Monitor 7As

Options
kkritsilas
kkritsilas Posts: 14
edited October 2015 in Vintage Speakers
afopvx4fxk2w.jpg
kg8l2uipfhze.jpg
I just picked up a pair of Monitor 7As from a pawnshop. They were $13. As you can guess, they have some issues, but I do have a two week period in which I can return them, so it was worth the gamble.

On one speaker, the tweeter seems to be blown. I would guess that it needs to be replaced; probably end up replacing both of them. I think the correct replacement is the RO194 ( I will, of course, check the crossover network, first)? I think, because I live in Canada, that I would need to get the tweeters from Walter Moser.

I was also thinking of changing the resistors & capacitors in the crossover, just on the basis of the original parts being about 30 years old. Are Solen capacitors the way to go, or is there something better? Can somebody recommend resistors that would be better than just standard carbon composition acoustically? Is it necessary to change the inductors, or is there some sort of inductor that will improve the sound?

Post edited by kkritsilas on
· Share on FacebookShare on Twitter

Comments

  • tonyp063
    tonyp063 Posts: 1,046
    Options
    You'll want to post a picture of the tweeter. I believe the 7As used Peerless & the RDO-194 is *not* a drop in replacement for them.

    Copying a post from Dave (westmassguy) in another thread where he says:

    "Your Crossovers most likely have a mix of Mylar and Non-polarized Electrolytics, with Sandcast Resistors. You'll want to replace all of them.
    You'll want Metalized Polypropylene Caps, and Mills or Mundorf MOX Resistors.
    Entry Level, I.E. inexpensive, would be Dayton or Solen MP Caps, and Clarity PX would be a step above. The much better, and expensive Caps would be Sonicap Gen I, or Clarity ESAs."
    · Share on FacebookShare on Twitter
  • kkritsilas
    kkritsilas Posts: 14
    Options
    Sorry, I will get that soon. I haven't opened up the speakers yet.

    Thanks for the information about the crossover components.
    · Share on FacebookShare on Twitter
  • Nightfall
    Nightfall Posts: 10,067
    Options
    You can't drop in RDO-194's. You either need a used original:

    http://www.ebay.com/itm/Sweet-Polk-Audio-Peerless-Pinhole-Tweeter-No-5-514-05-82-Free-Shipping-/252121415767?hash=item3ab39b8057

    ...or a new Midwest clone:

    http://www.ebay.com/itm/8-ohm-Tweeter-for-Polk-Audio-HF1000-SL1000-for-Monitor-RTA-Speakers-MT-4115-8-/150791478865?hash=item231bdf5e51
    afterburnt wrote: »
    They didn't speak a word of English, they were from South Carolina.

    Village Idiot of Club Polk
    · Share on FacebookShare on Twitter
  • pitdogg2
    pitdogg2 Posts: 24,553
    edited October 2015
    Options
    Might be a fuse issue as some were fused. Check binding cup got fuse holders
    · Share on FacebookShare on Twitter
  • Cfidave
    Cfidave Posts: 5
    Options
    I used Sonicaps for the high freq. capacitor and Solens pollys for the low freq. Mills resistors. I have 7A's as well and that combination sounds great.
    Amps: Dynaco ST 70 (rebuilt), Hafler DH-200, Preamps: Perreaux SX1, Akitica PR 101, CD Players: Onkyo RDS 511, Teac RW 900 MKII, Sony SACD S9000ES, Turntable: Pioneer PL630, Sony 5520 Speakers: Ohm Walsh 4's, Large Advents, Rogers LS7's, POLK Monitor 7A's.
    · Share on FacebookShare on Twitter
  • F1nut
    F1nut Posts: 49,787
    Options
    Yep, check the fuse.

    Don't use Solen in the high pass.
    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

    · Share on FacebookShare on Twitter
  • leftwinger57
    leftwinger57 Posts: 2,917
    Options
    When I got my M7s a few months ago I didn't know what generation they were.I'm guessing since the x-overs were from '78 they have to be 7A also w/ the out board 1a fuse. For my taste the Peerless tweeters are still smoother than the RDO-194-s but a boatload better than the SL-2000 silver 2nu1dny7s0v0.jpg
    domes. If only tweeters are beat than replace them , I got mine for $60 w/ chewed up corners but the sound was great. Xx-overs are now out for Dave to do his magic and these will be keepers.21oi80m4xn4a.jpg
    2chl- Adcom GFA- 555-Onkyo P-3150v pre/amp- JVC-QL-A200 tt- Denon 1940 ci cdp- Adcom GFS-6 -Modded '87 SDA 2Bs - Dynamat Ext.- BH-5- X-Overs VR-3, RDO-194 tweeters, Larry's Rings, Speakon/Neutrik I/C- Cherry stain tops Advent Maestros,Ohm model E

