Jump to content

AR 58s to AR 91 Board Swap


lARrybody
 Share

Recommended Posts

November 4th I posted in Dareen James Thread about my recap of some AR 91 boards to install in my AR 58s speakers.

I have finished the second board and swapped one into the first AR 58s.  

ekjzvnvh.jpg

 

I was lucky that the crazy glue person wasn't involved when they were assembled. Neither was the mega staple employee because they only had 14 staples. After the staples were removed and with a little heat the boards lifted right out. 

s14mc3Yh.jpg 

 

The new boards are 2 inches longer and after aligning the binding post and switches in the opening they were attached with construction adhesive and fourteen #8 1/2 in. truss head screws. I also put a bead of glue around the perimeter of the new board. 

par5MKyh.jpg

I used the foam tape from Parts Express around the baffle cutouts. 3/8 in wide around the tweeter and midrange opening and 1/2 in wide around the woofer. 

V4HU5q2h.jpg 

The poly fill batts were reinstalled in the same position as they came out. I just want to say that the poly fill is so much nicer than the fiberglass to deal with. The refoamed original woofer was reinstalled and the Tonegen replacement went back on the shelf.

OLBAgKmh.jpg

Now on to listening to the two different  configurations and letting the new caps and surrounds settle in.

Link to comment
Share on other sites

Really a good job, excellent excision and brilliant intuition to replace the crossover board from AR58 to AR91.
This is something that I would like to do too with my AR58s in which I find the mid / high range too intrusive (although this was probably wanted by AR technicians to adapt the sound to the request and conform to other producers of the time) .
I think that I will not replace the crossover boards, too difficult to find in Italy and too expensive to buy from the USA (burdened by production, customs and taxes!), But as soon as I find two pairs of three-way switches appropriate, there will be on original crossover the only addition of switches and resistors.
IARrybody I ask you if after a break-in period you can make a report with listening to the switches: -6 db mid, -6db tw and also -6 db mid and -3 db tw.
Also if you can compare these 2 types of adjustments with AR3a pair with the settings of the pots as per the AR specifications (3.25 ohm mid. - 1.75 ohm tw.), In my opinion your AR58 improved should approach in the overall performance at "old" sisters!
I hope for one of your reports that I would like very much and I think it is also useful for many other enthusiasts who want to make AR58 more flexible.
Last thing, you said you put the TNG woofers to rest, the last picture seems to show a TNG woofer on the left and an AR woofer on the right: is the photo before the change?

Giorgio

Link to comment
Share on other sites

The speaker on the left is with the original crossovers and replacement woofer. The speaker on the right is with the recapped AR 91 crossover and original refoamed woofer. I compared them for 5 days with the new crossover set to flat (0db) most of the time because the original crossovers were not adjustable. Both speakers sounded excellent to me at first, but after time the recapped speaker opened up and just kind of disappeared into the room. Sometimes I thought the original sounded better and other times the recapped excelled. I moved them around and varied my listening position. I swapped channels. I had tried them with several receivers and amps, but settled for a recapped Pioneer SX-1010 which was slightly better than a Sansui 990DB not recapped. I listened to a lot of vinyl, FM, CD's and Bluetooth streaming. Everything from Beethoven to Bon Jovi . A lot of Natalie Cole, Donald Fagen and Neil Young.  They both were excellent, but finally decided that the new caps were more transparent and smoother. It was time to finish the second speaker. 

AP1oGqhm.jpge5hmuBJm.jpgYazhbLSm.jpg 

After the second speaker was done I realized the serial numbers were on the old crossovers. I glued small labels on above the openings. I should of included them inside the cabinets like Advent did, but I was not going to open them back up. I also glued tiny ones in the corner of the front baffle. 

