1990 Chorus II with 18x10 Mid-Horn Top hat

[StevePaul]

Being a Chorus II owner for the last 31 years, I wondered how a 18x10 horn would look on top of a Chorus II (Chorus Top Hat?), how other modifications would affect the sound, and also what the overall dimensions of the speaker would be, CTC spacing, physical height of the Mid-horn throat compared to ear level, etc.  

 

I ordered the 18x10 and took a pic and took some basic measurements this morning (working from home is great...until I find myself completing RASIC charts & data sheets for work at 11:30pm).  Below is a pic of the 18x10 on top of my Chorus II and also all of the info and physical measurements I took.

 

Original Speaker: 1990 Chorus II (standard K-48/K-61/K-79 drivers, passive radiator, and xovers)

Original Speaker DIMS: 39"H x 18.5"W x 15.5"D  (includes the 3.25" risers)

Original Floor-to-Center of Midrange DIM: ~30"

Original C-T-C spacing between woofer and mid-horn DIM: ~11.75"

 

Initial Speaker Modifications to be completed: 

* ZXPC 18x10 2" throat Midrange Horn on top of Chorus II

        * John Allen A55G/2 driver (w/PRV ADM25-50 adaptor)

        * PRV Audio D2200Ph driver (no adaptor required)

        * Horn External DIMS:  17.75"L x 9.8125"H x 8"D

* LMAHL V2 Tweeter installed in factory location

* Original K-48 woofer in factory location

* Passive Radiator in factory location (no modifications)

* Crites Chorus II new xover

* Dynamat on horn walls

* Seal and brace cabinet

Modified Speaker DIMS: 48.8125"H x 18.5"W x 15.5"D (including 3.25" risers)

Modified Floor-to-Center of Mid DIM: ~43.875" 

Modified C-T-C spacing between woofer and mid-horn DIM: ~25.5" (this CTC spacing at 600hz nags at my OCD a little, but maybe it isn't important?)

 

 

Below is a pic of the 18x10 on top of the Chorus II.  The cabinet is 0.75" wider than the horn flange length...leaving 0.375" on each side of the horn to build a little top hat.  The overall aesthetic of a ~ 49" x 18.5" x 15.5" speaker is actually very elegant and attractive.  My specific wife-acceptance-factor hinges upon the length and width of the speaker...she doesn't care how tall it is.  She is an absolute 'no-go' on Cornwall or LS cabinet dimensions. 

 

Another plus, is that I am a long-bodied, 6'6" person, which places my ear at a measured 44"-45" off the floor when sitting comfortably in my listening chair.  Placing the 18x10 on top of the cabinet puts the center of the mid-horn at approx 44" off the floor.  Perfect for a guy my size, the chair I sit in, and who 'lives in the midrange'.  Removing the risers would reduce the floor to center horn DIM to approx 40.5", if desired.  The room they will be in is our 25' x 30' great room with a 9' ceiling height. 

 

No xover changes (other than the Crites new xovers) will be made.  This is purely a by the ear, do I like the mid on top, is the giant 2" horn more enjoyable than the 1" smaller K61 horn, does the PRV driver sound nice, is the LMAHL V2 wonderful-er, did the bracing tighten the bass, etc etc etc.

 

If all is good/wonderful, xover changes due to driver changes and horn changes will need to be made. 

 

Sorry for the long book of an explanation...I thank you for not nodding off during my dissertation of thoughts and goals.  I thought it might be helpful for other Chorus owners on the forum who may be interested in some/all modifications.

 

 

 

[Racer X]

Was also inspired by pictures of the large format horns plopped on top of various bass cabinets.  This is an amazing upgrade well worth the trouble of trying to integrate the various drivers.  Will be following this thread closely.  My Heresy with the Crites CS top end:  JBL D405 on 2380 copy horn, Crites B&C 120 tweeters:

[StevePaul]

8 minutes ago, Racer X said:

Was also inspired by pictures of the large format horns plopped on top of various bass cabinets.  This is an amazing upgrade well worth the trouble of trying to integrate the various drivers.  Will be following this thread closely.  My Heresy with the Crites CS top end:  JBL D405 on 2380 copy horn, Crites B&C 120 tweeters:

Part of the problem with modifying the Chorus speakers with any off the shelf passive 3-way xover is that the Chorus K-48 woofer (which I really like) is not in any of the other Heritage speakers (mostly K-33's, etc).  Combined with me not being a passive crossover expert, or wanting to go 3 way active, puts me in a little bit of a bind.  I'll figure it out...just have to ask for some help along the way. 

[carlthess40]

Looks pretty cool on top of the speaker cab.
Does having the tweeter back so far for time alignment interfere with the vertical disbursement of the tweeter?

[Racer X]

I do not believe it does.  One could always raise the tweeter, I just went with what looked about right.  Upper frequencies of course are more directional, and I believe the horn lens is more oriented for horizontal rather than vertical dispersion.

 

The tweeter is now right at ear level, I believe that has major impact on the sound.  

[Curious_George]

On 12/15/2021 at 2:27 PM, StevePaul said:

Part of the problem with modifying the Chorus speakers with any off the shelf passive 3-way xover is that the Chorus K-48 woofer (which I really like) is not in any of the other Heritage speakers (mostly K-33's, etc). 

There has to be an impedance curve from someone here on the forum of a K-48. In any event, we can get the K-48 rolled off some how to mate with the ZXPC horn. If you need help, let me know.

[StevePaul]

2 hours ago, Curious_George said:

There has to be an impedance curve from someone here on the forum of a K-48. In any event, we can get the K-48 rolled of some how to mate with the ZXPC horn. If you need help, let me know.

Thanks for the offer.  We shall see how this rolls out.

[NBPK402]

Did you either time align your new horn or do it with an active crossover...if you have not, I would do it as it will sound better.