D1050 Restoration Project Nearing the End

[Howe]

Its been a 6 month project. I originally found these as a pair but not perfectly matched. One had an enclosure made of redwood plywood and the other was a mahogany vernier. Both were pretty rough. I enlisted a talented cabinet maker / audiophile, Michael Christ who re-did the vernier in prima vera blonde. The enclosures are at the refinisher who is appliyng many coats of hand rubbed lacquer with a patina appropriate for a blonde finish of 50 years age. The drivers, as many of you know, are two 15" 32 ohm in parallel to make 16 ohms and a D175 driver on a sentorial horn lense. The drivers and the speakers are a couple of years apart. Hal Cox himself looked st the enclosures and remembers selling them to a lawyer here in the Bay area back in the day. I've included some photos of the drivers for the benefit of comments. :D

The correct model is D1005 (at least that's what it says on the back pannel) for my units but it is a D1050 system since there are 2 woofers.

[Howe]

Reached the limit of 5 pic uploads so here's the last 2.....:)

I believe the serial numbers indicate manufacturing dates of 1949 and 1951 repectively but I welcome any expertise so I that I know what is what. Curious that one of the 175's has no red wax seals and by the looks never did while the other has only one. Hmmmmm.......

[spkrman57]

Thanks for sharing with us!

Ron

[Howe]

Thanks! I realize these may not be the best sounding JBL's ever produced but from my preliminary tets, they are a lot of fun. I get this funky smooth sound that brings back memories of good juke boxes and live bands in less than symphony standard halls where beer rather than fine wine was the fare of the venue. The double 15" woofers really put out an impressive sound with popular and R&B music. I will have more to report when they are properly placed in corners. My initial comments were just listening in my garage with a small Bell 6V6 amp and a discman. ;)

[glen]

I believe the serial numbers indicate manufacturing dates of 1949 and 1951 repectively but I welcome any expertise so I that I know what is what. Curious that one of the 175's has no red wax seals and by the looks never did while the other has only one. Hmmmmm.......

Hi Howe,

Great thread, great to hear how you're restoring these speakers!

There's not a lot of expertise available about these old serial numbers, but I believe you'd be right interpreting 11-49 as November of 1949 and 5101 as January of 1951 which would place them only 14 months apart.
Did you check for serial numbers on the cabinets too? There may be a "cut-corners" model/serial number label similar to the ones on your drivers.
The few cabinet serial numbers I have seen from this era do not seem to be following the same date-code scheme used for components.

11-49 is the second earliest date-code serial number I've seen so far, and the only one in the form mm-yy instead of the more common form with the month following the year (yym or yymm).
I'd guess all of your drivers have the same Racetrack oval Van Nuys label and both woofers from the same enclosure have matching serial numbers.

Not sure when the red wax seals started, saw a D-175 serial number 5009 that had red wax remnants in the screw heads. The earliest serial numbered D-175 serial number 499 (September 1949) had no red wax seals present.
Your 11-49 driver may be evidence that the advent of the wax seals was between November 1949 and September 1950. But I don't know if we could ever be sure if a driver more than 57 years old really started life without seals, or if sometime during it's long life they were removed or lost.

As for model numbers, when your corner cabinets were being made it was only listed as part of a complete speaker system including the D1050 system and would ONLY have been offered with that top of the line system.

D 1004 Dark Mahogany Corner Cabinet with D-1050 system
D 1005 Prima Vera Blonde Corner Cabinet with D-1050 system
D 1006 Utility Gray Enclosure with D-1050 system (Corner)

It wasn't until the August 15, 1951 price list that the cabinet was offered with any other speaker options:

D 1007 Dark Mahogany Corner Cabinet with D-1001 system
D 1008 Prima Vera Blonde Corner Cabinet with D-1001 system
D 1009 Utility Gray Corner Enclosure with D-1001 system

the same August 15, 1951 price list for the first time showed a corner cabinet available as a separate enclosure, but NOT for a D1050 component system

C-620 Utility Gray Corner Enclosure for D-130
C-621 Dark Mahogany Corner Enclosure for D-130
C-622 Prima Vera Blonde Corner Enclosure for D-130
C-623 Utility Gray Corner Enclosure for D-131
C-624 Dark Mahogany Corner Enclosure for D-131
C-625 Prima Vera Blonde Corner Enclosure for D-131

http://www.lansingheritage.org/images/jbl/reference/price-lists/1951-08-15/page1.jpg

So your systems were the very best JBL speakers available when they were made, the "statement speakers" of their time!

I personally love this vintage stuff and would appreciate even more pictures, including the crossovers.

Congrats on your magnificient system!

[johnaec]

Could you also post a pic of the front of that multicell horn?

Thanks - John

[Steve Schell]

Howe, I have nothing but admiration for your efforts to restore these classic JBL systems. There are a few of us out here who obsess over these early ones. They are very rare as relatively few of them were made by JBL, which was a small struggling company in those days. Yours have certainly fallen into the right hands. I find these pieces to be a true reflection of Jim Lansing, and it is fair to say that he invested his blood, sweat and tears into their design and construction. As Glen has mentioned, the ones you have were the finest model produced by JBL at the time.

