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View Full Version : 'Poor Boy' 434X Cabinet Questions.



cgregory4
09-26-2014, 08:29 AM
I suppose I've squirreled away enough components now to build at least 4 of the 434X critters. The cabinets are another matter entirely. :(

While I try to tame my Clair S4 beasts (or, be tamed :o:), I thought I'd turn my clever cousin loose on the cabinets. So I have a few questions for those of you fortunate enough to have actual hands-on/eyes-on experience with one, or more, of these scarce models.

1. I am aware of the various cabinet plans on the LH site, so I'll try to stay away from the 'known'.

2. Does the material matter? Say that I decide to ask Jerry (my cousin) to build every outside surface, including front baffle, from pecan or red oak, or whatever; does that matter, as long as the thickness is equal, or greater, than the original panels?

3. How about the same question wrt interior enclosures, baffles, supports? I am considering laminated cedar for the interior pieces. Again, all thicknesses will be equal to, or greater, than OEM spec.

4. On the original 434Xs, are all exposed 'hard' interior surfaces covered with acoustic 'blanket' material?

5. As long as supports are more than adequate for driver/horn/hardware weight, is there anything 'holy' about the exact shape of the supports -- assuming all critical volumes and vents are preserved.

6. What other constraints need to be met in order to preserve a reasonable respect for the original 434X product?

Sincere thanks to those of you who are fortunate enough to have been exposed to the originals -- or successful clones thereof -- for your assistance in this matter. My cousin lives in central Texas with enough dry wood under cover to build several houses entirely from hardwood. But he is a hard-headed son-of-a-gun, and he will have his own ideas about how to build these cabinets. I would like to be ready to respond concerning what is 'sacred' vs what is negotiable. ;)

Greg

Doc Mark
09-26-2014, 08:59 AM
HI, Greg,

Being from Texas, myself, originally, I completely understand about some folks being hard-headed, me included!!

I am thinking that hardwood is a poor cabinet choice, and that it might be better for you to use a material like MDF, or as I did "back in the old days", high density particle board, of at least 3/4" thickness, and probably a bit thicker, for your actual enclosures. Then, you could "skin" them with planed down hardwoods of your choice, which would make them look lovely. But, if memory serves, most hardwoods are not stable enough, nor acoustically dead enough to actually build an enclosure from them. My JBL L300's look to have been made as I was doing it, back in the old days, with high density particle board enclosures, with walnut veneers on the outside, along with some edging of solid hardwood. I hope that makes sense, and if not, I'm sure an adult will be along soon, to fill in whatever I might have left out.

Your project sounds like a great one, and I'm sure you will have some fun getting it all together! Good luck, and God Bless!

Every Good Wish,
Doc (GO Permian Panthers!!!)

cgregory4
09-26-2014, 05:19 PM
HI, Greg,

Being from Texas, myself, originally, I completely understand about some folks being hard-headed, me included!!

I am thinking that hardwood is a poor cabinet choice, and that it might be better for you to use a material like MDF, or as I did "back in the old days", high density particle board, of at least 3/4" thickness, and probably a bit thicker, for your actual enclosures. Then, you could "skin" them with planed down hardwoods of your choice, which would make them look lovely. But, if memory serves, most hardwoods are not stable enough, nor acoustically dead enough to actually build an enclosure from them. My JBL L300's look to have been made as I was doing it, back in the old days, with high density particle board enclosures, with walnut veneers on the outside, along with some edging of solid hardwood. I hope that makes sense, and if not, I'm sure an adult will be along soon, to fill in whatever I might have left out.

Your project sounds like a great one, and I'm sure you will have some fun getting it all together! Good luck, and God Bless!

Every Good Wish,
Doc (GO Permian Panthers!!!)

Thank you for the response, Doc.

Yes, it's Friday night, and every place in Texas -- from the mega-schools in the Houston/Dallas areas to the hamlets like Balmorhea (6-man football there! :)) -- will have the lights on the fields with marching bands, cheering squads, and rival fans all going crazy! It's fall in Texas and Football is King! Your Permian Panthers aren't the state powerhouse they used to be, but that doesn't seem to matter much. The whole deal is more of a social phenomenon: the folks in Winters could not care any less if anyone,anywhere else on the planet is interested in their yearly game with Brownwood! They are just having fun! But you already know all this -- having experienced it first-hand!

Thank you for your thoughts on the MDF vs hardwood. The MDF density per cubic meter is about the same as the lower-to-middle hardwood range, while HDF approaches the high end of hardwood density. I assume -- maybe incorrectly -- that any material that equaled, or exceded, the MDF rigidity would be OK, provided the interior acoustic 'blanket' treatment was adequate. However, I've never had the pleasure of sticking my head through the 18" opening of an 'original' (or exact copy) to know just how extensive the acoustic treatment is.

I may be very mistaken, but I have the feeling from a lot of the posts on the various LH forums, that there are a lot of folks who would, and could, buy custom cabinets for our precious JBL cache of drivers, crossovers, etc......... If we could find someone to do it. I haven't been able to find a single soul who would build me a set of 4345 cabinets .... and I've tried. Plus I've seen woofer boxes with horns and 2405s lying on top: the chap is proud of his design -- acoustically -- but he cannot find anyone to make it 'furniture'!

