Rectilinear III (Highboy) checkout and refurb

[JRhoBurton]

I described finding these here...

https://audiokarma.org/forums/index.php?threads/speaker-id-have-i-seen-these-before.999589/

I got 4 of these for free. The project will take a while.



I've done a little testing. The woofers are like new. The mids look rough but work well. Maybe they need redoping or other treatment? The tweeters vary. Some are dead, others have erratic impedance.









The screwed in baffles invite DIY variations. One could be a template for many more.



I reinstalled them inside out for safe keeping and checkout.



A couple of the crossovers are "heat treated".

 

[clang444]

They make a great starting point for a new set of speakers - all you have to do is cut a new baffle if you are putting new drivers in it. I picked up a pair that were "worked on" (butchered really) and made a pair of 3-ways out of them. There wasn't anything left of the original drivers to work with. Before:


After. These boxes make base monsters:

 

[JRhoBurton]

I think I have enough good tweeters to make one "showroom stock" pair (replacing bad crossover parts of course).

The other pair could be a variation or totally different setup. So many options in life...

 

[JRhoBurton]

I had time to work on this a bit. I tested the woofers and tweeters with DATS. Tweeters here...



Only 1 is dead. A couple more have very erratic impedance down low. There are enough good ones to do a stock pair.

The woofers have high Vas, around 11 ft3. This yields higher sensitivity but requires a big box, or infinite or open baffle approach, if you want to avoid peaky bass. I modeled the factory design in WinISD Pro Alpha, and also a sealed box of same size. Both are peaky. The factory vented version has only slightly more peaking than sealed, because the tuning frequency is low, about 29 hz.



I'm still thinking about the desired end state for the 4 boxes and big load of drivers.

 

[JRhoBurton]

Our holiday activity today did not work out. No matter. Work resumes on this project. I decided to get 16 buyout cone tweeters from Parts Express.



https://www.parts-express.com/JZ2-678H-2-Paper-Cone-Pressfit-Mount-Tweeter-6-Ohms-69-289-2358

This way I can end up, at minimal cost, with 4 identical speakers close to original, for stacking or quad, if I go that route. These tweeters could be glued right into the smaller existing baffle holes, but I'd rather avoid that. I found that they will press into a 2 inch hole. I have a lot of hole saws. I had a big scrap of 1/8" MDF so I cut 18 rings (a couple of spares are good). First, I cut a bunch of 2" holes. Then I cut rings, half with a 3" hole saw, half with a 3 3/8. I will seal and paint them. A bead of glue around the back junction should hold OK.







I plan to use Omnimic to test some of the old and new tweeters. Hopefully the new, with crossover tweaks, will be compatible.

 

[JRhoBurton]

Yes, I am still working on this. It's sort of a "megaproject" because I intended to make some additional baffles that can be screwed into place like the originals, for various DIY configs. Yesterday I picked up a couple sheets of 4 x 8 x 3/4 MDF and did rough cuts. I managed to remove the siliconed-in Philips mid from an original baffle, then stripped off all glue, staples, the port.



Next, clamped this to a slightly oversized new piece. Then, drilled 1/8 holes thru the originals, screwed the 2 together, and removed the clamps, which would get in the way of a router. Then, edge trim with router to match original. Next, drill out screw holes to factory 11/64ths, countersink for flatheads, check fit. It was right on.



Now, for you folks, a finish question that pertains to all versions of these beasts: How do I fix the somewhat mangled front edges? There appears to be solid walnut trim all the way around the front, 3/4" deep. The damage is confined to the trim.





It's tempting to just sand it down and refinish, without all the headaches of matching.

Edit: yes there would be some fill where the wood is split

 

[aje123]

I have a stock pair from 1970. I recapped with film caps and they are amazing!
The sound stage is dispersed wide!