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Hoffman Amps Forum image Author Topic: rheostat as dummy load?  (Read 4660 times)

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Offline EW57

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rheostat as dummy load?
« on: June 09, 2011, 08:58:15 am »
Greetings, I recently purchased a fairly large rheostat, the biggest one I'd seen before, a bit over 10" in diameter,  about 8lbs & 25 ohms. I havent seen much about using a rheostat as a dummy load, any ideas why not?

Thanks!

Offline jjasilli

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Re: rheostat as dummy load?
« Reply #1 on: June 09, 2011, 05:59:49 pm »

Offline Ritchie200

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Re: rheostat as dummy load?
« Reply #2 on: June 10, 2011, 11:42:46 am »
Way back in the dark ages I used two 100watt Altair attenuators in parallel on my Major.  The interior component that did the work looked like a toaster element with taps coming off it.  I also tried the Governor and the Power Soak.  The Altair beat them both hands down in tone and longevity.  I wonder if it wasn't because it was more inductive than resistive?  Of course I am talking about attenuators and not dummy loads.  However, based on the tone, I think the amp liked the Altair more than the others!  A famous amp tech that works on Ritchie Blackmore's Majors uses a 200 watt wire wound 8 ohm resistor mounted in a paint can filled with oil, like the amateur radio dummy loads, to set the bias.  He also had them biased to 260watts on good tubes.  I can tell you that when I was running full tilt into the Altairs you could grill a steak on them!  I'm sure your rheostat will get warm as well.  

Way, way, way back in the 60's I had a 6v6 hi-fi amp that my dad and I converted for guitar use.  In my total and complete ignorance, I used a headphone rheostat as a power soak.  I used to woodshed every day and had that rheostat set all over its range and that amp is still alive today.  Unfortunately, I have no idea what the total resistance was on that thing, sorry!

I don't know if any of this helps - ymmv!

Jim

My religion? I'm a Cathode Follower!
Can we have everything louder than everything else?

 


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