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La Scala Industrial (splits) mid driver questions


Curmudgeon
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I bought a pair of La Scala splits a while back that sounded decent but kind of on the lifeless side.  The crossovers were marked Type ALs and appeared to be original so I surmised that the caps were aging and decided that a set of ALKs would be a better choice than rebuilding.  I picked up a pair of older style ALKs (with Hovland/Harmony/Solen caps) off the forum recently and installed them.  While inside I noted that the tweeters were K77 square magnet types and the fiberglass mid horns had massive Eminence drivers.  I had read that Eminence made some OEM mid drivers for Klipsch so I didn't give them much thought at the time. Per the ALK instruction sheet I started out at Al's "normal" attenuation but after a few weeks of listening to movies and music the mids seemed a bit hot so I decided to change settings.

 

I had noted the Eminence mid drivers before but forgot to write down the model number.  While I changed the ALK tap settings today I copied the model number off the paper tags and out of curiosity looked up the specs (and of course opened a can of worms).

 

Eminence PSD2002S-16 (Link: http://www.eminence.com/pdf/PSD2002S16.pdf )

 

Throat Size: 1”, 25.4mm
Nominal Impedance*: 16 ohms
Power Rating: 80W (EIA426B Secification, 1.6kHz @ 18dB)
Resonance: 550 hz
Usable Frequency Range: 1.2kHz - 20kHz
Recommended Crossover: 1.2kHz/18dB or 1.8kHz/12dB
Sensitivity (1W @ 1m on axis horn): 105dB
Magnet Weight: 34 oz
Voice Coil Diameter: 2"
Re: 6.1
Le: 1.6 mH

 

The first thing that jumped out at me is the usable frequency range: a PSD2002S-16 isn't rated down to 400 hz so unless I'm missing something this doesn't appear to be a proper mid driver for La Scala's.  Since these are older pro speakers with unknown history my guess is someone installed the PSD2002S-16's without giving much thought about the crossover point.  I can't seem to find out the exact mid driver Klipsch specified for the pro series back then and on paper the Eminence driver just don't look right.

 

The La Scala HF cabinet #'s are 8764119 & 8764121, the LF cabinet #'s are 8764123 & 8764131 so they should be late 1980's models.

 

My questions are:

 

1)  Am I right about the Eminence PSD2002S-16 driver in that it's pretty much leaving a big fat hole from 400 to 800 hz and doesn't belong in a La Scala?

2)  If needed should they get replaced with K-55's or is there something more appropriate for La Scala splits?

 

Any help y'all could offer would be greatly appreciated as I don't want to spend money unnecessarily but if I need different mid drivers I'll suck it up.

 

** As a side note also I have a pair of `79 Klipschorns with ALK Universals and Crites tweeters that I'm very happy with the sound of. The La Scala splits didn't seem to improve as much with the ALKs so I'm figuring the (what appears to be) mismatched mid drivers are why they still sound a bit wonky to me.  Of course different room, electronics, cables, etc. makes you doubt what you're actually hearing sometimes.

 

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Good idea but the Klipschorns are not easy to access & I would rather not mess with them - they're at the "if it ain't broke don't fix it" leave it alone stage.

Mainly I'm asking if my suspicion is correct because if the mid drivers aren't appropriate they need to come out and something correct go in. If Eminence specs the usable low end at 1200 hz I can't fathom why they're on K-401 horns unless someone just chucked in whatever they had laying around. I don't know enough about compression drivers or what Klipsch originally used but to me it raises a big red flag.

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That is certainly the wrong driver to be used with the LS crossovers. It could also really damage the diaphragm crossing that low.

 

I have some LS cabs I am redoing, purchased cheap, that had NO Klipsch parts. The mid driver was an EV that would play low enough, but it was on an 800Hz horn and crossover. Left a bit of a hole.

 

Bruce

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