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Thread: Earliest JBL crossover with hi-frequency level control?

  1. #1
    Senior Member glen's Avatar
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    Earliest JBL crossover with hi-frequency level control?

    A very unusal 050 system is being offered on ebay in three different auctions. From the date code serial numbers this would seem to have been assembled in late 1951 and early 1952.

    The most unusual aspect is the crossover which has the high frequency
    and low frequency sections built in separate boxes with unique model numbers! The high frequency section includes what looks like a continuously variable level control. Was this a custom crossover for a finicky client? An experimental system used by the JBL to determine values for the later N1200 with three position high-frequency attenuation? (I believe it was sometime in 1952 that the N1200 got it's knob)

    The Low frequency section is house in a box bearing model number 1-1200A-3, there are empty holes in the platic plate where the terminals for the high frequency section would be.

    The high frequency section is housed in a box bearing model number 1-1200A-4, the knob and a dial plate are positioned where the low frequency terminals would be.

    in ebay auction:
    http://cgi.ebay.com/2-JBL-1-1200A-3-...QQcmdZViewItem

    from auction description:
    A pair of 16 ohm crossovers.
    Model numbers 1-1200A-3 and 1-1200A-4
    This set came out of a cabinet with the JBL 130-B speaker and JBL 1217-1290 Horn, we have for auction at this same time


    The description reveals the second unusual aspect of this system, a single 32 ohm 130-B is listed. And it is also unusual in posessing an aluminum dome? Another custom feature? A very old recone?
    It's a little hard to tell in the picture but it looks like the wires connecting to the voice coil through the holes in the cone have not been glued down.


    from auction description:
    JBL 130-B VINTAGE 15" 32 OHM SPEAKER FOR REBUILD
    The foam surround is in need of replacement and the voice coil rubs quite badly.
    Sold as is for repair only


    The 175 driver and 1217-1290 horn are the most pedestrian part of the system with the wide lip circular mounting flange and no acoustic lens.
    But even this is unusual in that the driver and horn have different style cut-corners label. The 175 driver serial number 11239 has version of the cut-corners label with the name above and "Los Angeles" address below.
    The 1217-1290 horn serial number 20280 has a no-name cut-corners label.


    from auction description:
    JBL 1217-1290 HORN WITH 175 COMPRESSION DRIVER
    Both in very good condition as pictured.
    It sounds very good too, with no problems.
    16 ohms.
    Includes front mounting flange.
    Attached Images Attached Images      
    glen

    "Make it sound like dinosaurs eating cars"
    - Nick Lowe, while producing Elvis Costello

  2. #2
    Senior Member Steve Schell's Avatar
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    Glen, I'm glad that you got the image of the crossovers when you did, as that auction seems to have been pulled. Perhaps somebody made the seller an offer that he liked.

    Those crossovers seem to have been set up to allow biamping, although it was not done much in those days. They do look like experimental pieces, or a custom order as you theorized. That numbered scale plate on the rotary control was probably a stock electronics store item. I have a Venice era C-502 cabinet (looks like D-1000 but for a single 15" driver) that has a similar though not identical plate on the side where a level control was once installed.

    JBL probably did a fair amount of custom work back then (as now). A fellow here locally who ran a hi fi store in the '50s told me that somewhere he has a blueprint drawing for a special C-34 that William Thomas drafted for him. It seems that his built in hi fi cabinet did not quite have room for a stock C-34, so Thomas reworked it to fit his installation.

    That woofer is a strange one. The cone and gasket look correct and certainly old enough, but the aluminum dome should not be there on a 130B. It looks like a repair job to me- is that a glue line or a crimp around its edge? Either way its not right, nor is the piece of tape or something over the leads.

    I have only seen a few of the round clamping rings for the horn; it was the earliest type. The "undocumented" cut corner labels are a puzzle also. They were the first ones to appear, on the Van Nuys era pieces if I remember right. Perhaps a few were left over after the move to Fletcher Drive.

    More questions than answers with this one, but I'm sure glad they come along to keep us guessing. I'll write to the seller to see if he still has the cabinet, or a picture of it.

  3. #3
    Senior Member glen's Avatar
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    Quote Originally Posted by Steve Schell
    Glen, I'm glad that you got the image of the crossovers when you did, as that auction seems to have been pulled. Perhaps somebody made the seller an offer that he liked..
    I had emailed the seller asking for the serial numbers on the crossovers and they replied that the auction was terminated because they listed "JBL?" in the title, but weren't completely positive that the crossovers were in fact made by JBL, even though the crossovers, driver and single woofer came out of the same cabinet. They said the crossovers would be relisted later. It the confusion they forgot to include the serial numbers. I told them I thought they were probably right in believing they were JBL crossovers.

