Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: navdave on August 14, 2011, 07:43:02 pm
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If I ran two 470Ω 10 watt resistors in parallel would this give me a 235Ω rated at 20 watts?
Or would I have to run two 100Ω 10 watt resistors in series to get a 200Ω 20 watt resistor?
Trying to build a solid ultra linear power supply like the one used in the Sunn Model T without having to
use two Dyna chokes in parallel like Sunn did.
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If I ran two 470Ω 10 watt resistors in parallel would this give me a 235Ω rated at 20 watts?
Or would I have to run two 100Ω 10 watt resistors in series to get a 200Ω 20 watt resistor?
The answer to both questions is yes.
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Thank you steve I wasnt sure if the same rules applied to resistors as they do to capacitors as far as wattage is concerned.
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> solid ... without having to use two Dyna chokes in parallel like Sunn did.
That's a four-6550 amplifier. It will pull up to 600mA (0.6A) at full roar, closer to 200mA idle.
The proposed 235 ohms will drop 141 volts!! And 84 Watts!! That at full roar. At idle maybe 50V.
That's not "solid".
That's #1 why to use a choke: low voltage drop (and less change-of-drop with load).
Actually in this case that's #2. The Sunn uses WAY-too-small filter caps, and makes it up with chokes to give excellent ripple rejection. (Re-)Designing (and constructing) a HIGH-power supply like this is not trivial.
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navdave, Right about resistor.
For capacitor is not the same rule;
1- If you put 2 cap of 10 MFD 100 volts in parallele this give 20 MFD at 100 volts.
2- The same caps in series give you 5 MFD 200 volts.
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navdave,
The resistor won't do the same "job " as the choke do. You'll have "sag" with resistor A kind of poor performance.
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Hmmmmmm damn it I guess two Dyna chokes for 30bux sounds good right about now.
Thanks for the cold slap of reality PRR you are a true wealth of knowledge.
> solid ... without having to use two Dyna chokes in parallel like Sunn did.
That's a four-6550 amplifier. It will pull up to 600mA (0.6A) at full roar, closer to 200mA idle.
The proposed 235 ohms will drop 141 volts!! And 84 Watts!! That at full roar. At idle maybe 50V.
That's not "solid".
That's #1 why to use a choke: low voltage drop (and less change-of-drop with load).
Actually in this case that's #2. The Sunn uses WAY-too-small filter caps, and makes it up with chokes to give excellent ripple rejection. (Re-)Designing (and constructing) a HIGH-power supply like this is not trivial.