I would say that your assessment of the dates of manufacture from the serial numbers is correct, though Glen has studied this much more carefully than I have. JBL was located in Van Nuys between late 1948 and early 1949, but I imagine they were still using the Van Nuys decals for a time after the company's sudden move to Los Angeles. John Edwards has told us that Jim Lansing cut out the cabinets and assembled them himself. By the time your second one was built Jim Lansing was gone, as he died in September 1949, and William Thomas was running things at the Fletcher Drive facility. As far as I know the red wax seals were introduced after Lansing's death, as was the "big L" Jim Lansing logo.

These early, pre potato masher horn systems are about as rare as Lansing Iconics, or nearly so. Jim Lansing used only multicellular high frequency horns; all the other types were done by others (for better or for worse...) later on. Here are a couple of pictures of another H-1000 horn, this one featuring a more elaborate application of the sawdust and glue damping material to the cells. I believe that they were done this way until Jim's death.

[Howe]

Could you also post a pic of the front of that multicell horn?

Thanks - John
John,

At this point the fronts are covered with the new grill cloth. Many staples were used to insure straight lines in the patterns. So the photo opportunity has passed on those. However, they look very similar to the other pic above. I'll be posting more pics soon. I have the cabinets w/o tops now in my living room. The tops needed a little extra work so I'm waiting on those.

[Howe]

Thanks for sharing with us!

Ron
Here's a pic of one of the cabinets that was restored. I'm very pleased with the excellent work done by Michael Christ (http://www.michaelchrist.com/fabrication.html). The prima vera blonde grain is matched and mirrored from left to right as perfect as anyone could have done. The finisher also got a nice tone that will only improve with age.

My thanks for everyone's comments.

I'll post more pics as they come together.

[Howe]

Hi Howe,

I'd guess all of your drivers have the same Racetrack oval Van Nuys label and both woofers from the same enclosure have matching serial numbers.

Only one has the race track Van Nuys label. The other has a Los Angeles label. The serial numbers match in each "system" but not left and right, as shown.

These are certainly early JBL speakers and rare. That is why I've put so much effort and money in restoring them to their former glory. Oddly enough, the dark mahaogany unit had a model number (1005) associated with the prima vera blonde which they now both are. Stuff like this does make you wonder what's up with the real thing and the catalog.

[Howe]

Here are a couple of pictures of another H-1000 horn, this one featuring a more elaborate application of the sawdust and glue damping material to the cells. I believe that they were done this way until Jim's death.
I wondered about the saw dust! Thanks for clearing that up. :applaud:

[Howe]

Here are pics of the cross-overs as requested.....

[Howe]

We finally got the speakers in. Its just wiring them internally, testing and then putting the remaining sides on and then placing into the corners of the room. Oh, and after all that wiring up a system to them! :D

[Howe]

BTW, does anyone know how to determine the polarity of the terminals on the cross-over I have pictured above? I don't see any "+" or "-" symbols for either input or output.

Thanks!

Howe

[Howe]

[QUOTE=Howe]I'm very pleased with the excellent work done by Michael Christ (http://www.michaelchrist.com/). The prima vera blonde grain is matched and mirrored from left to right as perfect as anyone could have done. Notice the great waterfall effect from the tops to the body of the cabinets. The finisher also got a nice tone that will only improve with age.
To anyone whose interested Michael's great work, the URL has been updated in this posting! :applaud:

[glen]

BTW, does anyone know how to determine the polarity of the terminals on the cross-over I have pictured above? I don't see any "+" or "-" symbols for either input or output.

Thanks!

Howe

Hi Howe,

I just happen to have gotten an N1000 crossover of a similar vintage. I'll see if I can open it up later and post some pictures of it's innards.

Meanwhile looking at many pictures it seems like slightly later versions came with the output terminals numbered(from left to right) 1, 2, 3, 4 and the left input terminal labeled "B" (black, presumably ground) and the right input terminal labelled "R" (red). And from a later N1200 schematic with the three way hi-frequency level switch the inner pair of the top row of four (numbers 2 and 3) are shown strapped together and connected directly to one of the input terminals (labelled "5" in the schematic) which makes think that they are the ground terminals.

Here's a couple of pictures of a D-1004 speaker with similar wiring

and a later C34 that matches Harvey Gerst's description of standard factory wiring (although I think your speakers are a little earlier than his time at JBL):


factory wiring would have been black/green for the woofer, and black/red for the HF driver.

[Howe]

I have green and black wires from the D175 and yellow and black wires from the woofer pair so I'll assume from this that black is common and will be the center terminals or 2 & 3. Interesting that the woofers in the picture are 16 ohms. Wonder how hey are doing that impedance-wise. I've heard about a later model (C31?) that is a similar configuration but with the later potatoe masher 175 DLH.

