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Thread: JBL 4343 restoration, progress and quite possibly a lot of question along the way

  1. #46
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    Got a little more work done today. Still plenty left as I want to triple check everything.

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    Quote Originally Posted by Ian Mackenzie View Post
    Great thread
    Thank you

    Quote Originally Posted by Fangio View Post
    Have to agree

    A bit late to the party, anyway I have walnut 4343s. Maybe these pics will help

    [REMOVED IMAGE]

    I did these once for Hardy aka Düse here at LH, another member who has veneered 4341 uitility cabs a while back. If you want the fullsize pics or need more dimensions let me know.

    Do you consider building grilles? If so you could have a look here..

    http://www.audioheritage.org/vbullet...l=1#post100805

    Cheers
    Thank you very much for the measurements. They will certainly come in handy when I model the walnut version and recess the fiberboard on my speakers. I want to make sure they're just like the original as this will probably have (minute) effects on the diffraction of the speakers, beneficial or not, who knows.

    If it's not too much trouble I'd love some more dimensions. I'm sure the trim is very close to 25.4mm (1") from your pics, but doesn't hurt to know for sure. If you could check with a caliper I'll be very happy. Same with the flat outer edge. If I know both of them I can calculate the angle precisely.

    Different numbers are thrown around, it's most likely 30 degrees (which some call 60 degrees), because they're talking about the same router bit but seen from another angle.

    The grilles I have are DIY and not up to spec. It's not first priority to be honest, as the speakers deserve to have them off to show their glory

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    Quote Originally Posted by ivica View Post
    Hi DingDing,

    Nice work has been done.
    After Your CAD work, we would have 'fabulous 4343' DIY documentation.
    Do You plan to do any measurements?
    I am especially interesting in the bass response, measured very near the dist cap, and port response too.

    Is there any idea why JBL on the 4344 model placed ports between bass and mid-bass drivers, while on 4343 ports are at the bottom?

    regards
    ivica
    Thank you.

    As for the ports I'm afraid you are a far more advanced than me. Maybe it has something to do with eliminating floor bounce? I noticed that Greg Timbers recommended getting 4345 up off the floor and we also see KenRick Sound elevate their 4343's in their beautiful showroom.

    I do have some measurements (didn't find the near field freq graph right now, sorry). Keep in mind that these have charge coupled crossovers, are actively xo'ed between bass and mid, utilizing 2235h, not 2231A.

    This is the impedance of the woofer loaded in the cabinets without any modifications to the ports.

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    So tuning around ~31 Hz w/2235h

    If I can't find the old measurements I'll just take new ones.

  2. #47
    Senior Member Fangio's Avatar
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    Quote Originally Posted by DingDing View Post
    ... Thank you very much for the measurements.

    If it's not too much trouble I'd love some more dimensions. I'm sure the trim is very close to 25.4mm (1") from your pics, but doesn't hurt to know for sure. If you could check with a caliper I'll be very happy. Same with the flat outer edge. If I know both of them I can calculate the angle precisely.

    Different numbers are thrown around, it's most likely 30 degrees (which some call 60 degrees), because they're talking about the same router bit but seen from another angle.
    I don't have a caliper right now (did have one though when I took some measurements back then), but this might be better.. another fellow who had some 4341 cabs veneered, has used my 4343 values and made a drawing for his carpenter (thanks Michael).

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    I'm sorry, metric system again..

  3. #48
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    Quote Originally Posted by Fangio View Post
    I don't have a caliper right now (did have one though when I took some measurements back then), but this might be better.. another fellow who had some 4341 cabs veneered, has used my 4343 values and made a drawing for his carpenter (thanks Michael).

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    I'm sorry, metric system again..
    Thenk you Fangio. Metric system is highly welcome and preferred. It's std here in NO too. Thank you.

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    What is that 2mm notch? From your pictures it seems like a small groove between the fiberboard and the solid. Probably a silly question, but better to know for sure than to assume.

  4. #49
    Senior Member Fangio's Avatar
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    Quote Originally Posted by DingDing View Post
    Thank you Fangio. Metric system is highly welcome and preferred. It's std here in NO too.
    I know. The sorry was adressed to the US/UK folks.

    What is that 2mm notch? From your pictures it seems like a small groove between the fiberboard and the solid. Probably a silly question, but better to know for sure than to assume.
    I'd say that is safe to ignore, should have edited it out. He probably included it looking at my pics, however there isn't a real gap. Actually the notch where the outer angled trim sits on the side panels is rather ~1mm (compare to the other pics in post #44).

    And I'd go with an even value of 30° ofc.

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  5. #50
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    Quote Originally Posted by Fangio View Post
    I know. The sorry was adressed to the US/UK folks.

    I'd say that is safe to ignore, should have edited it out. He probably included it looking at my pics, however there isn't a real gap. Actually the notch where the outer angled trim sits on the side panels is rather ~1mm (compare to the other pics in post #44).

