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Converting khorns to 2way


AHall

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I have some decorator khorns that I’d like to enclose the backs on and convert to 2 way. I’d like to talk about reaching the high end 20khz and I believe more importantly getting a horn/driver combo that will prevail at 400hz. 

 

Top candidates are k510 and zxpc horns. Most likely faital pro driver as it is decently priced and has good performance. 

 

Anyone succeeded here? I have jubes now so I don’t mind experimenting with the bedroom speakers. 

 

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I'm not too technical....but I'd guess if you used something like the 510 (or something similar) and used an active crossover, you could make it work.  I think you'd be a bit volume limited because of the crossover points to make it work (but don't know that)

 

Others that know more technical facts may chime in soon....  @Chris A ???

 

There was a picture floating about long ago where Rigma put his K402 on top of his Khorn bass bins.  Looked ungainly but as I recall him saying, it sounded ok (I don't think he used an active at the time to really dial it in....he was just horsing around)

 

(been looking for it and can't find it yet)

 

 

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Certainly, replacing the K-400 with a K-510 and a good 2" compression driver (probably a little better driver than a K-691 if you value the highest octave performance especially highly--10-20 kHz).  It turns out that the Khorn bass bin performance can be extended a little (the black trace in this Jubilee/Khorn bass bin comparison plot):

 

Jub-KhornGraph.jpg

 

and the K-510 can be stretched a little on the low end (K-510/K-69-A horizontal polars first):

 

K-510 with K-69-A horizontal polar sonogram.jpg

 

and vertical polars:

K-510 with K-69-A vertical polar sonogram.jpg

 

The other "ZXPC" horn, which is a little larger will do better in terms of extreme low frequency polars (horizontal, then vertical):

New Horn K-69-A horizontal polar sonogram.jpg

 

New Horn K-69-A vertical polar sonogram.jpg

 

The trick is using a 2" compression driver that can cover that wide band--and do it well. I'd recommend beryllium diaphragm drivers if you can afford them (TAD, Radian, Truextent replacement Be diaphragms in older JBL drivers), or perhaps the BMS 4592ND (dual diaphragm) if you can find them.  EQing and crossing carefully at 450-500 Hz and boosting the Khorn bass bin performance a little from 400-500 Hz will be required.  I would not try this with passive or analog active crossovers, but the Khorns' sound would be significantly improved in my estimation.  If you have older Khorns (before 1965), then the woofer motor boards in the bass bins would likely need to be replaced with ones having a narrower slot to facilitate the higher frequency performance of the bass bin. 

 

Chris

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True...but the dual ring diaphragms share the same compression space/exit, and they're time aligned using the supplied passive crossover (i.e., only one amplifier channel is required per driver), so simple EQ to flatten its response in the 5-10 kHz region will make that driver sound extremely similar to TADs or Radian Be drivers, and the price is about half--but only if you can still find them in stock. The key is the EQ.  The people that haven't used EQed carefully usually wind up selling them.  There are bumps in their response at ~5.5 and 7-7.5 kHz that must be tamed.

 

Chris

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One thing about the ZXPC vs. the K-510 horn: the K-510 will fit in the exiting top hat of a Khorn with its 2" compression driver with a little room to spare, while the ZXPC horn will need to have a top and bottom flange milling to make the mouth height shorter, or alternatively, the top hat heightened a bit to get the horn integrated into the top hat. 

 

The K-510 will probably sound a little more neutral at mid frequencies (500-1000 Hz) due to its straight sides from the throat to about 2/3s toward the plane of the mouth.  The more neutral sound would likely be pretty small, however.

 

Chris

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6 minutes ago, dtr20 said:

Just curious why you want to go with a 2 way design instead of the 3 way? I would think replacing the midrange and tweeter drivers from Bob Crites would get you what you are looking for.

 

Not to speak on behalf of anyone (indeed, he might not even be aware of this)....but when I went to a 2-way system, the intelligibility of the system went way up since I was losing a crossover point.

 

Out of ignorance, I thought it was because of the aligned signal but someone set me straight and how to "prove it to myself" which I did.

 

Losing that tweeter crossover point is not an insignificant tweak...

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I have some decorator khorns that I’d like to enclose the backs on and convert to 2 way. I’d like to talk about reaching the high end 20khz and I believe more importantly getting a horn/driver combo that will prevail at 400hz. 
 
Top candidates are k510 and zxpc horns. Most likely faital pro driver as it is decently priced and has good performance. 
 
Anyone succeeded here? I have jubes now so I don’t mind experimenting with the bedroom speakers. 
 

Can’t imagine why.


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I appreciate all the input. Chris has been very helpful and some of the info is repeat. I just wanted an open discussion as I move the khorns into my new room and can play with them. They are decorator 1969’s that have been filled in by the previous owner. I have crites crossovers, a55g, and ct120 tweeters. So the project will involve building a new top hat and filling the backs in. There are no limitations other than I want the final appearance to look similar to a B cabinet. Could be taller no problem. I have a friend with a cnc router and commercial table saw so the sky it the limit for final appearance. I don’t really want 402s because I have jubes in my main system. 

 

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

 

I see the eliptrac 400 kit is very inexpensive and an option as well. Dave said they can potentially work as 2 way. 

 

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