DavidR Posted November 9, 2016 Report Share Posted November 9, 2016 A lot has been written about replacement of speaker xover resistors including adding resistors to film caps to more closely match the ESR of the original NPE caps. I thought it would be nice to have all the questions and answers to resistors in one thread. Some of my questions include: (1) Unless there is a visual observation of overheating or a cracked/broken resistor, does it need to be changed? (referring to the AR sandcast resistors mostly) (2) Are Mills, Vishay Mills and Mundorf MOX and M-Resist resistors that much better (for SQ) than the sandcast resistors and it is worth the price to replace them 'willy-nilly'? (3) The AR resistors I've encountered are 22 watts. Can you get by with 20 watt rated resistors?; If you parallel two 12 watt resistors to get 24 (or use a 25 watt wire wound) does this affect the impedance, or is it always better to have more power handling ability. (4) ESR adjusting for film caps: Re: adding resistor to a film cap when replacing NPEs >Ken Kantor (copy and paste from a thread on AK) "For NPE's older than 25years, try 1 Ohm. For NPE's over 100uF, and/or between 15 and 25 year old, use 0.5 Ohm. For contemporary NPE's, use 0.2 Ohm. There were garden variety, decent, no-name industrial caps, purchased maybe 5 years ago. I tested them right out of the parts drawer, new, no bias or (groan) break in. Everything above about 33uF tested well under 0.2 Ohms. I would use 0.1 resistors, or nothing, in the rare event that these larger NPE's were being replaced by film. (The largest film cap I have around is 16uF, and it tested a bit below 0.01 Ohms.)" >RoyC (copy and paste from a thread here on CSP) "The ESR readings you measured were similar to John's as well, and was the motivation for his recommending the addition of 0.3+/- ohm series resistors to replacement caps for those who may want to try to mimic the higher ESR of the original caps. (I personally don't ascribe to this practice, as we really don't know what the original ESR was...and the level controls typically show variations of greater than .3 ohms.)" I seem to remember a thread here on CSP where (I think; I'm unable to locate the post) Ken agreed with RoyC that a good all-around resistor value to use would be a 0.3-ish ohm resistor. I understand the placement for this 'added' resistor is in series with the driver and after the cap(s). Link to comment Share on other sites More sharing options...
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