LS90 Crossover Mod

adam2434
adam2434 Posts: 995
edited March 2011 in Vintage Speakers
I was thinking that it might be approaching the time to refresh/upgrade the crossovers in my LS90s, given that they're pushing 18 years old or so.

Looking at the attached schematics, I was surprised to see only 1 capacitor and 1 resistor in the network (the rest of the parts are inductors).

There are 2 versions of the crossover. The newer one specifies a 10uf mylar cap. The older one specifies a 10uf electro.

I don't know which version I have - will have to remove the crossover to determine that.

If I have the newer version with the mylar cap, replacing the cap would be less of a refresh and more of an upgrade. In other words, the mylar cap's value should not change over time, whereas electros can drift over time.

If I have the older version with the electro cap, there could be more of a "need" to replace because of age.

In addition to the cap, I guess the resistor would be the only other part to consider replacing. I would leave the inductors alone.

Any thoughts on this?

Thanks.
5.1 and 2.0 ch Basement Media Room: Outlaw 975/Emotiva DC-1/Rotel RB-1582 MKII/Rotel RB-1552/Audiosource Amp 3/Polk LS90, CS400i, FX500i/Outlaw X-12, LFM-1/JVD DLA-HD250/Da-Lite 100" HCCV/Sony ES BDP/Sonos Connect. DC-1/RB-1582 MKII/Sonos Connect also feed Polk 7C in garage or Dayton IO655 on patio.
2.1 ch Basement Gym: Denon AVR-2807/Klipsch Forte I or NHT SB2/JBL SUB 550P x 2/Chromecast Audio.
2.0 ch Living Room: Rotel RX-1052/Emotiva DC-1/Klipsch RF-7 III/Sony ES BDP/LG 65" LED.
2.0 ch Semi-portable: Klipsch Powergate/NHT SB3/Chromecast Audio.
Kitchen: Sonos Play5.
Post edited by adam2434 on
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Comments

  • Earthy
    Earthy Posts: 488
    edited March 2011
    Your other option would be to plan a road trip to Oklahoma and sell those LS90's to me.:biggrin:
    Polk Audio SDA SRS 2.3TL
    Parasound Halo A21
    Parasound Halo P3

    Home theater
    Polk LSiM 707, 706c, 703, 705
    Polk Blackstone TL3 for height
    SVS PB12-ISD Sub
    Denon AVR-X6400h
    Parasound Halo A51
    LG OLED65B7A
    Sony UBPX800
    Logitech Harmony Elite
    PC LSiM 703
    Spare LSIM 702 and 706c

    Home Theater #2
    Polk Audio LS70, CS350LS, LSF/X, S4
    Onkyo TX-NR808



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  • adam2434
    adam2434 Posts: 995
    edited March 2011
    Schematics attached.
    5.1 and 2.0 ch Basement Media Room: Outlaw 975/Emotiva DC-1/Rotel RB-1582 MKII/Rotel RB-1552/Audiosource Amp 3/Polk LS90, CS400i, FX500i/Outlaw X-12, LFM-1/JVD DLA-HD250/Da-Lite 100" HCCV/Sony ES BDP/Sonos Connect. DC-1/RB-1582 MKII/Sonos Connect also feed Polk 7C in garage or Dayton IO655 on patio.
    2.1 ch Basement Gym: Denon AVR-2807/Klipsch Forte I or NHT SB2/JBL SUB 550P x 2/Chromecast Audio.
    2.0 ch Living Room: Rotel RX-1052/Emotiva DC-1/Klipsch RF-7 III/Sony ES BDP/LG 65" LED.
    2.0 ch Semi-portable: Klipsch Powergate/NHT SB3/Chromecast Audio.
    Kitchen: Sonos Play5.
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  • adam2434
    adam2434 Posts: 995
    edited March 2011
    Earthy wrote: »
    Your other option would be to plan a road trip to Oklahoma and sell those LS90's to me.:biggrin:

    Haha, I really don't see myself parting with them. :biggrin:
    5.1 and 2.0 ch Basement Media Room: Outlaw 975/Emotiva DC-1/Rotel RB-1582 MKII/Rotel RB-1552/Audiosource Amp 3/Polk LS90, CS400i, FX500i/Outlaw X-12, LFM-1/JVD DLA-HD250/Da-Lite 100" HCCV/Sony ES BDP/Sonos Connect. DC-1/RB-1582 MKII/Sonos Connect also feed Polk 7C in garage or Dayton IO655 on patio.
    2.1 ch Basement Gym: Denon AVR-2807/Klipsch Forte I or NHT SB2/JBL SUB 550P x 2/Chromecast Audio.
    2.0 ch Living Room: Rotel RX-1052/Emotiva DC-1/Klipsch RF-7 III/Sony ES BDP/LG 65" LED.
    2.0 ch Semi-portable: Klipsch Powergate/NHT SB3/Chromecast Audio.
    Kitchen: Sonos Play5.
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  • Earthy
    Earthy Posts: 488
    edited March 2011
    adam2434 wrote: »
    Haha, I really don't see myself parting with them. :biggrin:

    Thats how I feel about my LS70's. I have been looking for a pair of 90's close by for a while, but no luck so far. As you can see, I am updating my 70's and it looks like a piece of cake.

    When I get my parts and begin my update, it will be the first time I have ever taken the fronts off of them. I bought them new in the early 90's.
    Polk Audio SDA SRS 2.3TL
    Parasound Halo A21
    Parasound Halo P3

    Home theater
    Polk LSiM 707, 706c, 703, 705
    Polk Blackstone TL3 for height
    SVS PB12-ISD Sub
    Denon AVR-X6400h
    Parasound Halo A51
    LG OLED65B7A
    Sony UBPX800
    Logitech Harmony Elite
    PC LSiM 703
    Spare LSIM 702 and 706c

    Home Theater #2
    Polk Audio LS70, CS350LS, LSF/X, S4
    Onkyo TX-NR808



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  • quadzilla
    quadzilla Posts: 1,543
    edited March 2011
    Doesn't matter whether is poly or electro, replace the cap with a film cap or you're wasting your time. Soniccraft stocks a 10 mf sonicap. Biggest challenge will be figuring out how to place it. If you're not comfortable, there are several people on the board that rebuild xovers for people. I've done my LS50s and CRS+, but I'm not sure I'm ready to start doing it for other people yet.
    Turntable: Empire 208
    Arm: Rega 300
    Cart: Shelter 501 III
    Phono Pre: Aural Thrills
    Digital: Pioneer DV-79ai
    Pre: Conrad Johnson ET3 SE
    Amp: Conrad Johnson Evolution 2000
    Cables: Cardas Neutral Reference
    Speakers: SDA 2.3TL, heavily modified
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