Bookshelf Speakers

the weakest link we love so much

Bookshelf Speakers

Postby EWBrown » Tue Oct 16, 2007 7:00 am

I'd probably say that these 1967 vintage Bozak Speakers are about the largest "bookshelf" speakers i've ever owned. They contain two 12 inch woofers, an 8 inch midrange and a vertical line array of 8 tweeters, in each cab. They even made them in "left" and "right" side mirror image of each other. [:)

Located in the "southern command post" in western North Carolina.

Image

What is driving these speakers, you may well ask...

Image

This can probably claim to be the world's most compact DIY-35 rev D amplifier. Chassis is 9" X 10" X 1.5". Power trannie is Hammond 270FX, OPTs are Triode Electronics TF-110-48-ULs.

The only items below the chassis are the AC power primary side (fuse, switches, a neon light, some wiring, the volume pot, and the input jacks. and an all-important one watt blue "Luxeon" LED powered off the otherwise unused 5VAC winding, just for the cool blue glow and to act as a second pilot light.

I'll bring one of the "big gun" amps along, my next trip down there...

/ed B in NH & NC (and points in between)
Last edited by EWBrown on Thu Apr 23, 2009 6:40 am, edited 4 times in total.
Real Radios Glow in the Dark
User avatar
EWBrown
Insulator & Iron Magnate
 
Posts: 6389
Joined: Wed Mar 19, 2003 6:03 am
Location: Now located in Clay County, NC !

Postby TomMcNally » Tue Oct 16, 2007 7:16 am

Better glue that insulator collection down if you crank it up
too loud Ed ! We'd hate to hear you crying when they all
"walk" to that hardwood floor ! Yellow_Light_Colorz_PDT_13
User avatar
TomMcNally
Darling du Jour
 
Posts: 2729
Joined: Sat Nov 19, 2005 2:19 pm
Location: Northfield, NJ

Postby EWBrown » Tue Oct 16, 2007 8:35 am

That top shelf is pretty darn solid, at least 1.5 inch thick solid oak, and it's supported in many places! Good Old Dempsey did one helluva job building those shelves up... I've had those speakers hammering pretty hard and there is virtually no vibration of the stuff on top of the shelf. I've pushed the speakers pretty hard with a (gasp) SS receiver (Oh, forgive me...) and haven't had anything shake off yet...

The insulators will eventually have a new display location, outside in the screened-in porch, once i build up some appropriate shelving for them.

(That's only a small part of the entire collection) :o :o :o

/ed B in NH
Real Radios Glow in the Dark
User avatar
EWBrown
Insulator & Iron Magnate
 
Posts: 6389
Joined: Wed Mar 19, 2003 6:03 am
Location: Now located in Clay County, NC !

Postby TomMcNally » Tue Oct 16, 2007 10:31 am

Some mini telephone poles with crossbars with the
insulators wood look very cool.

Yeah - I saw your eBay feedback ... you must have
1000's of those ;)
User avatar
TomMcNally
Darling du Jour
 
Posts: 2729
Joined: Sat Nov 19, 2005 2:19 pm
Location: Northfield, NJ

Postby wiredbecker » Tue Oct 16, 2007 8:50 pm

The Concert Grands! If I had the money, I would have picked these up for a grand at my local antique shop. My dad has some Bozaks laid on their side in his living room that I hope to inherit someday. The sound is amazing even if it is being driven by a SS Mcintosh.
User avatar
wiredbecker
KT88
 
Posts: 301
Joined: Mon Mar 26, 2007 3:48 pm
Location: Albany Landfill, CA

Postby EWBrown » Wed Oct 17, 2007 7:13 am

My Dad gave me these speakers a while ago, and a few years earlier, I also received a pair of Bozak B302As from my Grandmother's estate. These play well, but did have some minor water cosmetic damage from long term storage.

These smaller cabs have the single 12 (or 15?) inch woofer with two tweeters mounted in front of the woofer's cone (not quite coaxial, the tweets are mounted on a bar in front).

The "Concerts" are very well travelled, from Massachusetts, then down to Florida, then to NC, over the course of about 40 years. There are a few minor dings from all the handling, and the front grille clots need cleaning, there is quite a bit of accumulated dust, etc which is kinda hard to get to because of the metal front grillework.

