inside the Bozak 300a
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Comments
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second picture didn't post... second try.
Thinking minor mods. -
I was just going to ask to see the rest.
Are they intact?
Are you doing any work on them?
How do they sound?
Did you know you have on one blue sock and one black?I disabled signatures. -
I've done that, but no. White today as I am wearing water proof shoes.I was just going to ask to see the rest.
Are they intact?
One single. I lost out on the concert grand and this is what
was left. I believe a doctor owned it.
Are you doing any work on them?
The first easy thing to do is move the resistance up to 16 ohm.
The Mid kind of runs wide open and overlaps the tweeters.
I'll follow the advice of the Bozak experts on the web and go slow
and see how it turns out. I don't have any room in the studio for this
thing.
How do they sound?
The tweeters are too harsh for me. I didn't notice it when I was
using it as a center channel. (audyssey)
The bass and mid-bass is real nice.
Did you know you have on one blue sock and one black?
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first surprise, the xover is not screwed in place. Just sitting there.
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Second surprise, this was behind it;
It reads
Mallory
4 MDF 50 VDC
ca 275
9-52 -
Next I'll take the sage advice of Pat Tobin;
"Here's what works best to curtail that upper end doubling: On the N-10102A xover, at terminal strip A, move the jumper from the N-101/N-104 terminal to the other one, marked N-102. That doubles the inductance feeding the midrange, which happens to lower the drive to the midrange in the 2.5 kHz ~ 10 kHz range, exactly what we need. (For technocrats: that inductance was used for an 800 Hz rolloff for the 16-ohm B-305 midrange.)"
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Time for some redbook Mono recordings. First up;
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In my house, the amp would be connected to the binding posts with 12-gauge wire...
...and then the drivers are hooked-up with doorbell wire inside the cabinet.
What's the ESR and capacitance of that '52 Mallory? -
funny you should mention rewiring as I was thinking about that...
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Another must Mod suggestion was replacing the mid range inductor and
I'll be giving that a shot. -
listening to DDC Japan Pet Sounds now...
It sounds pleasing if it isn't pushed to hard.
Some frequencies just fall apart turned up.
There is a bit of warm hollowness to the sound.
Great midrange detail after the simple change! -
any links to these suggestions? I was hunting around for solid core wiring
but no winner.In my house, the amp would be connected to the binding posts with 12-gauge wire...
...and then the drivers are hooked-up with doorbell wire inside the cabinet.
What's the ESR and capacitance of that '52 Mallory?
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o.k. so I finally placed a parts-express order two days ago.
I've three "projects" going.
picking sheet excerpt
266-350 ERSE 1.0mH 14 AWG Perfect Layer Inductor Crossover Coil
260-302 Gold Plated banana 5-way
I was able to install the Inductor and the modest parts express gold plated 5 way banana posts this morning.
Once again I'm listening to DDC Japan Pet Sounds at low levels.
Running this thru the Denon AVR-4520ci and it sounds real nice
up thru 40% to 60% power. It starts to get boomy up there. One wonders what a
nice tube amp would do for it... -
In my house, the amp would be connected to the binding posts with 12-gauge wire...
...and then the drivers are hooked-up with doorbell wire inside the cabinet.
I bought a spool of a couple hundred of feet of "Military Surplus" 12-gauge stranded silver-plated copper wire with Teflon insulation for in-cabinet wiring harnesses. The stuff is available on eBay in various lengths and gauge sizes. Beware of "spools" made from multiple shorter lengths of wire stripped from old aircraft vs. leftover spools of continuous-length wire. Small-gauge wire seems to be exceedingly common, 12-gauge less so. I don't think any of this is solid-core wire.rednedtugent wrote: »any links to these suggestions? I was hunting around for solid core wiring but no winner.
OTOH, you can simply drive to any home-improvement store on Earth (Home Despot, Lowe's, Menards, etc.) and pick up some solid core--or stranded core, your choice--THHN wire in a small variety of colors and gauge sizes. The insulation is PVC with an outer jacket of somethig else--oil, gasoline, and moisture resistant, slippery, and sturdy enough to accept some abrasion as the wire gets pulled through conduit (which of course is of no value in this application.) although it tends to be a "hard" plastic. You could go to any automotive parts store (NAPA, Advance, NaughtyZone, Pep Boys, or whatever) and get automotive "Primary Wire" in a color and gauge size pleasing to you, which will have a polyethylene insulation that's a bit more flexible. I don't think the flexibility is a particular advantage in this application. The automotive wire will be stranded. I'd use stranded THHN if I wasn't using my Military Teflon. The point being you have access to reasonable gauge, solid or stranded copper wire of low cost and adequate specification, although it's not going to be considered "audiophile approved".
