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Upgrade/mods on Polk Audio Monitor 5jr

Douglas Jett

New Member
I have a dilemma. Had a pair of Polk Audio Monitor 5jr from 1985 with SL2000 tweeters & they sounded muddled & the tweeter would turn into a buzzy mess every now & then. So I opened them up,cleaned up the fuse connectors (these have the first crossovers with the outside fuse above the the post connectors) replaced the cap with an Audyn foil cap & replaced the resistor with a Dayton Audio DNR resistor both generally the same values as the original, & I also lined the woofer area walls with 1.5 in memory foam blocks while shoving all the polyfiber fill up into the top half behind the tweeter. It helped clear up the bass & mids but the tweeter was still blah. It stopped the buzzing but just was kind of dead. Rather than changing the crossover to change the tweeters to the RDO 198 or buying OEM SL2500, I bought two Peerless K010DT that were new old stock for M&K 17050s. Now for my dilemma: after putting in those tweeters they sound just as good as my KEF iQ30s. Only difference is how the KEF aluminum woofers bass reacts vs the coated paper of the Polks & maybe a bit more depth of the sound stage with the KEFs, but the Polks full tone range seems to sound just a touch sweeter & warmer. Does this sound like I'm imaging things or were the first Polk Monitors with the original Peerless tweeters really something special? They're currently being run by a Marantz Nr1604 as a preamp with the power coming from a Shure HTS 50SPA amplifier. Would a regular 2 channel integrated or an AVR be able to handle my hodgepodge Polk 5jr "specials"?
 
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The correct replacement tweeter is the RD0194. The RD0198 and SL2500 are not. Using the Peerless the resistor should be 1.3 ohm.

Not sure what memory foam blocks are, but the correct amount of BH5 or Sonic Barrier is a 4" square directly behind the mid-driver. Too much damping material kills the mids and bass.

By your description of the sound of the original tweeters they were definitely bad, so yeah replacing them will improve the overall sound as will upgrading the crossovers.

The 5jr is ok in a limited way. The Monitor 7 is the home run.
 
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