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Tobin mods to Bozak B-401 ?

gadget73

gadget73

junk junkie
Subscriber
I'm a little lost reading the assorted threads about the Tobin crossover mods to Bozak speakers. I haven't found one specifically mentioning the B401. The 401 has the same driver compliment as the B302a, however the tweeters are not mounted coaxial in the woofer.

What I'm not clear on is which crossover to use here. I see reference to several different ones. Help ?


Subjectively, what do these sound like with the Tobin vs stock crossovers? Currently I find them to be a little bit too bright, and I run the control at "mellow" to deal with that. It takes care of the upper mids, but the very top range is slightly more muted than I'd prefer.
 
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'looks like the same drivers & crossover points as used in a number of Rudy's children:

https://stereonomono.blogspot.com/2016/06/bozak-b-401-rhapsody.html

so I would think the 104T would apply (greater Bozak authorities than I will likely chime
in on that). That said, I have trouble believing any Bozak would be described as shrill
& a b200y doesn't do much above 8k. Bringing things better into balance post-marketing
foolishness was what Tobin was all about so I think you are likely on the right track.
 
Not sure I'd call it shrill exactly, but it just sounds like its got a peak in the upper midrange. The tweeter control can help with the upper mid peak, but it makes the highs a bit flatter than I'd prefer.

I also have read things about reversed phase on some of the mids. Honestly when I started poking into this, I got so much information that it was just overwhelming.
 
I hear that, why I delayed getting to it for so long & likely just took the easy way out and bought new.
That can be pricey tho. 'Might want to start with a simple cap refresh (like for like, Dayton 5% seem just fine)
and maybe try reversing leads. Do it in stages. My guess is new caps will help a lot. If that alone doesn't do it for you, try reversing one of the mid leads to see what you think. This is my 105 to the new 104t by the way. Rudy hid the caps in the metal tower, it's a lot simpler if you do not do that & remember: one 50uf = two 25uf's wired in parallel, just as you see in the new piece.
F0C2605C-7F06-4AAF-AC93-1D0DC838D7F6.jpeg

PS: I love 60's Lincoln's, just picked up one of those medallions in September. Dream car: '63 convertible (not going to happen given how collectible they've become...sigh...)
 
I already rebuilt the stock crossovers with new film caps. It did make a huge difference.

Might try flipping the midrange just to see what it does.

All three of mine are rather newer models. An 84 Continental, 86 Towncar, and a 91 Mark VII.
 
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