AR 2ax midrange caps?

[BassoRider]

I'm planning to recap the cross-overs in my 1975 AR 2ax speakers.
To my surprise I found 4uF/50V (Industrial Royalitic Long Life) caps soldered across the plus/minus terminals on the midrange speaker elements. They look like original parts.

Should I:

1: Remove them?
2: Replace them with modern caps?
3: Leave them well alone?

I live in Sweden, so this is likely a European version. I think the cabinets were made in the UK, with speaker elements made in the USA, but I could be wrong.

Any help would be greatly appreciated.

 

[ozmoid]

http://layneaudio.hypermart.net/2axmids.jpg

AR added resistors across the mid to reduce the output in a later 2ax design revision (see photo linked above). I haven't encountered caps, though. :scratch2: Could be a re-design of the crossover?

 

[BassoRider]

Here's a pic of the arrangement. What purpose could a cap serve there?

 

[GordonW]

That would act as what's called a "pi-type low-pass filter".

The purpose would to shunt off high frequencies from the mid driver. Darn unusual way to do it (it causes significant impedence dips), but with those two resistors, I can see it working OK that way.

Regards,
Gordon.

 

[BassoRider]

Thank's Ozmoid and GordonW!

I'll replace it with a modern cap, to keep the speakers within original specs.

 

[ozmoid]

Thanks for posting the photo - first time I've seen that configuration. Learn something new everyday at AK...

 

[GordonW]

Bassorider, you might want to ask over at the Classic Speakers Page, to see if any of the "AR gurus" over there might have ever seen that crossover configuration. I'm not totally convinced it's original... could be, but it's not like anything else AR did, that I've seen...

Here's the web address: http://www.classicspeakerpages.net./

Regards,
Gordon.

 

[shrinkboy]

i just opened a pair of AR 2ax's and saw nothing like it....

 

[shrinkboy]

that's the mid on the upper right of the box, basso. no cap on it. seems like a work around of some kind

 

[BassoRider]

Thank's for the pics, Shrinkboy. The caps are "Industrial" brand, just like the cross-over caps, and they look 30+ years old. Maybe something AR UK came up with? I blew out the midrange element in the other speaker in the late 70's and bought an original replacement. It's the later high-ohm version, without added resistors, but it also has a 4uF cap across the terminals! So it seems pretty standard, at least in my part of the world... :scratch2:

I'll register at Classic Speakers and ask there. Maybe it's something for the AR historians! :thmbsp:

 

[ozmoid]

I'll register at Classic Speakers and ask there. Maybe it's something for the AR historians! :thmbsp:

I'd hazard a guess that if anybody could illuminate that for you it would be Tom Tyson over on the CSP forum - you're headed in the right direction!