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Thread: JBL 4343 restoration questions

  1. #16
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by DingDing View Post
    Next up might be to try those Crown amps for the woofers, since there seems to be some controversy regarding their performance on the highs and midrange.
    Can't imagine where you got that idea. I know Scotty Fitlin (R.I.P.) once talked about how the Crown Studio Reference might not be the best choice for full-range use but the PS400 and PS200 (and DC300A-II and D150A-II, and certainly the D75A) work quite well over the full range. I've been using them for years.

    You might be confusing the currently popular use of the Chinese-made Crown XLS and XLi series amps for subwoofer duty. Mostly those are amps designed for PA and DJ use, not hi-fi. 700-watts @ 8-ohms bridged for under $300 is tempting but not necessarily musical.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  2. #17
    Senior Member DogBox's Avatar
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    Enthusiasm...

    Quote Originally Posted by Odd View Post
    ...another enthusiast with 4-way JBL monitor...Mine has diy enclosure with 2235, 2123, 2450, 2405 and CC crossover designed by 4313B.Crossover was a big improvement. Thanks to 4313B.
    Now, there's an interesting combination of drivers.. If you don't mind me asking [being a little "off-thread sort-of"] did you just have those drivers in mind when you went to build? or, were you advised which ones were more suited to go together? I noticed the 2" Compression driver... How well does that "blend-in"...?
    In keeping to 4343, I am interested to hear your comments...

    Many Thanks,
    DogBox

  3. #18
    Senior Member Odd's Avatar
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    Quote Originally Posted by DogBox View Post
    Now, there's an interesting combination of drivers.. If you don't mind me asking [being a little "off-thread sort-of"] did you just have those drivers in mind when you went to build? or, were you advised which ones were more suited to go together? I noticed the 2" Compression driver... How well does that "blend-in"...?
    In keeping to 4343, I am interested to hear your comments...

    Many Thanks,
    DogBox

    There have been changes over the years. Today's edition is inspired by 4313Bs work with DIY 4345 in this thread
    Active filter for 2235. They now play very well. No more changes.

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  4. #19
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    Quote Originally Posted by Odd View Post
    Good to see another enthusiast with 4-way JBL monitor.
    There is more than one would think of them here in Norway.

    Mine has diy enclosure with 2235, 2123, 2450, 2405 and CC crossover designed by 4313B
    Crossover was a big improvement. Thanks to 4313B.
    Just to clear out where I'm "coming from" and my level of experience. I've been studying in Oslo for the past three years and due to living arrangements have not been able to have a proper stereo system. However, I was deeply into headphones as a substitute, but it's just not the same thing as a proper stereo.

    Every time I visited my older brother, I felt sorry when going back home to my stacks and rows of headphones, haha. He has a pair of Altec Lansing Model 19, and after my studies were over, I relocated and nearly got a pair of Tannoy DC10T, but big brother pitched and adviced me to get a pair of vintage JBL monitors. And as a good little brother is supposed to do, I listened and got 4430, was amazed at how great they sounded and this all began.

    Your loudspeakers look great, and I bet they sound the part too. I presume you built them yourself? If so, what a great job!

    Quote Originally Posted by BMWCCA View Post
    Can't imagine where you got that idea. I know Scotty Fitlin (R.I.P.) once talked about how the Crown Studio Reference might not be the best choice for full-range use but the PS400 and PS200 (and DC300A-II and D150A-II, and certainly the D75A) work quite well over the full range. I've been using them for years.

    You might be confusing the currently popular use of the Chinese-made Crown XLS and XLi series amps for subwoofer duty. Mostly those are amps designed for PA and DJ use, not hi-fi. 700-watts @ 8-ohms bridged for under $300 is tempting but not necessarily musical.
    Hi,
    Been reading a little bit about using Crowns in hifi systems on a Norwegian site for audiophiles and that's where I got the idea. You may very well be right about the models. As you can see from my answer to Odd, my own experience is lacking. Thank you for the advice on Crown models. Will read more about it here on the forums.

    I'm always intrigued about products that doesn't cost a fortune and come from companies with years of experience.

  5. #20
    Super Moderator yggdrasil's Avatar
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    Quote Originally Posted by DingDing View Post
    Basically, my first questions are:

    1. Is the original finish American valnut, and are there any suppliers of this I can contact that you guys know of?
    Prøv: Oslo Finerfabrikk AS – 23 00 61 60
    Johnny Haugen Sørgård

  6. #21
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    Quote Originally Posted by yggdrasil View Post
    Prøv: Oslo Finerfabrikk AS – 23 00 61 60
    Thank you! I see on their product page (Norwegian) that they have some American Walnut which is 0.6 mm thick. It doesn't say if it is paper backed or not, and I'm under the assumption that the best result is achieved by using paper backed veneer. I'll contact them and hear what they have to say about this particular application.

