Bozak Symphony B4000 crossover question

[Michael n]

I've been reading tons of information regarding the crossover and mods for the Bozak Symphony. I just acquired a pair that are loaded with N-101A crossover. I don't believe that is the correct recommended crossover for the symphonies (the N-101A shows cross at 800 and 2500 hz 6db per octave 8 OHMS ).
From info I have found, I want the crossover at 400 and 2500 hz.
My question is , what crossover do I need to get to swap out the 101A? I'm seeing N-104 or N-105, or the N10102? I can't find anything definitive though.
My pair of b4000 have the B199 woofer, B800 mid, B200Y tweeter.
Any suggestions on what I should look for as a crossover would be greatly appreciated.
Thanks,

 

[drbiggles]

Hey,

You want the N-105. But that 101 will do it, just need to use the right jumpers on the woofer and 50uf cap on the mid. Bam! You’re done.

Post a top down view of your 101 we can point out which goes where. Or look online to others work.

Biggles

 

[Michael n]

Thanks Biggles. If I can get away with keeping the 101 that would be great. I’ll grab some photos this evening. Thanks.

 

[drbiggles]

Yeah, it’s the same inductors on both crossovers. Rudy just added parts, recajiggered things to make it work. Freakin brilliant. If mid/tweeters are too bright we can move mid crossover point down on the mid to 1250hz and that’ll balance things out. That’s what Pat Tobin did. All within Rudy’s original plans.

Biggles

 

[Michael n]

 

[Michael n]

Here is the 101a. Sound is pretty great actually. I have very little experience with crossovers. Let me know what you think. If a modification might improve overall sound I’m up for any suggestions. Listening to these speakers for a few days now and really impressed. Thank you to the Bozak folks.

 

[twiiii]

I would stand the large coil on edge to reduce cross coupling effects. . Now I had Contemporary Symphony speakers with the 8 inch mids and my speakers which were built from kits by me and the cabinet man at the stereo shop and were crossed at 250 Hz and 1500 HZ. The big debate back then was whether the mids should be wired in phase or out of phase. But the later N-105 was a different crossover when the 4000 was first introduced and adding just a larger cap wasn't the total answer. It had a larger coil for the two woofers also. In this picture with the two 275's are awaiting my Concert Grands to be bi-amped in 1970. Yes, there is a 302A load in the bottom of the TV. I have always had three channel since the middle 60's.

 

[Michael n]

I’ve had some time to give a good listen to the speakers and I’m finding 1 speaker flat in the midrange (compared to the other). I think the crossovers need attention (or the mid driver on one is in bad shape).
Again, I have no experience with crossovers but I do have a soldering iron and im willing to learn. Would the best course be to try and update the 101a with new components or should I start looking for new used crossovers?
I really appreciate all the knowledge on the site. I’ve learned quite a bit from the site. Any opinions would be welcomed.
Thanks

 

[Michael n]

I’m almost certain that one of the crossovers is weak. I checked all the drivers with a multimeter and they check out. Can anyone direct me to where I might be able to find instructions on how to build a new crossover? Or does anyone in the community have a pair of N-105 they’d like to sell?
Thanks

 

[drbiggles]

There’s more than a decades worth of highly detailed notes, schematics, comments and how-to’s here on AK. There’s more here than any other website. You can use the N10102 as well, or build from new parts.

Biggles