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Tarheel TJ

Replacing the K400 with the 11"x17" ZXPC Horn

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It turns out that ~3-6 mm roughness/concentricity at 35 mm distance from the compression driver's phase plug is probably good enough, i.e., less than 1/20th the shortest wavelength produced by the midrange driver--which is about 5-6 kHz.  But it helps the psyche to see a nice smooth and concentric exit.  Also note that modeling clay will also take out depressions that might arise during the removal of the extra material at the adapter's exit. 

 

When assembling the adapter to the horn, I recommend using something like a large hex socket to center the adapter on the horn's mouth. I use a 1 7/16" socket wrapped with 2-3 layers of masking tape to bring it up to 2" diameter of the horn's mouth.

 

I have one of these 1"-to-2" horn adapters on order from Parts Express in order to be able to test a K-55 driver with the horn.  Since the horn itself appears to be pyramidal with straight sides, it is more of a controlled directivity horn than the K-400 series horns, and if so, then there will be a hump in its frequency response curve like the K-510/K-69-A horn and driver experiences--which is the tradeoff when using controlled directivity horns.  The benefit of course, after EQing everything flat, is much more consistent off-axis polars...which is a performance characteristic that cannot be corrected by EQ or signal processing. Those controlled off-axis polars, as well as the much lower levels of higher order modes (HOMs) due to the horn's straight sides are responsible for the majority of the smoothness that you're hearing in-room.

 

EDIT: Note that I'm using what appears to be the same horn:

 

http://www.ebay.com/itm/11-x-17-ABS-2-Bolt-On-Long-Throw-Horn-90-x-40-For-Many-2-Exit-Driver-/331676072699

 

Chris

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Glad to hear about everyone's experience with this horn.  It sounds like No.4's impressions are similar to mine.  I am impressed with the work done to smooth the throat of the horn, I may have to undertake something similar. 

 

I would love to see some measurements of this combo.  I think a usb mic may be my next audio purchase.

 

 

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24 minutes ago, Tarheel TJ said:

I think a usb mic may be my next audio purchase.

 

This would be a very good investment indeed.  You'll be amazed with the resulting sound and understanding of what is happening in-room using REW or TrueRTA providing measurement capabilities. 

 

I particularly recommend REW.

 

Chris

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I'm intrigued in using this horn in a 2-way setup using Belle bottoms (haha...sounds funny) and potentially the DH1A drivers "IF" the horn allows the driver to work that high.  My upper end hearing isn't that great anymore so if it has nothing above 15khz, I'll never know.  

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On 10/7/2016 at 9:36 AM, tromprof said:

It would be interesting to pair that horn with an EV DH1A driver. Might make an interesting low cost alternative to Volti and other more expensive mid options.

 

If anyone does make that swap to the DH1A they should make note whether or not it is the 8 Ohm version or the 16 Ohm version.  The version needed will be labeled DH1A-16.

 

http://pdf.textfiles.com/manuals/STARINMANUALS/Bosch - EV/DH1A, DH1A-16.pdf

 

The stock Klipsch K-55-V or the later K-55-M is 16 Ohm.

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21 minutes ago, avguytx said:

I'm intrigued in using this horn in a 2-way setup using Belle bottoms (haha...sounds funny) and potentially the DH1A drivers "IF" the horn allows the driver to work that high.  My upper end hearing isn't that great anymore so if it has nothing above 15khz, I'll never know.  

The horn I used was similar to the one posted in this thread along with the DH1a.  I didn't care for it,  I switched back to the EV hp640 and enjoy it a lot more.  That was with the Belle bottom.  Don't be discouraged to try it. 

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3 minutes ago, wvu80 said:

 

If anyone does make that swap to the DH1A they should make note whether or not it is the 8 Ohm version or the 16 Ohm version.  The version needed will be labeled DH1A-16.

 

http://pdf.textfiles.com/manuals/STARINMANUALS/Bosch - EV/DH1A, DH1A-16.pdf

 

The stock Klipsch K-55-V or the later K-55-M is 16 Ohm.

Good point, especially if you are using the stock crossover.  If you have gone active such as I have, then no worries.

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For those of you contemplating use of the DH1A, be advised it is HUGE and weighs 24 pounds.  Here's the DH1A beside the 4 pound K-63 from my CF-4. (FYI the horn has silicon seal on it)

 

 

IMG_4259.JPG

IMG_4260.JPG

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1 hour ago, The Dude said:

The horn I used was similar to the one posted in this thread along with the DH1a.  I didn't care for it,  I switched back to the EV hp640 and enjoy it a lot more.  That was with the Belle bottom.  Don't be discouraged to try it. 

