Polk Audio 5B bookshelf monitors

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p8nberger
p8nberger Posts: 2
in Vintage Speakers
I just started using a set of Polk Audio 5B bookshelf monitors that were my Dad's in the mid '80s. Online reviews seem to be pretty good. My problem is that one speaker doesn't sound great, dull and not very loud. It was suggested that the tweeter may be blown. I bought a used one from the same era and swapped it in. It sounds better, the highs are more pronounced. The thing now is that the same speaker just isn't as loud as the other. I've changed the channels and connector wires, so that's not the culprit. I also tried new fuses with no difference. Any thoughts?
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Answers

  • pitdogg2
    pitdogg2 Posts: 24,559
    edited February 2023
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    Since they have fuses, there could be corrosion either on the wires behind the block or the fuse holder. The fuse holder may not be readily apparent. Some use a pencil eraser to clean or maybe something like 2000 grit wet dry sand paper to lightly clean the fuse holder.
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  • slow_polk7
    slow_polk7 Posts: 33
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    p8nberger wrote: »
    I My problem is that one speaker doesn't sound great, dull and not very loud. Any thoughts?

    Your problems may well be crossover-related.
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  • gp4jesus
    gp4jesus Posts: 1,969
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    XO cap refresh perhaps? Both speakers of course
    Samsung 60" UN60ES6100 LED Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga - LCR mids, inside* & out 8 ga Powerline: LR woofers, inside* & out *soldered LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & “Plugged*” Mids - 981, connected w/MP Premiere ICs Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s *Xschop's handy work
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  • Tony M
    Tony M Posts: 11,015
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    Does the woofer cone move freely in the bad speaker?
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • p8nberger
    p8nberger Posts: 2
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    slow_polk7 wrote: »
    p8nberger wrote: »
    I My problem is that one speaker doesn't sound great, dull and not very loud. Any thoughts?

    Your problems may well be crossover-related.

    I'm thinking so. I was looking for a schematic and believe I found one here: https://forum.polkaudio.com/discussion/38755/polk-audio-speaker-wiring-schematics-amp-more-all-models-except-sda The one labeled mb5_orig. My local audio guy is looking to see if the parts are still available.


    gp4jesus wrote: »
    XO cap refresh perhaps?

    Would this be different than the crossover? I'm still learning all the outs and ins.


    Tony M wrote: »
    Does the woofer cone move freely in the bad speaker?

    I think it does, but I'll check to confirm.
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  • F1nut
    F1nut Posts: 49,794
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    My local audio guy is looking to see if the parts are still available.
    Not much of an audio guy if he doesn't know where to buy high quality caps and resistors.

    Here's two places to help you/them.
    https://www.soniccraft.com/
    https://www.partsconnexion.com/
    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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  • heiney9
    heiney9 Posts: 25,079
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    There are also at least a dozen threads (or more) on upgrading the 5B x-over. I did mine years ago and since I used Photobucket to upload photo's, there are no photo's any longer on my upgrade thread.

    H9

    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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