Monitor 10 Series 2 crossover upgrade

Redknife
Redknife Posts: 5
in Vintage Speakers
Hello, new here.
I am upgrading my Polk Monitor 10 Series 2 circa 1990 speakers. After a move, they are now in a prime listening area and I am not happy with the sound. I hadn’t listened to them closely for a while so I don’t know all the reasons I now don’t like the sound vs before.

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After a lot of reading here and elsewhere, I upgraded the SL2500 tweeters to the RD1098s. Big difference. SL2500s were harsh and fatiguing. RD0198s are better in these regards and also measure differently using REW. Still lacking some clarity, detail and smoothness for vocals and mids.so, on to the crossovers.

Here are the questions:
1: based on a schematic here https://us.v-cdn.net/5021930/uploads/attachments/4/6/7/2/8/18778.pdf
that appears to match my crossovers, I believe I would choose these components:
C1: 16 uF Sonicap gen 1-16 uF #506806
C2: 27 uF Sonicap gen 1-27 uF #506897
C3: 12 uF Sonicap gen 1-12 uF #506767

R1: 2.7 ohm Vishay Mills 2.7 ohm 5 watt

L1: coil 0.22 mH 22 awg. (reuse)
L2: coil 1.75 mH 18 awg (reuse)
Are these choices correct??

2: Is there a sonic role for replacing the air and solid core inductor coils?


As an aside, the room is also a problem but I am addressing that separately.

Thanks in advance for your input!
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Comments

  • tonyp063
    tonyp063 Posts: 1,083
    Use a 12 watt resistor. Better heat dissipation.
    Personally I would leave the inductors be & just replace the caps & resistor first.
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  • Gardenstater
    Gardenstater Posts: 4,459
    edited May 2020
    I agree on the 12 W resistors and leave about 1/8" clearance from the board to help even more with heat dissipation. I also used Sonicaps and I have absolutely no complaints! Tremendous improvement.

    I used Neotech UPOCC 12 gauge wire for the midbass drivers. Going to use Cardas Litz 15.5 gauge for the tweeters, and Cardas 11.5 gauge for the fuse and binding posts, when I replace the existing binding posts with Cardas ones. That's next on deck.

    I'm not real sure about the advantages of replacing the inductors but the theory is to get a lower DCR, which will undoubtedly improve the bass somewhat and lower the impedance somewhat. Not everybody may want to do that, especially if their amp is having trouble already.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • Redknife
    Redknife Posts: 5
    Thanks guys. Very helpful.
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  • F1nut
    F1nut Posts: 50,542
    FYI for Redknife, Cardas wire requires the use of a solder pot.
    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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  • Redknife
    Redknife Posts: 5
    F1nut wrote: »
    FYI for Redknife, Cardas wire requires the use of a solder pot.

    Ahh, got it.
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  • Redknife
    Redknife Posts: 5
    One speaker reworked. I was going to somehow configure the new components in the factory location but gave up because it was just too tight. I left the L2 coil on the back of the binding post and fashioned an MDF plate for the rest:
    3mdhxh6555hu.jpeg
    1pad97d7ojcc.jpeg
    geutbmg424eg.jpeg

    Maybe not perfect looking but solid- not my day job. I hooked it up and I believe the reworked speaker sounds noticeably better than the other. My wife walked in the room and said "did you do the left one?". Yes.
    Not very scientific but it was nice to appreciate a difference. I’m going to test new and old with REW.
    Thanks for the help.
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  • F1nut
    F1nut Posts: 50,542
    Forget REW, use your ears.
    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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  • Redknife
    Redknife Posts: 5
    I hear ya F1nut. Got both up and running. Very happy with the sound. Vocals are clear and natural sounding. Crowded midrange songs retain clarity. These were some faults before. High end is smooth. No fatigue so far, which was also a problem.
    Interestingly, the L1 coil on the second speaker negative lead was not soldered to the board. It was sitting in the hole, but no solder and no evidence of prior solder. No discoloration of the copper at all. Odd.
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  • BinKY188_5
    BinKY188_5 Posts: 133
    Redknife wrote: »
    I hear ya F1nut. Got both up and running. Very happy with the sound. Vocals are clear and natural sounding. Crowded midrange songs retain clarity. These were some faults before. High end is smooth. No fatigue so far, which was also a problem.
    Interestingly, the L1 coil on the second speaker negative lead was not soldered to the board. It was sitting in the hole, but no solder and no evidence of prior solder. No discoloration of the copper at all. Odd.

    I had the same thing on my SRS's. The lead on a capacitor was pulled through the hole and bent down but never soldered.
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