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AR3a improved UK edition 1976 and others...


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This is one of my UK build, improved, bought from 1st owner who bought them jn 1976 in the Netherlands. Refoamed with rubber surrounds in 2003. Still all good to go. Playing nicely on a Bryston pre and main 19 inch rack set of 2 x 100 watt @ 4 ohms.

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This is a set of AR6 i bought in Germany and i refoamed them myself. The case was empty and i added fiber glass. Thanks to RoyC i now know that i have to open them up and can add or subtract weight as he was kind enough to inform me of the needed volume/weight for this model. Also an Audyn 10uF cap was added.

The set plays on a refurbished and modified Quad 303 and 33. The boards have been emptied and/or replaced by me and only the best modern equivalents low tolerance parts are used like metal film resistors, transistors, mkp caps etc...

The mod is one that takes out the 4 ohm restriction which was inserted into the amp originally to not fry the Quad 57 electrostatic speakers as they had no overload protection and the impedance drop could ask too much current from the amp at 4 ohm frying the treble panels. It now delivers all the current it can give at 4 ohm and some may know 303 stands for 30 volts @ 3A. This was with 8 ohm btw, so for 4 ohm it will now give much 20240202_204019.thumb.jpg.b82a5c41b071a2378e42649ccb79eb06.jpgmore punch. All discrete stages... This combo sounds excellent! Very different to non-discrete hifi or tubes. Mellow i would call it.

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Am i correct in saying that either the tweeter or mid is out of phase in the AR11 and AR3a improved? I always get lost in reading xo schematics...

I am also correct in quoting someone in another forum that a dutch man was very much involved in the development of the 3a improved version and that it was never sold in the USA?

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The AR -11, AR-3a Improved, and the AR-3a Limited tweeters are all wired with reverse polarity to that of the woofers. I believe the wiring of the mid of the AR-3a Improved has never been conclusively determined. I have two schematics, one showing the Improved mid wired in phase and the other out of phase.

Roy

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Friend of mine has original unhassled ar11, i have the improved unhassled and sunday possibly the limited, if your deduction is correct, Roy. Maybe it will give more credibility to which schematic is more likely to be correct. I have still not yet found the time to open my improved.

Cheers

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I have been able to get my hands on a set of original ar3a stands. I want to make some oak stands for the lst/ lst2 combo.

Here is a preview what that will look like...

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I will follow the contours of the lst2 with solid oak, so it has to be cut twice at 45⁰ angle and glued together. Ofcourse the back will remain open as i dont want a resonating box underneath them.

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12 hours ago, Andre_Db66 said:

Friend of mine has original unhassled ar11, i have the improved unhassled and sunday possibly the limited, if your deduction is correct, Roy. Maybe it will give more credibility to which schematic is more likely to be correct. I have still not yet found the time to open my improved.

Cheers

Part of the problem is that the Improved crossover is buried in glue (see attached photo). Since there are no pots to clean or replace, and the switches are typically ok, there is an understandable reluctance to dig through the mess unless there is an obvious issue.

 

3a imp xover photo.jpg

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Why o why....?

😪

AR went down the same road of less quality and faster production techniques, cutting samecorners as i have seen in my days with Sansui. Vinyl vineer, glue, materials etc...

How sad.

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I still have to open up the improved speakers. I am curious to see what i will find. Driver types xo glue....

Too busy at the moment. Day after tomorrow i hooe to have the coils for the HiVi tweets...

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