quiet
Addicted Member
Well, judging from the performance of the tweeters in my Bozak Century 302a's I would say yes.
Bozak Concert grands speaker replacement
- Thread starter swimlvr591
- Start date
Woofers are missing here so don't use a B199.
Rob-F
Likes Vintage Gear and DIY
Do you really want to say that? After all, the B199 with tweeters mounted in the ring was very popular, and sounded good! I think it was crossed over at around 1500 to 2000, so the B199 must be OK for about an octave above 800, no?
Yes. I didn’t make it up. Pat Tobin and others have tested the B199 with computer aided equipment to come to that conclusion. Others here have tried it in econowaves and state the B199 is lousy for that application. I’ve run it as a 2 way with the B209y’s and it sounds like crud, huge hole in the midrange. Others here have posted the same. In my opinion, there is no worse 2 way.
This is the main reason pat Tobin put his woofer and mid to crossover at 400hz rather than 800. The B199 has breakup in the 800Hz range.
Biggles
quiet
Addicted Member
The B199 and tweeters was used with the assumption that the mid was to be added later. Pay as you go.
rider33
Active Member
so here's the thing: you were given some really big boxes with what I assume is a line array of tweeters still in place. It's a box that is easy to work on/in once you remove the oh-my-god-how-many screws, the back panel pops right off. My advice: play with it. Try the single woofer as Steve suggests, hell, buy some inexpensive 12" Utah's, even Coaxial's & have at it. Fully Kosher? No, but a lot of fun. You don't need to have a PHD in EE to frolic. Remember, this is a hobby, don't forget to have fun. You can always full-boat in back to spec at some point. Don't be afraid to color outside the lines.
Retrovert
Addicted Member
Exactly.
Since it might be of interest, here's what I elsewhere posted on this subject, slightly edited:
Bozak's two-way to three-way upgrade path was excellent marketing for a small company selling a very expensive product which could be broken down into pieces purchased over time. This was like layaway, except the saver could use the product in the meantime. The two-way B-300 is a poor-sounding coaxial speaker, but, again, it was a means to acquire customers which otherwise would have purchased from another manufacturer.
Bozaks were very expensive back in the day, and only professionals with consider disposable income could afford to purchase a full system fully tricked out. We today purchase vintage speakers, not just Bozaks, at scrap value. All of the purchase price has long since vanished, and we're paying a pittance for the products of once-great manufacturers. HiFi clearly is not the place to park one's money, as it generally poorly performs. The S&P 500 greatly outperforms most "investments" in tangibles, such as collectible cars, HiFi, gemstones, or comic books, Superman No. 1 notwithstanding.
At the time Bozak was selling it upgradeable systems, a single Bozak B-209 midrange cost $51 from Lafayette (plus shipping) which in today's debased currency is roughly $1,000 of buying power. Here's why I write that. a PhD engineer (in short supply) made about $8,000 per year, or $4 per hour, and that was PRE-TAX. A factory worker made $2,500 per year, or $1.25 per hour, again PRE-TAX.
So a single Bozak midrange roughly represented, again PRE-TAX, 12.5 hours of engineer labor or 40 hours of semi-skilled labor. A pair of Bozak midranges was thus roughly 25 hours of PRE-TAX labor for the engineer and 80 hours PRE-TAX for a factory worker.
These numbers are worse after taxes! Now, federal taxes were lower in those days, averaging about 22% for the engineer and 20% for the factory worker. Add maybe 5% for the state. So figure roughly 27% and 25%. If we use 25% to make the math easier, the cost for a pair of Bozak midranges works out to be 33 hours of pre-tax labor for the engineer, and 53 hours for the factory worker.
So roughly nearly a week's pay and over a week's pay, depending upon how much the worker made, for a pair of midranges.
That omits the cost of a crossover, which was comparable.
So upgrading that speaker from a two-way to a three-way was an EXPENSIVE proposition!
I don't have handy the prices for 1960. (My Bozak folder is in a filing cabinet I'd have to root through.) But I do have the 1963 prices from Lafayette. The street price (plus shipping) of a B-302 was full $250 in the least expensive configuration, or roughly 83 hours of the engineer's take-home pay. Over two weeks of salary for an engineer. Figure about $5,000 in today's money. (A comparable engineering salary today is $120,000 so figure $2,300 per week, so the numbers work.)