    H/T- Toshiba au40" flat- Yamaha RX- V665 avr- YSD-11 Dock- I-Pod- Klipsch #400HD Speaker set-

    Bdrm- Nikko 6065 receiver- JBL -G-200s--Pioneer 305 headphones--Sony CE375-5 disc
    · Share on FacebookShare on Twitter
  • michaeljhsda2
    michaeljhsda2 Posts: 2,170
    edited October 2015
    Options
    More than likely the fuse is making poor contact with the fuse holder due to corrosion. Spray contact cleaner on it and rotate the fuse in the holder to distribute the cleaner. If you don't have contact cleaner, try rotating the fuse while music is playing and listen for sound trying to get through to the tweeter. A piece of wire can be used in place of the fuse to test for continuity in case the fuse is blown.
    SDA SRS 2.3TL's
    Silk Audio MS-90-BT integrated tube amp
    Yaqin MS-20L integrated tube amp
    SDA 2B TL's
    · Share on FacebookShare on Twitter
  • kkritsilas
    kkritsilas Posts: 14
    Options
    I will try the fuse idea tonight or tomorrow. Thanks for the idea. It may be worth the time and effort to clean up the fuse holder with steel wool, and replace the fuses; they should be cheap enough.
    · Share on FacebookShare on Twitter
  • pitdogg2
    pitdogg2 Posts: 24,553
    Options
    kkritsilas wrote: »
    I will try the fuse idea tonight or tomorrow. Thanks for the idea. It may be worth the time and effort to clean up the fuse holder with steel wool, and replace the fuses; they should be cheap enough.

    that a boy excellent idea :p
    · Share on FacebookShare on Twitter
  • leftwinger57
    leftwinger57 Posts: 2,917
    Options
    If the cleaner doesn't do it and you see corrosion try a little emry cloth but be gentle ,you don't want to rip the crap out of the holder. Any car parts place has those fuses.
    2chl- Adcom GFA- 555-Onkyo P-3150v pre/amp- JVC-QL-A200 tt- Denon 1940 ci cdp- Adcom GFS-6 -Modded '87 SDA 2Bs - Dynamat Ext.- BH-5- X-Overs VR-3, RDO-194 tweeters, Larry's Rings, Speakon/Neutrik I/C- Cherry stain tops Advent Maestros,Ohm model E

    H/T- Toshiba au40" flat- Yamaha RX- V665 avr- YSD-11 Dock- I-Pod- Klipsch #400HD Speaker set-

    Bdrm- Nikko 6065 receiver- JBL -G-200s--Pioneer 305 headphones--Sony CE375-5 disc
    · Share on FacebookShare on Twitter
  • kkritsilas
    kkritsilas Posts: 14
    edited October 2015
    Options
    Tweeters are the ones with the pinhole in the middle, so Peerless.

    Tonight, I will be cleaning up the fuse holders; one of the speakers had a slow blow fuse, which will be going (I have new 1A fuses). We'll see if the tweeter works after I clean up the fuse holder. If not, I would like to check the resistor values, and the wiring of the crossovers, just to make sure that everything is wired up properly (looks like somebody got in there at some point in the past).

    Regarding the tweeter that is blown, is there some way of doing a resistance test on it? I know with midranges and woofers, you can check DC resistance (an 8 ohm driver will have a DC resistance of 6-7.2 Ohms), so is there a value for the tweeter that I should be looking for? I figure if it is blown, it will be open, and if it is just damaged, it may (or may not) show up as an altered resistance value.

    · Share on FacebookShare on Twitter
  • kkritsilas
    kkritsilas Posts: 14
    edited October 2015
    Options
    4nqcfk57y6yl.jpg
    Here is the tweeter picture. The tweeter is dusty, so the pinhole in the middle is not as obvious.
    · Share on FacebookShare on Twitter
  • F1nut
    F1nut Posts: 49,787
    Options
    Do NOT use steel wool on the fuse holder.

    If you don't have a purpose made non-scratching metal cleaner product on hand, use a clean pencil eraser.
    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

    · Share on FacebookShare on Twitter
  • westmassguy
    westmassguy Posts: 6,850
    Options
    kkritsilas wrote: »
    Tweeters are the ones with the pinhole in the middle, so Peerless.

