AR9LSi Info Needed

[briodo]

I recently acquired a pair of AR9LSi through Craigslist from the original owner who bought them while stationed in Germany around 1985-86. Overall condition is very good with few nicks in the wood or grills. The 8 and 12" drivers had been refoamed, but the speaker never had the original sound he remembered and I showed him the 10" was rotted on both as well. The owner knew very little about AR's or how critical the seal is to get good sound from a pair. I have a 10" foam kit on order from Vintage-AR to take care of that problem.

The major issues are the wood finish and I assume the crossover capacitors due to age. The speakers were built in England and have some twists from what I have seen in researching US AR9LS/AR9LSi versions. Some differences are the 12" driver having a round hole as opposed to the typical side cut hole found on other 12" AR's, shiny coating over wood veneer, and a crossover circuit card rather than the hand soldered connections found in my other AR's. Also, the drivers appear to be Tonegens based on pictures from the AR3a Restoration Driver appendix.

I have attached some pictures, including the crossover circuit card. The capacitors are underneath that circuit card with massive amounts of hot glue holding the whole assembly to the rear of the cabinet. Not sure if I want to remove it due to opportunity for damage.

My questions are:

1) Wood finished with lacquer or varnish. The walnut veneer is in beautiful condition, so why did they put the glossy stuff on top of this gorgeous wood? Is this a UK only feature?

2) The crossover matches the AR9LSi schematic found in the library, except I can't see the values on the caps. Are they the same and should they be replaced? Were the NP electrolytics of that time reliable enough to stand the test of time?

3) Foam in the 10" slot location has rotted out. What was the purpose of the foam and what are some recommendations for replacement?

Thanks,

Brian

[briodo]

I found a great UK brochure called "AR UK BXi & LSi Brochure" under the AR library->Special Sections->AR International->Brochures with marketing info on the UK versions of the AR product line at the time. While the version I have does differ cosmetically from the AR9LSi picture in the brochure, they discussed the 10" downward firing driver and the "special, foam-damped bass contour chamber". The design prevents bass cancellations due to rear wall and floor reflections, filling any dip in the 12" unit's response due to the floor or wall reflection. I will assume the foam should be replaced with some type of acoustic dampening foam material to match original configuration.

Still would appreciate any recommendations on replacing the "computer grade" crossover caps. I figure I can reach at least one lead on all the capacitors and snip it, then attach new caps in on the top surface of the PCB. It would be good to hear others experience with the reliability of caps from the mid-90s ARs. I know the older version were certainly almost guaranteed bad after 30 years.

[briodo]

Update on the wood finish problem:

After doing some research online on the wood finish problem with this particular pair of AR's, I found a great article by Shannon Smith on determining wood finishes: What Type of Finish Does Your Furniture Have

I posted a picture earlier showing the glossy finish separating from the wood and flaking off. This flaking appears on both speakers over much of the walnut finish.

Using the article led me to the finish being varnish, requiring stripper to remove the finish.

After disassembling the AR9LSi's, I started experimenting with strippers. The stuff I found to be most efficient at removing the finish is called CitrusStrip which I found after trying regular gel strippers. The CitrusStrip smells like oranges and worked with a single coat allowing me to rapidly remove all of the gunk in a single afternoon on both speakers. The other strippers required multiple applications, taking way too much time.

Final steps were sanding and cleaning the walnut then applying 3 coats of Penofin oil finish. Results look very good.

Next update will be on my fun updating the caps mounted to the crossover circuit card.

[Carlspeak]

I found a great UK brochure called "AR UK BXi & LSi Brochure" under the AR library->Special Sections->AR International->Brochures with marketing info on the UK versions of the AR product line at the time. While the version I have does differ cosmetically from the AR9LSi picture in the brochure, they discussed the 10" downward firing driver and the "special, foam-damped bass contour chamber". The design prevents bass cancellations due to rear wall and floor reflections, filling any dip in the 12" unit's response due to the floor or wall reflection. I will assume the foam should be replaced with some type of acoustic dampening foam material to match original configuration.

Still would appreciate any recommendations on replacing the "computer grade" crossover caps. I figure I can reach at least one lead on all the capacitors and snip it, then attach new caps in on the top surface of the PCB. It would be good to hear others experience with the reliability of caps from the mid-90s ARs. I know the older version were certainly almost guaranteed bad after 30 years.

The 'computer grade' caps you refer to, I suspect, are the Compulytic brand. They are of very good quality and don't drift much based on my measurements. I do recomment replacing the midrange and tweeter caps with modern film types. Let your budget be your guide to choosing which ones to get. Personal favorites are Sonicap and Jantzen for more critical applications.

I often wonder if old time woodworkers who venerred these and other vintage AR, Adven, KLH and other cabs visit these forums. It sure would be nice for them to see their handiwork revitalized like the work you have done.

[briodo]

The 'computer grade' caps you refer to, I suspect, are the Compulytic brand. They are of very good quality and don't drift much based on my measurements. I do recomment replacing the midrange and tweeter caps with modern film types. Let your budget be your guide to choosing which ones to get. Personal favorites are Sonicap and Jantzen for more critical applications.

I often wonder if old time woodworkers who venerred these and other vintage AR, Adven, KLH and other cabs visit these forums. It sure would be nice for them to see their handiwork revitalized like the work you have done.

Thank you for the capacitor information. I will purchase new ones and figure out how to wire into the circuit card. That should be interesting.

I was amazed at the beauty of the woodworking. Each speaker is a single sheet of veneer starting from bottom of one side around the top to bottom of other side. You can see how the grain matches so well in the last picture. They were artisans of their craft for certain.

[briodo]

Update on the capacitor change out. I found new film types online and was ready to start. The only downside with this particular AR9LSi version is the capacitors are mounted under the printed circuit card crossover card. That means cutting them out is a non-starter (can you say hot glue palooza) so I went through process to isolate all the old caps from the crossover circuit by cutting one lead from each cap.

After that it was just finding good spots to wire the new caps into the card.

I did a little documentation package, taking liberty with part identifiers on the AR9LSi schematic and labeling parts and wiring locations using pictures taken of the circuit card. I hope this will make it easier for the next person who needs to do this same task.

Brian

AR9LSi_Crossover_Oct_2010.pdf

[lance G]

Briodo/Brian, you deserve some serious recognition for this, if only for the amount of effort you have put into the project and the production of your pdf write up.

Consider it as having been seriously recognised !

Likely useful to raise it to the front of the forums page/s again.