Monitor 12 Series 2 upgrades?

jmitchnh
jmitchnh Posts: 31
edited January 2012 in DIY, Mods & Tweaks
I received a belated Christmas present today when I spotted a pair of Monitor 12 Series 2 on the local CL this morning for a whopping $50! :cheesygrin: Needless to say I raced to pick them up before the seller had a change of heart. I was very pleasantly surprised by their condition as I was expecting the worse considering the low price.

I have always considered my (now departed) SDA-1Cs the nicest sounding loudspeaker I have ever heard and have yet to find anything that comes close to them. The M12s are the perfect size for my modest listening area and I love the multi-driver array, reminiscent of the SDAs.

Now onto the fun part, I was very excited to learn that these speakers use the highly regarded RDO 198-1 tweeters as replacements for the stock SL2500s. They will be the first tweak. Next is the x-over. I pulled one out of the cabinet tonight (discovered the build date was 1991) to get cap values but could not find any on them. The way they are mounted/oriented on the board makes it impossible. Does anyone have a schematic of the x-over with values or has anyone recapped a M12 S2?

I am so happy to have a killer set of Polks again and will keep you all updated on the transformation. And now, back to more listening!
Life's too short too listen to bad speakers
Post edited by jmitchnh on
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Comments

  • agfrost
    agfrost Posts: 2,430
    edited January 2012
    I don't recall ever seeing a M12 mod thread before. I'll enjoy hearing of your progress. There are schematics for most vintage Polks in sticky threads at the top of the Vintage Speaker forum. Here's the one you need:SCHEMATIC

    You can upgrade your capacitors (from mild to wild) with the brand caps of your choice, and if you have quality amplification and a reasonable touch with the volume control, you'll get some benefit out of removing the polyswitch.

    Good luck and post any questions and updates you have. I remember lusting after the M12 when I was in college, but my budget was M5jr+ at the time. Good looking speaker, but I've never heard 'em.

    Jay
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
    Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
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  • thsmith
    thsmith Posts: 6,082
    edited January 2012
    Go here for the schematics.

    http://www.polkaudio.com/forums/showthread.php?38755-POLK-AUDIO-Speaker-Wiring-Schematics-amp-More-ALL-MODELS-except-SDA

    BTW, congrats on some great speakers. SPike them or add the stand they should have came with.
    Speakers: SDA-1C (most all the goodies)
    Preamp: Joule Electra LA-150 MKII SE
    Amp: Wright WPA 50-50 EAT KT88s
    Analog: Marantz TT-15S1 MBS Glider SL| Wright WPP100C Amperex BB 6er5 and 7316 & WPM-100 SUT
    Digital: Mac mini 2.3GHz dual-core i5 8g RAM 1.5 TB HDD Music Server Amarra (memory play) - USB - W4S DAC 2
    Cables: Mits S3 IC and Spk cables| PS Audio PCs
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  • agfrost
    agfrost Posts: 2,430
    edited January 2012
    I forgot to add that you'd want to upgrade the resistor as well. If you do a search for "crossover upgrade" that reading should give you something to chew on as you plot your upgrade path...

    Jay
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
    Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
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