Monitor 5B Hidden Gems

xschop
xschop Posts: 4,636
edited April 2019 in Vintage Speakers
I was out of town, which always seems to be the case when vintage Polks appear in a local CL ad. Called up my FIL and being the trooper he is, goes and picks these up for me. 60 deflated dollars and next day later, they are in my possession. Hooked them up, SL2000's work but as always are hard to listen to for long periods. Cracked open the spare set of rebuilt and modded RDO-194s on hand and they dropped right in. MUCH better highs, smooth and balanced. Can't wait to rebuild the X-overs and and do some other mods. These things IMAGE. Last I remember hearing a set of 5Bs, they sounded better to me than the 7B's in the midrange dept. The mid base and low 30's hz are so accurate on these playing my favorite instrumental jazz, old school and new. Very happy to reminisce over these jewels...

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Best Answers

  • RandyCroissant
    RandyCroissant Posts: 475
    Answer ✓
    Congrats on a nice pair of M5s, they should sound great with a small investment in up grades.
    Yamaha RXA1030, Yamaha CD-S2100, Yamaha AS-2200, Bluesound node 2i
    Polk SDA2btl highly modded
    Polk SDA 1C modded
    Polk CS350 LS x2
    Kimber 8TC
    Sony 55" Bravia
    Wish list SVS sub

  • xschop
    xschop Posts: 4,636
    Answer ✓
    Thanks Randy. I wasn't trying to ask a question or was I lol.
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  • xschop
    xschop Posts: 4,636
    edited April 2019 Answer ✓
    stevep wrote: »
    Looks like those will need the spacer/washer behind the tweeter screws so the faceplace isn't distorted. I love my 5B's.

    These were the burnt set I got from VSAT and rebuilt with aftermarket silk domes. These frames have been butyl-matted on the back sides. I believe that once they have been torqued down at the mount screws, those indentions are there to stay.

    P.S. can someone please explain to Vanilla that I meant to say indentions, not intentions. Damn computers are getting dumber by the day.
    Don't take experimental gene therapies from known eugenicists.
«134

Answers

  • xschop
    xschop Posts: 4,636
    edited May 2019
    Would 3/4" dia. Hickory dowel rod be a good choice for front to back baffle bracing?
    Just don't want to take up any significant airspace/volume in these cabs.
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  • xschop
    xschop Posts: 4,636
    Well what do you know, it's not the end of the world. I managed to locate my original thread using forum search.

    Question is, can these be "officially" updated to RD-0198's? Anyone here done a set before?
    Thanks
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  • stevep
    stevep Posts: 327
    There is a Monitor 5 SL3000 schematic in the vintage forum. The RD-0198 replace the SL3000 so it's a potential starting point.
    https://us.v-cdn.net/5021930/uploads/attachments/4/6/7/2/8/18767.pdf

    If you could find a M5b series 2 crossover I would expect you could use them directly with the RD-0198.
  • xschop
    xschop Posts: 4,636
    Hey thanks, I thought it would just be an extra 5.8uf cap. I will get a set and mod them with the new billet tweeter plates I'm working on.
    I'll see what it takes to modify the factory 5B crossovers.
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  • xschop
    xschop Posts: 4,636
    Is there a benefit to adding 6x6" square sound barrier foam to the back wall directly behind MW when the Factory polyfill remains?

    Also the 33uf Dayton film caps that shipped measured 33.3and 33.6uf FYI.
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  • F1nut
    F1nut Posts: 49,707
    There is a benefit, but too much damping will kill the sound. 6x6 is likely too big, but that also depends on the thickness of the Sound Barrier.
    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

  • xschop
    xschop Posts: 4,636
    I just have 1/2" thick open cell foam with extra sticky backing. So once it's stuck, it's there.
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  • xschop
    xschop Posts: 4,636
    I won't be going to this extreme with standoff cones, but this pic is the foam back-to-back.

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  • lightman1
    lightman1 Posts: 10,776
  • xschop
    xschop Posts: 4,636
    Did you get hit by 3-phase 480 again?
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  • pitdogg2
    pitdogg2 Posts: 24,474
    xschop wrote: »
    Did you get hit by 3-phase 480 again?

    He eats that for breakfast
  • xschop
    xschop Posts: 4,636
    edited May 2020
    Interesting how far out of range the Factory caps are... I'm going with a 2.2 ohm wire-wound resistor to make up for the polyswitch removal...

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    Don't take experimental gene therapies from known eugenicists.
  • mhardy6647
    mhardy6647 Posts: 32,926
    lightman1 wrote: »
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    Rookie....

    Now yer talkin'.

    B)
  • xschop
    xschop Posts: 4,636
    pv8jv2tnlq5h.jpg

    Factory MW tabs had to go... Probably about the same area removed that may be obstructed from the future backing rings (albeit radiused). The extra tabs on the fast-on mounts are also a moot point.
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  • xschop
    xschop Posts: 4,636
    edited May 2020
    The factory binding post-to-pcb wires looked whimpy, so I replaced with some leftover CRS-build wire after modifying the baffle cups to mount the billet terminal plates.....

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  • xschop
    xschop Posts: 4,636
    I won't mod these up with 5.8uf caps yet until I can thoroughly test out the RD-0194 diaphragms in the billet tweeter frames.

    dk43v0nmwhcm.jpg
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  • xschop
    xschop Posts: 4,636
    Going the extra step on the phase plug modification to make them easy to remove/install.

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  • xschop
    xschop Posts: 4,636
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  • xschop
    xschop Posts: 4,636
    Thanks F1, simplest mod yet....

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  • xschop
    xschop Posts: 4,636
    edited May 2020
    Has anyone compared nickle-plated vs gold-plated binding posts for sound difference? The satin nickel binding posts would look stealthy along with all the billet pieces going into this build....

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  • xschop
    xschop Posts: 4,636
    before I forget or loose my info....

    Base plate ID.... 1.085"
    Voice coil ID..... 1.010
    Voice coil OD..... 1.060
    Pole piece OD....0.995"

    This all calculates to only 0.010" air gap on either side of VC and and confirms why a 0.020" thick plastic shim half the circumference of VC, inserted between VC and pole-piece will re-center the pole-piece, if you remove the dust cover to accomplish the task.
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  • agfrost
    agfrost Posts: 2,421
    xschop wrote: »
    Has anyone compared nickle-plated vs gold-plated binding posts for sound difference? The satin nickel binding posts would look stealthy along with all the billet pieces going into this build....


    The Cardas CCRR is rhodium plated; not satin in finish but not high-shine either. Got a set here waiting for me to get to work.

    http://www.soniccraft.com/product_info.php/cardas-ccrr-binding-post-p-1669

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    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
  • pitdogg2
    pitdogg2 Posts: 24,474
    edited May 2020
    I used these on mine. They work very well I like them.

    http://www.soniccraft.com/product_info.php/cardas-ccgr-binding-post-p-1389


    I've also used both the dayton gold and nickel plated. They both did the job I noticed no difference.
    To be fair i used the gold for speaker cable input and the nickel for the interconnect cable on both my SDA 1 signature and SDA 2a speakers.