    And I'd go with an even value of 30° ofc.

    [IMAGE REMOVED]
    Cool Fangio, then we're clear. Don't think it's possible to get a cutter with that awkward angle unless you have it custom built. I'm sure the original is 30° too.

    ---

    For future readers: I've found two cutters which are affordable and will do the job.

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    1/2" http://www.precisionbits.com/30a-cha...ico-13905.html
    1/4" http://www.precisionbits.com/30a-cha...co-13905q.html

    *** for other router noobs on the metric system: 1/2" is not the same as 12mm and 1/4" is not the same as 8mm.

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    Saeman says he uses a 60° cutter, but I think he's talking about the angle drawn in by me above. We're all talking about the same cutter here, it's a 30° bit.

    This should clear up any confusion about that damn trim, haha.

  6. #51
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    Calc's...

    Hey DingDing, Coming along nicely!

    As I had to deal with metric/imperial in my trade, it was easy enough just to remember if you had metric, say 22mm : 22 / 25.4 = Answer in thousandths of an inch.

    Grab yourself some size charts and 0.866 is just under 7/8" [0.875] Or if you had imperial 0.875 x [multiplied this time] 25.4 = 22.225mm.

    Which will get you close enough to the saw blade to cut yourself. It takes a good cabinet maker to cut within 0.006" and fine machinery to do it. That's what

    sandpaper is for. I'll probably get ribbed for my workings out and carpentry skills, which is ok seeing that I normally work with metal! But, hey...!

    I have some "corner shots" I borrowed from Kenrick that show they use a "moulding" piece of trim that has been cut to size which they seem to glue on. Done.

    Not sure if that's the norm, but clearly shown in some shots.

    You can be pretty sure JBL dealt in imperial in those days too! so feel happy! to carry on as you are! Whats that Drawing Program you're using? It's cool!!

    DB

  7. #52
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    DogBox, I take all measurements in mm down to a 10th of a mm using caliper wherever possible. The program I'm using is Google Sketchup and it's free + there are tons of tutorials on Youtube on how to use it. The great thing about it is that you can choose the units you want to work with. So even if I'm doing this model using the metric system it's easy to see all the dimensions in imperial by changing the units. I'm sure that my measurements won't be precisely what JBL used but it will be very close.

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    It can do very complex shapes too, but I'm not skilled. Here's a model of JBL M2 and here is one of JBL 4430. Not made by me but available for download.

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    Unfortunately these models are mainly exterior as there are no details on the internals. Also not sure about the scale.

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  8. #53
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    Just a quick update:
    1) Still working on the model but have not had time to do much lately.

    2) Got a solid plank of American walnut (gorgeous wood) which will be cut into pieces for the front trim. The plank is 2440x200x26mm and cost about $80 from my local supplier. Lots of trims in a big plank like that.

    3) Veneer will probably be here tomorrow. Yay!

    4) 2.4kW (3 1/2 hp) Triton TRA 001 router w/ 1/2" collet and Kreg router table inlay is coming next week. Going to build a router table for future projects to get those lock miter seams and being able to copy bracing from templates I make and what not.

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    Excited? You bet!!

  9. #54
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    Quote Originally Posted by DingDing View Post
    Thenk you Fangio. Metric system is highly welcome and preferred. It's std here in NO too. Thank you.

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    What is that 2mm notch? From your pictures it seems like a small groove between the fiberboard and the solid. Probably a silly question, but better to know for sure than to assume.

    Hi Ding Ding!
    Your answer is here around about the groove! If I find it I'll send you the link!

    I did my edge like that! I didn't like all blue. The walnut gives a more classy look, I think.
    Are you planning to build 4430?
    Have fun!
    Christophe
    Attached Images Attached Images  

  10. #55
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    Blue paint, veneer and solid walnut in the house. Got some requested veneer scraps for experimentation, so excellent service from Oakwood veneer where I ended up buying. Still waiting for Titebond II and some minor things and need to figure out the specifics about the black color for the rear and the blind panel on one of the UHF slots.

    Quote Originally Posted by Challenger604 View Post
    Hi Ding Ding!
    Your answer is here around about the groove! If I find it I'll send you the link!

    I did my edge like that! I didn't like all blue. The walnut gives a more classy look, I think.
    Are you planning to build 4430?
    Have fun!
    Christophe
    Everything about the trim dimensions are in the clear now and posted in the thread thanks to many helpful people like yourself.

    Agree that the trim looks better the way you've done it. Walnut all the way to the baffle also look very good. Have a look.



    This looks spectacular, but on the other hand I want it to look original even though I'm not fooling anyone. Have not decided what to do just yet.

    My brother and I may eventually end up building another pair for him (4343 or 4355) but after this project I will try to bring my own ideas to life having 4343 to fall back on if I fail.

