Did you know ( AR speaker pots ) trivia

[dynaco_dan]

Hi there.

Until I have un-packed from moving, I think I'll do a tidbit on different brands if its ok with you. I worked at a warantee station during the early '70's so that is where some of my spotty knowledge comes from.

Did you know that the pots used by AR during the golden era of hifi had red or black plastic shafts. I saw on occasion where the heat had been so terrific that the shaft had melted off. There was a replacement pot with an aluminum shaft. I do not remember and don't have any data as to which came first. I feel the aluminum shafted pot came later to eliminate the meltdown. Same manufacturer.

Part of the free downloads that Mark will be receiving from me is AR's "Adding a Headphone Adapter" to an AR amplifier. This single sheet shows what is necessary to add a headphone jack to an AR amp but it is applicable to most any amp or receiver where you can use common grounds.

AR's receiver had a center channel output to feed a separate center channel amplifier. The receiver schematic shows this detail and it also can be used on other similar stereo amplifiers and receivers equipment I'm sure.

There is on ebay always someone selling the AR 3 tweeters as suitable for 3a's, and 2 series. For one, the 2 series is 8 ohms and the 3 series was 4 ohms. If a 3 tweeter was subbed for a 2 series tweeter there will be ( someone else may know better ) 2db +/- more output of the tweeter than the original. Reversing and putting a 2 series tweeter 8 ohms into a 3 series enclosure will reduce the tweeter output ( someone elso may know this answer also ) by 2+/-. The only difference between the AR 3 and 2 tweeters was the former was 4 ohm and the later 8 ohms.

I have ( still packed ) a 3/4" AR tweeter with an wire-wound resistor hot glued to the steel casing covering the magnet. I believe this was an attempt to provide one replacement driver for the 4 and 8 ohm tweeters. If the resistor is parallel to the tweeter leads on the back, the tweeter could be 8 ohms but ( I don't know off hand the resistor value ). The true reading of a 4 ohm tweeter is not 4 ohms but 2.5 - 2.7 ohms ( I have the exact readings in my note still packed up ) so the resistor would be ( my guess ) 6 ohms +/-. If the lead was cut on one end of the resistor then only the true tweeter ( 8 ohms or really 5.7 ohm +/- would be utilized. In otherwords one tweeter would serve two jobs, less inventory for one. The resistor would not be used in series with a 4 ohm tweeter as I had read that someone was advised by sales outlet in the AR forum I believe.

Hello you can wake up now.

If you found this of interest please comment. I have a wealth of trivia to offer to those who are interested. Have a great day.