Model 11 / RTA 11 questions

Hello everyone, This is my first post so be kind. I recently purchased a pair of Model 11 or RTA 11 speakers. They are in amazing shape and sound fantastic. Given their age though, I'm sure the capacitors are tired. When I opened the speakers (and I think I was the first to do so) I noticed the black foam that is supposed to be behind the inner? driver had fallen down and at this point is too deteriorated to reuse. So I have 2 questions mainly, are my crossovers original or do they appear to be reworked? see the attached picture. Again these speakers sound amazing as is and id like to modify as little as possible. Will using them with degraded caps cause any damage to the drivers or my amp? Second, I attached a picture of some other foam that I have. I realize its not exactly the same stuff, but will it work? I'd figure its gotta be better than nothing at all. Thanks for any help you can provide.

cwso71iyeyxa.jpg
hb38jrt8zv9t.jpg
zzotrc192o9t.jpg

Comments

  • pitdogg2pitdogg2 Posts: 12,557
    Looks like maybe model 11. I believe the RTA11 is not what you have. Pictures of the front would be great. Do the have 1 tweeter 4 midwoofers and a 12" passive radiator?

    I personally have not seem that kind of foam in Polk speakers. To me it don't look original, the crossover from what i see look original.
  • Sorry yes, not sure why i didnt show those pics. BTW, the foam pictured, the small piece is what I believe to be original, the large one is what I have on hand and wish to replace it with. Anyhow, heres some more pics:

    dnv3axyawmkv.jpg
    09gtyr7pbi9l.jpg

  • DaveHoDaveHo Posts: 2,142
    edited February 2018
    I've never seen black foam like that in a pair of Polks. The stuffing at the bottom of the cabinet should be behind the mid-woofers, not behind the passive.
  • F1nutF1nut Posts: 41,224
    edited February 2018
    The foam should be there, behind one mid-driver only in each speaker. The Monitor 11 corrects the inherent flaw of the Monitor 10 by restricting the frequency of one mid-driver to prevent comb filtering. The foam helps accomplish that goal.

    Note that your speakers are marked Left and Right and need to be set up that way for the best results.

    Yes, those crossovers are 100% original and should be upgraded. Use Sonicap caps and Mills resistors. While you're in there remove the fuse, cut the fuse lead wires and make a bypass connection. The fuse wires are heavily oxidized by now. You can compensate for the loss of resistance from removing the fuse by increasing the tweeter resistor by 0.3 ohms.

    If you want to use the exact foam that Polk used, look at Sonex.

    Nice speakers, do them justice.
    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."


  • I found this thread here:

    http://forum.polkaudio.com/discussion/151057/repairing-model-11-speakers

    Seems like this person had the same thing I did, and the same white foam at the bottom. If you look in the picture, there is evidence that the foam was attached to the inside left side of the right speaker. The magnet seen is that of the left hand driver.

    5rpgoegpji7n.jpg
  • F1nut wrote: »
    The foam should be there, behind one mid-driver only in each speaker. The Monitor 11 corrects the inherent flaw of the Monitor 10 by restricting the frequency of one mid-driver to prevent comb filtering. The foam helps accomplish that goal.

    Note that your speakers are marked Left and Right and need to be set up that way for the best results.

    Yes, those crossovers are 100% original and should be upgraded. Use Sonicap caps and Mills resistors. While you're in there remove the fuse, cut the fuse lead wires and make a bypass connection. The fuse wires are heavily oxidized by now. You can compensate for the loss of resistance from removing the fuse by increasing the tweeter resistor by 0.3 ohms.

    If you want to use the exact foam that Polk used, look at Sonex.

    Nice speakers, do them justice.

    Thanks for the info, I've been browsing this forum for a while and hope you in particular would reply as it seems you are quite familiar with this rather rare model. So as for the placement of the foam, it looks like it isn't behind the mid driver but rather to its side. I think my replacement foam, while not original should be okay, certainly better than nothing. Might as well save some money, esp if I rebuild the crossover as I bet those caps wont be cheap. I imagine I can just use something like 3M spray adhesive to attach the foam to the cabinet?
  • F1nutF1nut Posts: 41,224
    The foam should span from the center to the outer side of the cabinet. It should be slightly below the driver.
    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."


  • F1nutF1nut Posts: 41,224
    edited February 2018
    Yeah, any foam is better than none, but if you notice the original valleys are much deeper meaning it can absorb more sound waves.

    One other thing, the white batting should at the bottom in these speakers. There's no where else to put it.
    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."


  • F1nut wrote: »
    The foam should span from the center to the outer side of the cabinet. It should be slightly below the driver.

    I noticed a bad connection (probably from removing and handling the crossover) so I pulled the LH driver and saw just that:

    fx5dsj3repoh.jpg

    No big surprise that after 36 yrs the foam could fall, just hanging from the brace and the side of the cabinet. Interesting design for sure. I'll use that location, but try to come up with some sort of support to hold the foam up.

    Now, and this could be a bit of an ask, is there a schematic of the crossover posted, or the parts values? Id like to keep the original assembled and operational before I order new parts and due to how things are mounted, I can't see all the values.
  • F1nutF1nut Posts: 41,224
    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."


  • So i rigged this up:

    4co4ba3us6ke.jpg
    5cuwm8m0yqlp.jpg

    I'd imagine it should be okay, and the foam won't be able to sag in the future. I figured the dowels would be better than using a cut board that could act as a baffle and do weird things to the sound. What do people think?
  • agfrostagfrost Posts: 2,243
    I like it.
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Marantz DV-9500 * Modded Adcom GDA-600 DAC * Rythmik F8
    Micro Seiki DQ-50 * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
  • F1nutF1nut Posts: 41,224
    It won't matter, in 10 years or less that foam will be so rotted it'll crumble and fall down anyway, but nice effort.
    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."


  • Hello again, so for the last few days, I have been trying in vain to source the necessary capacitors to redo the crossovers. The 45mfd and 5mfd have been easy enough to find. but I swear, the .5mfd does not exist lol. closest I have found is .47mfd or .56mfd. Will a .47 be "close enough" to .5 or would it cause problems?

    Here's the culprit, I think..
    884i0mq93rmi.jpg
  • FestYboyFestYboy Posts: 3,379
    .47 is within tolerance... But hey, what's .03uf between friends? ;)
  • JPeteJPete Posts: 250
    Resurrecting this year old thread as I am preparing to do crossovers and dynamat treatment on the baskets in my 11s soon. If @rmurad38 is still around, how did this build go? What capacitors did you end up using and how do they sound?
    Lexicon RT-10, Parasound P5, McCormack DNA 0.5, Polk SDA CRS+, SVS Sub
    Schiit Modi, Luminous Audio Axiom II, McCormack DNA-1, Digital Phase AP 2
    Marantz AV7701, Emotiva XPA-5, Paradigm 11se Mkii, DCM Time Windows, NHT 2C, SVS Sub

    Spares - Kenwood C1 Pre, NAD 2200PE, Polk Monitor 10B, Polk Model 11, other odds and ends
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