Thanks Glen, I'll follow that configuration with the black wires at 2 & 3 (center 2 terminals) since its the best information I have at present. I can always reverse the polarity on the inputs from the outside if I have phase problems with the output (input) polarity. Nevertheless, I follow the convention you recognize. I hope to have these installed later tomorrow.

Best Regards,

Howe

[glen]

Interesting that the woofers in the picture are 16 ohms. Wonder how hey are doing that impedance-wise. I've heard about a later model (C31?) that is a similar configuration but with the later potatoe masher 175 DLH.
Howe


Hi Howe,

Sorry if I confused the issue. I just didn't have any good close ups of that D-1004 speaker (first two pics). The 16 ohm 130A is from a single woofer C-34 system (last 3 pics) with a 175 potato masher horn, just as you said.
The dual woofer systems like yours used two 32 ohm woofers.
I think Steve Schell has speculated about whether there was different resistance padding in the crossover for the high frequency when a crossover was built to be used with the single vs. double woofer systems. I've opened up my N1000 (will post pictures soon) and the HF is definitely padded down significantly.

[Howe]

Hi Howe,

Sorry if I confused the issue. I just didn't have any good close ups of that D-1004 speaker (first two pics). The 16 ohm 130A is from a single woofer C-34 system (last 3 pics) with a 175 potato masher horn, just as you said.
The dual woofer systems like yours used two 32 ohm woofers.
I think Steve Schell has speculated about whether there was different resistance padding in the crossover for the high frequency when a crossover was built to be used with the single vs. double woofer systems. I've opened up my N1000 (will post pictures soon) and the HF is definitely padded down significantly.
Glen,

Thanks for clearing that up. I do wonder at this point if there is padding on the N1200 that comes with the later system. Serial numbers match up so it could be but then again, I do wonder. Sweeping both with a frequency generator I didn't see a noticable difference. but my phasing was reversed on the HF driver. I wouldn't think that would make a difference on high frequencies?

[glen]

Hi Howe,
I just happen to have gotten an N1000 crossover of a similar vintage. I'll see if I can open it up later and post some pictures of it's innards.


Posted the N1000 pics and info in a new thread:

http://audioheritage.org/vbulletin/showthread.php?t=11949

Hope that can be useful to you.

[Howe]

Glen,

Nice job. I think this clears up the connection configuration. I'll assume the early N1200 follows the same. Would be nice to compare schematics though. I'm also assuming the R1-R3 resitors form a pad to the HF driver.
Is there a N1200 (early) schematic somewhere in the forum?

Thanks,

Howe

[Zilch]

http://www.jblproservice.com/pdf/Network%20Schematics/N1200.pdf

[Howe]

http://www.jblproservice.com/pdf/Network%20Schematics/N1200.pdf
That is an interesting schematic. I've never owned a N1200 with a selector switch for HF attenuation. I should assume the not so fully featured unit or a system with a selector placed elsewhere in the enclosure would default to the 0 dB scenario?

[Zilch]

That is an interesting schematic. I've never owned a N1200 with a selector switch for HF attenuation. I should assume the not so fully featured unit or a system with a selector placed elsewhere in the enclosure would default to the 0 dB scenario?Unknown. Somebody'll have to dissect one, or we wait for Giskard to come back and tell us....

[Howe]

Posted the N1000 pics and info in a new thread:

http://audioheritage.org/vbulletin/showthread.php?t=11949

Hope that can be useful to you.
Does anyone know approximately at which frquency the N1000 and the older N1200 (without selector switch) are supposed to cross over at? I'd like to verify my crossovers are working correctly using an audio generator. I could imagine some of those 50 year + capacitors aren't what they used to be. Glen, you know that. don't you?

[glen]

Does anyone know approximately at which frquency the N1000 and the older N1200 (without selector switch) are supposed to cross over at? I'd like to verify my crossovers are working correctly using an audio generator. I could imagine some of those 50 year + capacitors aren't what they used to be. Glen, you know that. don't you?
They are both supposed to crossover at 1200 cycles.
Both specified as 18db/octave

N1000 here:
http://www.lansingheritage.org/images/jbl/catalogs/1950/page6.jpg

Early N1200 here:
http://www.lansingheritage.org/images/jbl/catalogs/1951/page2.jpg

Both had the same case and shipping weight.
Was the name change just to be more desciptive of it's function?
Was the N1000 originally intended to crossover at 1000 cycles?

[Howe]

They are both supposed to crossover at 1200 cycles.
Both specified as 18db/octave

N1000 here:
http://www.lansingheritage.org/images/jbl/catalogs/1950/page6.jpg

Early N1200 here:
http://www.lansingheritage.org/images/jbl/catalogs/1951/page2.jpg

Both had the same case and shipping weight.
Was the name change just to be more desciptive of it's function?
Was the N1000 originally intended to crossover at 1000 cycles?
Glen,

Thanks for your help. I should have dug deeper. I'll give a critical test with my function generator. I've already done a casual sweep but I'm not convinced I'm getting that kind of performance. 18 dB / octave is a steep slope. But, it is a 3rd order filter. The individual drivers tested separately are in very good health, however.