Ordinary people did not have that kind of cash. My mom spent about 1.5 weeks after-tax pay on one of the fancy Zenith 845 tabletop radios around that time, and she had a decent job with a Master's degree.
Housing has inflated at roughly three times faster than other commodities, which is why the multiplier in real terms is far more than the ten which it might otherwise appear to be.
Bozaks were expensive speakers, and in an effort to amortize the price over time the midrange and crossover were eliminated to permit upgrading as money permitted.
Retrovert
Addicted Member
Yeah, ok, but those 12" Utah speakers are, ummm, well, not the best drivers, and won't have the same performance. The ones with the larger magnets cost a bit more, too. BTW, did you mean to write University, which are decent drivers, far better than Utah. (I own a pair of the U-312 diffaxials which are fine drivers once the waxed-paper tweeter capacitor is replaced. That's a tricky job, though, because the stamped-metal sticker must be removed without damage.)
Otherwise, with a non-coaxial single-woofer, the OP still needs a midrange and that's the most critical piece since, as Klipsch noted, we live in the midrange.
A good coaxial or tri-axial, such at the U-312, would be roughly $100 apiece, eliminates the need for an additional crossover, but the tweeter capacitor always requires replacement, so add ten bucks for the pair.
I think Steve's earlier suggestion is more likely to be successful and it provides an upgrade path to the four-wooder, dual-midrange Concert Grand:
While I agree with Steve that a three-way in that cabinet would be an excellent choice for an infinite baffle Bozak — the B-199 would have zero back pressure at that volume — the proposed configuration simply isn't doable with Bozak drivers at the specified price point of $100 apiece, $200 for the pair. A Bozak woofer is about $50 apiece. The midranges is about $50. A new crossover may be built for about $75 using decent air-core inductors. So that project is going to be $175 per speaker, plus some shipping. Oh, and plus the $5 for the flowerpot. Plus incidentals So figure $360 to $400, which is roughly twice (taking into account shipping and parts) the $200 budget for the pair as originally proposed by the OP.
It might be possible to find a Bozak three-way system with a crossover for about $200 in a junker cabinet, and then rebuild the crossover for about $50. So $250 total or $125 per cabinet, which would be about the lowest reasonably possible expense. I have seen on Craigslist pairs of B-313 advertised for $200 to $250 and B-302 advertised for $250 to $300. I paid $250 for my B-313, but the cabinets and grill cloth were nearly immaculate.
quiet
Addicted Member
I still think the whole kit and caboodle out of the B301 Tempo would do a fine job. Does a single 199 in a big infinite baffle cabinet need any back pressure? I thought the whole Bozak big cabinet thing was to get ride of the back wave, not build a big acoustic suspension box. I can see where the four 199's make for the big bass weight sound and that's good for organ and such stuff. But what does it do for pitch definition?
And I'm not so sure I like the larger 302 mid any better than I do the smaller Tempo mid. I think the Tempo mid is plenty good. Not sold on the B-200y tweeter even though it works better in the Tempo. Other than that the only thing wrong with the Tempo that I can tell is the tiny cabinet. And that's a big wrong.
I have the B 302a Century and B301 Tempo.
Still want to know what the 199 sounds like in the big cabinet.
And I'm not so sure I like the larger 302 mid any better than I do the smaller Tempo mid. I think the Tempo mid is plenty good. Not sold on the B-200y tweeter even though it works better in the Tempo. Other than that the only thing wrong with the Tempo that I can tell is the tiny cabinet. And that's a big wrong.
I have the B 302a Century and B301 Tempo.
Still want to know what the 199 sounds like in the big cabinet.
Retrovert
Addicted Member
Bozaks are infinite baffle, not acoustic suspension. While both techniques require a sealed box, the two are very different.
The Bozak woofer best functions with as little back pressure as possible.
TL/DR: I would not suggest the OP use a B-450 in any project, and the only useful donor from a Tempo would be the woofer, which could be acquired at far lower cost as a pair than by gutting a pair of Tempo speakers. The tweeter is 8 Ω, the wrong impedance for the line array which, I believe, the OP still has.
Here's some of what I've previously written about Tempos and the B-450, slightly edited.
