KLIPSCH RC52
CENTER CHANNEL V1





In 2008 I upgraded the center channel speaker in my home theater. My main speakers were Klipsch Fortes with 98db/watt sensitivity and I was interested in the RC52. Klipsch sold it as part of their Reference series and at 96db/watt it wasn't an exact pairing with my Fortes but the extra sensitivity put it very close. To demo I went to a brick and mortar audio salon near my home. When they cranked up the RC52 I thought they were playing a pair of large speakers. It turns out they were playing the RC52 by itself(!) The sound was large and dynamic, bass was deep and punchy with no distortion or edge. I had to walk up the speaker to make sure they were not playing a trick on me. I bought one immediately and the speaker has graced my home theater since then with zero issues.

   
  QUESTION: What made the original RC52 different from the later RC52 series II?
ANSWER: Klipsch designed the original RC52 for unique off-axis response by using a "Tapered Array" design.		  

"Klipsch Tapered Array™ technology operates both woofers at the lowest frequencies – maintaining the high output capability necessary for good center channel performance – but only one operates all the way through the midrange to where the tweeter takes over. This eliminates acoustic interference between the woofer outputs, a flaw in conventional speaker designs that can severely impair sound quality at the sides of the listening area."

EXPLANATION: A speaker with a tweeter midway between two midwoofers is known as the Joseph D'Appolito design (or MTM). At off-axis listening positions both midwoofers are in phase (time-aligned). But the waves from each side reach the listener at different times (and therefore have a phase difference). Klipsch sought to fix this anomaly by giving each woofer a different crossover point: one is 1400hz and the other 1600khz.

 

  RC52 with dual crossover points  
 

  RC52 series II with single crossover point  
 

Why did Klipsch change the RC52 (and RC62) in 2010 by removing the Tapered Array?

I'm guessing for several reasons. Trying to explain that each mid-woofer has different response may have been confusing to customers. In addition, this invisible feature doesn't increase specs on paper and requires a more complex crossover with extra parts. It may have been that Klipsch couldn't quantify the extra expense for what was an esoteric design.

BELOW: the faceplate unbolts to reveal a horn tweeter with an interesting heat sink. Each end of the faceplate has an oval woofer port tube extending into the cabinet that appears to be the secret to producing strong bass.

   
 
BELOW: A gasket is used across the front. Thick baffled foam is used inside.

 
   

  BELOW: the midwoofers are heavy and stamped specifically for the RC52.  

   

THE CROSSOVER
Below is the crossover in my original RC52. For such a simple speaker this is surprisingly complex. It has a two level design with a total of 5 resistors, 2 iron core coils, one air coil and 4 film capacitors. The wire is heavy gauge stamped "Klipsch custom high frequency wire". Good job Klipsch! The capacitors aren't the common blue KSC (King-Sun) brands that Klipsch used for decades. It appears by 2008 they were using yellow caps with a Klipsch logo. These are mentioned as polyester in Klipsch Reference speaker literature.

- The film caps on the top are 20uf, 6.8uf and 2uf, all 100V.
- the hideen first level film is a 30uf 100V.
- iron cores are marked 2.5mh, 1.0mh and air core is .68mh

   

CONCLUSION
My RC52 has a clear, dynamic sound and retains its clarity, bass punch, and low distortion at very high volumes. I'm using a Denon AVR4306 as a preamp and a mono Hafler XL280 chassis with Musical Concepts PA-6 board to push it. While it would be easy to replace the tweeter caps with polypropylenes, Klipsch dialed in this complex crossover based on the ESR of polyester caps. I would rather retain the feel of its response being "correct" than gamble with changing the frequency response by using lower resistance caps.

So there's nothing I would mod on this speaker except to recommend a high quality amp. It would be interesting to hear a sound comparison between this model and the Series II to see how well the tapered array works.




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