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Tarheel TJ

Replacing the K400 with the 11"x17" ZXPC Horn

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    I have been looking to replace the K400 horns in my LaScalas for some time.  My plan was to buy either the Elliptrac or Fastrac horns that are well known to members of this forum.  The price being the only thing holding me back.

    Recently, in this thread:

SkyDover mentioned a horn that he bought from seller ZXPC on Ebay.  This one: http://www.ebay.com/itm/11-x-17-ABS-2-Bolt-On-Long-Throw-Horn-90-x-40-For-Many-2-Exit-Driver-/331676072699  I was intrigued by his reports of their excellent sound.  Seeing as my LSI's have separate bass bins with no top cabinets (they were badly damaged), I have no limitations on the size of horns I can use.  They were significantly cheaper than other solutions and are big enough to reach 400hz, so I bought a pair.  I am still using the K-55 mid driver, so I also bought an adapter to allow the screw-on K-55 to mate up to these 2" throat horns.  It turns out, these adapters are not an ideal solution.  They do not mate well to the mouth of the K-55.  They mate better to the 2" horn, but there is a bit of a lip there that I am sure is causing some diffraction.  I eventually plan to upgrade to 2" midrange drivers, so I can live with this for now.

    Despite the imperfections of this setup, the improvement in sound over the K400 is nothing less than remarkable.  I have not done any measurements, just listening.  As much as I have loved my LSIs over the years, I have always been bothered by the harshness of the upper midrange coming out of the K400.  This setup completely obliterates that harshness.  The sound is so much more smooth and open.  You still get the razor-sharp precision and detail of a horn-loaded setup, but without the buzz-saw effect that K400s can produce.  For less than $100 invested, I am a happy camper.  If you don't have to fit your mid horns inside of a stock cabinet, I highly recommend you give this a try.

   Next, I plan on upgrading my AL-3 crossovers to ALK Universals, and then swapping in a 2" throat driver for even further improvement.  I am sure that will be quite nice indeed!  I have learned a lot from the members of this forum over the years (mostly lurking), so I thought I would share my experience in hopes that others may benefit.

 

 

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Are you having to EQ your midrange or tweeter sections vs. the K-400 over and above what the AL-3 passives?

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So far, all I have done is remove the K400 and replace it with this horn and adapter.  No crossover changes or EQing has been done.  Like I said, I have not done any measuring (though I probably will invest in a USB mic soon), but I have been listening for about 2 weeks now, and everything sounds balanced to me.

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Wow. 

 

I bought one of those horns from ebay a couple of weeks ago as an alternative to the K-510 horns that I have, since it is a larger horn and will likely have a lower loss-of-polar frequency than the K-510. 

 

If I test it in the near future, it will be with a K-69-A (P.Audio) 2" driver.  I noticed that it has straight-sided walls out to about 2/3s its length, then an exponential mouth flare. 

 

Thanks for the report.

 

Chris

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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.

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Yeah, I am still trying to decide what 2" driver I want to eventually go with.  I would love to go with something Beryllium, but I definitely don't have the budget for that.  I would be interested to try the DH1A, although they seem to be hard to come by online.  Maybe a B&C or a Radian?

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EV ND6X which I'm using now sounds great. I understand it is the modern day equivalent of DH1A except with neo magnet.   Moray James can jump in here since he loves the DH1A. First time I've heard it on EV SM120A horn and it is clean and sweet crossed at 500hz

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It is a 1.4" exit so yo would need adaptor. 4 bolts spaced at 3.5" . 3" EV built titanium diaphragm. 

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On 10/6/2016 at 1:56 PM, Tarheel TJ said:

They do not mate well to the mouth of the K-55.  They mate better to the 2" horn, but there is a bit of a lip there that I am sure is causing some diffraction.

I'd recommend modeling clay to fill any depressions or low areas, and a half-round or even a rat tail file on any portions that intrude into the smooth bore.  Works great.  Roy used modeling clay in an older version K-510 horn to try out the "mumps" for the new-version K-510 horn.