The B-301 Tempo uses the B-450 midrange, a low-cost aluminum-cone 4.5" driver. It is a poor-sounding midrange compared to the 6" aluminum-cone B-209, and was reportedly not a design blessed by Rudy Bozak. It crosses at 1,200 Hz, because it can't go lower (unlike the B-209 which may be crossed as low as 400 Hz), and crosses to the tweeter higher at 3,600 Hz (the B-209 crosses to the tweeter at 2,500 Hz), because the single tweeter in the Tempo can't do all the heavy lifting. Because the midrange crosses so high the B-199 is well into its cone-breakup region, and the distortion does not sound good. This is the same problem with crossing the B-199 at 1,200 Hz in the coaxial systems intended to be upgraded by adding a midrange and crossover.
The Tempo was designed as economy speaker, whose low price-point and small footprint was intended to compete with low-cost ported bookshelf speakers which had eaten Bozak's lunch and broken its rice bowl. It consequently required a ported design to reduce the size, but porting is not suitable for the B-199. The cabinet is lined with the evil fiberglass, unlike the other Bozaks which use thick batting to absorb the backwave, and it has no curtain. The Tempo uses a three-position switch to controls tweeter attenuation using two resistors. Even an L-pad was too expensive for that speaker. The crossover inductors are iron core, which has high distortion. The port is not chamfered and neither are the holes for the drivers. The single tweeter is a specially wound 8 Ω voice coil variant of the 16 Ω B-200Y, but it's too small and has poor dispersion.
The earlier Tempo line used cabinet far too small for a B-199, which sounds strangled. The cabinets for the later Tempo line, such as the B-301CD, furthermore, were not merely too small, but ported, instead of being infinite baffle, which wrecks the sound of the B-199.
I have owned ported B-301CD Tempos, which I gifted to get them out of my house as a bad influence, as their degenerate ways might lead my other Bozaks into the ported-cabinet lifestyle. (Ok, the speakers are not horrible. Not significantly worse than any other inexpensive bass-reflex cabinet of the day, assembled in a flakeboard cabinet with vinyl cladding. But no comparison to the larger Bozaks.)
Edit: added B-209 driver size to show difference from B-450.
Last edited:
damacman
Resident Psycho
The more of this type of knowledge imparted in a thread like this, the more readily it is ignored.
Retrovert
Addicted Member
Yes. Quite well at that. I would, however, suggest that the midrange and tweeters be moved as close to the woofer as possible to create a more point-source emission of sound.
It is well known by the owners that the dual-woofer Symphony has poor sonic convergence in a small room without adequate distance between the listener and the cabinet. The Symphony simply will not converge in a smaller room. Just look at the inter-driver distances! You'll need to be at least fifteen feet back to make it work. Any of the giant speakers, be they Bozak or Electro-Voice, will have this problem. Biggles went to enormous trouble and expense to find those 16 Ω woofers, couldn't stand the sound, and sold it all off when it did not work in his living room. Not every Bozak works in every space.
Steve's successful single-woofer Symphony conversion project has been elsewhere documented. With infinite baffle size really does matter, and the bigger cabinet will always sound better. An infinite baffle can be formed by using a large cabinet, but also by building speakers into a wall or closet with a large volume. This was, in fact, a common trick, and Bozak encouraged the building of speakers in this fashion.
So, yes, the Symphony cabinet would be ideal for a B-199.
I had a friend over yesterday so that I could recap his B-501 crossovers for him. I have a pristine set of Symphony with completely rebuilt crossovers (caps and inductors) and a line array of B-200z Tweeters. We listened to these for a bit and then listened to the Retrovert 4-way Bozak, single B-199 woofer Symphony that I built. He said the stock Symphony were very nice, and the single woofer Symphony was even nicer.
So that is another vote for “bigger is better.” I cut some lumber to build an add-on cavity to the back of another Symphony cabinet I have. It will add another 8.5 cubic ft to them, doubling the internal volume. I’m going to try that with one and two woofers and see what I like better.
Too bad the OP hasn’t been around since his first post. A lot of good info shared. I wonder what path he took...
Cheers!
Smiley
Looking at the building plans for the 410 more like a little shy of 15 cu/ft without any bracing reductions, if I figured it right.
Last edited:
That is an interesting idea of adding onto the cabinet. Actually I thought of that also. Seems like it would not be too difficult to achieve. I'm pretty sure I saw in some old Bozak literature they said like 9 cu/ft for that woofer was ideal but OK for some lesser range that I don't recall. So would that be like adding on another 14-15" of depth?
Yes, you might be right. Doing quick math, I was dividing by 1628 instead of 1728... not sure when I had my ah-hah moment there. Sometimes I get a number in my head and it just sticks.
Smiley
Last edited: