jimjimbo Posted October 2, 2017 Share Posted October 2, 2017 Given the choice between a 250 V or a 630 V woofer capacitor which one would be the proper choice? Can the 250 V Handle pretty much any load? Quote Link to comment Share on other sites More sharing options...
Deang Posted October 2, 2017 Share Posted October 2, 2017 250Vdc is fine. Quote Link to comment Share on other sites More sharing options...
moray james Posted October 2, 2017 Share Posted October 2, 2017 in a passive crossover the caps at maximum only ever look at the rail voltage and most smaller amps are 50 - 60 volts with large amp running 90 volts, a few might run as much as 120V but you don't see those often and it would not make a difference. Remember that even the cheapest cap is good for at least double its rated voltage. 250 volts is lots. Quote Link to comment Share on other sites More sharing options...
Peter P. Posted October 2, 2017 Share Posted October 2, 2017 100 watt output into an 8 ohm woofer is only 28V. You're plenty covered with a 250V capacitor. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted October 2, 2017 Author Share Posted October 2, 2017 Thanks gents! Quote Link to comment Share on other sites More sharing options...
Davecv41 Posted October 5, 2017 Share Posted October 5, 2017 On 10/2/2017 at 4:57 PM, moray james said: in a passive crossover the caps at maximum only ever look at the rail voltage and most smaller amps are 50 - 60 volts with large amp running 90 volts, a few might run as much as 120V but you don't see those often and it would not make a difference. Remember that even the cheapest cap is good for at least double its rated voltage. 250 volts is lots. Not a good rule of thumb for capacitors. In today's throw away society, parts are frequently used that are running at the edge of their rated voltage specification. My Pentium motherboard had 6 volt electrolytics in the 5 volt circuit. They dried out and shorted. I pulled them off the board and replaced them with higher voltage caps and got the board running again. In researching the problem online afterward, it appeared that most electronics is made that way now to save a few pennies for the bottom line. Apologies for changing the subject from crossover caps to something else. Quote Link to comment Share on other sites More sharing options...
JohnA Posted October 5, 2017 Share Posted October 5, 2017 Power = I (current) x V (voltage) Ohms Law is V = I * R (resistance) so, P = V^2/R (250*250)/8 ohms = 7813 watts. 100V = 1250 watts 50V = 313 watts. Pretty much any cap you can buy will be sufficient, but go for 100V, maybe save a little $$. 2 Quote Link to comment Share on other sites More sharing options...
moray james Posted October 5, 2017 Share Posted October 5, 2017 2 hours ago, Davecv41 said: Not a good rule of thumb for capacitors. In today's throw away society, parts are frequently used that are running at the edge of their rated voltage specification. My Pentium motherboard had 6 volt electrolytics in the 5 volt circuit. They dried out and shorted. I pulled them off the board and replaced them with higher voltage caps and got the board running again. In researching the problem online afterward, it appeared that most electronics is made that way now to save a few pennies for the bottom line. Apologies for changing the subject from crossover caps to something else. I really think that you were dealing with crappy caps, a six volt cap on a 5 volt rail is just fine. Cheap little speakers usually have 35 volt caps to save money you can run them on any size amp with no problems what so ever. that's not to say you could not blow them up but the drivers would likely fry before the caps blew up and you would know you were doing wrong long before that even from another room or the basement. Never the less your amplifiers rail voltage is all you speakers will ever see unless of course it dies and go DC. Quote Link to comment Share on other sites More sharing options...
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