Altec 890A Bolero questions

Love the final product. They look sweet and I'm sure sound fantastic. I'd love to hear that Amber sometime.
 
Excellent work on the speakers and the vid. Appreciate the additional work in the vid denoting what is going on, very nice.
 
I read somewhere that the Boleros and Maderas were designed to be positioned vertically.
 
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All the beleros need a recap by now. I used the Dayton 1%ers and it made a pretty dramatic change for the better to speakers that were already good. Very nice video.
 
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I am still kicking myself in the ass for not picking a pair of those up from a TS for $20 each. I was staying in my little fish camp place in the Summer and had no place to put them. The same thing happened the next Summer with a pair of Bozak 802s. What can you do; their gone. o_O
 
All the beleros need a recap by now. I used the Dayton 1%ers and it made a pretty dramatic change for the better to speakers the were already good.

Yeah, I also used Dayton 1% caps in these (extras that I had ordered when recapping the Maderas) and it made a profound improvement in the sound.
 
Both of those speakers ring the bell just right for me, but the Boleros come closest to delivering that "magic" that devoted Altec owners always rave about. And that sound track was perfect for demonstrating the kind of mid and mid-hi reproduction that makes music sound almost hyper-realistic.

GeeDeeEmm
 
Very nice! They both sound great even through the camera. What song were you playing in the demo?
 
The Boleros gave me a bit of a scare this week when it seemed like one of the (essentially unobtainable) 3000G tweeters died. Fearing the worst, I: (1) checked the auction site; (2) posted a WTB thread in BT; and (3) asked some of my sources if they had a line on a 3000G. These efforts turned up nothing, so last night I pulled the tweeter and crossover network and checked them out.
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The DC resistance of the tweeter looked about right (10 Ohms), which was an encouraging sign. Turning to the crossover network I quickly discovered that the L-pad had failed open, meaning that I could detect no conductance between any of the three terminals.
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So I pulled the L-pad apart completely and cleaned everything with alcohol, Deoxit, and Scotch brite. I also made sure that the leaf-spring was still making contact and that the barrel of the knob was properly lubed. None of this restored conductance, however, and I banged my head against the problem until finally, in desperation, I heated and reflowed the solder contacts between the flat leads on the outside and the wire coil on the inside of the rheostat. That fixed the problem. Apparently the solder joints on both of the outer leads had cracked.

After buttoning up the speaker I gave it a listen and, like a Christmas miracle, the tweeter came back to life.
 
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Well, the left tweeter dropped out again so I decided to completely replace the L-pads on both speakers. After a bit of digging on digi-key, I found a nice (expensive) pair of ceramic 25 OHM variable resistors with the right dimensions. If you are planning to replace yours, the relevant dimensions are:
stem diameter - 0.25"
threaded bushing diameter - 0.375"
stem length (including bushing) - ~0.75"

new_rheostat.jpg

Last night I swapped out the rheostat from the problematic speaker and the tweeter returned, with even more presence than in the other speaker. As soon as I can, I will replace the old rheostat in the other speaker as well.

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I loved these speakers from the beginning but they just keep getting better.
 
I just picked up a pair of these last week, only they are the 890c's. They have that great Altec sound, beautiful midrange, and I mirror imaged them..
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I just picked up a pair of these last week, only they are the 890c's. They have that great Altec sound, beautiful midrange, and I mirror imaged them..
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Interesting. I also have a pair of later model 892b Maderas with the same Heppner/mystery horn. I have never seen anyone slap an acoustic lens on these horns before. Does it make a noticeable difference?+
 
Interesting. I also have a pair of later model 892b Maderas with the same Heppner/mystery horn. I have never seen anyone slap an acoustic lens on these horns before. Does it make a noticeable difference?+
My Bolero's are a little above ear level, so I thought I would do a DYI, and make a set of lenses for the tweeters, so I could angle them to help direct the signal to my sitting position. It worked out very well once I figured out the proper angle. It was a very simple mod that I was able to make without doing any modification to the speaker itself.
 
Quick update on the Boleros: I finally got around to replacing the grill cloth. As you may recall from earlier in the thread, the original cloth was dry-rotted, discolored and, in places, badly ripped.
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The material itself was quite sexy: a 22-ish thread-count raw linen with occasional thick fibers woven in to create a horizontal pattern like rain streaks on a windshield
grill_cloth.JPG

Initially I wanted to find an exact match to this cloth. Following advice from @SFBayArch (in another thread - no pun intended), I checked 123Stitch.com, but couldn't find a match on their website. I also emailed customer service with the specs and the photo above. They were very helpful but they didn't have any material quite like this, so I decided to hit the discount fabric outlet and find something I could live with. After a bit of digging I came up with a nice 20-ish thread count linen with a similar pattern.

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Not _quite_ as classy as the original, but not bad. I pulled all the original staples from the frame and removed the old grill cloth. Underneath, I found a thin, coarse-woven black cloth that was apparently added to increase the opacity of the grill. This material was in good shape so I just steam-pressed it flat and reused it.
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Everything else was pretty straightforward. I wasn't too careful about keeping the threads exactly aligned with the edges of the frame but life is short...
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I did have to run to the hardware store to get some 1/4" staples, because my 5/8" staples would have punched all the way through the frame.
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The result might not be quite as sexy as the original was when it was brand new but it's not bad.
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insitu_done.jpg
 
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