Question on our favoite pots .... Roy, help!!

[onplane]

I was chatting with a guy on another board and he claims that after he cleaned his pots throughly that he gets readings of 0.4 to 0.7 ohms with the pots full ON.

Now, this guy cleaned the pots with an acid solution and then "buffed with a fiberglass bristle polisher".

Those readings seem awful high to me! Can anyone confirm the typical readings with good/new pots in the full ON position.

Roy ... help!!!

Regards,

Jerry

[genek]

That guy is me, BTW.

[RoyC]

That guy is me, BTW.

Hey Gene and Jerry...

.4 to .7 ohms does seem to be on the high side for cleaned pots. Typically they measure .2 to .3 ohms fully "increased".

Could it be the meter? One of my old meters measures .4 ohms with the leads fully shorted...so that one typically gives me a .6 or .7 ohm reading

on a clean pot. Unless you aren't getting enough output, small discrepancies shouldn't matter much with the old drivers.

IMO, most of the surviving original 3/4" inch tweeters are variable and somewhat restricted in response, and are likely near the end of the line. (Gene, like you, I have been experimenting with replacement tweeters with some promising results.)

Roy

[genek]

Hey Gene and Jerry...

.4 to .7 ohms does seem to be on the high side for cleaned pots. Typically they measure .2 to .3 ohms fully "increased".

Could it be the meter? One of my old meters measures .4 ohms with the leads fully shorted...so that one typically gives me a .6 or .7 ohm reading

on a clean pot. Unless you aren't getting enough output, small discrepancies shouldn't matter much with the old drivers.

IMO, most of the surviving original 3/4" inch tweeters are variable and somewhat restricted in response, and are likely near the end of the line. (Gene, like you, I have been experimenting with replacement tweeters with some promising results.)

Roy

Shorting my VOM leads produces readings between zero and 0.2 ohm. I had four pots from two speakers, and there turned out to be two with the lower resistance (on the tweeters) and two with the higher resistances (on the midranges). The speaker S/Ns are close, but not consecutive, which leads me to speculate that perhaps someone was selecting pots for mid and high level controls based on resistance...?

[RoyC]

which leads me to speculate that perhaps someone was selecting pots for mid and high level controls based on resistance...?

Having been into many AR "pot pairs" from 3a's, 5's and 2ax's, that hasn't been my experience. I have seen no pattern to the variations, the most notable of which have been parallel resistance measurements of just under 15 to nearly 17 ohms. Given the .2 ohm lead resistance of your meter, I wouldn't worry about the readings you are getting if the range of adjustment is satisfactory for you. As I implied above, the variations in the old tweeters likely exceed the differences in the controls.

Roy

[genek]

Having been into many AR "pot pairs" from 3a's, 5's and 2ax's, that hasn't been my experience. I have seen no pattern to the variations, the most notable of which have been parallel resistance measurements of just under 15 to nearly 17 ohms. Given the .2 ohm lead resistance of your meter, I wouldn't worry about the readings you are getting if the range of adjustment is satisfactory for you. As I implied above, the variations in the old tweeters likely exceed the differences in the controls.

Hasn't been a problem for me. The subject just came up because Jerry thought the pots should have zero resistance at full up and mine don't.