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AR2a level question (another one)


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#1 Guest_dogmeninreno_*

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Posted 26 November 2004 - 12:54 AM

>>
>>More than likely your pots can be restored. I have several
>>dozen of these pots and charge $7.50 ea to supply cleaned
>and
>>lubed original pots. This price is only good if you trade in
>>your old units. The price is the same if you send me your
>pots
>>and I clean and return them to you. I don't want to sell
>these
>>without trade because they are getting hard to find. Dale
>>dald@sbcglobal.net
>
>Dale,
>
>Refurbishing the Aetna-Pollock level controls through an
>exchange program is a great service to offer to restorers of
>old AR speakers. I think that most will agree that using the
>original Pollock controls is usually the best way to restore
>the correct "spectral balance," so-to-speak, to pre-1975 AR
>speakers. Some people want to bypass the controls, but it
>usually results in over-bright or unbalanced sound from some
>models. With the AR-3a, for example, the best balance seems
>to be to turn the tweeter level control close to max and the
>midrange control to the "dot," or mid position. In this case,
>the midrange driver is more efficient than the tweeter, so
>this setting helps to even the output from those drivers.
>Obviously, the level controls have to work properly to enable
>one to make these fine adjustments.
>
>The level controls were originally designed to compensate for
>variations in room acoustics in different listening rooms.
>Some rooms were very reverberant with little or no absorption
>while others were overly damped with lots of stuffed furniture
>and so forth, and the controls helped to adjust the output of
>these speakers to compensate for these differences.

Tom, I fully agree. Most of these old timers are fixable but the hardest part I find is removing and replacing them in the cabinet. I have restored probably 200 of the old Pollock pots and have only found a handfull that are beyond repair. These have usually come from a humid climate area too. I finish my repair with a thin layer of di-electric grease applied to the wire (which you can find at a auto parts store) and it sure seals the repair for a long time "I don't know about 40 years" but you and I may not care about that and the nubies can use maybe Nano-lube on the future?? Dale

#2 tysontom

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Posted 25 November 2004 - 02:40 PM

>
>More than likely your pots can be restored. I have several
>dozen of these pots and charge $7.50 ea to supply cleaned and
>lubed original pots. This price is only good if you trade in
>your old units. The price is the same if you send me your pots
>and I clean and return them to you. I don't want to sell these
>without trade because they are getting hard to find. Dale
>dald@sbcglobal.net

Dale,

Refurbishing the Aetna-Pollock level controls through an exchange program is a great service to offer to restorers of old AR speakers. I think that most will agree that using the original Pollock controls is usually the best way to restore the correct "spectral balance," so-to-speak, to pre-1975 AR speakers. Some people want to bypass the controls, but it usually results in over-bright or unbalanced sound from some models. With the AR-3a, for example, the best balance seems to be to turn the tweeter level control close to max and the midrange control to the "dot," or mid position. In this case, the midrange driver is more efficient than the tweeter, so this setting helps to even the output from those drivers. Obviously, the level controls have to work properly to enable one to make these fine adjustments.

The level controls were originally designed to compensate for variations in room acoustics in different listening rooms. Some rooms were very reverberant with little or no absorption while others were overly damped with lots of stuffed furniture and so forth, and the controls helped to adjust the output of these speakers to compensate for these differences.

--Tom Tyson

#3 RoyC

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Posted 22 November 2004 - 02:32 AM

Its best to restore the pots if you can. As mentioned on this board before, the silicone dielectric grease sold in auto stores works very well to slow down the corrosion once they are cleaned. A small tube goes a long way.

Its possible to replace them with fixed resistance if you know your preferred pot settings. Resistors equivalent to the values between terminals "1" and "B" (in series with driver) and terminals "2" and "B" (parallel) would work. The sum of those values will equal the pots fixed resistance between terminals "1" and "2".
The pots fixed resistance will measure from 15 to 16.5 ohms depending on the speaker model.

Contrary to popular belief the pots are NOT the same for every model. The pots fixed resistance for the 4 ohm rated AR3a is 15 ohms. The 8 ohm rated AR5 and (I believe the AR2ax pots) measure around 16.5 ohms. I've noticed that of the pots I've dealt with, the ones with the red plastic stems have been 16.5 ohms and the metal stems have been 15. That may be a coincidence.

Impedance differences, can effect the character of your vintage sound and, can endanger your hard to find tweeters. The pots were an integral part of the x-over design.
Roy Champagne

#4 Guest_dogmeninreno_*

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Posted 19 November 2004 - 03:47 PM

>OK guys, I have seen many different ways of dealing with the
>fried level control problem. I have been told not to just
>bypass them, and on the other hand not to use 16ohm L pads
>commonly available. I don't know if mine can be cleaned up
>enough yet but I would rather replace if possible. What is
>the CORRECT way to fix the dreaded problem and not mess up the
>sonics. Why can't you use the L pads? The originals are long
>unavailable. Please help me get these sweet speakers back to
>100%. By the way, I have one bypassed because I was getting
>next to nothing from the tweeter and it seems fine but I was
>told it messes up the crossover points? Very confused by the
>multitude of solutions. Please some AR guru help me. BTW
>these are 2a models with the dual midranges that for some
>reason get bashed all the time, I rather like them myself!
>Think they are at least as good as the AR2ax models I had a
>while back.
>
>Jeff

More than likely your pots can be restored. I have several dozen of these pots and charge $7.50 ea to supply cleaned and lubed original pots. This price is only good if you trade in your old units. The price is the same if you send me your pots and I clean and return them to you. I don't want to sell these without trade because they are getting hard to find. Dale dald@sbcglobal.net

#5 Guest_jeffczar_*

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Posted 19 November 2004 - 04:45 AM

OK guys, I have seen many different ways of dealing with the fried level control problem. I have been told not to just bypass them, and on the other hand not to use 16ohm L pads commonly available. I don't know if mine can be cleaned up enough yet but I would rather replace if possible. What is the CORRECT way to fix the dreaded problem and not mess up the sonics. Why can't you use the L pads? The originals are long unavailable. Please help me get these sweet speakers back to 100%. By the way, I have one bypassed because I was getting next to nothing from the tweeter and it seems fine but I was told it messes up the crossover points? Very confused by the multitude of solutions. Please some AR guru help me. BTW these are 2a models with the dual midranges that for some reason get bashed all the time, I rather like them myself! Think they are at least as good as the AR2ax models I had a while back.

Jeff




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