Setup as a 2-way or 3-way?  Did you go passive crossover or active?

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Setup as a 2-way or 3-way?  Did you go passive crossover or active?



2 way active. If i was going to use that horn i would try it with a tweeter of some sort.

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On 10/21/2016 at 8:08 AM, Tarheel TJ said:

I would love to see some measurements of this combo.

 

Here is an on-axis frequency response plot of the K-55V driving this horn with the PRV adapter (no modifications to smooth the throat junction of the adapter to the horn).  You'll see the recommend two PEQs, a positive-going one at 510 Hz, and a negative-going one at 1800 Hz.  The Q and the gains for each PEQ filter are shown in the figure:

 

K-55 with Brazilian horn two PEQs.GIF

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Here's the frequency response on axis after those two PEQs are dialed in:

 

K-55V on  Brazilian Horn-with two PEQs.png

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Chris, thanks for posting the measurements. I do not have any experience with these programs but I do have a question about the correction. There appears to be a large dip around 3500hz but the program did not correct that. Is that because it is inconsequential or because of the horn design preventing correction?

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The real measured frequency response is the top red curve.  That blue-green curve that you refer to is one of the two parametric equalization filters that are used to correct the top red curve to yield the second red curve...also shown in the second figure.

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19 minutes ago, Chris A said:

The real measured frequency response is the top red curve.  That blue-green curve that you refer to is one of the two parametric equalization filters that are used to correct the top red curve to yield the second red curve...also shown in the second figure.

Ok, I get that (Hopefully) what I am asking is based on the  program correcting the spl at 510hz. The drop at @3500 is almost as low as it was at 510 but it did not make an adjustment there. I guess I'm asking why. 

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The blue-green curve at 510 Hz is also a PEQ correction filter, but in that case a boosting filter. 

 

The criteria that I applied for generation of the correction EQ filters is the tolerance above and below an 88 dB average (another parameter that I chose looking at the first measured response without correction).  The two PEQs (one attenuating at 3500 Hz, the other boosting at 510 Hz) were generated to correct the basic measurement on-axis to yield a +/-4 dB resultant curve around 88 dB within the range 400 Hz to 6 kHz.

 

I chose a tolerance of plus or minus 4 dB.  I could've used any value within reason, but I chose 4 dB because it yielded only two correction filters, which seemed reasonable. 

 

In real life the passive crossover filters begin to modify the response on both ends of this response for most people using these loudspeakers.  Since I use active crossovers as a rule, I would probably choose a tighter tolerance (like +/- 3 or even +/- 2 dB-which would generate more PEQs that must be used to correct to that level of tolerance), and I would use the active crossover to cross--instead of using a passive crossover.  In my case, I'd probably cross at about 2.8 kHz to a Beyma CP25 tweeter on the high end (instead of using the K77 tweeter, which has some problems going that low), and at 400 Hz on the low end to the bass bin.

 

 

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Got it thanks Chris. I did some A to B listening this morning switching back and forth from this horn and the k401. There are some levels where this horn sounds great but I can't help but feel like something is missing. The mids seem attenuated through most of the program material. However at times certain parts of songs usually vocals would stand out and sound like I would expect them to. Going back to the k401 everything integrates better and the SPLs sounds right....even with the occasional harshness. My wife even asked if I had "turned up" the bass. It just stands out that much. Tarheel have you noticed a stronger presence in the bass program while using these horns?

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10 minutes ago, No.4 said:

There are some levels where this horn sounds great but I can't help but feel like something is missing. The mids seem attenuated through most of the program material...

 

However at times certain parts of songs usually vocals would stand out and sound like I would expect them to...

If you look at the two correction filters above, they will tell you why it sounds like that.  That's also the reason why I posted the measurements and the EQ correction filters. 

 

If you were to listen to this horn using a K-55V driver, but using those two correction filters, like say, in a computer-based music player upstream of your preamp with a parametric or even a graphic equalizer, it would most definitely sound better (assuming that you got the overall midrange gain right). 

 

Chris

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18 minutes ago, Chris A said:

If you look at the two correction filters above, they will tell you why it sounds like that.  That's also the reason why I posted the measurements and the EQ correction filters. 

Understood, so what sounds right to me is probably the uncorrected peak @1800hz? 

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