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AHall

Converting khorns to 2way

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I would stick with a constant dispersion horn like the K-510 or K-402. As mentioned above, using the K-510 horn can be done but some care must be taken to get the bass bin to go up high enough and to get the driver/510 to go low enough.

 

If you are concerned about the price and you are building new top hats, you might consider a used Electrovoice HP640. 

All of my suggestions are constant dispersion horns with 2 inch throats. 

 

Good luck,

-Tom

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On 7/4/2018 at 1:22 AM, AHall said:

I just worry about the smaller horns blending well at a 400hz crossover point. 

 

I'll talk about polar coverage here so that you'll see more on the tradeoff using either your current K-400 midrange horn,  or the K-510 or ZXPC horn instead:

  1. The horn mouth dimensions (horizontally, vertically) determine the frequencies at which the horns lose polar coverage control in each axis.  The biggest difference in the three midrange horns is the vertical dimension of each horn's mouth.  The stock K-400 horn begins to lose vertical polar control at about 2500-3000 Hz, and spills increasing amounts of acoustic energy in the vertical direction below that frequency.  This is called a "collapsing polar" midrange horn.
     
  2. The other two midrange horns considered here have about double the horn mouth height than the K-400, which means that they don't start to lose polar control in the vertical direction until an octave below the stock K-400 horn.  The ZXPC horn is about the same width and double the height of the K-400 horn--so its polar control will match the K-400 horizontally and exceed the K-400 vertically by about one octave (i.e., 1200-1500 Hz).  The K-510 horn is somewhat smaller than the ZXPC horn in both directions, but apparently has better higher frequency characteristics due to its flat-sided horn walls close to the horn's throat.
     
  3. At higher frequencies--above the point where vertical polar control begins to be lost due to mouth size--both the K-510 and ZXPC horns cover 90 degrees by 40-60 degrees.  The K-400 appears to cover 40-50 degrees vertically above its vertical polar control loss frequency, and about 90 degrees horizontally.
     
  4. The Khorn bass bin polars start to get very narrow above perhaps 150-200 Hz due to the dual-mouth bass bin splay angle and distance between the two mouths horizontally. This has an effect on the midbass sound of male and female voices, etc. sounding a bit "thin".  The midrange horn (the K-400) counteracts some of that narrow bass bin coverage angle around the 400 Hz crossover frequency, where its polar coverage is very tall and getting wider rapidly.  (Polar coverage mismatch at the crossover frequencies don't sound nearly as good as horn combinations matching their coverage angles at their mutual crossover frequency band.)
     
  5. Low frequency horizontal coverage: the K-510 polars start to get very wide at 700 Hz and below.  The ZXPC horn mitigates that polar coverage widening a little more--by perhaps 200-300 Hz lower than the K-510--due to its slightly larger horn mouth horizontally than the K-510.  The stock K-400 loses its horizontal coverage control at 300-400 Hz--the so-called "cutoff frequency" of the horn.  The ZXPC horn is almost exactly the same width as the K-400, so their low frequency horizontal polar coverage angles vs. frequency are similar. 
     
  6. Low frequency vertical coverage:  the original K-400 horn the vertical coverage angle really begins to take off below 2500 Hz so all Khorn owners experience that type of loss of polar coverage control presently.  That extra bandpassed acoustic energy winds up on the floor and ceiling and it needs to be controlled/absorbed using acoustic absorption on at least the floor, and have a ceiling that is at least 4 milliseconds away (or having absorption tiles on the ceiling), else the loudspeaker will sound tonally unbalanced because of this extra midrange energy in the vertical direction.  The K-510 and ZXPC horns lower that frequency about an octave, so they will sound much better across the majority of the midrange horn's band without needing in-room acoustic absorption and a higher ceiling in the vertical plane.
     