    I have owned original 4430's for a few years and unfortunately they fall short in comparison to 4343. I think a 4430 with an additional cabinet with 2123 and 2404 stacked on top may yield better results, but never tried it as I fell in love with 4343. 2235h does not sound that good when xo is as high as 1khz as in 4430 imo. Other than that they are fun speakers and they look awesome.

    The reason I'm not building 4355 for myself straight away is I want to experiment with JBL components, DSP and active crossovers. If I'm unable to get solid performance I will build 4355 too, probably a fully active one with stepped attenuators replacing the L-Pads.

    Hope you're (all) having a good weekend.

  11. #56
    Senior Member macaroonie's Avatar
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    Good work chief , I'm looking forward to seeing these come back to life. I'm sure you will do a super job.

    Be careful with that lock mitre cutter for 1" material , it's almost 3" across. In use I would suggest that you do your cuts in stages , leaving the last cut to be only 1mm as a cleanup. You will need to create a fence for this of course. Maybe your router table has this. Make sure it is all locked down securely and that your panels are safely supported when feeding through the cutter.
    Vacuum is a good idea if you can rig something up , even a Henry will lift a lot of cuttings.

    Skol .

  12. #57
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    Quote Originally Posted by macaroonie View Post
    Good work chief , I'm looking forward to seeing these come back to life. I'm sure you will do a super job.

    Be careful with that lock mitre cutter for 1" material , it's almost 3" across. In use I would suggest that you do your cuts in stages , leaving the last cut to be only 1mm as a cleanup. You will need to create a fence for this of course. Maybe your router table has this. Make sure it is all locked down securely and that your panels are safely supported when feeding through the cutter.
    Vacuum is a good idea if you can rig something up , even a Henry will lift a lot of cuttings.
    Thank you for the support Mac, it's daunting to say the least but no turning back now. Must admit that this restoration has been procrastinated for the past two years partly due to sheer terror, but the hour is here now and it needs to be done. Just need to be patient.

    Was gobsmacked when I saw the size of that cutter. Very good advice and it gave me an idea. The ambition is to build a router table using a table top from IKEA with a smooth surface. Also need to build a good and fairly tall fence for the vertical cut, so this is a whole project all by itself. To get to the point here: These cutters seem hard to set up, and when I need to do multiple passes it will be even harder, but I figured I could try to put a locking pin, marking or similar in the table behind the fence to set it up for each pass.

    I overspent a lot on this setup already, but at the same time I'm very excited about being able to rout those seams and having a powerful router that can trim MDF like butter. It opens a lot of opportunities. I've watched a lot of videos on pros handling routers on Youtube, and it's very inspiring.

    Fortunately, I have a Vac already. Been looking at cyclones too, but you got to draw the line somewhere, I'm not a pro shop, haha.

  13. #58
    Senior Member macaroonie's Avatar
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    One thing to remember is that due to the larger diameter of the cutter for a given rotational speed ( RPM ) the blade speed will increase. There is always a sweet spot cutter speed , mostly depending on the material and also the rigidity of the tool system. You will most likely want to run at a lower speed than normal with that big cutter , that's if your motor is equipped to do that.

    Since the profile is end-on to the sheet and since the remaining profile has a sharp 45 deg point that you want to preserve intact I suggest that you either register your work piece to a sled that is jigged to run across the cutter. Ie. no fence.

    or

    Use a fence at the other end of the workpiece , no fence at the cut edge. You will need to rig up repeatable stops or marks to get your sizes to repeat ( sides , tops all the same )

    Go back to the build thread I posted ages ago

    http://www.audioheritage.org/vbullet...l=1#post181001

    Footnote : Those canteen tables with a steel frame and a formica top can be found at the reclaim places for pennies. Plenty of area to work with and a good surface. It's usually laminated to birch ply.

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    Mac: The Triton has variable speed and recommended speed settings depending on the diameter of the cutter, but it didn't take account for the material density. I guess you just need to work some things out by experience.

    Good ideas about the canteen tables and the sled. The reclaim places are far away from where I live and IKEA ships so I'll see what I can find. I saw a guy who built a sled that attached to his custom fence when doing the horizontal cut. Would be ideal for bigger panels.

    ---

    Have been experimenting a little today.

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    The blue is two coats of RAL5007 matte finish on one coat of primed MDF. It's a little less deep than the blue which was on and has a little more gray to it. The picture doesn't quite capture the color of the objects, but I think this color will work very well.

    The left piece of walnut was laminated on using contact cement. I think there was something wrong with the cement as it would not stick to the paper backing properly and was impossible to distribute evenly on both surfaces (MDF). Was impossible to get rid of the uneven buildup no matter how much pressure I put on it. It was probably a problem with the contact cement or it was just a poor product. If it had distributed evenly it would have been a good choice for smaller projects which should be done as fast as possible. The sample is also oiled with two coats (will do more) of some cheap teak oil I had sitting. Going to get better oil which brings out more of the red color.

