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Squawker Driver Tests, K-55V, K-55M, K-51V, K-52H


BEC

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Since so many have "fixed" the glitch of the K-55V by replacing it with a K-55M that also has a glitch, I don't think anyone can hear it. Bob Crites

You kidding Bob? Everyone is going to hear it now that it has been documented.

What I am taking away from these tests is that my JBL 2470's should be just fine in the K Horn with no loss in performance due to their "rolloff" at 400 hz because they are no worse than the K55's.

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Michael -- you can create a bigger impact on the response with speaker placement than the differences in those drivers. And don't forget the effects of the room -- RTA the speakers without any applied EQ and the response is all over the place. A year ago I would have looked at those plots and thought about how different those drivers are -- now I look at them and see how close to the same they are. Bob is right -- it doesn't amount to squat difference, and you're fine with the networks you have.

Nice work Bob.

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Since so many have "fixed" the glitch of the K-55V by replacing it with a K-55M that also has a glitch, I don't think anyone can hear it. Bob Crites

You kidding Bob? Everyone is going to hear it now that it has been documented.

What I am taking away from these tests is that my JBL 2470's should be just fine in the K Horn with no loss in performance due to their "rolloff" at 400 hz because they are no worse than the K55's.

With the other parts of the network terminated with resistors, my RTA shows the 2470 as being almost 5dB down at 400Hz (on the Trachorn). When I add the bass bin back in, the response through the RTA looks the same at 400Hz as it did when I used K-55-V's.

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Bob,

Thanks for taking the time to do this and to share the results with us.

-Tom

Yes, thanks for the hard work and sharing! I was hoping to get opinions

from you as to whether or not my my K-55V drivers seemed to be up to

snuff... I just rescaled your measurement of the single phase plug

driver to make a direct comparison with mine and it seems that they do

indeed pretty much agree with each other within what I would consider

normal tolerances.

Is there an overall preferred driver based on subjective listening? Do

the newer horns exhibit a similar sound quality or have there been

changes?

Widget

post-23229-13819307351006_thumb.jpg

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  • 3 weeks later...

Just adding another test trace to the group. This is a K-55V 1 piece phase plug model tested twice with the only difference in the test set-up being the added P-trap used in the test with the red trace.

Bob Crites

post-9312-13819308005736_thumb.jpg

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Mr. Widget,

The speaker is spec'd at +/- 5 db in your vintage, so I'd say your's are just as they should be.

In general, horns are not as smooth as some direct radiators when tested, but usually sound more alive and real.

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. . . . . But, the particular one I tested at least gives up a couple of dB in output compared to the K-55V single piece phase plug and the K-55M.

And this is bad why?

I'd take this driver for being smooth and just a tad set back in the mix. Of course with SET I'm getting all the great midrange I could want. I would also bet that it would be very difficult to pick out the difference in sound between any of these.

How does one tell a K-55 with a two piece phase plug vs. a one piece?

Greg

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  . . . . . But, the particular one I tested at least gives up a couple of dB in output compared to the K-55V single piece phase plug and the K-55M. 

And this is bad why?

I'd take this driver for being smooth and just a tad set back in the mix.  Of course with SET I'm getting all the great midrange I could want.  I would also bet that it would be very difficult to pick out the difference in sound between any of these. 

How does one tell a K-55 with a two piece phase plug vs. a one piece? 

Greg

 

Oh, I don't think it is bad. Just seems they gave up a bit of output to get a smoother frequency response. There are almost always trade-offs. I agree that all of them test so close that picking out a difference between any of the K-55s would be tough.

The two piece phase plug K-55Vs were all built in the early 80s and have solder terminals on them instead of push type terminals.

Bob Crites

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Mr. Widget,

The speaker is spec'd at +/- 5 db in your vintage, so I'd say your's are just as they should be.

In general, horns are not as smooth as some direct radiators when tested, but usually sound more alive and real.

Thanks John. That is what I assumed, but I was hoping for confirmation

from those with much more Klipsch knowledge than I have. The horns and

drivers that I have came out of Radio City Music Hall in NYC years ago

and I would assume they saw some pretty hard use at times. It's nice to

know they have stood up to it well.

Widget

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Oh, I don't think it is bad. Just seems they gave up

a bit of output to get a smoother frequency response. There are almost

always trade-offs. I agree that all of them test so close that picking

out a difference between any of the K-55s would be tough.

The two piece phase plug K-55Vs were all built in the early 80s and

have solder terminals on them instead of push type terminals. Bob

Crites

I don't think the 2-piece phase plugs give up any output. I think

you are seeing a normal variation in driver to driver output. I

*think* I remember reading that moving the phase plug closed to the

diaphragm gets more output and more highs at the expense of lows (the

diaphragm hits the plug) and that's part of what Mr. Paul did.

Maybe that dB or 2 is the evidence that AlNiCo magnets sometimes need to be recharged.

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