Polk RTA 12 - what are they worth?

Made in 79. I bought them slightly used in 1982. The rosewood vinyl has been covered in black vinyl, otherwise they look nearly new. What are these worth? Thanks!

Best Answer

  • Jazzhead
    Jazzhead Posts: 151
    Accepted Answer
    The crossovers on the original version cannot be modified to roll off the outer drivers. That's why Westmassguy came up with the idea to do something sonically similar by using damping material (Black Hole 5 or Sonic Barrier) to overdamp and "absorb" some upper frequencies of the outer drivers (so the drivers don't produce identical frequencies) . After this mod is done the speakers are mirror imaged like later models (there is a designated right and left speaker). This mod does not affect bass output and to my ears actually improves the midrange (as well as imaging), as it reduces some of the frequencies that can make the stock original model "shouty" at higher volume. Your speakers can however sonically benefit from a re-build by replacing/upgrading the aged capacators and resistors. Westmassguy, (DHS Speaker Service) did a beautiful job on mine. There are several other mods that can be done (search the forum), such as gluing driver magnets, sealing cabinets, Dynamatting driver baskets, upgrading binding posts, upgrading internal wiring, renewing driver gaskets, etc. The original model is a very nice sounding loudspeaker once these mods are done.

    I hope this makes sense.
    Polk Audio original RTA-12s w/ 12 inch Polk Stands; DHS Speaker Service upgraded crossovers w/ Sonicap/Mills; comb filtering mod (hyperdamped outer drivers/mirror imaged); tweeter diffraction mod; Cardas silver-rhodium binding posts; Neotech UPOCC internal wire; Sonic Barrier 3-layer; Dynamat Xtreme
    Ayre K-5xeMP preamplifier
    Cambridge Audio 840C CD player; Herbie's Audio Lab Super Black Hole CD Mat
    D-Sonic Custom Audio M3a-600M monoblock amplifiers
    NAD 4155 FM/AM tuner
    Silnote Audio Morpheus Reference II Series II balanced interconnects; Virtue Audio single-ended interconnects
    Furez 10/2 speaker cable & connectors, shotgunned
    VH Audio Flavor 4 power cables w/Furutech connectors (G)
    Herbie's Audio Lab system isolation: Tenderfeet, Big Fat Dots, Grungebuster Dots, Little Fat Gliders
    Dedicated 20A/10 AWG circuit; Furutech GTX-D (G) outlet; Furutech eTP80; Shunyata Research Venom Defender; Synergistic Research Orange fuses

Answers

  • F1nut
    F1nut Posts: 46,292
    What you are willing to accept and what someone is willing to pay.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • Nightfall
    Nightfall Posts: 9,554
    edited January 24
    The vertical tweeter version without the riser or the good crossover? ~$150?
    afterburnt wrote: »
    They didn't speak a word of English, they were from South Carolina.

    Village Idiot of Club Polk
  • Mystery
    Mystery Posts: 2,543
    I sold RTA-12C in excellent condition for little over $200 but that was 8 years ago.
    https://forum.polkaudio.com/discussion/comment/1830999

    Sonus Faber Concerto Grand Piano, Klipsch, B&W DM602.5, Epicure 20+, T/E 280, 100V, Polk.
    Subwoofers: Monitor Audio, B&W ASW300, Triad ProSub Bronze.
  • ddinnsen
    ddinnsen Posts: 6
    Nightfall, what do yoiu mean by "good crossover"? Mine looks like this...7i2ulb2c08tw.jpg
  • CH46E
    CH46E Posts: 3,357
    They are the RTA12A. Unfortunately they are the least desirable of the 12, 12b and 12c. If they are in great shape id guess you would have no problem getting $200.00 on CL.
  • Jazzhead
    Jazzhead Posts: 151
    ddinnsen:

    "Good crossovers" refers to later versions (RTA-12B, RTA-12C) having the outer driver frequency rolled off to prevent the comb filtering problem present in the original model (comb filtering is detrimental to imaging/SQ) because both drivers operate at identical frequencies. There is a mod for the original RTA-12 that can greatly mitigate this problem:

    https://forum.polkaudio.com/discussion/173834/westmassguys-idea-employing-damping-to-mitigate-comb-filtering-and-lobing

    Another improvement made to later models was the tweeter diffraction ramp/device that prevents reflections/diffraction off the top of the cabinet and perimeter of the tweeter bezel. I fabricated a mod for that as well (largely copying what the Polk engineers did) that further enhances the detail and imaging performance of the original model:

    9ty8px3zdckn.jpg
    Polk Audio original RTA-12s w/ 12 inch Polk Stands; DHS Speaker Service upgraded crossovers w/ Sonicap/Mills; comb filtering mod (hyperdamped outer drivers/mirror imaged); tweeter diffraction mod; Cardas silver-rhodium binding posts; Neotech UPOCC internal wire; Sonic Barrier 3-layer; Dynamat Xtreme
    Ayre K-5xeMP preamplifier
    Cambridge Audio 840C CD player; Herbie's Audio Lab Super Black Hole CD Mat
    D-Sonic Custom Audio M3a-600M monoblock amplifiers
    NAD 4155 FM/AM tuner
    Silnote Audio Morpheus Reference II Series II balanced interconnects; Virtue Audio single-ended interconnects
    Furez 10/2 speaker cable & connectors, shotgunned
    VH Audio Flavor 4 power cables w/Furutech connectors (G)
    Herbie's Audio Lab system isolation: Tenderfeet, Big Fat Dots, Grungebuster Dots, Little Fat Gliders
    Dedicated 20A/10 AWG circuit; Furutech GTX-D (G) outlet; Furutech eTP80; Shunyata Research Venom Defender; Synergistic Research Orange fuses
  • ddinnsen
    ddinnsen Posts: 6
    Jazzhead, the linked post mentions, but does not document the crossover mod. Should I contact Westmassguy for documentation? I'm compatent with a soldering iron and a schematic.
  • CH46E
    CH46E Posts: 3,357
    edited January 26
    You have had them since 82? I'm guessing by your question that you are done with them? Do you not like thier sound anymore? Did you upgrade?
    What's the story here?


  • ddinnsen
    ddinnsen Posts: 6
    I still like them. The story is I also have a pair of RTR 180D which I also like. The plot thickens because I'm out of work due to the virus (I work in the cruise industry) and I need to sell one of them. I decided that I should sell the one that will generate the most cash, but I did not know what they are worth. I'm thinking that I will sell the RTRs and keep the Polks, maybe with modified crossovers?
  • ddinnsen
    ddinnsen Posts: 6
    Thanks. I already glued my magnets because one of them failed. I do hate those binding posts, but they work because I use spade terminals on my wires. is the insulation mod documented?