A whimsical Monitor 4.6 upgrade, with pics

geoff727
geoff727 Posts: 546
edited September 2013 in Vintage Speakers
Hello all,

This is a project that's going to Salt Lake City very shortly. I've had these speakers for a few years. The pictures show a Monitor 4.6 pair that was on ebay recently. I don't have any pictures of mine in their original state, but they looked just like those black ones in the photos, except not in as good of shape.

The agenda for these included:

1. Build out the enclosures. For this, I debated on what I wanted to do, but finally settled on making the enclosure walls 1/2-inch thicker, all the way around. I've been curious about the look of a larger bevel on the Monitor speakers, and with these I had the chance to experiment.

2. Crossover work, of course.

3. New oak veneer and finish.

4. New grill cloth and refinished metal badges, which replaced the plastic ones.

5. Replacement of the vinyl front face with a twill-weave carbon fiber (the real thing, not vinyl look-alike).

6. Inserts for spikes, furniture gliders, whatever.

7. Mix and match better individual drivers.

8. Beef up the mounting for the woofer.

Pics following....
Polk SDA SRS 2
Polk RTA 15tl
Polk Monitor 7C
Polk Lsi9

Infinity RS-II (modded)
Infinity RS-IIIa (modded)
Infinity RS 2.5 x 2

Magnepan 1.6QR (modded)

System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
Post edited by geoff727 on
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Comments

  • geoff727
    geoff727 Posts: 546
    edited September 2013
    I'm just going to post a bunch of pictures....

    Here are the new crossovers, built on MDF. The inductors were retained from original, but that's all. The original PCB was hung off the back of the spring-clip cup. This one is obviously much more robust.

    The underside looks messy, and it is. I quickly hand-routed channels for each of the wire runs. Everything is soldered up and tucked into the channels, after which it's all sealed in epoxy. There is no exposed copper anywhere on the crossovers, binding posts, or quick-disconnects. Everything is soldered and sealed. Thus, one never has to worry about oxidation of the Monster Cable wire. Even though the bottom looks messy, I wanted to keep top-side nice and neat.

    The crossovers are very chunky-feeling. Thumping on them yields a very dull and quick-decaying 'thud'.

    One small thing that I think is kool.... The nuts on the underside to hold the terminal strip- in order for one to loosen, it has to force a tightening of the other one, and vice versa. I like details like that.
    X1.JPG 208.3K
    X2.JPG 191.4K
    X3.JPG 187.8K
    X4.JPG 176.5K
    X5.JPG 163.4K
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    I added some MDF material behind the cutout of the woofer mount. It is 1/4-inch thicker now, for the woofer to have a bit more material to work against when producing sound. I subtracted some material from the rear wall, since I was thickening out the enclosures anyway.

    The T-nuts are cemented and contoured in. Yes, I know about hurricane nuts, but T-nuts are what's available when I go to the hardware store down the street, so that's what I use.

    There are two pictures which show the difference between original and the better mounting.
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    On the outside...

    I far prefer the look of the larger enclosures and more pronounced edge bevel. At least when the grilles are off. With the grilles on, at some angles the look is slightly awkward. I think it would look better with the softer-lined grilles of the '80's Monitor series instead of the highly angular Series 2 grilles.

    The angles of the grilles don't match the angle of the enclosure bevel, and this may be part of the odd look at certain angles. Not to mention that the grilles themselves are not made with a perfect fit. The angle of the bevel is the same as what existed when the speakers were stock.

    Stock, I thought, it's too much grille for the speaker. Now, it's too much speaker for the grille at certain angles. I say, ditch the grilles! :) Most things sound better with the grilles off anyway.

    I notice that in some of these photos, the stain appears blotchy. This bothers me, as the appearance of the speakers in real life is not that disturbing. Most of this is the background that is being reflected off the semi-gloss finish.
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    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    Enough of the grilles :) They look better without them!
    01.JPG 104.2K
    02.JPG 176.4K
    04.JPG 198.2K
    11.JPG 239.6K
    27.JPG 172.2K
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    Some more....
    26.JPG 108.2K
    20.JPG 173.5K
    21.JPG 173.5K
    22.JPG 149.4K
    24.JPG 262.2K
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    The rear....
    25.JPG 122.6K
    28.JPG 121.9K
    29.JPG 109.1K
    31.JPG 95.1K
    32.JPG 144.8K
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    The attachment hardware, stainless steel. The back of the tweeter (SL2500) faceplate was molded with lots of recessed cavities. This is nice, as I was able to fill each one with an epoxy/Repti-sand mixture to help damp vibrations in the faceplate. A knuckle rap on the faceplate now gives a quick-decaying "thud" instead of a long-decaying "theeeeng".

    For the woofer, I did things a little different this time. Accompanying the bolt is a lock-washer, then one of those plasticized washers with one flattened edge (for the sake of the woofer surround), and then a contoured speed-nut. I put the speed-nut on there so that pressure from the bolt was a little more evenly distributed around that immediate area. I like the way this came out.
    12.JPG 172.7K
    13.JPG 226.1K
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    And a few more pictures to finish up.