Are you able to test them, or are you simply replacing 'em?.What's the ESR and capacitance of that '52 Mallory?
I would dump them if they couldn't be tested for ESR/dissapation, and capacitance. -
I would not just dump those caps. The good Doc Hardy pointed out in another thread certain caps of that type are highly prized. Even if you replace them do a bit of research to figure out what you have. Maybe Mark will see this and comment.
I think would be well worth the effort to have them checked but could be wrong.
When set up well I enjoy listening to old Bozak's. Cool project. I would love to run across a pair of CG's and would buy them even knowing there would be a 50/50 chance my wife would shoot me for doing it. -
I don't think I'll replace the caps. I don't want to change the flavor too much.
The wiring OTOH needs replacing for sure.
As it stands now I can at least listen to it. Before I started, not so much.
Gives me time to ponder the next move.
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Do I understand the stamping on the capacitor? They were made in 1952?
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Seems so. A little early for this speaker I believe. I need to look into it.
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o.k. so I replaced the wiring to the drivers.
I did the second Tobin mod suggestion of moving the
woofer leadwire to the upper N-102/104 tap.
Things are coming into focus. -
In reading threads from Mr. Tobin I discovered the blanket over the Xover
was really a curtain that hung a little over 1/2 way back in the cabinet.
He HIGHLY recommended putting that in place. Well, the old one is disintegrating
so I made one.
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At lower volumes this speaker really shows its potential.
I fear a Xover rebuild is the next and final step to make her really sing.
I guess protecting the drivers is good enought reason. -
so I popped open the hood on the med/tweeter crossover.
Caps made in Chicago;
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Doesn't look to easy to get those out.
In looking at the cap config I sumised that if I made one well placed snip,
the old 5 MFD tweeter caps would be out of the circuit...
...I ran it with the tweets disconnected and it was obvious that the balance
was off between the woofer/mid vs the tweeters.
Next I placed a couple of Solens 5.1 caps in parallel (for another project but handy)
with a .5 ohm mills resistor in front. Buttoned it up and sound check....
sounds the same as before I started! The tweets are too hot as before.
Well Mr. Tobin knew all that and suggested a resistor that is now on order
from parts express. I went ahead and ordered ONE
Dayton Audio DMPC-50 50uF 250V Polypropylene Capacitor
to replace all the other mid capacitors.
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after breaking a dayton 7.5 resistor
I received a new parts Xpress order and now the tobin mods are done.
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so I saved some Infinity SM-122's from the scrap heep and reappropriated
one of the tweeters to cover the highs. This replaces the Pyramid squawker.
Using a 2.2 uf cap that I had laying around...
Could have gone 1.5 as I had one of those too...
not bad...
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rednedtugent,
I've been following your thread. These are on CL in the Atlanta area.
Not as old as yours - Bozak B-302A Century (1967).
https://atlanta.craigslist.org/nat/ele/d/bozak-vintage-speakers/6196843633.html
"Sometimes you have to look to the past to understand where you are going in the future"Anger is just anger. It isn’t good. It isn’t bad. It just is. What you do with it is what matters.
You can use it to build or to destroy. You just have to make the choice. Jim Butcher
Harry / Marietta GA -
Hi @BlueBirdMusic
If memory serves, the woofers are basically the same so age doesn't matter
to the sound. People like the aluminum mids and tweeters so they would
be early to mid sixties as well.
I'm driving my Bozak 300a w/ a Pioneer Elite AVR VSX-90 and it can handle
anything it can throw at it. I wanted to do airplay to send mono releases from
the macbook. Works well. I was kicking around a 3 channel hybrid but went Elite.
The VSX-90 gives me the opportunity to add sub-woof to the proceedings as well.
I should throw 100 watts of clean power at it to see what it can do.
If one does the strick Tobin mods they may find the upper range a bit too
recessed. That is why I added a squawker and now replaced with a tweeter.
If I stopped being lazy I would add the @mhardy6647 type L-Pad.
With the crazy prices on vintage gear Bozaks are still a good deal after the mods.
I should add that it is sitting on anti-vibration pads purchased from
SupplyHouse. If I raised it more...
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I like the vintage stuff, and I have noticed more speakers are appearing for sale. The Bozaks are about 6-7 miles from my house. I would like to hear them. Thinking!!"Sometimes you have to look to the past to understand where you are going in the future"Anger is just anger. It isn’t good. It isn’t bad. It just is. What you do with it is what matters.
You can use it to build or to destroy. You just have to make the choice. Jim Butcher
Harry / Marietta GA -
I would set up a listen if you can. $400.00 is a little on the high side but I have no idea what has been put into them. Good luck.
Oh, with that style of Bozak raising them off the floor wouldn't look so good IMHO.