/ed B in NH
Real Radios Glow in the Dark
User avatar
EWBrown
Insulator & Iron Magnate
 
Posts: 6389
Joined: Wed Mar 19, 2003 6:03 am
Location: Now located in Clay County, NC !

Postby Sal Brisindi » Thu Oct 18, 2007 7:11 pm

Hello Ed,
Nice speakers! I have a question, how does the amp sound with the Triode Electronics TF-110-48-ULs output transformers. I have a set and was wondering how good they are.

Thanks,
Sal Brisindi
User avatar
Sal Brisindi
KT88
 
Posts: 374
Joined: Thu Mar 22, 2007 5:21 am
Location: Freehold N.J.

Postby EWBrown » Fri Oct 19, 2007 10:30 am

Hi Sal

The amp sounds pretty decent, I can definitely still tell the difference between the "Fender" trannies and Z565s, on decent speakers. They do lose a little at the low and high ends of the spectrum, But for the price of $20 each, and running the B+ voltage a tad lower, around 325VDC, and still biased at 35 mA, I definitely can't complain!
I didn't bother with "fancy" coupling caps, the orange drops are more than good enough here!

6,600 ohms P-P may be a tad low for 6BQ5s, but I've had no problems at all. I may still have to tweak the NFB loop, the pot is still set at 20K which was good for the Z565s 8 ohms tap, aand it may have to go up around 3 to 4K ohms to get it set correctly.

They were $20 (actually 19.95 back then, I think they're up three bucks each, now).

FWIW the volume control is one of those nice $3 Radio Shacks 100K stereo units, and the aluminum knob is also from "radium shark".

Shannon also built up a 6V6 PP amp on a once very rusty and crusty "alligator poacher" ST70 chassis, using these same trannies.

I may go with a set of the TF-100-48-ULs for the S-5 K-16LS amp upgrades, instead of the Hammond 1620s, they'll still be nicer than the OPTs provided with the kit.

/ed B in NH
Real Radios Glow in the Dark
User avatar
EWBrown
Insulator & Iron Magnate
 
Posts: 6389
Joined: Wed Mar 19, 2003 6:03 am
Location: Now located in Clay County, NC !

Postby Sal Brisindi » Fri Oct 19, 2007 10:52 am

Ed,
Thanks for the information on the transformers. To bad they don't cost $20.00 anymore. Triode Electronics price for the transformers are now $29.95, but on sale for $27.95 at the moment. With the price of copper now a days, I just ordered 4 transformers from Edcor for future projects, probably sometime around 2010 at this rate... :-)

I do have 2 ST-70's to restore too..

Regards,
Sal
User avatar
Sal Brisindi
KT88
 
Posts: 374
Joined: Thu Mar 22, 2007 5:21 am
Location: Freehold N.J.

Postby EWBrown » Fri Oct 19, 2007 11:57 am

I've restored several ST70s, and have three ST35 carcii to resrtore, probably also around 2010, the way I've been going....

When the TF-110-48-ULs first became available, I snagged four , figuring that they would increase in price, or become unavailable, in the future...
I still have one unused "silver" pair of their non-UL predecessors, the other set went into the 6EM7 PP amp project.

Then there are the "strange" projects, including attempting to restore an old (pre-WWII era) Farnsworth radio (which was also serving as a multi-generational mouse condo) , an oddball "Blonder-Tongue" 10W 6V6-based mono integrated amp amd a matching FM tuner. In 1950s style "deco" light blue plastic cases. And I always thought that B-T only made UHF TV converters...

And there's also one slowly rusting-away Grommes "Little Jewel" 6V6 based amp, in which all the tubes were absolutely "stone-dead" just plain used up... As a friend used to say, JPFROG (Just Plain F***ing Ran Outa Gas). Then there were several broken-off octal tube-locating plastic pins rolling around the inside of the chassis... :o

All this stuff, too nice to simply cannibalize, but not really nice enough to put in a major repair effort, either...

/ed B in NH
Last edited by EWBrown on Tue Nov 06, 2007 10:19 am, edited 3 times in total.
Real Radios Glow in the Dark
User avatar
EWBrown
Insulator & Iron Magnate
 
Posts: 6389
Joined: Wed Mar 19, 2003 6:03 am
Location: Now located in Clay County, NC !

Postby Sal Brisindi » Fri Oct 19, 2007 7:04 pm

Did you say Blonder and Tongue? Here is a photo of me holding a B-T UHF converter with Ben Tongue on the left and Issac Blonder to the right.

Sal..

Image

and my prized autographed Blonder - Tongue BTR-98B AM/FM radio.

Image
User avatar
Sal Brisindi
KT88
 
Posts: 374
Joined: Thu Mar 22, 2007 5:21 am
Location: Freehold N.J.

Postby EWBrown » Mon Oct 22, 2007 10:12 am

Cool! A bit of electronics history there...

If I decide to put these units up for "adoption" you will be the first to know... I got 'em cheap, and I won't be looking ot "retire" on them, either...

I figure the caps are all shot, at least, and the dial cord drive mechanism is "somewhat awry" in the FM tuner. Perhaps the flay rod is somewhat askew on the treadle... (a little more Monty Python reference) Yellow_Light_Colorz_PDT_03

I have never given them the "smoke test"...


This weekend, on the way back from an "antique radio" swapmeet, I decided to stop by the local town dump and see if there were any goodies worth adopting...

Well, I hit it lucky, someone was just unloading a pair of KLH Model 20 speakers, and I got them before they even hit the swap table.

They seem to work OK, though they definitely need some cosmetic work - and perhaps upgrading the drivers and crossovers (TBD, once I pull the grill covers and look inside).

He also told me if i had ben there ar the right time, the previous week, I could have scored the KLH system that went with the speakers. Oh, well, win some, lose some...

/ed B in NH
Real Radios Glow in the Dark
User avatar
EWBrown
Insulator & Iron Magnate
 
Posts: 6389
Joined: Wed Mar 19, 2003 6:03 am
Location: Now located in Clay County, NC !

K L Humbug...

Postby EWBrown » Tue Nov 06, 2007 10:11 am

I tried out the KLH-20s last night :o Yellow_Light_Colorz_PDT_21

They sound like crap... Muffled and tinny, at the same time. Think of a mid-1960s "all transistor" pocket radio.
Yuh, hhat bad... :scared: :parp: Yellow_Light_Colorz_PDT_13 Yellow_Light_Colorz_PDT_21 Yellow_Light_Colorz_PDT_09 Yellow_Light_Colorz_PDT_13

A quick removal of the front grille, the tweeter is covered woth some perforated steel plate, and even though the woofer cone looks OK, I'd SWAG that the magnet is shot. I pulled it out to get a look inside, the "crossover" is just some cheap NP caps, with a switch to select one of three levels (in my case, dead, deader and deadest) Yellow_Light_Colorz_PDT_04

The woofer cutout is pretty much standard size for a generic 10 inch woofer, but the tweeter cutout is huge, wit a 5 5/8 inch diameter routed out area going to a 4 1/4 inch diameter cutout.

The input to the speaker is a crappy cheapola RCA connector.

Interior dimensions are 6.5 inch deep, 10.25 wide and 21.5 inch high, for a total interior volume of 1432 cubic inches, less the space taken up by the speakers. I dunno if it is worth while trying to install new speakers and crossover, or just return them to the freebie table at the dump and let some other "lucky" person mess with them... Yellow_Light_Colorz_PDT_05

I oiled the very dry wood veneer and removed the assorted paint and other mysterious splatters, so now they don't look too bad, other than some scuffs and dings, and a bit of eroded veneer at a couple of the corners. At least they look a LOT better than they sound...

The infamous Karlsons started out in a similarly inauspicious way, but with new drivers they have gained excellence. Maybe these will too. someday...

/ed B in NH
Real Radios Glow in the Dark
User avatar
EWBrown
Insulator & Iron Magnate
 
Posts: 6389
Joined: Wed Mar 19, 2003 6:03 am
Location: Now located in Clay County, NC !


Return to loudspeakers

Who is online

Users browsing this forum: No registered users and 10 guests