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replacement pots


ra.ra

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I recently picked up a couple of these potentiometers (first pic) at the MIT flea market and am seeking some opinions -- advice -- assistance to determine how suitable they might be as replacements for the original Aetna-Pollak pots found in vintage AR's. The printing describes them as having ratings of 25 watts but only 10 ohms, and indeed the sweep measures from near zero to just over 10 ohms.

These pots appear nearly identical to the 14 ohm pots Roger recently used in his AR-6's (second pic), but if I try to use these, would I need to add any extra resistance to the circuit, or will they allow the tweeter to operate at near maximum output (my typical setting) without any further tweaking?

post-112624-0-18582600-1437437171_thumb. post-112624-0-36661000-1437437195_thumb.

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Add a series power resistor before or after (6ohms) depending on ohmage you want. Depending on what you prefer you can get 0-10ohm (16ohm in total) or 6-16ohm (16 ohm in total). Pick your choise :)

Regards

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Adding 6 ohms in line with the pot will only make it worse.

It is the parallel resistance that is the primary issue relative to ra.ra's question, and too little (10 ohms vs 15 or 16 ohms) will result in too much attenuation at every setting. Adding 6 ohms of resistance to the parallel leg of the 10 ohm pot will make it act more like the original pot near the maximum side of rotation, but this tweak is required...and it is only valid for some of the rotation.

Roy

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The HK pots are only $11/ea delivered to your mailbox. I don't think I would use them on a three-way but like them on the the two-ways and just ordered a set for the 4x tribute speakers.

Item number 351344561363 on the auction site.

25W 15Ω 15 Ohm Power Wirewound Rheostat Rotary Potentiometer

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Thanks, everyone, for the excellent advice. At a buck apiece, I took a gamble that there might be a simple modification that would enable these to function similar to the originals, but alas, my pipe dream goes up in smoke once again.

Roger, those HK pots look just like the ones I have (except the pics in the listing do say 20 ohm), but why is your opinion of these different between two and three-way speakers?

Roy, you lost me with that last sentence in post 4, but I'll not be using these in vintage AR's.

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...

Roger, those HK pots look just like the ones I have (except the pics in the listing do say 20 ohm), but why is your opinion of these different between two and three-way speakers?...

They are considerably larger than the AP pots. Haven't really measured the space but it just seemed easier to use the L-pads and not have to make a cover for the open backed pots.

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