Bozak B-305 Urban Restore

[moondogtn]

Wow....I am about to begin work on a pair of 305s that I have had since February. You did an amazing job on those. I had planned to concentrate more on the electronics but after seeing the work you did....inspiring. Thanks for all the pics! BTW, where did you gents find those legs?

Bill

 

[Hawkeye83]

@mccuskerkt - how these working out in your studio? I would imagine filling the space quite nicely with that smooth, Bozak sound.

 

[mccuskerkt]

Hi folks! I kinda fell off the map for a while (who knew opening a business would be so time consuming) Anyway my Bozaks sound awesome and get lots of compliments from folks. Just for fun I have them hooked up to my Denon 3806 and ran the Audyssey room correction and it actually really helped with the high end and extended the lows a little. @moondogtn Those legs can be found at your local hardware store near the castors. simple and cheap! I used an angled base plate for the legs as well.
Finally, here is a finished view of the speakers in the studio!

 

[Bigyank]

Hi folks! I kinda fell off the map for a while (who knew opening a business would be so time consuming) Anyway my Bozaks sound awesome and get lots of compliments from folks. Just for fun I have them hooked up to my Denon 3806 and ran the Audyssey room correction and it actually really helped with the high end and extended the lows a little. @moondogtn Those legs can be found at your local hardware store near the castors. simple and cheap! I used an angled base plate for the legs as well.
Finally, here is a finished view of the speakers in the studio!

 

[Bigyank]

I really like the look. Very simple and clean lines. Awesome workmanship!

 

[Shinju]

Amazing work and a keen eye for detail, those look like they rolled off the factory floor!

Well done!

 

[Drugolf]

Outstanding!
Great styling.
The little MCM peg legs are a wonderful way to add a little something to these pieces. Kinda like heels on a pretty woman. Just a little sexier.
Did the same to some Altecs I restored.

 

[OLEGv]

Greaaaaaat work!!!!! I've restored a couple myself in the past (Boak B-401Rhapsody, Wharfedales W90,) Have to ask you what did you use for grill cloth?
I've used good quality burlap. Thank you. Again good job.

Getting really, really close. I'm about a dozen screws and two badges away from completing this project. Ended up using the hardware store tapered legs with angled top plates. Looks pretty good,although I'm still keeping my eyes peeled for an set of original legs or somebody who can build a new set. Here's a couple teasers.

Before attaching the grill cloth.



After. You could bounce a quarter off that.



Oh and here's the preamp I'll be using

 

[twiiii]

The one problem with the 305 was the separated tweeters, creating very un even off axis HF response. If I were going to your extremes I would stand the speakers vertically, remove the tweeters from in front of the woofers and make a short vertical line array with the 4 tweeters. The 209 mid is very problem prone, too. You need find some 209Bc mids and some 200 Zc tweeters and re-build the crossovers .

 

[Hawkeye83]

These were for sale at some point, I think the OP got into building open baffles and was going to use those instead. Not sure if these ever sold or not. Good job on the restore though! They were mine at one point and they played well enough but were rough cosmetically. I would own Bozaks again if I had a larger space. For now I have Quad 57's sitting where the Bozaks were. Really, they take up as much physical space as the Bozaks did!

 

[Retrovert]

The 209 mid is very problem prone, too. You need find some 209Bc mids and some 200 Zc tweeters and re-build the crossovers .

Yes, correct. To clarify, that is the original paper-cone B-209 midrange. It has no suffix.

Avoid the B-209A at all costs. This was the first generation of the aluminum cone drivers. It requires a special damping ring which has long since a shriveled and hardened lump, or turned to dust, or some combination of the two. Without that damping it rings and causes distortion. Conclusion: do not buy the A version.

The B-209B, Bc, and C use a different surround to damp the driver. The B and Bc are rear-mount, the C is front- or rear-mount. The B is alnico, while the Bc and C are ceramic magnets.

The B-305 is different from the B-302 because it nearly always uses a 16 Ω mid-range, so be sure you don't buy the 8 Ω. The 8 Ω B-199 woofers are series-wired to form 16 Ω. So the midrange is 16 Ω as well. This is not guaranteed to always be true, as Bozak made a 16 Ω B-199, so two of those in parallel would be 8 Ω allowing an 8 Ω midrange to be used. In theory. I do not know of any of these B-305's, but there are a lot of Bozaks created by third parties or modified, so check what you need before buying drivers. I know of other dual B-199 configurations which used 8 Ω or 16 Ω configurations.

An AK member posted in BT that he has a pair of the 16 Ω drivers for sale, as he requires the 8 Ω variety for the B-302. No connection with the seller, just noticed them up there and mentioned it if you want to go that path.

 

[rhodus]

Early Sunday morning crossover work. When I am trying to understand a circuit I often separate each part. Helps me make sense of the whole thing. I also have to do the same thing when dealing with almost any type of math. Anyway, this is base off the original 1959 N-102 schematic posted over at the Bozak yahoo group. I believe this will set the Xover points at 800Hz and 2500Hz with 6db falloff. Tobin mods bring the high pass down to 400, but I'll start with the original specification.

Break it down Barney style.




Cap from the N-102 crossover. I'm gonna go ahead and say this isn't original. Capacitance is spot on, but it's not staying.




Meanwhile on the N-10102 crossover, the 50uf Chicago caps are all over the place. This one is reading 33 nf




Time to order parts.

The caps in my n10102 are 5uf.

 

[rhodus]

I know this is an old thread but I don't know who else to ask...I'm looking for the source of the so called "Tobin Mods". I see them referenced but no source or complete info. Also, I have a pair of B305s that I believe to be Factory, but not a matching set. One appears to be about a year newer. The Tweeters are connected parallel, not series as the Factory diagram I have shows.