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    Senior Member saeman's Avatar
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    4350 Monitor Plans

    At the suggestion of Bo Putnam I'm putting this thread out to start gathering information on the 4350 monitor. Hopefully everyone out there with 4350's will slam this thread and pile in the info. Let's try to break it down to specific versions of the 4350. From my research over the years I have 3 versions - 1. The original 4350 offered in 1974 only. Called the 4350 with white compliance 2230 woofs, 2202 mid base, 2440, early style 2405 with split ring mounted on face of baffle and 3107 x-over. The serial numbers (written on the baffle plate around the hi-freq adj was a simple 5 digit number 10 _ _ _. I have never seen a pair of these in person, only pictures. 2. The second version, also called the 4350 (but loosely refered to as 4350A's by some) came out in 1975. 2231 dark cone woofers, 2202, 2440 and new style 2405 with 4 hole mounting plate and same x-over. The serial numbers looked to be an extension of the 1 0 _ _ _ numbering but had an "A" suffix added. They ran up to the start of the 4350B's and only changed with the addition of the 2231A woofer when it came out. I suspect that there may have been one or more revisions to the x-over schematic but have no way of knowing for sure. I think the 4350B hit the streets in 1980 with the intro of the ferrite magnet(have to check my notes). 2231H, 2202H, 2440, 2405 and 3107. The serial numbering started new with this series. The scale of calibration also changed on the hi freq. control. The cabinets also changed slightly over the different series and I have some details that I can add to the thread later. These are my observations from being a 4350 fan. If you own 4350's and can supply additional info (even to the contrary) on your model please post it. Detailed pics of the internals and baffle would be nice. I have detail drawing of cabinet internals from 4350's and 4350B's and will try to get that info posted soon. Rick

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    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    Obey the Giskard...!!

    Quote Originally Posted by Giskard (on a parallel thread)
    Go ahead and do it in your newly created thread... Hopefully everyone will stay out of it until you're finished.
    And to that end - FAIR WARNING!!

    As one Moderator of this sub-forum, I will shield this thread against unneccessary gibberish or chat. Let's give Rick a chance to build it, first.

    If you have legitimate 4350 dimensional information to share (measurements, cabinet interior photos with scale, etc) then pm me FIRST!!!

    We have a very generous offer here to build a very useful and dearly sought-after thread. From doing the 4345 Plans thread, I know the time and efforts involved. Be patient...

    Thanks, Rick!!
    bo

    "Indeed, not!!"

  3. #3
    Senior Member saeman's Avatar
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    4350 Monitor Plans

    The best place to start this thread is with a bit of philosophy/history/observation on how JBL built their cabinets. In the mid 60's (like 1967) JBL made a serious effort to build something other than a box with speakers in it. To that date they had the Paragon and Metregon on the market and the Olympus too. All of these made a fashion statemtent and sales went fairly well. Everything else they made was a box with goofy skinny Ricky Ricardo era legs, i.e. al the C34, C35, etc. cabinets. By the time 1970 hit they had carefully styled Sovereigns, the Verona, and others. Even though some of their designs like the Aquarius Series were somewhat of a marketing flop, it showed that JBL was inovative and serious about their cabinetry. They truely had the best cabinets on the market. Altec only came close with the Model 19, not just with eye appeal but with quality of construction. Altec stayed with screw on cabinet backs for most of their systems and behind the baffle mounted woofers. JBL closed their cabinets up and front mounted their woofs. There are some exceptions to this rule however JBL produced a far superior cabinet (remember the term - Living Room Friendly) than did any of their competitors. Besides the sound of a system, I have always looked past that to the build quality. JBL ran a legitimate cabinet shop, with old cabinet makers with fingers missing, etc. If you asked for something special JBL would do their best to build it. I got a quick tour of their Casitas Ave. facility in 1975 while in the service and on my way from Hawaii to Maine. I could have spent a week there. I had been building a pair of Sovereigns and JBL was absolutely awesome with their willingness to help (plans, pictures, advice). They were happy to see their components in any home brew box you might come up with. When I told them I was building Sovereigns, they couldn't believe it. Somewhere out there, if they didn't end up in someone's fire place, there exists a pair of South Americam Black Walnut Sovereigns. Will post some pics of them in another thread.

    Their stab into the pro market came a few years later and even though the 43XX series were just boxes, they were built to the same quality as all of their furnature styled systems. Quality veneers and trim were used and precision assembly was the order of the time. Reproducing that quality on a commercial scale won't happen today. Material and labor costs won't allow it. Producing that quality today, in a home work shop environment is possible, and with only basic tools, some experience with the task and a LOT of patience. JBL used big cabinet presses that they fed their cabinets into after glueing all corners. Step on the foot pedal and ka-chunk. The press came down on all four sides and held the cabinet square while the assembly dried. They had hugh crosscut tables and a finishing shop to die for. Truely a woodworkers dream. My shop is bare bones in comparison but I have the basic tools necessary. Table saw, joiner, several routers (one will do), radial arm saw for crosscutting long pieces, a compound miter saw for doing the best job cutting trim pieces, a bunch of wood clamps and a sander. Enough said, I could ramble on forever on the virtues of JBL's cabinet work. I hope to add enough information and details to this thread to allow those who have the necessary tools and patience, to build a very accurate duplicate of their 4350 monitor.

  4. #4
    Senior Member saeman's Avatar
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    Question 4350 Monitor Plans - 1

    I will probably make each post with dialog and rambling and followup by adding pics and diagrams later. Having the post started will motivate me to add the pics ASAP so as not to leave everyone hanging. The base cabinet is the place to start. All details and dimensions are of course a function of the cabinet outside dimensions. From all printed literature I have seen on the 4350/4350B, the outside dimensions are 47 5/8" wide x 35" tall x 20" deep. Those numbers include the cabinet base in height and the grill in depth. The base cabinet is 47 5/8" W x 33" H x 18" D. All of the info that I post on this thread will be based on these dimensions. The removable base was actually 1 7/8" tall so their listing was off by 1/8" on the height.

    The 4350 and 4350B cabinets that I have seen are made of 3/4" baltic birch. Top, Botton and Sides veneered with walnut, baffle painted blue (black on the utility gray models) and back painted black. I have seen two variations on how the cabinet corners were joined together. My 4350's have lock-miter joints and the 4350B cabs I am restoring have plain 45 degree miter joints. I would suspect that there are some dowel pins or splines hidden in the mitered joint somewhere. I would not expect JBL to just glue a joint that long. The baffle and back panels have a 1/4" wide x 3/8" deep rabbet edge cut all around them and they mount or plug into the top/bottom/sides in a dado cut 3/8" wide x 1/4" deep. This method supported their desire to make all of the seals air tight and solid. They go out of their way in printed literature to brag about their well constructed, heavily glued and air tight seams. When I add the sketches this info will make more sense.

    ALL internal bracing is made of cheap pine lumber that is 1 1/2" x 2 1/2". Each piece is glued and screwed to the inside surface of the cabinet, in a predetermined location. On most models there are NO screws showing on the outside of the cabinet except the two screws visible on the baffle that hold the two braces between the baffle and the cabinet back. One exception that I have noted is on the original 1974 vintage 4350. On that model the long horizontal brace across the inside of the cabinet back panel is screwed from the outside thru the back and into the brace. The screw heads are therefore visible on the cabinet back. All others are screwed from the inside, thru the brace into the panel.

    The mid-base box is constructed of 3/4" Particle Board, four sides and a back panel and is mounted directly to the baffle, and suported by the back panel cross brace. It's important to note that this box needs to be precision built and securely mounted to the baffle to ensure proper performance of the 2202. This is supposed to be a sealed air tight chamber of predetermined internal volume.

    Those are the high-lites of the basic cabinet. I will have to add quite a few pics and drawings to support all of this information, and need to do that before going on to talk further about cabinet construction.
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    Senior Member saeman's Avatar
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    4350 Monitor Plans - 2

    The method of joining the cabinet corners warrants further discussion. Now that I have posted a detail of the two miter joints that JBL used, here are some considerations for deciding how you might want to proceed. Assume that you are looking at your cabinet top and it's 47 5/8" long and 17 5/8" wide and you've gone to no end of trouble to make sure that it has perfectly square corners and you've spent a bunch of time and money to veneer it. And now you're ready to cut the miters across the edges. It's a big piece of wood and weighs a bit too. Can you push it thru a table saw and be assured that the resulting cut will remain square with the sides. You can if you buy a neat little cross cut jig/attachment from Porter-Cable that costs near $300. When you've made your cut and it comes out square, will the edge of the cut be knife sharp without your veneer being chipped along the edge? Maybe. In order for this project to be worth your time the end product must have sharp corners that aren't full of plastic wood and if every piece of the cabinet ( sides, top and bottom ) isn't square the assembly will rock back and forth on a flat surface. Problem two is the effort that it will take to clamp the assembly together (assuming that you are able to cut 4 perfect pieces). It will require 8 big cabinet clamps that will span the height and width of the cabinet. That's a fair cash outlay. Considering these problems, and they're significant ones for the home wood worker, I've found a way around them. To my knowledge you can not buy walnut veneered baltic birch or P.B. so you'll have to veneer it youself. I consequently do my veneer work after the cabinet is put together. This opens up a better option for joining the corners together. No miters, just easy to cut rabbets and dados. You still need all corners square but the whole cabinet will sit together dry with no glue like a puzzle. The trim can be added afterwards, with mitered corners and the end appearance will be the same. From the detail you can see how easy the cabinet corners are compared to the stressing ordeal of mitering every corner. The only evidence of having used this method is when you look at the corners from the back of the cabinet. You'll see an outline of the joint. Who cares, you're building these for yourself. If someone gives me a blank check and says "Completely Duplicate Them" to the "n"th detail I'll do the time. Otherwise for my own enjoyment this is great. This method will cut your cutting time for cabinet prep by 2/3's and almost eliminate the risk of trashing possibly half of your veneer. Next post will include cabinet internal pics and a couple of details showing location of all internal bracing.
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    Senior Member saeman's Avatar
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    4350 Monitor Plans - 3

    Attached to this post are several 4350B cabinet interior pics and a drawing that shows the layout of the cabinet bracing. There are a couple of side braces that are not on my drawing. Just noticed that after posting it. Will update and repost later. All dimensions are referenced to the outside edge of the cabinet back panel. Remember that there is a rabbet cut 1/4" wide x 3/8" deep all around the edge of the cabinet back. The interior pics show the long horizontal brace across the cabinet back and the two vertical back braces. There are two braces attached to the bottom - front to back and two braces per side front to back. The mid-base box acts as a large brace between the baffle and the back. Not shown on my drawing, but evident in the pics, are two braces between the baffle and the back just above the woofer cutouts. JBL attached all of the panel braces before assembling the cabinet. They were glued and screwed to their respective panels. You will notice wedges driven in between a couple of the braces and one between a bottom brace and the baffle. They were glued in and acted to stiffen everything up and eliminate any rattling or vibrations. It's not uncommon to open up a vintage cabinet and find one or more of these wedges laying loose in the cabinet. Over years of exposure to changing humidity they are known to work loose. If you choose to build a pair of 4350's (or any other big monitor) you would be wise to install the braces individually after the cabinet shell is constructed, measure them exact and glue and screw the hell out of them. Wedges will then not be necessary. The pics also show the 6 port duct tubes. They are 12" tubes and are recessed 1/2" into the baffle from inside. They are 3" ID. More on this when I post info on the baffle. As stated in an earlier post, all of the internal braces are 1 1/2" x 2 1/2" pine. If you're interested in improving upon this you could use poplar instead. It's a bit harder and not too expensive.

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    Senior Member saeman's Avatar
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    4350 Monitor Plans - 5

    I knew I had some pics that would show the cabinet corners fab'd using the dado/rabbet technique. They're of a pair of 4331A's I built about 5 years ago. On your browser, blow up the corner detail and you'll see a faint outline of the joint.
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    Senior Member saeman's Avatar
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    4350 Monitor Plans - 6

    The below posted drawings show the details of the cabinet bottom and the base. Remember that all of the dimensions assume that the cabinet bottom is 47 5/8" wide x 18" deep. Adjustments will have to be made to these drawing dimensions if it is not. The base is painted black. I used Satin Black Enamel - two coats with a roller to fill the grain and give it some texture. Let the enamel dry two or three days before you put the cabinet on your wife's carpet.
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    Senior Member saeman's Avatar
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    4350 Monitor Plans - 7

    BAFFLE - The following drawings show the layout of the baffle. There are 52 holes that range in size from 9/64" to 13 15/16".To cut these holes I made router templates from 1/4" plexiglass (lexan) and have had and used them on other projects. With templates the baffle can be cut complete in about two hours. Without templates you have a job ahead of you. REMEMBER - the desired end result is ROUND holes. All of my templates have X-Y cross hairs on them and they're simply lined up on the baffle and clamped in place. The router rotates around the inside of the template (no screw-ups that way). I use templates to cut all woofer holes, holes for the 2311 and 2405, duct holes and the associated recess for the tube and for the terminal board opening on the cabinet back. I'll lay some of them out and take a couple of pics so you can see what they look like. I also made templates for the 2311 and 2405 mounting holes. Nothing's more frustrating than to try mounting components just to find that the mounting holes are off. Here's a list of hole sizes in the baffle.

    10) 9/64" - 2405, L-Pad mount
    26) 9/32" - 2311, 2202, 2231, steel brackets
    1) 5/8" - L-Pad knob
    6) 3" - Ports
    2) 3 1/16" - 2405
    2) 4 1/4" - 2311
    1) 11 1/16" - 2202
    2) 13 15/16" - 2231
    2) - 10 x 2" wood screws for baffle braces

    More baffle details later - Rick
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    Senior Member saeman's Avatar
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    4350 Monitor Plans - 8

    Baffle - Included in this post are 3 drawings (post later this evening) showing the remaining baffle details. Included are dimensional drawings of the 2231's and 2202 and their mounting holes and a dimensional drawing of the mounting details for the 2311 and 2405. The last drawing shows the layout on the baffle for the Velcro Tabs that hold the grills on, including the plastic grill pegs.

    This will be the last post showing construction details until I start fabricating the grills. I think all information necessary to build the 4350 is supplied in the various posts. I will shortly include some pics of the templates that I have made and used for the project. Right now my 4350 project is on the back burner but I'll add info and pics to this thread as I continue to work on the cabinets. When they are ready for veneer I will post again and I can then add pics and dialog on my approach to that task; taking all interested parties through to the finished product.

    Throughout this post I have refrained from discussing the minor detail differences that I have found between the early and late cabinets and also the minor differences between the 4350 and 4350B cabinets. I'm not sure I have seen enough 4350's to be able to draw any significant conclusions. If anyone out there is interested please feel free to ask.

    I only have pics of the Gray utility 4350's and have never seen a pair. I would appreciate hearing from gray owners and need detailed pics of the baffle and front edges of the cabinets. I would also appreciate seeing good close-up pics of the baffle foil cal on your 4350's.
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    Senior Member saeman's Avatar
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    4350 Monitor Plans - 9

    Baffle Foil Cal - Attached are two pics that show the foil cal for the 4350 and the 4350B. The differences are obvious. Unless there were changes in the x-over circuitry is there any reason why the scale of calibration for the hi frequency control would be changed?

    I also had a pic of the foil cal from the early 1974 1st year 4350 so have added it. You can see that is identical in design and wording to the later 4350 version. Unlike the later 4350 variation, it does not have the "A" suffix after the serial number.

    Most won't see or care about the differences. For those out there who want to accurately restore a vintage pair, all of the info in this thread will hopefully lend to that goal. There are a lot of pairs of 4350's out there that have been chopped, hacked and had who knows what off the wall, non-JBL components put in them. Restoring them is a worthy goal, and cheaper than doing a 57' Chevy.
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