I'm back in on Monitor 7's.....finally...or sort of....I think.

Ten or so years ago I got pulled into the vintage Polk sound after getting a free pair of 5jr+'s that I subsequently gave to my daughter. Those sweet little babies pulled me into a pair of 7B's that I eventually made stands for and recapped.

During that time I was going through a good amount of gear, buying, selling, repairing etc... But the 7B's rose to the top and I loved the way they sounded with a variety of associated gear. Particularly after the 'surgery'.

Things changed, we moved and stuff had to go. Since then I've thought about stuff I parted with; Infinity, Snell, EPI, AR, KEF, but eventually the ones I regretting selling off the most was the 7B's.

Recent events have gotten me bit by the bug again and damn if I didn't run into a pair of 7's locally listed. Paid too much? Maybe. But they are in very nice shape and play beautifully as is. Of course given my previous experience I am not going to be able to leave them alone and I am looking forward to getting these into reference condition.

So I believe I'm dealing with Monitor 7 Series II's. The lineage is a bit confusing as we all know Polk made changes willy-nilly but the date stamps on the tweeter and one of the caps are from 1987.

My 7B's had a flat front edge, badge on the wood, peerless tweeter and external fuse. These have a beveled front edge, badge on the grill, the SL2000 tweeter and no external fuse and no poly switch either.

As I've read much on the original 7 models I haven't focused much on the series II. Is there a prevailing opinion on if the II's are as update worthy as the earlier models?

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Comments

  • aprazer402
    aprazer402 Posts: 3,087
    edited September 2018
    Definitely not Monitor 7 "Series II" They were not out until 1990 +/- 6 months. Crossover dated 1987. Series II had the SL2500 tweeter, the one shown has the SL-2000. No fuse on rear above binding posts, I'd say 7C's. 7's and & 7B's had fuse(s) and most had Peerless tweeters.
  • delkal
    delkal Posts: 764
    I guess I always thought for most of the original Monitor line..........

    The A's had the fuse and Peerless tweeters
    The B's had the polyswitch and the Sl-2000 tweeters (like yours has)
    And the Series 2's had the newer SL-2500 tweeters.

    This is the way the original 5's and 10's were set up so I don't see why this would not apply to the 7's also ( but I am sure we will find out soon though).
  • Jonesy
    Jonesy Posts: 189
    Well isn't Polk archeology fun!

    There seems to be as many opinions as there are posts on as many different forums. One post states series II doesn't start until 1990 and has the sl2500. The 'official' SDA series chart doesn't show anything produced in the 7 line after 1990 except the II's yet mine have the sl2000's dated 1987, along with the 12u cap dated 1987.

    Possible these are 7 series II's that had the tweeters replaced with sl2000's (why? stranger things have been done I guess)? The SDA lineage timeline shows 7C's only at 1979. This would make a difference when it comes time to replace the tweets. 194's to match the 7C's or 198's to match the series II's.

    Thanks Polk. Love ya Polk! Really. It's kinda fun (sorta).

    Perhaps the only definitive answer is to call Polk to order the tweets, give them the serial # and put it on them.

    Regardless, I think were down to either tweeter hacked II's or very late production C's that aren't reflected in the SDA chart.
  • Jonesy
    Jonesy Posts: 189
    Well I don't see an edit function so I just wanted to be clear. My old eyes failed to see the poly switch until I looked at the pics. It's there.
  • pitdogg2
    pitdogg2 Posts: 24,477
    It would be easy to check. Take tweeter out are both quick connects the same size or two sizes?
    Both same RD-0194
    Different sized RD-0198

  • motorhead43026
    motorhead43026 Posts: 3,892
    edited September 2018
    My 10's are series 2, thought my 7's were but they are 7C's.

    Anyway, these 7's no matter the series are a great speaker.
    2 channel: Anthem 225 Integrated amp; Parasound Ztuner; TechnicsTT SL1350; Vincent PHO-8 phono pre; Marantz CD6005 spinner; Polk SDA2BTL's; LAT International speaker cables, ZU Mission IC's and power cables all into a PS Audio Dectet Power center.

    Other; M10 series II, M7C's, Hafler XL600 amp, RB-980BX, Parasound HCA-1500 amp , P5 preamp, all in storage. All vintage Polk have had crossover rebuilds and tweeter upgrades.