  7. The bottom line is that a two-way Khorn configuration will work well as long as the 2" compression driver used can go low enough (good output below 400 Hz is preferred) while providing good chatter-free output above 10 kHz.  The dual-diaphragm BMS 4592ND fits this bill nicely, but note that 2" Be diaphragm drivers (like TAD, Radian, and the JBL retrofitted Truextent Be diaphragms) will also do very well if the low end crossover frequency is moved up to 450-500 Hz and the upper end of the Khorn bass bin response is boosted slightly (about a maximum of 6 dB overall) above 400 Hz. This will, course, result in a further narrowing of bass bin polars in this region, but that is something that is quite tolerable as compared to the effect of the design trades using the stock K-400 collapsing polar midrange horn.  Much more consistent coverage vs. frequency above the crossover point (where the ears are most sensitive to those type of disturbances), the absence of phase issues and time misalignment, and lower harmonic/modulation distortion from the 2" compression driver--even at very high in-home SPLs--will be the offsetting characteristics of a well implemented two-way Khorn design.
     
  8. (I've mentioned this before) It would be nice to have a midrange/treble horn midway between the K-402 and the K-510 in terms of mouth size--especially in the vertical direction.  This would delay the widening of midrange horn polar coverage to below its nominal 400 Hz crossover frequency, thus making the horn sound about as good as the K-402 in-room when used down to that frequency (but crossed no lower).  When that horn exists, then I believe that there will be a strong interest in using it for midrange duties on all conventional horn-loaded loudspeakers.

Chris

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For all who like the idea of Beryllium diaphragms please be aware that Be is an extreme carcinogen and a good part of the high price on these is involved in the equally extreme care  they have to take to safely manufacture these and not kill employees. Personally I would not use these and run the risk no matter how slight of having one fail in service and spew even minute amounts into the air I breathe or on the floor of my house. Go look up toxicology reports before you buy.

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Understood, but the risks are no more than other IARC Group 1 hazards already in the home--and there are many, as I enumerated in that other thread. If you also don't focus equally on those other hazards at the same time, then you begin to look like a liberal environmentalist that demonizes one hazard of much lower importance while tolerating the elephant in the room--which is all the other stuff that really is going to get you--including, and not leastly, alcohol (ethanol) consumption and tobacco smoking.

 

However, working in an environment where Be is being machined--that's a very different story.  All industrial shops in the US must take special precautions while using Be.  These regulations go back to the at least the mid-1970s--which was when I first became aware of the issues while working the geophysical exploration industry, and where we were using a fair amount of the stuff in our air gun manufacture--beryllium copper. 

 

Chris

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Chris,   There are many different horns sold by eBay seller "zxpc". Most of their horns do not have model numbers, but are identified by size info, such as the model 11 x 17 ABS 2" long throw horn, pictured on the left, or model 2" throat horn 18 x 10, pictured on the right. Which one is written about in the above posts?

 

IMG_3018.JPG.69ce4dc1138ea6c609a70ca69356ddac.JPGIMG_1134.JPG.423c5d93172c460ee93cf66d57278c69.JPG

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This one:

 

On 7/3/2018 at 9:48 AM, Chris A said:

The other "ZXPC" horn

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I have a few of those 2" throat 18 x 10 horns. I am thinking of trying a pair with K-55 drivers and 2" adapters.

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Not opposed at trying a 3 way system. It just adds quite a bit of money to the system with tweeters and another amp. The zxpc horn and faital seems like a winner. 

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On 7/3/2018 at 4:04 PM, Deang said:

Filter and measurements by Bill Woods. Compliments of DJK. 

 

 

231B5BAF-4F8F-4CC7-B158-4C818F478E37.jpeg

 

Thanks for posting. Two of the most trustworthy guys out there. Not sure if you've heard but DJK passed away. Very sad. One smart dude.

 

 

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15 hours ago, AHall said:

The zxpc horn and faital seems like a winner.

 

The Faital Pro 2" compression drivers have been used in a few projects posted on the forum over the years, with good comments. One thing that concerns me is the advertised 900Hz minimum crossover frequency. I realize that is based on the unit's full power rating, but I am curious how many watts it can handle when used with a K-horn's 450Hz crossover. 

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7 minutes ago, Khornukopia said:

 

The Faital Pro 2" compression drivers have been used in a few projects posted on the forum over the years, with good comments. One thing that concerns me is the advertised 900Hz minimum crossover frequency. I realize that is based on the unit's full power rating, but I am curious how many watts it can handle when used with a K-horn's 450Hz crossover. 

