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Crossover: Heresy III / CW III : 25 Watts Resistor really needed??

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Having recently figured out the resistor values in mid and tweeter section for H III Xover, now I am going to convert my CW III Xover to H III Xover by substituting the resistors. These resistors are all spec'ed at 25 Watts. Where I live I can only get 10 Watt Daytons. So only option is to buy two 10 watts resistors of half value and use them in series (to get up to 20 watts) which I rather not do as physical layout will not be a simple swap of resistors.


Do I really need 25 Watts resistors for mid and highs? Can I get away with 10 Watts? 





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Hi @radiogramme


@JohnA's comment is a good thing


For me the 10W resistors are already well sized, but if you want to increase the reliability of the resistors, I advise you to mount them with a space of 1/2 inch between the printed circuit and the body of the resistor: the cooling by convection will be much better and the reliability greatly increased.














Otherwise you can't find 25w Mundorf resistors on the net?


https://www.mundorf.com/audio/en/shop/Resistors/?reload_filter=true&p (max)_25watt=true&p (max)_1x15watt=false&p (max)_2x7%2C5watt=false&p (max)_5watt=false&p (max)_10watt=false&p (max)_20watt=false&p (max)_30%2F3watt=false

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@mustang_flht Thanks for the cooling tip.  I am India and have no access to 25 Watt resistors of decent quality easily. For now I am going to experiment with 10 Watt resistors and once I am satisfied I will probably get them from mouser/madisound etc when my sister comes here next month.


BTW, I am now using Bi-Amping to make up for sensitivity difference between bass and mid-highs with the Integrated Amp driving the bass is boosted up. In this I actually find that I prefer the mid-highs 4db lower instead of 3db.


I am also curious that a much less sensitive speaker (only 85 db) like JBL A130 I have, uses 1only 10 watt resistor when I would expect much more power going into this than the Heresy.



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@radiogramme  Ok it's noted, you are in India 😍 and no 25W resistors.


I have 10W resistors on my CWIII in the sqwaker between 800Hz and 5000Hz without any problem for 2 years: they are far from the board for better cooling,

as I explained to you above 😉


My R18ohms 10w green in middle on home network


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