Polk Audio LSiM703 Crossover Modification Thread

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Comments

  • sk88
    sk88 Posts: 158
    edited February 2014
    Just listened to the recordings with my online system. Both high an low end sound a lot more articulate than stock. Congrates!
    • Online - Focal Solo6 BE, Polk PSW10, Focusrite Saffire Pro 24 DSP, Lenovo x220t
    • Music/HT - Lsi25, Lsi9 (Vr3), Lsi7, LsiC, Pioneer SC-68 & BDP-62FD, PS3
  • Hello, I know this is an old thread , but I just bought a pair of Polk LSiM 703 and I want to upgrade the capacitors. Is the crossover schematic posted somewhere?
    Thank you
  • pitdogg2
    pitdogg2 Posts: 24,474
    It is not to my knowledge. You can get cap and resistor values from the current xo.
  • K_M
    K_M Posts: 1,627
    VR3 wrote: »
    This is true...

    I had a buddy over here and we were comparing the modified 703 versus my stock 705 and the 703 was substantially better in the mids and highs. So I can say with confidence this is a worthwhile modification... :)

    Are you altering the tweeter level in any way?
  • skrol
    skrol Posts: 3,330
    asuslover wrote: »
    Hello, I know this is an old thread , but I just bought a pair of Polk LSiM 703 and I want to upgrade the capacitors. Is the crossover schematic posted somewhere?
    Thank you

    Unfortunately, Polk like most companies and rightly so, keep their design docs under tight wraps now. We are fortunate that we have the vintage product schematics. It was more fun when Polk used to publish articles on their new technologies. Maybe someone will analyze an LSiM-703 XO and draw up the schematic one day but it would probably be within Polk's right to demand it be removed.

    For now, you can component swap better quality parts based on the original values.
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • K_M
    K_M Posts: 1,627
    skrol wrote: »
    asuslover wrote: »
    Hello, I know this is an old thread , but I just bought a pair of Polk LSiM 703 and I want to upgrade the capacitors. Is the crossover schematic posted somewhere?
    Thank you

    Unfortunately, Polk like most companies and rightly so, keep their design docs under tight wraps now. We are fortunate that we have the vintage product schematics. It was more fun when Polk used to publish articles on their new technologies. Maybe someone will analyze an LSiM-703 XO and draw up the schematic one day but it would probably be within Polk's right to demand it be removed.

    For now, you can component swap better quality parts based on the original values.

    I was more curious to see about altering the tweeter level a tad.
    TO me, maybe being a bit younger, the high end of the Lsim703 is a bit strong, not unbearable but a definite rise.

    But one must factor in, with "Better" parts, there may be differences in ESR of the caps, that actually mildly reduce the resistance and boost the tweeter level even a bit more than it is presently.
  • Hello guys,
    I opened up the speakers and I have the components values.
    For the tweeter I would need one 22uf/100v , one 7.5uf/v and one 1.8 ohms/5w resistor. For the mids I will need one 1.8ohm/10w resitor and one 82uF/150v capacitor.
    Woofer stays the same for now.
    I am not planning to play with the levels for now.
    Thanks