In a home environment, I found that 10 to 30 MILLIWATTS was normal for those drivers. That's 0.03 Watts. They will never see more than 1 Watt, even at "stupid loud" levels.

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36 minutes ago, Khornukopia said:

 

The Faital Pro 2" compression drivers have been used in a few projects posted on the forum over the years, with good comments. One thing that concerns me is the advertised 900Hz minimum crossover frequency. I realize that is based on the unit's full power rating, but I am curious how many watts it can handle when used with a K-horn's 450Hz crossover. 

 

 

I cross my Faital pro hf20at between 400 and 450hz with 48 db slope on jubilees and mwm's with no problems and I listen very loud. Amps I've used with them are Parasound JC-1, Mcintosh mc452. They are fantastic drivers.

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On 7/4/2018 at 12:18 PM, Chris A said:

Understood, but the risks are no more than other IARC Group 1 hazards already in the home--and there are many, as I enumerated in that other thread. If you also don't focus equally on those other hazards at the same time, then you begin to look like a liberal environmentalist that demonizes one hazard of much lower importance while tolerating the elephant in the room--which is all the other stuff that really is going to get you--including, and not leastly, alcohol (ethanol) consumption and tobacco smoking.

 

However, working in an environment where Be is being machined--that's a very different story.  All industrial shops in the US must take special precautions while using Be.  These regulations go back to the at least the mid-1970s--which was when I first became aware of the issues while working the geophysical exploration industry, and where we were using a fair amount of the stuff in our air gun manufacture--beryllium copper. 

 

Chris

Hi Chris,

   Yup we all make choices as to what we care to live with. I think many times the danger is overrated by people who want a government agency job and I love the taste of "carcinogen" laden grilled meat. Even still eat peanut butter which they were trying to convince us was carcinogenic also some time back. I prefer the crunchy carcinogen over the smooth carcinogen myself ;D

 

I just happen to find the Be warnings rather stark and quite severe and worth mentioning. At the very least people need to know not to play with these things during install and later disposal.

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54 minutes ago, ClaudeJ1 said:

In a home environment, I found that 10 to 30 MILLIWATTS was normal for those drivers. That's 0.03 Watts. They will never see more than 1 Watt, even at "stupid loud" levels.

Claude, just how much efficiency is lost when I use crossovers instead of bi or tri amping?

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Just now, Dave A said:

Claude, just how much efficiency is lost when I use crossovers instead of bi or tri amping?

When I did mine with K1133's, I was only using ONE capacitor, for seemingly zero loss, but I never measured the difference, which is what you are asking. My answer of 10-30 mW was based on going through a 20 uF Dayton Capacitor.

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Well with  Dayton caps of that size I have measured the ESR was .002 or .001 so it did not have much resistance. I was thinking more along the lines of a regular crossover with caps and coils and autoformers and wondering what they did to things.

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1 hour ago, ClaudeJ1 said:

In a home environment, I found that 10 to 30 MILLIWATTS was normal for those drivers. That's 0.03 Watts. They will never see more than 1 Watt, even at "stupid loud" levels.

 

That is good to know. Also, as I understand it, the compression driver will produce a specified SPL @ one watt across its terminals, whether that watt is straight from the amp, or if it is filtered through a passive crossover network. Amplifier output required for an active system vs. through a passive network is a different subject, but either way, horn loaded speakers are still very efficient.

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35 minutes ago, Dave A said:

Well with  Dayton caps of that size I have measured the ESR was .002 or .001 so it did not have much resistance. I was thinking more along the lines of a regular crossover with caps and coils and autoformers and wondering what they did to things.

This is why crossovers have "orders." 1st, 2nd, 3rd, and so on. Things get way too complex with too many parasitics (especially with inductors, the bane of electronics) when you get to 4th order and beyond, so you are better off, cost-wise and flexibility-wise (with PEQ and time delays) to go with Active Digital Xovers (96Khz./24bit) and Class D amplifiers as the best of the best in modern times.

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I am heading that way with the upcoming S MWM build and when I can find some used 402 horns to go with them.

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