Kappalite coaxials!!

[kesslari]

I cleaned up the OT side discussion.
Let's stay on track, folks.

 

[5StringPocket]

I'm thinking about using a Subway 12" driver in this hybrid cab instead of the KL3012LF. It looks like an OEM version of an Eminence Kappalite with similar full bandwidth power handling and slightly higher sensitivity. There would probably be more presence in the 2k-4k octave where the 3012LF drops off. I already have most of the supplies needed for the build and for the cost of a driver it might be worth checking this out. The slant top with KL3012CX-8 coax has a smooth treble and good dispersion that I really like. The low weight and extra side handles (not shown here) make it easy to move and the duratex coating is rugged and easy to maintain. If the lower driver plays well with the top and is voiced a bit more aggressively I think it should sound good. If it doesn't work as well as hoped the KL3012LF could be swapped in.

 

[5StringPocket]

I really wanted to build the hybrid 212 shown above but picked up a GK Neo IV 212 a few months ago that hits a sweet spot. So instead of building another 212, I decided to build a 112 with the KL3012CX-8 coax woofer and ASD-1001S HF driver I had. I've incorporated some helpful insights from an earlier build and submitted this design to Jerry McNutt at Eminence to check that I hadn't overlooked something that mattered. Here is the corrected design drawing with Eminence Designer model screen shots.

With the design in place, it was time to make some saw dust. I had some 12mm Sande and Poplar ply on hand but needed to get a piece of 18mm ply for the baffle. I looked at both birch and Sande at Home Depot. Birch is solid but so much heavier that I went with Sande ply. It has good laminates with no voids and I've used it several times before with good results. An 18mm thick piece makes a strong baffle. Here are shots of the baffle with port shelves, braced sides and back, and a couple angles on the assembled box. Weight of the raw wood box was 14.8 lbs.

 

[agedhorse]

I would shorten the ports from your plots by about 30-40%

 

[5StringPocket]

The assembled box had edges rounded, holes filled, and then sanded in preparation for 3 coats of Duratex. Once dry, hardware and acoustic foam were installed and the wiring was done. Here are shots of the finished cab. Final weight is 29.6 lbs.

I ran an impedance scan on the finished cab with my DATS setup. The measured tuning frequency was 52.15 Hz which agreed with the Eminence Designer model with typical damping. Finally, here is a stack I couldn't resist with a 410 on top. Of course it's more than I'd typically need but they play quite well together.

 

[Type-55]

Nice looking cab build.

 

[5StringPocket]

Nice looking cab build.

Thanks, I really like the voicing of this driver. I've shied away from 112's in the past but with a solid low end, well-balanced midrange, and smooth treble extension this is a compact cab that doesn't sound small. A bump at 2kHz is useful to bring out the upper mids when playing finger style. I played it for a few days as built to get familiar with how it sounded, then shortened each port shelf from 5.75" to 4". I re-measured the tuning with my DATS rig and found the new Fb=55.5 Hz. It's a subtle difference, but from the model there is a change of almost -1dB deep bass around 40Hz and +1dB upper bass around 100 Hz. I think this is a change in the right direction.

 

[5StringPocket]

I had some further thoughts on this hybrid KL3012CX-8/KL3012LF cab first discussed in Post #330. Enlarging the enclosure to 3.81 cu-ft and tuning still higher at Fb=55.1 looks like it would improve the upper bass and still have plenty of low end. The F3/F10 on the cab drawing is given for the KL3012CX-8. For the KL3012LF driver in this cab F3/F10=53.4/40.5 Hz. Also, using the F151M HF driver with higher max output than the ASD1001 and crossing over a bit lower at 3150 Hz seems like it would reinforce the 2-3 kHz response and the phase alignment between drivers looks well behaved. Even though the KL3012LF normalized response is +1.5dB higher at 100 Hz, higher sensitivity of the KL3012CX makes the output about even. At 400 watts per driver, the KL3012CX reaches Xmax at 43.3 Hz while the KL3012LF reaches Xmax at 41.1 Hz. Based on my experience playing my KL3012CX-8 single cab at robust volume this is a non-issue. Also, even though the KL3012LF response is down -12dB from peak by 3500 Hz, it is still about 88dB/W which sums with the KL3012CX and F151M HF driver as it rolls in.
Here are updated cab and response drawings:

