Polk Audio RTA 12
sleestak
Posts: 1
Hi, new guy here.
I have an old pair of Polk Audio RTA 12 loudspeakers and while they sound fine, given their age of approximately 34 years I'm thinking the capacitors should be replaced. I looked at the caps, but there is no indication of the uF values. Would anyone be able to share what I need. Also, who are good suppliers for these capacitors? Thank you.
I have an old pair of Polk Audio RTA 12 loudspeakers and while they sound fine, given their age of approximately 34 years I'm thinking the capacitors should be replaced. I looked at the caps, but there is no indication of the uF values. Would anyone be able to share what I need. Also, who are good suppliers for these capacitors? Thank you.
Answers
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Hi Sleestack:
Welcome to the forum. I too am the owner some original RTA-12's (I bought them in 1980). They've been fully modded and the results have been far beyond what I ever imagined from this speaker. I had the crossovers re-built by DHS Speaker Service (westmassguy here on the forum). Sonicaps and Mills resistors replaced the original components. There are other capacitor/resistor options (depending upon $$). Here's a post regarding the crossover work. It was a complex project due to the increased size of the new capacitors :
http://forum.polkaudio.com/discussion/172763/rta-12-original-project
You might contact westmassguy, as I imagine he recorded the capacitor values. He as well as others on this forum are extremely knowledgeable and generous with their advice. I've been told however that Polk sometimes changed capacitor values "on the fly", and each set of crossovers capacitors must be verified specifically. Your crossovers may possibly have different values from mine. Sounds like your caps, like some of mine, were soldered with the values on the underside.
Of all that I upgraded, replacing the capacitors yielded the greatest (a vast) sonic improvement, but you can gain much, much more through additional mods. Most of these mods were recommended by the fine folks on this forum. This post outlines the additional upgrades:
http://forum.polkaudio.com/discussion/173834/westmassguys-idea-employing-damping-to-mitigate-comb-filtering-and-lobing
The damping mod in the previous thread was a huge improvement - the full potential of these speakers cannot be realized without it. Replacing the binding posts is a "must do" in my opinion. Be sure to epoxy those driver magnets before you get a notorious magnet shift. My speakers sit atop some original 12-inch Polk Stands (now filled with sand). Using four Herbies Audio Labs "Big Fat Dots" under each speaker makes them come alive. I also use four Herbies "Little Fat Gliders" under the stands to decouple the whole works from a wood floor that is above a full basement. This prevents low frequency sound from traveling through the floor and muddying things up (in my room with my set up, YMMV). If my room was over a concrete slab I would have experimented with spikes. I am amazed at what these 30-some year old speakers are capable of.