    Things I like about this project:

    1. The carbon fiber. This is a big improvement. Aside from the exotic looks, it helps the damping of the front baffle. Using a stethoscope held to various spots on the front baffle, I tapped on places around the enclosure of the speaker which was not yet treated with the carbon fiber vs. one that had the fiber applied. The difference in damping was immediately noticeable. Although I am not good at identifying frequencies by ear, there was a very prominent frequency present in the untreated front baffle vs. the treated baffle. On the untreated baffle, this frequency 'hung on' for an identifiable period of time. On the treated baffle, it was gone, or at least so short in duration that I could no longer detect it by ear. Finances allowing, I'll be doing this on future Polk projects, including the SRS 2s. This stuff is not cheap; and with a (45-degree) twill weave, if you want a symmetrical look between the two speakers you have to rotate the fiber 90 degrees. This requires buying a lot more material. In the future, I will probably use a plain weave for large projects.

    2. I like the way the semi-gloss finish turned out.

    3. Much better vibration damping across the board- thicker enclosures, tweeter faceplates, woofer Dynamat (of course! :) ), more stout crossovers, custom tweeter and woofer gaskets, front baffle damping, etc.


    Things I don't like about this project:

    1. The somewhat awkward look of the grilles. It might have been better to make new grilles.

    Anyway, I hope you all enjoy!

    Geoff
    33.JPG 178.9K
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    35.JPG 137.4K
    36.JPG 161.3K
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • Nightfall
    Nightfall Posts: 9,404
    edited September 2013
    Good lord man. Those might be the nicest Monitor 4's on the planet.
    afterburnt wrote: »
    They didn't speak a word of English, they were from South Carolina.

    Village Idiot of Club Polk
  • [Deleted User]
    [Deleted User] Posts: 7,659
    edited September 2013
    Very nice project, well done!
  • Nightfall
    Nightfall Posts: 9,404
    edited September 2013
    I have to know. How much money and hours?
    afterburnt wrote: »
    They didn't speak a word of English, they were from South Carolina.

    Village Idiot of Club Polk
  • westmassguy
    westmassguy Posts: 6,725
    edited September 2013
    Beautiful job! Just a suggestion, the RDO-198-1 Tweeters are much smoother and more detailed than the SL2500s.
    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
    Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
    Cables: Speaker: Furez 10/2 with GLS Locking Banana Plugs
    Interconnect: Furez 10/2 with SpeakONs
    ICs: Custom Furez by Douglas Connections
    Den:
    Bose 901 Series II Continentals Restored, Re-Built Equalizer with Elna Silmic IIs, Sonicaps, and Silver Mica Caps
    Carver CT-3 Pre, Carver C-500

    dhsspeakerservice.com/



  • heiney9
    heiney9 Posts: 24,135
    edited September 2013
    Awesome, but how do they sound?

    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 Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • drumminman
    drumminman Posts: 3,396
    edited September 2013
    Really nice Geoff. Outstanding workmanship as usual.
    "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
  • Mr. Bubbles
    Mr. Bubbles Posts: 736
    edited September 2013
    Very nice work! I didn't see any blotchyness, just some reflections from the carpet/ rug it appeared. Again; Very nice
    If con is the opposite of pro, is Congress the opposite of Progress?!


    Monitor 5Jr, Monitor 5, RTA12, RTA 15TL, SDA 2A, 1c, SRS 2, 1.2TL, CRS, Atrium.
  • Easy Runnin
    Easy Runnin Posts: 484
    edited September 2013
    Beautiful work. I really like the carbon fiber. Wher do you get it?
    HT- Samsung PN50B860/Integra DTR 30.3/Rt55 Fronts
    Rt35i Surrounds/Cs1000p Center/SVS BP1000 Sub
    2CH - B&K MC-101 pre/B&K EX-442 amp/NAD 2400 amp
    Polk SDA1C, Polk Monitor 7, New Large Advents and Polk RTA 8T
    BR - Yamaha CR800/Polk monitor 5
  • Face
    Face Posts: 14,340
    edited September 2013
    Nice job!
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
  • zingo
    zingo Audiophile Posts: 11,255
    edited September 2013
    You are a mad scientist of the best kind, and I bow to all your knowledge and talent.

    Wanna bring these speakers over when you come to checkout my SRS 2s? :)
  • gmjungbluth
    gmjungbluth Posts: 232
    edited September 2013
    These are beautiful! Excellent work!!!!
    HT System:
    Marantz NR-1403
    Front: Klipsch CF-4
    Rear: Paradigm Atom V3
    Center: Boston Acoustic VR12
    Sub: Bowers & Wilkins ASW600

    2Ch:
    Restored Fisher 500C
    Yamaha P-500 Turntable

    Living Room:
    Harman Kardon 3380
    Restored Polk Monitor 7B

    Bedroom:
    Harman Kardon VR-3750
    Cambridge Soundworks Ensemble
    Polk PSW10

    In and out of rotation:
    KLH Model 6,
    Polk LSI7
    NAD 7100
  • cnh
    cnh Posts: 13,286
    edited September 2013
    Absolutely "beautiful"! Too bad I spent most of my shop days daydreaming and carrying around copies of Camus' The Stranger, Oscar Wilde's De Profundis, and Hesse's Magister Ludi. I spent a lot of my time outside the practical world of tools and labor. And I'm still pretty much of a dreamer who'd rather read, write or just listen to music than solder, sand, or saw. lol

    But I can appreciate the beauty of good craftsmanship. And that's pretty impressive. But don't expect yours truly to ever do anything like that. lol

    cnh
    Currently orbiting Bowie's Blackstar.!

