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Old 11th January 2007, 11:39 AM   #1
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Default Resistors -- using higher-than-required watt rating

Hello all, a quick and probably simple question for you all. I've been experimenting with different kinds of resistors in my Fender tube amp, especially the plate resistors, as I'd like to reduce hiss.

My question is, is it possible to simply switch a 1/2 watt 100k ohm resistor with a 1 or 2 watt 100k ohm resistor? That is, would a 2 watt 100k ohm, for example, still provide the *same resistance* as a 1/2 watt 100k ohm?

I know that I would need two 200k 1/4 watt resistors in parallel to equal a 100k 1/2 watt. Is there any similar rule in raising the watt rating of a resistor, or can you just substitute, knowing with confidence that the watt rating is simply better than it needs to be?
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Old 11th January 2007, 11:44 AM   #2
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Wattage refers to the maximum that a resistor can dissipate. So subbing a higher wattage for lower is perfectly fine without any changes.
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Old 11th January 2007, 06:56 PM   #3
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I fixed my old 19" TV once, it had a burned resistor in the horizontal section(due to some cold solder joints elseware) The resistor was a 91K 1W. Couldn't find one without paying for it (I can be cheap sometimes), so I used 2) 180K 1/2W resistors in parallel. Still works fine years later.
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Old 11th January 2007, 08:31 PM   #4
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Using a higher wattage is fine, and is probably advisable with a valve amp. Assuming by 'plate' you mean the anode loads of the triodes?, these are probably the biggest cause of failure in valve amps - replacing them with good quality higher wattage resistors should make the amp a LOT more reliable, It 'might' help your hiss problem as well?, as it's quite likely the existing ones are already higher than they should be?.

Whenever I replace a faulty anode load I always use a higher wattage one, and always replace them all - not just the faulty ones.
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Old 12th January 2007, 07:58 PM   #5
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Thanks for the info...all the signal resistors on the Pro Jr are cheap 1/2 W carbon films, including the plates. I replaced the first one with the Kiwame, and the rest of the plates (and some others) with PRP non-magnetic metal films. The hiss has gone from way too much to a very acceptable level. And, it just sounds nicer
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Old 12th January 2007, 08:28 PM   #6
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In one of the Audio Anthology collections, there's an interesting article titled "The Sad Tale of a Half Watt Resistor." This dates back to the mid 1950s, so your experience is not a new one.
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