    The best way to predict the future is to invent it.

    It is imperative that we recognize that an opinion is not a fact.

    Imagine making politics your entire personality.
  • Jonesy
    Jonesy Posts: 189
    pitdogg2 wrote: »
    It would be easy to check. Take tweeter out are both quick connects the same size or two sizes?
    Both same RD-0194
    Different sized RD-0198

    Both are sl2000
  • pitdogg2
    pitdogg2 Posts: 24,477
    Jonesy wrote: »
    pitdogg2 wrote: »
    It would be easy to check. Take tweeter out are both quick connects the same size or two sizes?
    Both same RD-0194
    Different sized RD-0198

    Both are sl2000

    Right I see that. If they originally had the SL2500 it would take two different sized quick connects. You made the comment that they may of switched tweeters. Therefore the quick connects would give it away and also tell you which replacement tweeter to get.
  • aprazer402
    aprazer402 Posts: 3,087
    edited September 2018
    I found a few threads regarding Monitor 7's. There are probably several hundred of them. These might be helpful, if not, maybe somewhat interesting.

    http://forum.polkaudio.com/discussion/52499/monitor-7a-b-c-question

    http://forum.polkaudio.com/discussion/137297/polk-monitor-7as-vs-7cs-comparison

    http://forum.polkaudio.com/discussion/51647/monitor-7s-and-7as

    http://forum.polkaudio.com/discussion/comment/2381456#Comment_2381456

    http://forum.polkaudio.com/discussion/comment/2397566#Comment_2397566

    http://forum.polkaudio.com/discussion/comment/2385411#Comment_2385411

    http://forum.polkaudio.com/discussion/comment/2299582#Comment_2299582

    http://forum.polkaudio.com/discussion/comment/2038818#Comment_2038818

    http://forum.polkaudio.com/discussion/comment/319187#Comment_319187

    In the last thread listed note the photo GrahamT attached to his post, his post is the fourth from the bottom, it shows his early 1985 7C's with a fuse and a SL1000 tweeter. Some 7C's lacked the fuse, they had a polyswitch, and used the SL-2000 tweeter.

    The Monitor 7's probably have most confusing time-line to follow. The individual models overlapped years and different components were used apparently interchangeably. Monitor 5's & 4's can also be difficult to follow. Labeling did not always include a letter suffix on the rear label after the model number.

    My 1986 Monitor 10B's are only shown as Monitor 10 on the label on the speaker back, but the cardboard box they came in had a large "B" stamped on the box.












  • Jonesy
    Jonesy Posts: 189
    pitdogg2 wrote: »
    Jonesy wrote: »
    pitdogg2 wrote: »
    It would be easy to check. Take tweeter out are both quick connects the same size or two sizes?
    Both same RD-0194
    Different sized RD-0198

    Both are sl2000
    If they originally had the SL2500 it would take two different sized quick connects.

    Copy that. Thank you sir. I finally get it. So these must be original sl2000's. Which means, 7C's? I guess?
  • F1nut
    F1nut Posts: 49,708
    Those are 7C's, period.

    Best thing you can do is upgrade to RD0194 tweeters, upgrade the caps and resistors and get some real speaker cables.
    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

  • Jonesy
    Jonesy Posts: 189
    (not meant to be sarcastic at all)

    Ahhhhh......I feel much better.

    Thank you Nut. The definitive authority has chimed in at the right time.

    Can we call them 1987 7C's?

    Now that I have a vintage, a model and am able to plan an update path I will post progress as it occurs.

