asking all of you KPT456 owners or pro audio owners out there that use them in a home application for 2 channel listening. The high frequency roll off on the 456 is 15.5 KHZ. Im exploring ideas to add another 5KHZ to the high frequency channel. These are unbelievable in a 2 channel listening experience but just missing that bit of tinkle or shine if you will. Any ideas welcome. Thanks guys

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If it were me, I'd look at the following driver instead of the K-1132 driver you have, and tri-amp the setup using a DSP crossover, thus taking out the time misalignments at the same time: 

http://www.bmsspeakers.com/index.php?id=bms_4592nd

 

Then you get all the "tinkle" without the issues of shifting time alignment when standing up or sitting down with a separate tweeter (due to the very short acoustic wavelengths involved above 10 kHz).  This is the reason why "super tweeters" really don't work: they can't stay time aligned if you move you head up or down by more than perhaps one inch at the time-aligned axis of the midrange-supertweeter at the listening position.

 

Chris

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1 hour ago, Chris A said:

If it were me, I'd look at the following driver instead of the K-1132 driver you have, and tri-amp the setup using a DSP crossover, thus taking out the time misalignments at the same time: 

http://www.bmsspeakers.com/index.php?id=bms_4592nd

 

Then you get all the "tinkle" without the issues of shifting time alignment when standing up or sitting down with a separate tweeter (due to the very short acoustic wavelengths involved above 10 kHz).  This is the reason why "super tweeters" really don't work: they can't stay time aligned if you move you head up or down by more than perhaps one inch at the time-aligned axis of the midrange-supertweeter at the listening position.

 

Chris


Excellent, thanks. Any idea where I’d find the driver?

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I ordered mine from Thomann US.  It arrived on my doorstep two days later.  The price was also quite a bit lower than US Speaker--who has since discontinued them.  They're not cheap, but they are at half the price of beryllium-dome drivers--like the Radian 950BePB and their performance is audibly the same as Be diaphragm drivers (I have TAD TD-4002s in the Jubs and a BMS 4592ND in the center K-402-MEH). 

 

Chris

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Yes, their passives are apparently first order filters that cross at approximately 6.8 kHz (I cross mine at approximately 5.6 kHz using the Xilica).  That puts the HF diaphragm about 1 wavelength in front of the midrange diaphragm (2 inches) at the crossover frequency. 

 

You'll probably need a way to EQ the loudspeakers flat again and matching channel gains after replacing the K-1132s.  That's why I recommend a DSP crossover.  You could use two miniDSP 2x4 HDs or a 4x10 HD, and have two output channels left over for integrating subwoofers and time aligning, matching channel gains, and doing subwoofer EQ. 

 

Chris

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Yes, that's the reason why you get a three-way from a compression driver and your 15" woofer.  It's also the reason why you can time align the two diaphragms in the compression driver. 

 

You also get much lower FM distortion ("Doppler" modulation distortion sidebands from having one diaphragm covering the entire 800 Hz--20 kHz).  And you don't have the horn mouth offset issues of a separate tweeter--it's all integrated into the 2" compression driver.  Off-axis polar directivity is much better than separate horns/mouths.

 

Chris

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Well, the alignment of the driver to the woofer is much less critical due to the longer wavelengths at the ~800 Hz woofer-midrange crossover point. The acoustic center in the BMS 4592ND is probably a little different than the K-1132, but since the wavelengths are ~10x longer than at tweeter crossover frequencies, you don't see much phase response effects from the different compression driver body lengths.

 

The SPL response of the BMS 4592ND on the K-506 horn is probably a little flatter than the K--1132, so if there is EQ built into the Klipsch-supplied balancing network/crossover, that will affect the flatness of the new BMS 4592ND response (like with any other change in drivers or adding tweeters to the loudspeaker).  It pays to measure the output (using something like REW or TrueRTA) and flatten the response again after switching drivers.

 

Chris

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10 minutes ago, Chris A said:

Well, the alignment of the driver to the woofer is much less critical due to the longer wavelengths at the ~800 Hz woofer-midrange crossover point. The acoustic center in the BMS 4592ND is probably a little different than the K-1132, but since the wavelengths are ~10x longer than at tweeter crossover frequencies, you don't see much phase response effects from the different compression driver body lengths.

 

The SPL response of the BMS 4592ND on the K-506 horn is probably a little flatter than the K--1132, so if there is EQ built into the Klipsch-supplied balancing network/crossover, that will affect the flatness of the new BMS 4592ND response (like with any other change in drivers or adding tweeters to the loudspeaker).  It pays to measure the output (using something like REW or TrueRTA) and flatten the response again after switching drivers.

 

Chris

In understanding in this way I will definitely go to the electronic crossover. I really dont see how it could work well without trying modifying the existing crossover  

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Passive crossovers really present a large impediment to doing DIY work on loudspeakers.  You can't really do anything to the loudspeaker without totally redesigning the passive crossovers, too (and using in-room acoustic measurements to guide that redesign).  Most folks don't consider all the things that they need to address when changing out drivers--or even just crossover components, etc.  Passive networks are custom-made for each loudspeaker, and really preclude any of those changes, while the DSP crossovers make the changes a much easier task.

 

Once you hear the difference in DSP crossovers (i.e., much more apparent power headroom, greatly increased clarity/cleanness), my experience has been that those that have heard the difference are really motivated to go with bi-amping/tri-amping. 

 

If you need REW support in measuring and dialing in your DSP crossover, PM me.  I've helped a quite a few forum members dial-in their setups to date over the past 2-3 years.  Using email to send REW measurement files and to return DSP crossover configuration files works great.

 

Chris

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Luke Husqvarna vs. Stihl, or oak vs. hickory?  Anyway, I thought I'd just throw that out there.  I see little bundles of wood for several dollars each at the gas station.  A few cords ought to net enough to buy some nice stereo gear!

 

I've usually been fairly careful around loud things but even so, at bumping 60 years now I doubt I'd notice much detail above 15k.

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