diVine Audio

Copying content from the original thread main post verbatim. Design by CJD; Original build thread author —k—

DA Khancenter – a RS180/RS150/RS28A Center

NOTICE 11/29/10: Parts Express has discontinued the original RS Shielded drivers these were designed for. CJD has done some limited testing of the new unshielded 8 ohm drivers and believes that they are near drop-in replacements in the Khan designs. No alteration of the crossover is believed to be required in the standard sealed condition. Ported alternatives may require slight changes in the box size and tuning. See the Statements for ideas. Also note, the RS28F fabric dome tweeter can also be substituted without crossover modifications. If you have questions, please start a new thread in the main forum.

It is finished….

Note: This post has been updated after the build was complete. However, if you build this, please let me or CJD know, so we can make sure you have the most current info and to fill in any details I may have left out.

This is a center design to match the Khanspire RS225/R150/RS28 WMTMW designed by CJD. The desire is to have a center channel that will fit into my entertainment/shelving unit seen above.

I considered a couple of the existing center designs, including Jon’s Modula NeoCC and the RS225/RS150 WMTW center with CJD’s crossover. The RS WMTW center wouldn’t fit. It is both too tall and too wide. I made several sketches to see if I could make it work, but no go. It was very tempting to build Jon’s Modula NeoCC. It was appealing on several fronts, but it was a bit expensive, the RS180 version isn’t done yet, its ported, and it changed both the mid and the tweeter from the Khan’s, so voicing could be slightly different.

Because it is going to be placed on a shelf, and against a wall, it can’t be ported out the rear. To match the Khans, it is going to be sealed and expected to cross to a sub. Ideally, the RS180s sealed should be crossed ~80hz, while the Khanspires should be crossed at 50hz. This could cause some issues, but newer receivers/processors (Like Outlaws) are allowing different crossovers for the center from the mains. (Building a ported version wouldn’t be an issue though if others like.)

CJD used real measurement taken with the drivers in the box to design the crossover. Please note the design is intended to be used above or below a TV set. If you place the speaker away from a TV, it will sound thin due to having less BSC.

Size: 10.875″Hx23.5″Wx19″D Sealed Enclosure
Woofer: RS180-8 Shielded
Mid: RS150-8 Shielded
Tweeter: RS28A

Cost of Drivers: $141.
Cost of Crossover: $138

BOM, as of 1/8/2008:
Drivers:
Part Number Description Qty. Price Ext. Price
295-362 Dayton RS150S-8 6″ Reference Shielded W .. 2 $32.14 $32.14
295-364 Dayton RS180S-8 7″ Reference Shielded W .. 1 $34.96 $69.92
275-130 Dayton RS28A-4 1-1/8″ Aluminum Dome Twe .. 1 $48.65 $48.65

Subtotal: $150.71

Here is what I got for the better crossover:
Part Number In Stock Description Qty. Price Ext. Price Remove
004-10 Yes Dayton DNR-10 10 Ohm 10W Non-Inductive .. $1.25 $1.25
027-410 Yes Dayton DMPC-1.0 1.0uF 250V Polypropylen .. $1.06 $1.06
027-414 Yes Dayton DMPC-2.0 2.0uF 250V Polypropylen .. $1.42 $1.42
027-421 Yes Dayton DMPC-4.0 4.0uF 250V Polypropylen .. $1.92 $3.84
027-424 Yes Dayton DMPC-6.8 6.8uF 250V Polypropylen .. $2.53 $2.53
027-428 Yes Dayton DMPC-10 10uF 250V Polypropylene .. $3.75 $15.00
027-438 Yes Dayton DMPC-25 25uF 250V Polypropylene .. $6.58 $13.16
005-2.5 Yes Mills 2.5 Ohm 12W Non-Inductive Resisto .. $3.50 $3.50
255-210 Yes Jantzen 0.20mH 18 AWG Air Core Inductor .. $3.26 $3.26
255-214 Yes Jantzen 0.25mH 18 AWG Air Core Inductor .. $4.07 $4.07
255-238 Yes Jantzen 0.70mH 18 AWG Air Core Inductor .. $6.28 $6.28
255-246 Yes Jantzen 0.90mH 18 AWG Air Core Inductor .. $7.16 $7.16
255-272 Yes Jantzen 2.7mH 18 AWG Air Core Inductor .. $11.49 $11.49
255-294 No Jantzen 10mH 18 AWG Air Core Inductor .. $32.04 $32.04
027-443 Yes Dayton DMPC-50 50uF 250V Polypropylene .. $11.38 $11.38
027-447 Yes Dayton DMPC-100 100uF 250V Polypropylen .. $21.00 $21.00
Subtotal: $138.44

Please make sure you really check those baffle dimensions prior to building. I tend to wing things in the garage.

Note:
1) The RS180s are wired in parallel.
2) The RS180s are wired with reverse polarity.
3) Solid 4 ohm design, with some regions of the impedance dipping down to 3.5 ohms.

FAQ

1. Does it have to be so deep?
No. It can be built shallower.

2. I Want BIGGER!

For those that wish to have a larger center channel than the Khancenter to match their Khans, a good alternative would be CJD’s version of the RS225 WT/MW. Dennis Murphy originally took the in-box driver measurements and then shared the data (there . Curt Campbell, CJD and Jon Marsh all modeled and posted crossovers using these measurements. Each takes a little different approach. Brian Bunge built CJD’s version and said that it matched CJD’s large RS 3-ways very well, so it should match the Khans well also. I believe that there have been a few other builds also.

This design really only varies in the size of the woofers. The larger RS225 will give you a little bit deeper extension and some more head room. It is a little shallower, but that is only because I built my Khanceter deeper than needed. The crossover is a little bit more complex (I don’t think CJD had anyone building it at the time, so there weren’t cost constraints. ).

This design is intended to be place close to the wall, where a normal center channel is placed, but not necessarily directly under/over a tv where you would get more of an infinity baffle loading.

It is a solid 3 ohm design and will need a decent amp. Receivers probably shouldn’t apply. Note, the polarity on the mids and tweeter is reversed. The crossover only shows one woofer, but there are two and they should be wired in parallel. Where two caps have the same ID, they should be tied together in parallel to get the value shown in the crossover.

FAQ #3: Khancenter Placement

The Khancenter was designed to be placed directly above or below a large screen TV. Using the Khancenter in other configurations may change the voicing slightly. For example, if you have an LCD mounted on the wall and the Khancenter below and no other surfaces to extend the baffle, there will be a slight difference. The change will mostly be BSC related resulting in a slight reduction in bass.

To counter this slight reduction in bass, it is recommended that you use a lower gage inductor. Options are:

15 ga inductor from PE that has about .3 ohm less DCR.
http://www.parts-express.com/pe/psh…r=255-434&DID=7

Erseaudio.com has a 14ga Perfect Lay that has about .5 ohm less. That is like removing a .5 ohm resistor from in front of the woofer.

An ironcore will have about .75 ohm less.
http://www.parts-express.com/pe/psh…tnumber=266-910

Those are ways to experiment and increase the response from the woofer. Minor changes, but I think that is what we’re talking about. Even mine isn’t a bass monster. It was never intended to be. It was designed to be clear and concise and let the sub to the fun work.

Also, it should be noted that famed audio researcher / designer Floyd Tool in his book Sound Reproduction talks about bsc and his opinion is that it can be addressed with EQ. Something like Audyssey will work well.

There could be minor differences up higher in the frequency range, but nothing you can do about these and addressing them is even more nitpicky, minor, perfectionist stuff.