4fCx6qel.jpg

Now my banana plugs fit all the way in. The new switches have longer levers and a nicer throw. I have decided on -3 db on the tweeters and 0db on the midranges. They are on stands approximately 8 in. above the carpet, 10 ft.apart and 1 ft from the walls. Bass is solid but not as overwhelming like my 9's.  Either my ears or my mind have convinced me that my efforts have yielded a improvement. One last thought. During the process I got to swap in a set of AR11's and some AR3a's which was a nice experience except for moving them around. I am going to ask for one of those mini folding hand trucks for Christmas. Peace Out

Link to comment
Share on other sites

Thanks IARrybody, splendid work, thanks for the report on the comparison of the listening between 2 speakers similar but not equal (before / after changes simultaneously).
I really appreciate the use you have made of quality bipolar electrolytic capacitors (up to now I used expensive and large polyester), I am more and more convinced to use this type of capacitors myself!
Since you've handled both AR3a and AR11 lately, I renew to you the request to listen to your renewed and improved AR58 with mids and tweeters both at -6db and another step at -3db, I ask you this because you have the chance to soften the range medium high and the reason why I want to make the same change to my AR58 is to be able to make them sound similar to AR3a (certainly not the same for many reasons, but I want to bring all my 12" speakers closer to the AR3a specifications).
Thanks to your help, I can first know the result that I can get with your change.

Link to comment
Share on other sites

1 hour ago, lARrybody said:

Now my banana plugs fit all the way in. The new switches have longer levers and a nicer throw.

Very nice job.  Well done.  And I like those new binding posts too.  I use them on my refurb's.  Also, which switches did you use?  I'd like to try those.

Thanks.

Link to comment
Share on other sites

21 minutes ago, Stimpy said:

Very nice job.  Well done.  And I like those new binding posts too.  I use them on my refurb's.  Also, which switches did you use?  I'd like to try those.

A lot of people here like those economical binding post. I keep several pair in my parts box. The Single Pole Dual Throw Center Off switches came from Parts Express. I was impressed with the quality for a two dollar switch.

https://www.parts-express.com/spdt-medium-duty-toggle-switch-center-off--060-552

xzfhUAJl.jpg9uwCVuWl.jpg

Link to comment
Share on other sites

It would be interesting to compare the 58s and 91 crossover schematics in this thread if you 

have them handy to post.  I'm sure that they're around CSP somewhere.

Nice job on the rebuild and XO swap by the way!

Link to comment
Share on other sites

5 hours ago, Pete B said:

It would be interesting to compare the 58s and 91 crossover schematics....

Pete, the drivers are identical in these two speaker models, and the crossovers are, too, with the exception of the switches and associated resistors included with the 91. Larry's objective here is to add the switching capability to the 58s which originally had no such control. From what I can tell, aside from significant variations in styling, the only other difference is the interior cabinet volume:  46.8L (1.65 cf) for the AR-91; and 43.6L (1.54 cf) for the AR-58s.

AR-91 and AR-58s schematics.jpg

Link to comment
Share on other sites

That makes sense to add the level controls.

It is interesting how different these are from the AR-11 for example that has 10 uF in the tweeter

circuit and a bigger inductor on the woofer.  The midrange differences are expected since a 

different mid driver is used.

Link to comment
Share on other sites

  • 3 weeks later...
On 11/30/2019 at 5:50 PM, lARrybody said:

The Single Pole Dual Throw Center Off switches came from Parts Express. I was impressed with the quality for a two dollar switch.

I had meant to comment earlier to say how nice this new circuit work has been done. Also, I admire the use of those truss-head screws for fastening the new panel, and I really appreciate your sharing the specific switch product that was used. I get all confused trying to translate the schematic to the actual switch terminals, and your pics are helpful at getting a better understanding of this arrangement. 

Link to comment
Share on other sites

  • 4 months later...
On 12/27/2019 at 2:17 PM, ra.ra said:

I had meant to comment earlier to say how nice this new circuit work has been done. Also, I admire the use of those truss-head screws for fastening the new panel, and I really appreciate your sharing the specific switch product that was used. I get all confused trying to translate the schematic to the actual switch terminals, and your pics are helpful at getting a better understanding of this arrangement. 

Amen on the confusion when translating schematics into a real-life circuit! I understand diagrams much better than a schematic!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...