HPM-100 Capacitors

Discussion in 'Speakers' started by jozeppy26, Sep 11, 2017.

  1. jozeppy26

    jozeppy26 AK Subscriber Subscriber

    Messages:
    149
    So I'm researching a re-cap for my HPM-100's both using this forum and elsewhere and i'm discovering that only the super tweeter uses an electrolytic non-polar cap. All crossovers i've recapped in the past were all electrolytic and it seemed like a no-brainer but these HPM-100's should have capacitors at their original value right (except for the super tweeter which is barely audible anyway)? Is it crazy to leave the crossovers completely alone?
     
  2. F1nut

    F1nut Super Member

    Messages:
    1,401
    Location:
    The Mars Hotel
  3. jozeppy26

    jozeppy26 AK Subscriber Subscriber

    Messages:
    149
  4. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

    Messages:
    29,304
    Location:
    Central Missouri
    Usually the caps for tweeters and supertweeters are more likely to be film caps (not always) as they are relatively small and inexpensive at those values. Caps in the woofer circuit and to some extent in the midrange can have values large enough that the size and cost would be high. So nonpolar electrolytics tend to show up there. That's what I typically do when recapping an average speaker - film up to about 10-20 uf and NPE for caps higher than that. I would think a supertweeter cap would be very tiny if NPE were used. But I don't know what Pioneer originally used.

    In any case you definitely want to use close to the same uf value and equal or higher voltage rating, completely aside from the type of cap you choose.
     
  5. NAD80

    NAD80 Super Member

    Messages:
    1,289
    Location:
    Carlisle PA
    Is the cap for the supertweeter a 0.15mfd non polar electrolytic? If it is that would be the one to upgrade. The change of the film caps were upgraded to solens caps, the Ecap was changed to a film cap. A coil was changed , wish the values were listed. The flash tends to white out the writing on the caps. Looks like the values changed 4.4mfd to 10 mfd, 3mfd to 5mfd, 0.6uH to 0.9uH coil change. The .15 mfd cap was kept the same value. The crossover frequencies were changed. Original frequencies were 3000hz, 4000hz, 12000hz. Have to find the calculator for crossovers to see where the new frequencies are. Looks like the 12000 hz point was unchanged (.15ufd).
     
  6. jozeppy26

    jozeppy26 AK Subscriber Subscriber

    Messages:
    149
    Right so I'm thinking, since I want to preserve the original crossover values, I should only replace the 0.15 mfd NP electrolytic capacitor with a film capacitor of the same value and leave the original 4.4 mfd and 3 mfd MP capacitors alone. I get switching all capacitors if you desire a crossover frequency shift, however, I am confused as to why anyone would replace their original MP capacitors with same value MP capacitors.
     
  7. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

    Messages:
    29,304
    Location:
    Central Missouri
    Replacing nonpolar film with nonpolar film caps may be to correct drifting caps (which does happen), bad caps (I've had films that failed open on old speakers), caps with high ESR (even though they may still read correct uf), and last but not least, just putting a higher quality film cap in. But I think your general point is that most films don't drift and fail so why replace them in the first place. And I'd generally agree, at least relative to electrolytics (and ancient paper-foil caps which you don't really find in speakers much).
     
    jozeppy26 likes this.
  8. jozeppy26

    jozeppy26 AK Subscriber Subscriber

    Messages:
    149
    Fabulous, thanks! It feels good when the geniuses of audiokarma confirm my rationale. :banana:
     

Share This Page