    Polk Lsi-7s, Def Tech 8" sub, HK 3490, HK HD 990 (CDP/DAC), AKG Q701s
    [sig. changed on a monthly basis as I rotate in and out of my stash]
  • Mystery
    Mystery Posts: 2,543
    edited September 2013
    Man, some people have all the time and skill.
    Good job!

    Sonus Faber Concerto Grand Piano, Klipsch, B&W DM602.5, Epicure 20+, T/E 280, 100V, Polk.
    Subwoofers: Monitor Audio, B&W ASW300, Triad ProSub Bronze.
  • TNHNDYMAN
    TNHNDYMAN Posts: 2,145
    edited September 2013
    Very, very nice. The finish is gorgeous.
    2-ch System: Parasound P/LD 2000 pre, Parasound HCA-1000 amp, Parasound T/DQ Tuner, Phase Technology PC-100 Tower speakers, Technics SL-1600 Turntable, Denon 2910 SACD/CD player, Peachtree DAC iT and X1asynchorus USB converter, HSU VTF-3 subwoofer.

  • VR3
    VR3 Posts: 24,488
    edited September 2013
    Those turned out great! Very nice!
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    Regarding time, money, sound, etc.

    These were done for somebody else, of course. And there are always priorities given as far as what to spend money on and what not to. RDO198 vs. SL2500....not a priority in this case. The veneer and finish...using veneer and dyes/stains/finishes I already had on hand. Building out the enclosures...not expensive, just some MDF. The carbon fiber...willing to take the plunge here.

    Ultimately, one can spend incredible amounts of money on what really is, and will always be, just a Monitor 4.6 (albeit a much better one). Same drivers, same internal volume, same vented alignment. In that respect, projects like this are kind of goofy. But, if someone has a specific need (like a bookshelf speaker no taller than 18" for example) then they fit the bill nicely while maintaining a fairly reasonable cost. In other words, they are going to someone who has a specific need for something this size. Were I going to keep them for myself, I would sell the 2500's, buy two more 6502's, take a full round of measurements on the drivers, and re-engineer as a flat vented alignment (like a QB3) in an MTM configuration - in other words a whole new speaker that looks more like an 8tl. This would take a little more time though. I've actually toyed with this idea. See the attached photo, a picture of an 8tl that I modified.

    As far as the time committed, these took me about 3 months.

    I'll see if I can find a picture of the network mounted inside the enclosure.

    G~
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    Here's the photo I was thinking of, the crossover mounted inside the enclosure. It's hard to see, but it's on 1/4" standoffs, screwed down with just a bit of cement so nothing comes loose in transit. Plus, one more of the carbon fiber finish.

    Thank you guys for the compliments, it's nice to see the same names as last time!

    Jake, I would be happy to bring them over. But honestly, I want them boxed up and out of here, as quick as possible :)
    X6.JPG 127.7K
    cf.JPG 121.8K
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • boston1450
    boston1450 Posts: 6,714
    edited September 2013
    Beautiful job well done. Now time for them to enjoy them :)
    ...
    ...
    Randy/Maine .. SDA-CRS+TL-RTA15TL-Cs1000p
  • geoff727
    geoff727 Posts: 546
    edited September 2013
    geoff727 wrote: »
    Were I going to keep them for myself, I would sell the 2500's, buy two more 6502's,

    I should have said... 6502's or other appropriate driver considering the parameters.
    Polk SDA SRS 2
    Polk RTA 15tl
    Polk Monitor 7C
    Polk Lsi9

    Infinity RS-II (modded)
    Infinity RS-IIIa (modded)
    Infinity RS 2.5 x 2

    Magnepan 1.6QR (modded)

    System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373
  • Oldfatdogs
    Oldfatdogs Posts: 1,874
    edited September 2013
    As always beautiful work,good to see you posting again.
    Dan
  • kcoc321
    kcoc321 Posts: 1,781
    edited September 2013
    Those look awesome Geoff... but then I would expect nothing less ;)
    You are an artist ")

    The most amazing thing to me, aside of your dedication to 'perfection' is
    that you do this all out of a two bedroom apartment, with no shop/ garage or
    paint booth or nuthin... in your flippin dining room & deck ...lol
  • Mike Reeter
    Mike Reeter Posts: 4,070
    edited September 2013
    Love the new look, you have an amazing talent indeed.
    SDA SRS 2.3TL's/SDA SRS 3.1TL's/SDA CRS+4.1TL's and some other stuff
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