    Quote Originally Posted by Steve Schell
    Those crossovers seem to have been set up to allow biamping, although it was not done much in those days.
    It did not even occur to me they might have been biamped. I assumed that there was just not enough room to add a level control to a standard N1200 box so the network was split into two boxes. I know it would be impossible to add one to my N1000 after seeing the network components tightly packed inside.

    Quote Originally Posted by Steve Schell
    That woofer is a strange one. The cone and gasket look correct and certainly old enough, but the aluminum dome should not be there on a 130B. It looks like a repair job to me- is that a glue line or a crimp around its edge? Either way its not right, nor is the piece of tape or something over the leads.
    You're probably right that it's a funky recone, I don't know of JBL using an aluminum dome on any 32 ohm driver. If it was a recone then it is also most likey to be a 16 ohm voice coil which would explain the use of a single woofer. But it would have to be a pretty old recone for the edge to be that far gone.

    The whole system looks like some kind of experimental rig to me. I'm intrigued by the possibilty that this could be JIm Lansing's handiwork "breadboarding" the 4435 of it's time. I can see Jim grabbing some pieces and quickly prototyping the only 32 ohm aluminum dome speaker ever assembled to extend it's range to higher frequencies (you would only want to do this with the one of the two woofers that would be closest to the horn). The high frequency network in its own box could accommodate more components for a 4th order roll-off which would allow more power to be sent to the 175, balancing the woofers just right. That might explain the suffixes on the crossover model numbers 1-1200A-4 for the 4th order hi-frequency network and 1-1200A-3 for the 3rd order lo-frequency network (don't want a steeper cutoff slope to keep that aluminum dome from extending the woofer's reach higher) The woofer could be a hobbyist's hack job I suppose, but the crossovers look very nicely done in comparison. I'm beginning to wonder if they have model and serial numbers, but no JBL labelling, because they were never intended to leave the factory?

    Or maybe they were brought to Atlantis by Martians.

    Quote Originally Posted by Steve Schell
    The "undocumented" cut corner labels are a puzzle also. They were the first ones to appear, on the Van Nuys era pieces if I remember right. Perhaps a few were left over after the move to Fletcher Drive.
    The no-name cut corner labels are making sense to me. At the time they were introduced the "Jim Lansing Signature Speaker" logo decal which was still use carried the name and location of "James B. Lansing Sound Inc." The new label only needed to carry new information, model/impedance/serial number.
    Later some one decided to add the "James B. Lansing Sound Inc." name to the bottm of the label.
    But it was the introduction of the Alvin Lustig's simple, clean design of the script "L" logo decal that forced the cut corners label to carry the extra info about the company location.
    I think that some of the leftover "undocumented" cut corner labels may have been pressed into service when they were expecting to make the switch to foilcals and make have run low on the "name and address" cut corner labels. Things always seemed to get a little funky with the labelling when they were making a change. I remember seeing one 175 driver labelled with an oval horn decal: no slot for impedance.

    The introduction of the 175 driver is probably what made the first "undocumented" cut corners labels necessary. The cone drivers made before the introduction of the 175 had the model number cast into the edge of the frame. But the 175 and the H1000 horn that debuted with it had only one small casting for the throat that connected the driver to the sheet metal multicellar horn, and that did not have a model number cast into it. I have seen one example of the earliest version of this horn driver that has a simple rectangular piece of paper glued to the side of the driver bearing the model number "MODEL D-175" typewritten on it.
    Also arriving on the scene with the driver was the D130A (later just 130A). So now there is another 15 inch cone driver using the same basket as the D130, but still easily distiguishable by the type of dome/dustcap.
    It was the impedance variations with introduction of the dual woofer systems that really made use of the label a necessity.

    Quote Originally Posted by Steve Schell
    More questions than answers with this one, but I'm sure glad they come along to keep us guessing. I'll write to the seller to see if he still has the cabinet, or a picture of it.
    Yes, lots of questions, I tend to over-reach sometimes trying to suppose what various bits of information might mean, with so little concrete information available it's easy to get carried away with speculation.

    Picture below is the earliest D-175 driver I have seen which is actually labelled as such.
    Attached Images Attached Images     
    glen

    "Make it sound like dinosaurs eating cars"
    - Nick Lowe, while producing Elvis Costello

  4. #4
    Senior Member Steve Schell's Avatar
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    Looking things over again with a cup of morning coffee, I'd say the woofer was definitely reconed. It was probably done in the 1950s or 1960s, when the original cone and gasket was still available. Among the dome's other problems, it is too shiny to be that old; it doesn't really look like a JBL piece to me. There is also some glue slopped on the basket rim, which original pieces don't have. If this driver was used as part of some studio monitoring system, the original cone could easily have been worn out or blown out in five or ten years time.