    Aiming to recreate the conditions and take advantage of saeman's shared experience on this job, as is described in the quoted post below. He has many scattered posts about doing veneer, and it seems like he has perfected his method for long lasting and good results.

    Quote Originally Posted by saeman View Post
    Hi Widget: I can't show you any work that's 20 years old but I have been using this method for a long time with good results. 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.

    Buy some veneer and go for it. Rick

  7. #22
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    Norwegian veneer supplier

    Quote Originally Posted by yggdrasil View Post
    Prøv: Oslo Finerfabrikk AS – 23 00 61 60
    I shipped them an email asking if they had paper backed veneer in case I needed to research their answer before replying with more questions.

    For Norwegians that might come across this post in the future, they do have some paper backed American walnut veneer, and the product is called Decoflex and measures 0,6 x 2500 x 1240 mm and is only sold in sheets. However, Oslo Finerfabrikk does not sell directly to private persons, so you need to go through a retailer like http://www.thaugland.no/

    I wonder if 0.6 mm is thick enough?

  8. #23
    Senior Member DogBox's Avatar
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    Looks good to me!

    Quote Originally Posted by Odd View Post
    There have been changes over the years. Today's edition is inspired by 4313Bs work with DIY 4345 in this thread
    Active filter for 2235. They now play very well. No more changes.
    Hey Odd,
    Very nicely done! Gotta love those lenses!! I must ask though, You don't find the 'ports' a bit small? you would have to have plenty of length to get them to work - wouldn't you?
    Did you build the cabinets from scratch? But, back to the drivers:
    Is that what you "planned on using" from the start? It is certainly a 'different' combination to "sum" together...?

    DingDing's got the right help following Saeman... can't go wrong there!


    DogBox

  9. #24
    Super Moderator yggdrasil's Avatar
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    0.6mm is enough. I got some walnut (no paperback) directly from Oslo Finerfabrikk a few years ago, but as you say - invoiced to my company.
    Johnny Haugen Sørgård

  10. #25
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    Quote Originally Posted by yggdrasil View Post
    0.6mm is enough. I got some walnut (no paperback) directly from Oslo Finerfabrikk a few years ago, but as you say - invoiced to my company.
    Thank you. Is your company related to the industry? I've got a sole proprietorship which operates in another industry, but if I can order directly from them using that, I'll do it as the retailer they forwarded me to does not respond to my email.

    Decoflex details
    I got the gluing instructions from the importer (Oslo Finerfabrikk), and in case anyone would like to read it, here it is.

    DECOFLEX-gluing-instructions_en.pdf

    According to the instructions one should not use any water based glues.

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    Water based glue?
    saeman uses Tite-Bond II which it's possible to get here in Norway. However, I'm not sure if this is water based or not. Tried reading the specifications on the manufacturer's website, but did not grow any wiser.

    So, does anyone know if this is water based or not? On the website, it says it is easy to clean with water, which makes me suspicious that it's water based.

  11. #26
    Senior Member christo's Avatar
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    Tite-Bond II is water based and I have used it with great success with 10 mil paper backed veneer. Not sure why the manufacturer only recommends a solvent based glue.

    In my experience I applied three coats to each surface then used an iron to reactive the glue and I have found a roller is not required as long as you work from the center out. I'll never go back to a solvent based glue.

    The attached picture shows all the tools I used.
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  12. #27
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    Thanks christo

    Dang, seems like I'll have to find a substitute for the Decoflex veneer then, as they specifically recommend not using water based glue...

    yggdrasil, did you defy the recommendation of Decoflex and still use water based?

    I may have to contact the manufacturer to know why they recommend against it. Maybe they treated the wood with a compound which will react with water based glues...

  13. #28
    Senior Member christo's Avatar
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    Here’s a picture of the 4344 clones I built using saeman’s veneer techniques. I cut the front baffle trim from a 1x6 plank of walnut and glued them to the cabinet, used a router to get it flush with the side panels then applied the veneer.

    The picture below shows the trim applied and cut flush to the cabinet prior to the veneer application
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    Once the veneer was applied I then cut the 30 degree angle with the router. The trim and side panels blend virtually seamlessly, veneering with Tite-Bond II is very easy.
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  14. #29
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    Beautifully done, christo! Thank you for sharing your pictures and experience. Been wondering how to get the front profile (plank) to blend in well.

    Just to make it 100 % clear: You didn't apply veneer to the plank after the 30 degree cut was made, right? It is solid walnut, and you just cut it flush with the veneer? Have to ask because the end result looks like you applied veneer, since it looks so seamless.

    If I manage to do the finish properly there might be a DIY project based on other people's drawings in the future.

  15. #30
    Senior Member Mostlydiy's Avatar
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    Christo, wow, amazing looking speakers you got there.

    /Mostly

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