1st Gen SDA CRS Troubleshooting Numbers

Hello everyone;
Just joined. I've had my Polk SDA CRS since 1986. Amp: Technics SU-V8X.
Speakers - Crossovers all rebuilt (by a dedicated Speaker shop) when 1 upper came off the post, rotated over the lower and created some molten parts, last time volume was above 5.
Issue now is that the speakers go into safety mode at volume 4 or 5. (Just ran the Amp on my friends stereo, no issues with the Amp.) Checked all the speakers, and the outermost Right channel SL2000 doesn't cause the multi-meter to move, so I'll order a pair of replacement from Polk on my next USA trip.
Here are my numbers, as the resistance tends to be a bit higher than spec, is that the speakers showing their age?
Also, should I swap the 6503's so that each pair is the same resistance, flip a 6.7 and 7.1?
Thanks
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Comments

  • pkquatpkquat Posts: 601
    I'm surprised no one has replied yet. Maybe people are a little confused with all the info. It appears you have one blown tweeter, assuming the crossovers were rebuilt correctly. I am not sure about all the resistance values, but if one the the tweeters is blown, that is likely throwing the numbers off between pins, so i would not swap anything until the tweeters are sorted out. Pictures of the speakers and crossovers would be helpful.

    I'm not an expert on the CRS models, but from what I gather you have an early blade/blade 1984 model with two SL2000 tweeters on each speaker. Many people disconnect the dimensional tweeter on these. For the short term you could disconnect them and swap the bad one with one of the dimensional tweeters. A few searches on here should yield more information on this, or sometimes searching the forum via google gives more refined results. If not, hopefully someone will chime in soon.

    Polk offers the RD0-194 tweeter as a replacement for the SL2000's. You should not replace just one. They will not sound right. Either replace 2 and leave 2 disconnected, or replace all 4. The RD0-194 is a much better sounding tweeter too, so they are a recommended replacement regardless.

    The Schematics and additional info. can be found here:
    http://forum.polkaudio.com/discussion/55888/polk-audio-speaker-wiring-schematics-more-stereo-dimensional-array-sda

    I think the schematic specific to your model is this one:
    https://us.v-cdn.net/5021930/uploads/attachments/1/8/5/1/1/26679.pdf

  • pitdogg2pitdogg2 Posts: 11,154
    SDACRS86 wrote: »
    Hello everyone;
    Just joined. I've had my Polk SDA CRS since 1986. Amp: Technics SU-V8X.
    Speakers - Crossovers all rebuilt (by a dedicated Speaker shop) when 1 upper came off the post, rotated over the lower and created some molten parts, last time volume was above 5.
    Issue now is that the speakers go into safety mode at volume 4 or 5. (Just ran the Amp on my friends stereo, no issues with the Amp.) Checked all the speakers, and the outermost Right channel SL2000 doesn't cause the multi-meter to move, so I'll order a pair of replacement from Polk on my next USA trip.
    Here are my numbers, as the resistance tends to be a bit higher than spec, is that the speakers showing their age?
    Also, should I swap the 6503's so that each pair is the same resistance, flip a 6.7 and 7.1?
    Thanks

    In bold I'm confused with. Are the tweeters cutting at low volume is that what you mean? If so the polyswitch is bad and most here do away with it and replace with a .5 ohm resistor. You may want to evaluate whether or not this would work for you as you will then have no tweeter protection. If fed good power from a good amp it usually is not a problem, but if you just use a receiver you may need to replace the polyswitch.

  • codycatalistcodycatalist Posts: 1,688
    edited October 24
    pitdogg2 wrote: »
    SDACRS86 wrote: »
    Hello everyone;
    Just joined. I've had my Polk SDA CRS since 1986. Amp: Technics SU-V8X.
    Speakers - Crossovers all rebuilt (by a dedicated Speaker shop) when 1 upper came off the post, rotated over the lower and created some molten parts, last time volume was above 5.
    Issue now is that the speakers go into safety mode at volume 4 or 5. (Just ran the Amp on my friends stereo, no issues with the Amp.) Checked all the speakers, and the outermost Right channel SL2000 doesn't cause the multi-meter to move, so I'll order a pair of replacement from Polk on my next USA trip.
    Here are my numbers, as the resistance tends to be a bit higher than spec, is that the speakers showing their age?
    Also, should I swap the 6503's so that each pair is the same resistance, flip a 6.7 and 7.1?
    Thanks

    In bold I'm confused with. Are the tweeters cutting at low volume is that what you mean? If so the polyswitch is bad and most here do away with it and replace with a .5 ohm resistor. You may want to evaluate whether or not this would work for you as you will then have no tweeter protection. If fed good power from a good amp it usually is not a problem, but if you just use a receiver you may need to replace the polyswitch.

