CS1

• The CS1, introduced in 2004 and recently discontinued, is the matching center speaker in Polk's Monitor series, an inexpensive home theater speaker system. The frequency response is 55Hz-25kHz, though the real world response is 65Hz-24 kHz.
  
  

CSi3

• The CSi3 was the next center speaker Polk released to match in the monitor series. It is very similar to the CS1 in specs, though the frequency response on the high end is a little better, going up to 27kHz. The CSi3 is voice matched to Polk's RTi speaker line.
  
  

Tweeter

• The tweeter is one of the primary differences between the CS1 and CSi3. The CS1 has a Fabric/Polymer Dome tweeter, while the CSi3 has a Silk/Polymer Dome tweeter.
  
  

Power Handling

• Both the CS1 and CSi3 are rated to 89dB efficiency. The top recommended power amp for the CS1 is 120dB, while the CSi3 can handle a higher powered amp, up to 180dB.
  
  

Size

• The CSi3 is a little more compact than the CS1, but heavier. The CSi3 measures 6-7/8" H x 20" W x 9-1/4" D and weighs 20 pounds, while the CS1 measures 7" H x 18" W x 9-5/8" D and weighs 13 pounds.
  
  

Color

• Both the CS1 and CSi3 are available in black and cherry.
  
  

Reversible Cabinet

• Like the CS1, the CSi3 has a reversible cabinet design so that when your center speaker needs to be placed below the monitor, it can point upwards for excellent integration in your surround sound system.