    BTW, don't judge me on the speaker cable. Totally temporary slop that was laying around in order to test things out. I run 12 ga on all my permanent systems. But thanks for the concern.
  • ThomasD
    ThomasD Posts: 260
    Recently upgraded my 1985 7c's to TL status (via an outstanding x/o upgrade by @westmassguy) and performed the all the other basic improvements, i.e., RD-0198's, Hurricane nuts, Dyna-mat (or equivalent), BH 5, Armacell etc. Can not emphasize enough how much improvement in SQ happened. Can only describe it as 'Liquid' music now. Substantially improved smoothness & definition from the SL-2000's, more than enough low end bass (for me anyway). I don't even use my sub anymore with the 7's, prefer the crispness of the MW's & PR. All my digital & vinyl music has become a new experience to listen to now with so many more musical nuances that just weren't there before the upgrades. Makes my unmolested SDA2a's pale in comparison now. They are next on the upgrade list. As many on this forum & others have previously stated, the 7's were truly one of Polks 'Gems".
    Carver M4.0t, M1.0t, M200t, TX2, C1, C2, Marantz 2230, 2010, 4070, 1030, APPJ 2013, Rega Brio, Marantz Imperial 7's, Klipsch Heresy III, Quartets, KG4's, KG1's, 'The Sixes', R-12SW, Polk SDA 2a's, Monitor 7cTL's, SDA CRS's, 4a's, Zu Audio Dirty Weekends, Pro-ject Acryl TT, Cambridge 851N, 351C, Panamax 5300PM
  • Jonesy
    Jonesy Posts: 189
    Well that's an impressive testimonial for the TL mod. I've done a little initial reading on it, but now may have to investigate further. I remember the significant improvement after recapping my old 7B's. Considering those had the peerless perhaps the TL mod on these 7C's would put them closer to the old B's in performance?
  • rooftop59
    rooftop59 Posts: 7,952
    And if you haven’t already, there’s a little karma in the flea market. A chance to experiment will a little better cable for little investment... if ur lucky!
    Living Room 2.2: Usher BE-718 "tiny dancers"; Dual DIY Dayton audio RSS210HF-4 Subs with Dayton SPA-250 amps; Arcam SA30; Musical Fidelity A308; Sony UBP-x1000es; Squeezebox Touch with Bolder Power Supply
    Game Room 5.1.4:
    Denon AVR-X4200w; Sony UBP-x700; Definitive Technology Power Monitor 900 mains, CLR-3000 center, StudioMonitor 350 surrounds, ProMonitor 800 atmos x4; Sub - Monoprice Monolith 15in THX Ultra

    Bedroom 2.1
    Cambridge Azur 551r; Polk RT25i; ACI Titan Subwoofer
  • Jonesy
    Jonesy Posts: 189
    I appreciate the suggestions on cables and will play around with that aspect.

    Regarding the XO I'm starting to build a parts list but am not quite sure of what exactly I need as it's been a while since I did the old B's and there seems to be some difference between models, and even within models, as far as the XO design goes.

    It appears the 34u and 12u caps are the same, just a bit concerned on the resistor(s). I had 2 Mills on the build for the B's; 2.5 & 4.5 ohms at 12w but the lone resistor on these C's are labeled 2 ohm at 5w. Would the 2.5 @ 12w work for the resistor, and was the 4.5 ohm a replacement for the polyswitch?

    Man it sucks getting old.


  • pitdogg2
    pitdogg2 Posts: 24,477
    .5 ohm for the polyswitch 10 or 12 watt will work.
    While that 2.5 may work I'm not comfortable saying sure go ahead. Then again it may just quite the tweeter down a bit and be no problem.
  • ThomasD
    ThomasD Posts: 260
    I might be mistaken but Thoight that @westmassguy had a thread on a pair of 7c’s he did with a complete material list. Can’t find it right at this moment but can attest to his wealth of information regarding x/o questions on the 7’s and others. Was hoping he might notice this thread and chime in.
    Carver M4.0t, M1.0t, M200t, TX2, C1, C2, Marantz 2230, 2010, 4070, 1030, APPJ 2013, Rega Brio, Marantz Imperial 7's, Klipsch Heresy III, Quartets, KG4's, KG1's, 'The Sixes', R-12SW, Polk SDA 2a's, Monitor 7cTL's, SDA CRS's, 4a's, Zu Audio Dirty Weekends, Pro-ject Acryl TT, Cambridge 851N, 351C, Panamax 5300PM
  • Jonesy
    Jonesy Posts: 189
    DSkip wrote: »
    To piggy back on nuts post, if you can only describe your better cable as 12 gauge then you owe it to yourself to give some boutique types a try.

    Just FYI, this is the cable that will be running this little rig. Nothing fancy. Soundking 12 ga and Vampire spades. A friend and I went in together and made a pile of these things a while ago. Basic homebrew cable, but quite competent.