 

Chris

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The idea of modeling clay had crossed my mind.  It seems like it might be difficult to get a smooth transition, but I may give it a try anyway.  Whatever the result, it would probably be an improvement over the way it is now.

 

As far as the dust goes, it adds character!  Haha.  Seriously though, I am planning on replacing these crossovers in the next few weeks, so I just haven't put much TLC into them.

 

 

 

 

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After reading this thread and the one referenced in the first post I could not help but be very interested in these horns. Given the price I figured why not. I ordered a pair Tuesday night and they arrived last night from Florida to Illinois in three days is darn good. They were packaged well and out of the box appear to be well made. I only have the k401s with the atlas pd-5vh for a reference, and will be using the atlas drivers with these. That said I am waiting for the adapters to arrive from parts express. These horns appear to be intended for surface mount unlike the k401. When I was putting together my la scala clones I had no baffle on the k401 and reported that the sound was harsh. Thanks to the advice of the forum members I cut and installed a pair of baffles and it was a huge improvement. I am curious to see (or hear) if these will need the same treatment; or if by design they will not be necessary. Hopefully someone on the forum who has measurement ability other than ear will pick up a pair of these. For now I am waiting on the postman.

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I have not tried mounting them to a baffle yet.  I do eventually plan on enclosing them in a small box, much like the split LSI top cabinets.  I didn't anticipate this changing the sound at all, but I guess I'll just have to see.

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I received the adapters late last night and quickly checked the fit. The throat of the horn is a little rough cut compared to the rest of the horn and the adapter. I assume this is the ledge you mentioned. It seems that the entrance of the throat could use some smoothing. I think there is a simple fix for that issue. Otherwise I should have these in use soon.

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Update...this is what the entry way to thorn looks like out of the box. It is pretty rough and uneven. It measures about 150mm at the largest, give or take. The adapter exit measures 153mms so there is some room to remove some material and smooth the transition.

IMG_20161018_172219_kindlephoto-44569667.jpg

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This is the high tech device I used to clean up the entry. It is a hole saw wrapped with coarse grit sandpaper. I added layers as I went making short passes. In between layers I hand sanded with finer grit paper to remove the build-up around the hole. Once the build-up is sanded off I was able to get a good measurement in between layers. I tried finer grit on the hole saw, but the coarse grit worked much better in the drill press at speed. I was able to match the 153mm of the adapter almost perfectly. It took about 40 minutes to do both horns. Note...the monster high duct tape I borrowed from my daughter is essential to the success of this process:)

IMG_20161019_195040_kindlephoto-45141708.jpg

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This is the result. As I stated in the previous post I was able to match the adapter within a fraction of a mm. I am happy with the result.

IMG_20161019_170850_kindlephoto-44662761.jpg

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On to the listening test. Currently my DIY La Scalas consist of eminence kappa 15c woofers, Ct125 tweeters, Atlas PD-5VH mid drivers and A/4500 networks. I bolted everything together and listened to several very different albums for about an hour and a half. Immediately I noticed a smoothness that is different than what I am used to with the K401 horns. There seems to be less "shout" which I have become accustomed to, so its absence is apparent. I listen relatively near field about 8 to 10 feet from the speakers and they are in the corners about 10 feet apart from each other. Listening to Miles Davis ******* brew I could not help but feel like the mids have been attenuated at times. However listening to other discs with very heavy vocals the mids seemed to be very clear and at times made the vocals sound like they were in the room instead of being reproduced by a speaker. Off axis and out of the room the mid presentation is excellent. I will try to do some longer A to B comparisons this weekend. I need to finish the baffles and play with the placement of the tweeter a little more as well. These horns definitely have a different presentation than the K401. Hopefully someone will chime in with some measurements at some point. So far I would say these are definitely worth the money to experiment with.

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