    The right piece was glued on with some PVA glue I had by putting on two thin coats and letting them have a rubbery consistency to the touch. Used an iron and a scrap piece to add pressure along the grain. This method was preferred but took longer. Will practice some more with bigger pieces until I do the speakers and will use Titebond II and not what I have, because I know it works over time.

    So all in all a good experience with the wood glue iron method. Saeman made a very good post of his insights a while back. Here they are again for anyone who may want to try this.

    saeman's words and takeaways

    For what it's worth, here's a few comments on problems I have encountered.

    1. I have used paper back veneer, bubble free and phenolic backed veneers. Paper backed is the easiest to work with as it is thinner material. Phenolic backed resembles formica in overall thickness. It bonds well but since it is thicker it's harder to make sure there are no voids or bad bond spots.

    2. I have talked a lot about buying some kind of commercial heating iron and never have. My wife's clothes iron works great and she hates to use it anyway. Her current iron used to be teflon coated but I've worn patches of the teflon off pressing veneer.

    3. Temp setting is about 1/3 of max for most household irons, or about 160 degrees max. Too much heat and you will melt and puddle the glue under the veneer - TROUBLE - if this happens you need to turn the heat way way down and slowly dry the glue again. All you need is enough heat to re-activate the glue to allow both glued surfaces to bond (just like two surfaces coated with comtact cement.

    4. Going over the veneer with a hot iron is not enough. More pressure is required to ensure a solid bond. Heat about 1 square foot at a time and immediately (while the surface is still damn hot to the palm of your hand) roll over that area with a 4" veneer roller applying all the pressure you can. Roll slowly and listen for any crackling sounds. Roll with the grain and then roll side to side against the grain. If you hear crackling it indicates that the veneer is lifting. Heat - roll - heat - roll, until there is no crackling to be heard. After doing the whole surface go aroung all edges again. Let that panel/side sit for several hours and then trim off excess veneer. Then go over the whole surface again slowly with the roller and listen for any crackling. After sitting for a while if the bond is not good it will lift. If this problem occurs hit it with the heat again. I have always used Titebond II and have heated and reactivated as long as two days after laying the veneer.

    5. After you have trimmed off excess veneer - take your thumb and fan the entire edge (like you would shuffle thru pages in a book or a deck of cards) and listen for spots where the veneer is loose around the edge. Heat and roll any you find.

    6. Bubbles under the veneer usually happen when too much heat is applied. With some practice everyone using this method will find their own settings. Not enough heat and your veneer will be crackling under the roller until your supper is cold. TOO MUCH heat will melt the glue and quite often cause bubbles. If you have a bubble that persists, it can be sliced open using a thin blade modeling knife. Let any trapped air escape, roll the hell out of it and apply less heat in that area to get a bond.

    7. Applying the glue - I apply 2 (sometimes 3) coats to each surface using a 4" paint roller. Most veneer manufacturers recommend a 6 to 8 mil glue coating between veneer and substrate. If you skimp and apply only one coat you'll some day, after a big change inhumidity, find your veneer lifting from the surface. Titebond II turns clear when it's dry to the touch. When the first coat is dry you can apply the second/third coat. You can wait as long as a couple of days to apply your veneer but I have had the best results after waiting just an hour or two after the last coat is dry. It will appear dry but you will be able to penetrate the glue with your finger nail and it will feel a bit like a hard rubber surface. If you wait a day or more the glue will be HARD and even though heat will reactivate and bond, I have gotten the best results with the rubber like surface.

    That's a lot of rambling and babbling but maybe my techniques will help some of you achieve the results you're looking for. I've had a lot of frustration doing veneer work but have worked out the bugs and have been getting good results.

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    How Much..? That looks about right!

    Quote Originally Posted by DingDing View Post


    These cabinets must be routed a bit because the front "lip" extends too much. But by how much?

    Can't find plans for 4343 on the site.
    The amount you've got there [even going by your pictures] looks about right. What you may be forgetting is that the lens on the front of the baffle sticks out
    2 1/2" in front of the 2307 when it's attatched with it's velcro and the grills extend quite a distance out - so what you have looks close...
    Those cabinets came with the front trim, didn't they? You haven't changed anything in the boxes for it to 'be' any different have you? Well, you're ok!
    Check some pictures in the Kenrick site.
    You are doing a mighty job! I didn't mean to sound selfish about my carrying on about the drawings/plans. I know many others would love to be where you are at
    having a build going so well!
    Just do the drawings when you get time, for goodness sakes...! I meant to say - before it's all together "could you please.. make some measurements" that will
    benefit the members.. while you have the chance whilst it is still apart. ThankYou!

    DB

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