Infinity Crossover Terminology

Discussion in 'Infinity Loudspeakers' started by Ross6860, Jan 26, 2016.

  1. Ross6860

    Ross6860 AK Subscriber Subscriber

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  2. swechsler

    swechsler Frog Whisperer

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    My guess is that PF = Polymer (or plastic) Film. No idea what MM is.

    For the inductors, AC would be Air Core and IC is Iron Core. Not sure about FC. Part of me wants to say Ferrous Core, but that would be the same as IC, wouldn't it?
     
  3. okeeteekid

    okeeteekid Well-Known Member

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    Here's what I found on the web for the caps: When reading schematics, repairing radios and buying capacitors, you often must convert between uF, nF and pF.
    Paper and electrolytic capacitors are usually expressed in terms of uF (microfarads). Short forms for micro farad include
    uF, mfd, MFD, MF and UF. Mica capacitors are usually expressed in terms of pF (micromicrofarads) (picofarads).
    Short forms for micromicrofarads include pF, mmfd, MMFD, MMF, uuF and PF. A pF is one-millionth of a uF. In
    between a pF and a uF is a nF which is one-one thousands of a uF. Converting back and forth between uF, nF
    and pF can be confusing with all those darn decimal points to worry about. Below is a uF - nF- pF conversion chart.
    Just print a copy and tape it to your workbench....it will come in handy. Have fun with your radio restorations.

    As for the coils FC Ferrite core, AC air core, IC iron core.
     
  4. Ross6860

    Ross6860 AK Subscriber Subscriber

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    Thanks for the info on the inductors. That makes sense.

    For the caps, it's not for uF or pF because they are giving the capacitor specs in XXuF They then add the suffix. Example 600uF NPE, 4.6uF PF and 19uF MM
     
  5. Ross6860

    Ross6860 AK Subscriber Subscriber

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    Anyone have a recommendation for caps to recap these X-overs? I found 5-ohm pots at Digikey and I'm sure Mouser has them, also.

    These are the best speakers I have (so far), so I guess they rate some new caps and pots...
     
  6. slimpikkins

    slimpikkins Super Member

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    I would recommend the yellow and white film caps (mm pf) that are already in there. The NPE's can Be changed to Bennic non polarized electrolytic capacitors but I bet they are fine too. I have yet to remove one of those yellow film caps that was not in spec. (Has anyone?). The pots can be cleaned and function as new.

    Those are great speakers. I have the rs4 which are similar. Good luck with them.
    Jim
     
  7. okeeteekid

    okeeteekid Well-Known Member

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    Unless you have access to an anechoic chamber and testing equipment to test the speakers when adding the new caps I would leave them be, infinity spent tons of money testing/choosing the right crossover parts to get the speakers to sound their best and also to have a flat frequency response by computer design and by tweaking them by ear, by adding a better quality cap here and there doesn't guarantee better results, infinity chose the crossover parts to complimented the drivers to get them to sound their best, unless you have a bad cap I would leave them be, I once read on another forum a guy was asking what caps to recap his amp with because he felt that the caps were getting too old and Nelson Pass responded and said that unless your amp is broken he would leave it be because the caps last much longer than you think.
     
    Last edited: Jan 27, 2016
  8. Maxamillion

    Maxamillion Super Member

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    MM = Metallized Mylar film caps. In other words, metallized polyester film.
     
  9. merlynski

    merlynski Curmudgeon Electronicist Subscriber

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    MM - metalized mylar

    PF - poly film
     

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