    I read that as in the crossovers were toast at one point. I do feel like it is the polyswitch as well Ivan.

    Maybe Bruce will understand, he speaks in this tongue all the time.
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  • pitdogg2pitdogg2 Posts: 11,154
    edited October 24
    It's very hard to comprehend Cody. The first bold part seems was a crossover repair from what ever happened. The second sounds very much like wore out polyswitch to me.
  • codycatalistcodycatalist Posts: 1,688
    edited October 24
    pitdogg2 wrote: »
    It's very hard to comprehend Cody. The first bold part seems was a crossover repair from what ever happened. The second sounds very much like wore out polyswitch to me.

    Yup that's how I took it as well.


    *Edit - OP looking at your diagram you have the left tweeter as the dimensional. The outer (right) tweeter should be the dimensional where as the left is the stereo.
    Living room

    Mains: Paradigm 90P
    Lows: Velodyne CHT12, Pioneer SW-8Mk2
    Power: Marantz SR7000
    Tv: Samsung UHD 55' Curved 4k

    2 Channel Den

    Mains: SDA2B Upgraded XOs and Binding Posts
    Pre: Denon PRA-1200
    Power: Adcom GFA-545
    TT: Pioneer PL510

    Noggin Rockin'

    Phillips L2
    Harman Kardon CL
    Little dot 1+/GE JAN 5654w

    Closet of Dreams:

    Polk RTA11TL
    New Large Advents 25th Anniversary Edition
    Bravo V2/RCA Clear top Conn branded 12AU7
    Yamaha AV-34

    "Temptation is the manifestation of desire which equals necessity." - Mikey081057
    " I have always had a champange taste with a beer budget" - Rick88
    "Just because the thread is getting views don't mean much .. I like a good train wreck doesn't mean i want to be in one..." - pitdogg2
    "Those that don't know, don't know that they don't know." - heiney9
    "Audiophiles are the male equivalent of cat ladies." - Audiokarma Member
  • SDACRS86SDACRS86 Posts: 6
    Thank you for the inputs. I was beginning to wonder how I managed tick all of you on my first post.
    To clarify my poorly written first post.
    1. 20 years ago I melted at least one of the cross overs.
    2. I found a dedicated speaker shop, and he rebuilt all the cross overs, with a slight change with the components, to give me more age appropriate sound. I'll see if I can post a pic of the boards.
    3. These days, when I use the stereo, if I push the amp above about 3.5, say 4 or 5, within that song, I hear the speakers subdue in sound until I reduce the volume knob. I don't know if this is a new problem, or has existed for years. The stereo doesn't go above 3 unless the house is empty.
    3. I use a dedicated Stereo Technics amp, old school, class A, SU-V8X, (100 amps a side)which I just confirmed on another quality system works fine.
    4. During the troubleshooting, I found that the right channel right most tweeter (SL2000) registered nothing on the meter.
    5. Looking at the wiring diagram again, I now see that dimensional tweeter connects to the blade connector.
    6. When you say I can disconnect the dimensional tweeter for now, do I simply remove both wires to the dimensional tweeter in each channel?
    7. I will see about getting at least a pair of the replacement tweeters.fbwxczfof0tm.jpg
  • SDACRS86SDACRS86 Posts: 6
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    pxd3uatcpcq2.jpg

  • pitdogg2pitdogg2 Posts: 11,154
    edited October 24
    What you describe is typical polyswitch problem. After being tripped many times they get very easy to trip at lower volumes. Since i cannot see them on the XO I'd think they are buried under the solen caps. Now some here including myself do not care for Solen caps. They also did no favors using a bypass cap as well. That in itself can create wierd sounds. With the better film caps bypass caps are not needed.

    Yes if those do not have fuses you just disconnect the SDA tweeter and tape off the ends so not to short on anything inside.

