Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: EW57 on June 09, 2011, 08:58:15 am
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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!
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http://www.ax84.com/bbs/dm.php?thread=92501 (http://www.ax84.com/bbs/dm.php?thread=92501)
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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