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Opinions on these pots....


lakecat

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I purchased four of these for a upcoming AR3a refresh. I liked the idea that they are self contained (sealed). Also at half the price of Ohmite's (RHS15RE) is a plus. The build quality seems very good. I tested them and they are true 16 ohm pots.  Here are two things I have noticed. 1. The movement is a bit stiff compared to the Ohmite's, which I also purchased.  I have not opened them up to see about adjusting the wipers. 2. The shafts are not keyed on the side like the Ohmite's, but have a slot on the top. To use the AR style knobs these probably should have a flat spot ground onto the shafts. One plus is the screw type terminals, which I like. I have not decided which one I will eventually use. I have a idea to fabricate some covers for the Ohmite's from Red Bull cans. Options are limited, but I have eliminated using L-pads ( they are not rheostats) and using rebuilt Aetna-Pollak potentometers is not quite the quality I am shooting for. I also have Chinese Ohmite knock-offs,which do not have the same build quality and some Russian built pots that seem nice, but the shafts would need cut down.  I am happy so far with the purchase and time will tell how they work out.

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One last thought about the seller. I have seen his work on a Fisher 400 receiver he rebuilt for my buddy. His restorations are top notch.

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5 hours ago, larrybody said:

Options are limited, but I have eliminated using L-pads ( they are not rheostats)...

It should have  nothing to do with the definition of a "rheostat".  AR pots (potentiometers) and variable L-pads both vary series and parallel resistance using 3 legs. A traditional definition of a rheostat says it varies resistance with two legs. Others say variable L-pads and potentiometers are both types of rheostats.

The new controls under discussion look very good from here, but the scare tactics this Ebay seller is using to steer people away from L-pads is nonsense. By far, the most numerous malfunctioning and melted controls (plastic shafts) I have seen are original AR pots.

Roy

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All variable resistors are rheostats. A potentiometer is a three-terminal rheostat configured to act as a voltage divider, and an L-pad is a parallel and a series rheostat combined to maintain a constant impedance load.

Two-terminal rheostats aren't terribly common these days; the more common configuration is the three-terminal such as the Ohmites. Use one end of the winding and the wiper and it's called "rheostat;" use all three terminals and it's a potentiometer.

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On 7/20/2018 at 1:53 AM, RoyC said:

It should have  nothing to do with the definition of a "rheostat".  AR pots (potentiometers) and variable L-pads both vary series and parallel resistance using 3 legs. A traditional definition of a rheostat says it varies resistance with two legs. Others say variable L-pads and potentiometers are both types of rheostats.

The new controls under discussion look very good from here, but the scare tactics this Ebay seller is using to steer people away from L-pads is nonsense. By far, the most numerous malfunctioning and melted controls (plastic shafts) I have seen are original AR pots.

Roy

I wonder if these will suffer the same issues with electrolysis as the originals pots? The combination of high current and dissimilar metals seems to be the original issue.

Roger

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