Welcome, Guest. Please Login or Register
Decware Audio Forums
01/28/23 at 02:51:28




Pages: 1
Send Topic Print
Crossover for Lii F12/ Eminence Kappa 12A (Read 229 times)
CharlesQ1
Verified Member
**




Posts: 1
Crossover for Lii F12/ Eminence Kappa 12A
01/10/23 at 19:57:53
 
Hi, I need your help. I bought a Lii Audio F12 + Kappa 12A at a garage sale yesterday.  The seller said he lost the crossovers somewhere. Can you help me build new ones? The whole thing is built as an OpenBaffle.
Back to top
 
 
  IP Logged
Same Old DD
Seasoned Member
****




Posts: 564
Re: Crossover for Lii F12/ Eminence Kappa 12A
Reply #1 - 01/11/23 at 00:07:19
 
Honestly, if this gear landed in my lap, I would not bother using a passive crossover.

I would set the F12s up on my main amplifier as a full range set and get a small plate amp from Parts Express so the Kappa drivers will serve more of a subwoofer function.
The plate amp will have an electronic crossover built in along with some adjustability to help in "tuning" things.

What ever you are using for a main amplifier, you would hook the speaker output to the Lii Audio F12s just like normal and add an additional cable from that same output to the plate amp High level input (speaker level input) which will then drive the plate amp with the same signal entering your F12 main speakers.


However if you really want to create a passive crossover network between the two, you can use an online calculator to get you close. Well not really close unless you get lucky, but within 40% to 50% accurate and it would be a safe option.
Here's one I have used to get started in the past. There are dozens of others out there:

https://www.omnicalculator.com/physics/crossover


Thing is, once you buy a pair of high quality coils large enough to passively cross over the Kappa drivers down low enough to not interfere with your full range drivers and a nice pair of capacitors for the F12s, you've already spent a good bit of money.

If you go with a 12dB/octave crossover it becomes even more complicated and the parts count doubles or more since we have not talked about resistors to balance the two together yet.

But this is why I recommend a simple plate amp for the Kappas and be done.

This is one of the most popular plate amps from Parts Express and I have used this same one in several installs over the recent years.

https://www.parts-express.com/Dayton-Audio-SA100-100W-Subwoofer-Amplifier-300-80...

Here is what I got just plugging in some perfunctory figures into the calculator.
This is simplest possible 12dB/octave crossover design.



Back to top
 

XO_125Hz_component_values.jpg

SE84Cs Mono'ed, Lii Audio F15 OB, McIntosh MC2500, Yamaha Pre, Dual TT, Ortofon, Kleenline Iso Power, Revox, Crown & Sony R-R, JBL "H" frame Subwoofers.
  IP Logged
Same Old DD
Seasoned Member
****




Posts: 564
Re: Crossover for Lii F12/ Eminence Kappa 12A
Reply #2 - 01/11/23 at 00:11:33
 
Sorry, not sure how to post more than one pic, but here is the way you would wire them up. Remember, this is just an example and I pulled these figures out of thin air.
You will have to figure the values out for your own system.

Get ready for some sticker shock when you price out some 14mH coils, even fairly light 18Ga coils. They are around $40 for cheapies and you'll need four of them. Half decent caps start around $8 bucks or so (need four of those too, going with 12dB/octave) and get very expensive very quickly.

That is the main reason I would just go with a plate amp for use in powering the Kappas. That plus the adjustability of the amp will give you a lot to play with to help get the two drivers to match more closely and work well together.

And, yes, you can still use the Kappas as subwoofers, even in an open baffle arrangement. Obviously watch to make sure you do not use too much cone excursion, but they should work for normal listening levels.


Go get a plate amp and have some fun!



Smiley
Back to top
 

XO_125Hz_diagram.jpg

SE84Cs Mono'ed, Lii Audio F15 OB, McIntosh MC2500, Yamaha Pre, Dual TT, Ortofon, Kleenline Iso Power, Revox, Crown & Sony R-R, JBL "H" frame Subwoofers.
  IP Logged
Doug
Seasoned Member
****




Posts: 227
Re: Crossover for Lii F12/ Eminence Kappa 12A
Reply #3 - 01/11/23 at 01:38:38
 
I would run the Lii F12 wide open and use a simple 10mh or 12mh air core inductor with the Kappa 12a.

The real challenge here seems to be the Kappa 12a. Eminence shows that it goes down to only 65hz, and with a Qts of 0.27 on an open baffle, its not going to produce any real bass. An Eminence Alpha 15a would be the ideal open baffle woofer.

Best wishes and good luck with your project.
Back to top
 
 

Jays CD2T-Mk3
Denafrips Pontus II
ZROCK2 25th Mods
CSP3 25th & Custom Mods
Cary 300SEI Mk6 WE300B Tubes
..driving Voxativ 1.6s with no crossover
LFD NCSE Driving 15 Woofers
PAP Quintets with Voxativ 1.6
Wireworld, XLO, Stager, Duelund
  IP Logged
Same Old DD
Seasoned Member
****




Posts: 564
Re: Crossover for Lii F12/ Eminence Kappa 12A
Reply #4 - 01/11/23 at 12:20:48
 
Doug is right and I am not contradicting him, but with some manipulation and a bit of power, any driver can be used as an air pump over about an octave, which is usually all we ask of subwoofers.

Doug also hits an important point in that Kappas are not subwoofers, by any stretch.
Acquiring a pair of Alphas to replace your Kappas would be ideal!
Get your Kappas into the realm of a pro audio situation they were designed for and they will be quite at home.

On the other hand, as Doug and I both suggest, hook up your Lii Audio F12s directly to your main amplifier and go with that until you can get yourself a proper subwoofer.

Forget the idea of building a passive crossover for the pairing of two mismatched drivers. (I was actually trying to gently discourage you by demonstrating pitfalls, if you did not catch that at first)

Getting your hands on a set of Alphas or similar driver set intended to be used for open baffle subwoofer duty will be the best option.
You will still want a plate amp of some sort to power the Alphas.
But that could be the second chapter.
Wink

Sorry if I tried to give you too much information at first.

Definitely keep us posted on which way you go with your project. Everyone is curious about the Lii Audio line of drivers.
Have fun and good luck!
Back to top
 
 

SE84Cs Mono'ed, Lii Audio F15 OB, McIntosh MC2500, Yamaha Pre, Dual TT, Ortofon, Kleenline Iso Power, Revox, Crown & Sony R-R, JBL "H" frame Subwoofers.
  IP Logged
Pages: 1
Send Topic Print