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New Chorus II Project w/ CF-4 Horn


jjptkd

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21 minutes ago, Randyh said:

-  great job ----------ok  --does it fit - and is the horn of the CF-4  that much better ----------than the stock  chorus 2 horn -basically , now , with pictures  -----how are these 2  different  ------side by side  ?

Horn doesn't fit I have to do a little cutting one advantage of the CF horn is it's a threaded insert ready for the A55-G mid driver 

 

Although I have not heard this in the Chorus II's as of yet it is the same horn / driver combo in my custom 362's which I love much bigger sound more La Scala like 

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1 hour ago, Randyh said:

the ideal horn is the new CW4 horn and the  driver combination , imho , but we all know that horn is BIG and may not fit , and is not sold by klipsch  -    

The CF-4 horn is the same exact horn minus mumps as what is used in the new Cornwall iv.

 

As far as drivers go I really like the A55-G from Crites I'm sure there's better out there but I'm familiar with this one and it can be used in place of the stock Chorus II driver without any changes to the crossover. 

 

My goal is to make this as easy as possible and have it look factory with the grill covers in place.

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11 hours ago, jjptkd said:

The CF-4 horn is the same exact horn minus mumps as what is used in the new Cornwall iv.

 

As far as drivers go I really like the A55-G from Crites I'm sure there's better out there but I'm familiar with this one and it can be used in place of the stock Chorus II driver without any changes to the crossover. 

 

My goal is to make this as easy as possible and have it look factory with the grill covers in place.

I have a diy chorus1.5 center (chorus 2 xover, diy cabinet with no radiator in rear. Upgraded to zxpc 11 by 17 horn, no room for tweeter. Drilled one inch hole in top of zxpc horn as far back as I could and mounted a de10 tweeter.

 

Have no way to measure it buts sounds good to my ears. Easily reversible with a little epoxy and the plug drilled from horn if you don't like the sound.

 

Looking at  pics again if you do a little custom grinding on horn flanges looks like tweeter could be made to fit. Had to do some grinding on the zxpc to make it fit.

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On 2/2/2020 at 1:43 PM, Randyh said:

thanks for the tip  -----------that's fantastic --now I understand your move ----- a side by side picture between the Chorus 2 horn and the CF-4 would be great - tx

This is the CF-4 horn next to the klf 30 horn basically both the forte III and Cornwall iv horns without mumps. The klf horn is roughly the same size as the original Chorus II horn

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On 2/1/2020 at 12:42 PM, jjptkd said:

Sizing up the space in the Chorus II cabinet I realized there's enough space to fit a CF-4 horn with the tweeter moved up to top of the cabinet. 

 

 

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No! put the mid horn on the top and the tweeter horn in between this way you will get some free time alignment between the tweeter and the mid horn and both will be well within the 1/4 wave distance rule and bonus you raise the mid horn up closer to your seated ear level which is where you want the centre of the mid horn to be about 39" up off the floor for best (most natural) stage and image. 

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7 hours ago, moray james said:

No! put the mid horn on the top and the tweeter horn in between this way you will get some free time alignment between the tweeter and the mid horn and both will be well within the 1/4 wave distance rule and bonus you raise the mid horn up closer to your seated ear level which is where you want the centre of the mid horn to be about 39" up off the floor for best (most natural) stage and image. 

You have a point.  That will better the time alignment between the drivers.  That should also reduce the need for tilting the speakers back more.

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Except for the fact that "conventionally" locating them will allow for only an edgewise shelf/brace behind the motorboard between the woofer and squawker (perhaps as well between the horns?), after enlarging existing holes as necessary.  The "swapped" implementation will require a replacement motorboard entirely, to do it right.  Good enough is good enough.

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4 hours ago, glens said:

Except for the fact that "conventionally" locating them will allow for only an edgewise shelf/brace behind the motorboard between the woofer and squawker (perhaps as well between the horns?), after enlarging existing holes as necessary.  The "swapped" implementation will require a replacement motorboard entirely, to do it right.  Good enough is good enough.

not sure are you suggesting that there is something wrong with mounting a brace on edge? For minimal material and close to maximum stiffness a brace should be 1.5 times as wide as it is thick and it must be mounted on edge to obtain maximum stiffness. Agree that this baffle is now getting tight for space to install horizontal braces but it can be done. I did in my H3 which is every bit as tight. Front to back stringers can also be installed to further increase cabinet rigidity. If you plan out your install you can often contrive for front to back stringers and side to side stringers to join and form a matrix which further increases the stiffness of the cabinet panels.

   Cabinet brace work pushes the first cabinet resonance up and if you push it up at least an octave above the highest frequency you intend the woofer to play to (crossover) then resonances past that point will not factor into what you hear as the woofer can no longer generate enough energy to excite them.

 

image.png.e738694e78519de66d707230446c88b4.pngBrace work in a Quartet showing horizontal brace below the woofer with stringers extending to the rear baffle.

 

 

 

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4 hours ago, moray james said:

not sure are you suggesting that there is something wrong with mounting a brace on edge?

 

Not suggesting that at all.  In fact it would be required to emplace a 1 x 4 or so on edge behind the lower mid horn flange in what's been shown way above.  With holes drilled behind the t-nuts for screw clearance.  There would be nothing but limp noodle effect without it.  Wouldn't hurt behind the top flange as well.

 

Certainly could get more elaborate as you've done, though I might not were I doing this "upgrade."

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  • 1 month later...

My many projects are moving quite slowly as work and personal life have been quite busy but thought I'd give an update on this one since I have made minor progress. 

 

Initially I wanted to slide the tweeter up to fit the larger mid horn but upon closer inspection I realized that the grill cover frame would completely block it, in fact in the factory position it appears the frame covers part of the top of the tweeter already. 

 

My goal here is to make the modification while still keeping the speaker looking stock with grill cover in place even if that means removing the motorboard and redoing it completely but really don't want to have to do that if at all possible. 

 

As the horn sits now it covers the bottom flat part of the tweeter horn but the CF-4 horn is pretty thin, I don't think it will be even a 1/4 inch thick with new gasket tape. At first I was a little put off by the idea of covering the tweeter at all but then I thought about my custom 362's which has similarly surfaced mount horn and the tweeter is a Crites CT-120 which is back mounted behind 1/2 inch plywood and they sound great.

 

There is still a little interference with the mid horn and grill cover as they sit but I think slight modification to the grill cover frame will straighten that out.

 

 

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As far as cabinet cutting went all I had to cut was the recessed portion where the factory horn sat and shave a slight bevel on the bottom lip of the cabinet barely anything really and it sits perfect. 

 

I really hated to cut these cabinets but as I stated in another thread I don't think I could have sold these for a price much greater than the cost obtaining all of the parts separately let alone the time cost and effort of building complete cabinets that look halfway decent.

 

When these are complete I believe they will be a close enough match to pair with my custom 362's so I will be keeping them for a long time anyway so resale is not an issue.

 

Just out of curiosity I'm going to see how the k-510 looks sitting in the cabinet, I think the cut-out should be the same or close as most of the added width over the k-603 is in the side flange. I'll take a few pictures and post them here. 

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