    It is a shame that the seller was uncertain of the origin of the networks, and that ebay pulled the auction down. IMO they were without question made by JBL as they are in stock N-1000 boxes, have cut corner labels with typed info, etc..

    Glen, that is an intriguing D-175 and horn. It is probably one of the first ones built in San Marcos. The H-1000 with the full packing of sawdust was definitely from Jim Lansing's era.

    I have photocopies of literature sheets of D-101, D-130, D-131, D-1000 system, D-130A and the D-175 / H-1000 combination curiously referred to as "D-1000." These sheets all say "FACTORY: SAN MARCOS, CALIF." The funny thing is that the labels depicted on the drivers look like the "racetrack" decal, but they appear to be drawn in by an artist rather than being part of the photographs. Perhaps this literature was created at a point in time when Lansing had just agreed with Altec not to use his round "Iconic" label, and had not yet had other labels made. How's that for wild conjecture? Anyway, the D-175 in your pictures could be from the same period.

    I'll scan the literature photocopies ASAP and post them here. Don has them also, so they will likely show up in the library at some point.

    Glen, are we the only 1940s JBL strangeos out there? There have to be more, as flat back drivers often sell for hundreds of dollars on ebay even with damaged cones. C'mon you other guys out there, 'fess up!

  5. #5
    Senior Member glen's Avatar
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    Quote Originally Posted by Steve Schell
    The funny thing is that the labels depicted on the drivers look like the "racetrack" decal, but they appear to be drawn in by an artist rather than being part of the photographs. Perhaps this literature was created at a point in time when Lansing had just agreed with Altec not to use his round "Iconic" label, and had not yet had other labels made. How's that for wild conjecture?
    Not bad conjecture at that, but more grounded than my weird fantasies. I know some of this early product literature was definitely retouched such as when they were switching to the big script "L" and painted out the old racetrack lables. So maybe the same thing might have happened when they were introducing the racetrack label.

    Quote Originally Posted by Steve Schell
    Glen, are we the only 1940s JBL strangeos out there? There have to be more, as flat back drivers often sell for hundreds of dollars on ebay even with damaged cones. C'mon you other guys out there, 'fess up!
    Well Steve, if they are interested they're too shy to de-lurk. I guess it's sort of like if you're living in a magnificient house you don't spend much time thinking about the solid foundation that had to be built first to hold everything up.
    glen

    "Make it sound like dinosaurs eating cars"
    - Nick Lowe, while producing Elvis Costello

  6. #6
    Senior Member glen's Avatar
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    Crossover crosses over pacific

    This crossover is now up on yahoo japan:

    http://page9.auctions.yahoo.co.jp/jp/auction/k34682898

    This auction has better pictures, enough of an improvement to see that the boxes are labelled with model numbers:
    N-1200A-3 and N-1200A-4

    instead of the models numbers listed in the previous ebay auction:
    1-1200A-3 and 1-1200A-4

    The "N"s looked like "1"s because only the right vertical of the "N" made it onto the uncoated part of the decal that properly retained the ink. The left part of the "N" was typed on the slick plastic section of the decal and the ink mostly wore away.

    The ebay auction ended with a final price of $45:

    http://cgi.ebay.com/ws/eBayISAPI.dll...m=190028984459

    It will be interesting to see what kind of bids these units bring in Japan.

    babelfish translation of auction description:
    It is JBL N-1200A-3 and N-1200A-4 network set. This item for LF N-1200A-3 and for HF N-1200A-4 (アッテネータto be attached) is set. You used for 2way of 175DLH and 130A, but in operational satisfactory state serial number both parties together becomes 20212. 16ohm input/output, it is crossover 1200cps. With the network which forms 175DLH and D130 and 2way of 130A type and is used for D1001 and the D1050 system, it seems that is the box of this form to around 1951. We ask may.
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    glen

    "Make it sound like dinosaurs eating cars"
    - Nick Lowe, while producing Elvis Costello

  7. #7
    Senior Member glen's Avatar
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    Quote Originally Posted by glen
    It will be interesting to see what kind of bids these units bring in Japan.
    High bid was 20,500 Yen, 171.40 U.S. Dollars.
    glen

    "Make it sound like dinosaurs eating cars"
    - Nick Lowe, while producing Elvis Costello

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