    No I will admit i have not studied the schematic but I'd think there should be some resistors on the board. If they are buried under the caps and hot glued that could be a problem. They need to be able to breathe as they can get very hot. It appears the guy just switched out all the electrolytic caps and replaced with the Solens and to me that appears to be the low pass range so the solens could be ok there. They can be very shrill in the high pass section (tweeters).

    If it were me I'd replace the polyswitch with a .5 ohm 10 or 12 watt mundorf or vishay-mills resistor. Once again there will be no tweeter protection but you being careful with the volume will help protect the tweeters.
  • F1nutF1nut Posts: 40,508
    I can see a resistor under the large Solen. As Pitdogg2 mentioned, a very bad idea. Whomever did that work did not do you any favors.
    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."


  • pitdogg2pitdogg2 Posts: 11,154
    Eagle eyes @F1nut .

  • SDACRS86SDACRS86 Posts: 6
    Thank you gents. Starts to make sense. If i understand correctly,
    1. I can disconnect the other channel dimensional tweeter, tape off both tweeter connections and listen to the speakers.
    2. if I wish, I can replace in pairs the sl2000s, but best is all 4.
    3. It appears that the safety, is now easily tripped, so removal is suggested, and a resistor substitute.
    4. Last option, I see a person on the forum offers several levels of cross over rebuild.

    Again thank you for your assistance.
  • pitdogg2pitdogg2 Posts: 11,154
    Just replace the two stereo tweeters. Polk never again used dimensional tweeters so that should speak volumes.
    reach out to @westmassguy he does great work you will be happy.
  • SDACRS86SDACRS86 Posts: 6
    Ok, both dimensional tweeters disconnected. Left channel poly switch tripped at 4, didn't make it thru a Super Tramp song. But, at least below 4 works...gives me some time to sort out the poly switch fix path..
    Thanks again, very helpful.
    cheers
  • pitdogg2pitdogg2 Posts: 11,154
    edited October 25
    you have some options.
    1. The reason we add .5 ohm resistor is that is the value of resistance going through the polyswitch to keep the circuit the same.
    2. some people have jumped the polyswitch by twisting the leads together. Be very careful not to brake the soldered ends loose under the board.
    3. others have just removed it and soldered a piece of wire in place of the polyswitch.
    4. both 2 & 3 will increase the loudness of the tweeter. To some it comes off as too much tweeter only you can decide what is best for you. some do also go up in resistor value to 1.0 ohm or more to get the tweeter to their liking (softer).

    Choose your path as to what you think sounds best for you.
    also the resistor in the circuit is 5 watt, we go up in wattage as insurance to keep from toasting the resistor same ohm value but higher wattage. So this is why I recommended 10 or 12 watt.


    by the way Welcome to Club Polk mention you are a member here for a small discount on the new and IMPROVED replacement tweeters RD-0194 replaces the SL2000.
    call Polk customer service to place your order.

    something to read for the new tweeters page 4 the positive side should be colored red so you may want to mark the magnet for the future in case you need to remove. Still lot of good info.

    http://forum.polkaudio.com/discussion/183597/the-sda-srss-have-landed-at-verbs-house/p4
  • gimpodgimpod Posts: 1,757
    That Technics amp, old school, class A, SU-V8X is not rated at 100 amps!
    It's an integrated amp rated at 120 watts per channel into 8Ω (stereo), It says it can handle a 4Ω load.

    I've never heard of an integrated amp that can output 100 amps especially from 1984-1985. I could be wrong but I don't think so.

    But the Gen 1 CRS's as you call them (are actually Gen 2 SDA's) are rated IRC at 4Ω and can dip as low as 2Ω or lower, also they have a polyswitch for each tweeter (4 all together), With that amp I would replace the with new ones. Hears a link.

    I would say that amp is not a good match, You need an amp that is stable at 2Ω and around 200 watts per channel into 8Ω (stereo), or just stop turning the volume up. JMO
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  • SDACRS86SDACRS86 Posts: 6
    @gimpod

    Thank you.
    Ya, 100 amps, not happening. Can I blame the drugs from the surgery for that goof up. I actually do know better, and still remember E=I timesR. Also, did my wife find you, as she says the same thing about the volume, "just don't turn it up", why it can't go above 3 unless she is out.
    The link to the parts is appreciated. That Amp worked for my listening needs, back in the day, so if I can just get the speakers functioning properly, should be fine for me. A lifetime around aircraft has decreased any fine tuning I could detect.
    I've learned a lot about my "classic" Polks the last few days..Thank you all.
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