    Tonight, I will be cleaning up the fuse holders; one of the speakers had a slow blow fuse, which will be going (I have new 1A fuses). We'll see if the tweeter works after I clean up the fuse holder. If not, I would like to check the resistor values, and the wiring of the crossovers, just to make sure that everything is wired up properly (looks like somebody got in there at some point in the past).

    Regarding the tweeter that is blown, is there some way of doing a resistance test on it? I know with midranges and woofers, you can check DC resistance (an 8 ohm driver will have a DC resistance of 6-7.2 Ohms), so is there a value for the tweeter that I should be looking for? I figure if it is blown, it will be open, and if it is just damaged, it may (or may not) show up as an altered resistance value.

    The Peerless should read about 7.5 ohms if the coil is good.
    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/
    · Share on FacebookShare on Twitter
  • kkritsilas
    kkritsilas Posts: 14
    edited October 2015
    Options
    F1nut:

    Would you care to elaborate? What is the issue with steel wool (0000 is what I had intended to use). Another poster suggested emery cloth, which is far more coarse than the 0000 steel wool. Alternatively, I have some 2000 grit wet/dry sandpaper. Is the concern with scraping off the plating on the fuse holder?
    · Share on FacebookShare on Twitter
  • F1nut
    F1nut Posts: 49,787
    Options
    It will leave fine scratches. Emery cloth and even 2000 grit W/D will too. Use a clean pencil eraser if you don't want to invest in DeOxit/ProGold.
    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

    · Share on FacebookShare on Twitter
  • dhart86
    dhart86 Posts: 1,594
    Options
    I have a couple of peerless tweeters sitting in reserve. If the tweeter is busted and needs to be replaced, shoot me a pm
    Main Rig:
    Antipodes DX > Roon > PS Audio Directstream Jr.>deHavilland Ultraverve 3 >Belles Reference 150a >Harbeth C7 ES3


    Second Rig:
    Roon> PS Audio Directstream Jr Bridge II > EE Minimax pre (Tutay mods) >Belles 150A Ref >Monitor 5 (Westmassguy-modded)


    · Share on FacebookShare on Twitter
  • kkritsilas
    kkritsilas Posts: 14
    Options
    dhart86 wrote: »
    I have a couple of peerless tweeters sitting in reserve. If the tweeter is busted and needs to be replaced, shoot me a pm

    Sent what I thought was a private message last week. Did you get it? or did I not do it properly? It was regarding your Peerless tweeters.
    · Share on FacebookShare on Twitter
  • dhart86
    dhart86 Posts: 1,594
    Options
    pm sent
    Main Rig:
    Antipodes DX > Roon > PS Audio Directstream Jr.>deHavilland Ultraverve 3 >Belles Reference 150a >Harbeth C7 ES3


    Second Rig:
    Roon> PS Audio Directstream Jr Bridge II > EE Minimax pre (Tutay mods) >Belles 150A Ref >Monitor 5 (Westmassguy-modded)


    · Share on FacebookShare on Twitter
  • kkritsilas
    kkritsilas Posts: 14
    Options
    Hi,

    Back with more questions, although I haven't located a Peerless tweeter yet. In regards to the crossover, I have read the part about using Clarity ESA capacitors, and maybe Solen being acceptable in the low pass section. My real question is the value of the low pass capacitor. The value, from the schematic in another posting, is 34 uF, yet none of the manufacturers make that value, they make 33 uF. Do I use a 33 uF capacitor, or do I use a 33uF capacitor and put a 1 uf capacitor in parallel with it? I am getting close to ordering the parts, and want to order them once, and correctly, as opposed to ordering them and then going back and ordering a second time (paying for shipping twice to Canada does not appeal to me).

    Gus
    · Share on FacebookShare on Twitter
  • westmassguy
    westmassguy Posts: 6,850
    Options
    33uf is fine for those. Best practice when combining two capacitors, is to match their values as closely as possible. Two 17ufs for example. No one makes those either, but you get the idea.
    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/
    · Share on FacebookShare on Twitter
  • Mike53
    Mike53 Posts: 21
    Options
    What luck...I'm glad I found this thread.

    Just last week I was given an pair of Monitor 7A's. They sound fine but I plan on upgrading the cross over...using the suggested components you guys have recommended.

    One question I do have, is it possible to tell where these were made using the serial #?
    I was told they were made here in Baltimore, at their original location.

    Any thoughts are greatly appreciated.
    · Share on FacebookShare on Twitter