    I drool over some boutique cables on occasion, but without a boutique budget this is the best I can do. Still appreciate the suggestion and will keep an eye out for some PNF's.

    jluvtpz0fxd0.jpg
  • tonyp063
    tonyp063 Posts: 1,044
    ThomasD wrote: »
    I might be mistaken but Thoight that @westmassguy had a thread on a pair of 7c’s he did with a complete material list. Can’t find it right at this moment but can attest to his wealth of information regarding x/o questions on the 7’s and others. Was hoping he might notice this thread and chime in.

    You aren't mistaken.
    Here's his thread with pics
    http://forum.polkaudio.com/discussion/175042/monitor-7-crossovers#latest
  • Jonesy
    Jonesy Posts: 189
    Brief thread but very helpful Tony, thanks.

    But it leaves me with a bit of concern. I already placed my order with PE for the Mills resistors. A 0.5 for the poly and straight 2ohm for the tweeter, which is what's in there now. I see westmassguy used 2.5's on that XO. Just concerned I got the wrong value.
  • F1nut
    F1nut Posts: 49,708
    You're fine, Dave used the 2.5 ohm instead of a 2.0 and .5 ohm.
    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

  • Jonesy
    Jonesy Posts: 189
    Thanks nut.

    So I pulled these out of the initial testing rig and put them in what will be their final resting position with some gear they will have to live with for a little while.

    I was really reminded of what I loved about the B's that I cut loose. Nice presence and well balanced everywhere. Yet I know these can do more. Puts even more anticipation on getting the mods done, but I am now also eager to put the right gear behind it.

    The Nakamichi SR-2A receiver sounds very nice, and I think the Polks show how good of a receiver it is, but I know these drivers are begging to be grabbed ahold of and controlled. Since I really enjoyed the Yamaha juice that the old B's had I think I'm going to get the M-4 I have sitting dormant right now refurbished and track down a C-4 to go with it.

    Keep in mind these are just sitting on temporary paving blocks just to get them off the floor. Custom stands are in the planning stage.

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  • mlistens03
    mlistens03 Posts: 2,767
    Yes. I accidentally pulled over my Mission speakers on em doing that. My dad’s Boston speaker’s were sitting on top, and they fell and broke, as I mentioned in PSOVLSK’s FS thread.
  • Jonesy
    Jonesy Posts: 189
    So I'm starting to gather parts for the mods and it occurs to me that the electronics behind them need attention.

    I recall the 7B's responded very well to quality improvements of associated gear; receiver to separates then higher current current amps. Remembering that I have a Yamaha M-4 sitting in a box doing nothing I find a NAD 1020 preamp locally and swap out the Nakamichi SR-2A receiver that was pushing the C's.

    While that Nelson Pass designed Stasis circuit receiver was very competent it just wasn't enough juice. Just like the old B's did, these C's have really opened up with the M-4/1020 combo. Bigger soundstage, better imaging and just overall better presence.

    I'll be itching to get these mods (and stands) done!
  • westmassguy
    westmassguy Posts: 6,850
    Sorry I missed this. As @F1nut pointed out, the polyswitch, and single resistor are in series, so a single 2.5 ohm was used to replace them both
    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

    dhsspeakerservice.com/
  • Isn’t the RD0194-1 the part number for model number SL2000 tweeter?

    Likewise the RD0198-1 is an SL2500?
  • pitdogg2
    pitdogg2 Posts: 24,477
    edited November 2022
    smolder wrote: »
    Isn’t the RD0194-1 the part number for model number SL2000 tweeter?

    Likewise the RD0198-1 is an SL2500?

    No the replacement for the SL2000 is the RD-0194-1.

    Likewise the RD-0198-1 is the replacement for the SL3000 but it so happens that it also works for the SL2500.

    Both are much better tweeters than the previous tweeters they are replacing.

  • pitdogg2 wrote: »
    smolder wrote: »
    Isn’t the RD0194-1 the part number for model number SL2000 tweeter?

    Likewise the RD0198-1 is an SL2500?

    No the replacement for the SL2000 is the RD-0194-1.

    Likewise the RD-0198-1 is the replacement for the SL3000 but it so happens that it also works for the SL2500.

    Both are much better tweeters than the previous tweeters they are replacing.

    I’ve read both on forums. Yet I see them listed as one product at Midwest Speaker…

    https://www.midwestspeakerrepair.com/shop/home-audio/tweeters/polk-audio-1-tweeters/polk-audio-sl2500-sl3000-1-inch-dome-tweeter/