New guy here. RTA 12b got me hooked.

bobivxx
bobivxx Posts: 14
edited August 2013 in Vintage Speakers
Hi everybody. I first found this site when I was looking at some RTA12s on craigslist. It seems like a great forum. Thanks for having me!

They seem to be well regarded over here; So it seemed like it was worth $160.00 for the pair. They were in excellent physical condition and even came with the 3 original boxes.
P1060419.JPG
P1060423.JPG


They sounded excellent and I've become very fond of them. I've listened to them for about a year now and they definitely "do it" for me with my Mcintosh MX110 and Music Reference RM-9.

I think I'd like to recap the crossovers now.

They are serial number L12B15065 and R12B15255. So I'm assuming they are 12B's? Right?

The tweeters are marked made in Denmark; So they should be the Peerless?

I can't tell what one of the caps are and some of the values are different then what I'm seeing on the other posts. Here's what I got
P1060422.JPG
I have no idea what the big yellow one on the left is. I don't see a 45uf on any of the lists here and there is only one 4.4uf. I am also assuming the little brown ones are the 750pf bypass caps and should be deleted.

The lower crossovers are just two 27uf's and a 7.5ohm resistor.

I was thinking of using something "mid-range" like Solens

Thanks in advance!
Post edited by bobivxx on
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Comments

  • F1nut
    F1nut Posts: 50,557
    edited August 2013
    The yellow mylar is the other 4.4uF and is bypassed with a silver mica. The one you say is 45uF has to be a 55uF, so either you're reading it wrong or Polk put in the wrong cap.

    Solen caps are on the grainy side, I would not recommend them for the HF circuit.
    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

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  • bobivxx
    bobivxx Posts: 14
    edited August 2013
    P1060410.jpg

    It's definitely 45
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  • bobivxx
    bobivxx Posts: 14
    edited August 2013
    What would you recommend?
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  • F1nut
    F1nut Posts: 50,557
    edited August 2013
    Ok, I see what they did. The yellow mylar looks like a 14.6uF, so connected in parallel with the 45uF you have the correct sum total.
    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

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  • F1nut
    F1nut Posts: 50,557
    edited August 2013
    bobivxx wrote: »
    What would you recommend?


    For the HF circuit, Sonicap.
    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

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  • bobivxx
    bobivxx Posts: 14
    edited August 2013
    Yeah they did. Thanks F1nut! It seems so obvious now.
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  • StantonZ
    StantonZ Posts: 444
    edited August 2013
    You can order Sonicaps and Mills resistors from the same place (http://www.soniccraft.com/index.htm).
    They will also quote you on "custom" values if necessary. I just did my XO's and am very happy!
    Yamaha RX-A2050 AVR (5.0.2); LG OLED77C2 4K TV
    (4) Polk Monitor 10B's w/SoniCaps, Mills, and RDO-194 tweets (R/L F/R)
    (2) Polk RC80i (Top Middle)
    Polk CS300 center channel
    Analog: B&O TX2 Turntable, Nakamichi Cassette Deck 1
    Digital: Pioneer CLD-99 Elite LD, Panasonic DMP-UB900 UHD Blu-Ray
    Bedroom: Arylic Up2Stream AMPv3 driving Polk Monitor 4's w/peerless tweets
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  • bobivxx
    bobivxx Posts: 14
    edited August 2013
    Am I right in thinking I can do 3 - 27uf's, 1 - 4.4uf, And a 33uf? But damn; That's $500+.

    Thanks
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  • F1nut
    F1nut Posts: 50,557
    edited August 2013
    Yes, that would work. To save some coin, you could use Solen for the two 27's in the LF section where it's less critcal.
    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

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  • bobivxx
    bobivxx Posts: 14
    edited August 2013
    Good call F1!!!

    That takes $150ish off! I can always do em again later then.
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  • drumminman
    drumminman Posts: 3,396
    edited August 2013
    If you like the 12B's now you'll be amazed after you redo the Xovers. They're worth dropping some coin on if you plan to keep 'em.

    I did both the upper and lower Xovers in my 12C's with Sonicaps. There are a few other mods you can do that are worthwhile and relatively inexpensive.

    BTW, congrats - those look to be in showroom condition.
    "Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer
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