 

[agedhorse]

The yellow plot looks "friendlier"

 

[5StringPocket]

The yellow plot looks "friendlier"

Agreed, the yellow plot for the KL3012LF shows it provides great low end support but the KL3012CX (red plot) is no slouch and picks up nicely where the LF drops off. An EQ bump at 100 Hz works well with this driver but may not be needed with the KL3012LF in the bottom. Fb would have to be increased to 60 Hz to bring the normalized KL3012CX response at 100 Hz to 0 dB, but this would move the -10dB point and Xmax up to 46.2 Hz which is higher than I’d be comfortable with. For a hybrid enclosure, I’m looking for an Fb and Vb which is a good compromise for both drivers.

The KL3012LF works well with a mid driver. I’ve had two different mid driver builds with this woofer. This unconventional hybrid would have a different voicing I’d like to explore. The elevated tilt back mount of the KL3012CX coax and F151M HF driver is good for projection of mids and highs while I think the low mounting position of the KL3012LF should help provide solid low end support and somewhat mitigate the pronounced 1700 Hz peak.

 

[agedhorse]

Separate the air spaces and then you have room to tune each section differently as required.

 

[Doug Parent]

Would a 3012LF and KL3012CX sharing the same chamber with no separation lead to any significant problems?

 

[agedhorse]

Would a 3012LF and KL3012CX sharing the same chamber with no separation lead to any significant problems?

Possibley, if the TS parameters are significantly different.

Also, if the compression driver isn't used on the CX (there were some threads about doing this), the horn throat needs to be sealed (separate air space or not)

 

[5StringPocket]

The KL3012CX definitely needs the throat horn sealed. In the upper position it also needs the HF driver to fill out the frequency response. The T/S parameters are different enough between the KL3012CX and KL3012LF that these would not be the best match. The driver I've found with the closest T/S parameter and response match to the KL3012CX is the Beyma SM-112/N.
https://usspeaker.com/beyma sm-112n-1.htm

The phase and impedance plots are spot on and the Beyma normalized frequency response shadows the KL3012CX response but +0.4dB higher as seen in the 1st plot. The Eminence sensitivity is about +0.4dB higher so the amplitude responses line up as shown in the 2nd plot. I think these two drivers should be able to share a common air space and tuning with no issues. At this point though, the single 112 from Post #347 is working out well enough I'd probably just build a 2nd one and go with a modular stack.

 

[agedhorse]

Shorten the ports a bit.

 

[SeayBass]

I was on Eminence.com today. It looks like they're discontinuing the coax KL series.
Anybody know anything?

 

[agedhorse]

I was on Eminence.com today. It looks like they're discontinuing the coax KL series.
Anybody know anything?

I wouldn't expect it to be a big seller outside of the pro audio area, and there are just a few production monitor wedge designs that use or something similar. The metalwork is unique enough not to stock it as a production item though it may still be available as an OEM item.

 

[5StringPocket]

Too bad. True, it's not a mainstream driver design but the KL3012CX-8 is the best of the line - a robust and good sounding driver. The cab shown in Posts #345-347 makes a good full range monitor but I've been very pleased with how it has performed as my rock band bass practice cab for the past year. It's also a great grab-and-go box for acoustic ensembles and the 19" height makes for a comfortable seat.

 

[SeayBass]

I was psyched about 12. Then I saw the price tag and thought 'one day...' which hasn't come yet. Maybe I'll get a screaming deal on a close out...

 

[genesound]

I was on Eminence.com today. It looks like they're discontinuing the coax KL series.
Anybody know anything?

Bummer. Certainly don't want to start something using a dying driver product line.
Sent them an inquiry.