Well, I am definitely going to have 2 custom 4345 cabinets built for me by my cousin. He has tons of hardwood aged 15 to 35 years. He has a complete custom woodworking operation where he has built everything from custom his/her caskets :) to 2000 pound solid pecan dining tables. I don't know any shape he can't saw, bend, plane, miter, or carve. Custom woodworking has been his passion for 35 years. And he has his handiwork in custom homes all over Central Texas to show for it.

When the cabinets are finished, I will 'fill them', delight in their sound :D, and then take photos to post here, on the LH site.

However, I consider myself fairly unselfish. And if others would offer some input, I would try to optimize my effort in light of any comments posted on this thread. Then others might benefit from my experience. C'est la vie.

In the end, the JBL/AL community might benefit from having a source for their custom speaker enclosures. I'm willing and committed to taking a first step toward that being a realistic option for others.

Thanks again, Doc, and God bless you, as well!

Greg

Doc Mark
09-27-2014, 08:16 AM
Morning, Greg,

Yes, indeed, when I went to Permian HS, they were on top of the heap of the large school Texas football teams. Gene Mayfield was the coach, and Permian seemed to win the Texas State Championship every single year!!! And, yes, you pegged it right on the money: No matter whether the town is someplace like Muleshoe, or Houston, everyone goes to the games, and the pep rallies, and all that other parties associated with football!! It really IS quite a thing to experience, and I'm glad I was a part of that, back in the 1960's!!

As for using hardwood to build a cabinet, it's been a very long time since I used to do much enclosure building, but I remember warnings about using such woods in that manner. If memory serves, hardwood cabinets have several major drawbacks. First, they are not acoustically inert enough to function as a speaker cabinet, without coloring the sound. Since you want a cabinet that adds nothing to the sound, or colors it in any way, hardwood seems to lose out on that front. Also, hardwoods can crack, over time, and develop "leaks" or whistles which mess up the alignment that you are trying to achieve in your cabinet design. Without digging out all my old books on speaker design, that's all I can recall at this time. But, back when I was doing it for a living (having fun, but not making very much $$!!), in addition to playing music professionally, the wisdom was, use acoustically inert materials, which would add nothing to the sound, and then cover them with a lovely hardwood veneer. If I were to make enclosures today, I'd still follow that path, and my enclosure material of choice would probably be multi-ply hardwood plywood, like baltic birch, etc.. The old boxes I built many years ago still sound and function as they were originally designed. Also, look at our precious JBL's of yesteryear: All of the ones I have (4408's, 2 pairs of L19's, 4312A, L300, and a pair of 4645 cabinets) were made using high density particle board, with hardwood laminates veneered to them on the outside.

Anyway, those are my experiences with cabinet building, and I am betting that your talented, wood-working cousin can do a bang-up job of using a more dense, acoustically inert material for your cabinets, and then cover them with either hardwood veneer, or thinly planed hardwoods, to make them lovely!! Heavy, yes, but lovely and wonderful just the same. Good luck, and thanks for the trip down memory lane, when it comes to Texas high school football! Take care, and God Bless!

Every Good Wish,
Doc

57BELAIRE
09-27-2014, 08:35 AM
I have to agree with Doc Mark about choice of wood for enclosures. In mfg. guitars, hardwoods are utilized exclusively for their sonic properties. Maple, walnut, ash and mahogany are all "tone woods" and each has it's own unique "sound"
which is desirable with instruments. In a speaker enclosure you want that cab to be totally inert. For instance, if you
had a beautiful solid maple enclosure, at certain frequencies, that maple could exhibit it's characteristic "tone" :eek:

If you look at my icon you'll notice this "59 Paragon's bottom is particle board. The rest of the enclosure is plywood.
I'm sure this wasn't just a cost saving idea from JBL engineers.

And yes, the entire interior surfaces , except the back of the baffle, are covered with fiberglass insulation. The 2202s
chamber is stuffed and sealed. Good luck with your project and I hope you show us some pictures of your progress.

cgregory4
09-27-2014, 10:05 PM
I have to agree with Doc Mark about choice of wood for enclosures. In mfg. guitars, hardwoods are utilized exclusively for their sonic properties. Maple, walnut, ash and mahogany are all "tone woods" and each has it's own unique "sound"
which is desirable with instruments. In a speaker enclosure you want that cab to be totally inert. For instance, if you
had a beautiful solid maple enclosure, at certain frequencies, that maple could exhibit it's characteristic "tone" :eek:

If you look at my icon you'll notice this "59 Paragon's bottom is particle board. The rest of the enclosure is plywood.
I'm sure this wasn't just a cost saving idea from JBL engineers.

And yes, the entire interior surfaces , except the back of the baffle, are covered with fiberglass insulation. The 2202s
chamber is stuffed and sealed. Good luck with your project and I hope you show us some pictures of your progress.

Doc and '57,

Your viewpoints make sense and seem well supported -- certainly the bottom of the '59 Paragon is an 'eye opener' to me. :blink:

Thank you so much for the 4355 (?) photos, '57. Every photo that I can discover, showing the original 'internals' (sans drivers) of any of the 43XX series, will be printed out in the highest possible resolution and delivered by me to my cousin.
'57: Your brace and support for the '41 driver: Is that original or your 'invention'? It's certainly clever -- additional bracing for the enclosure, while supporting the compression driver! :applaud:

Again, any additional photos and suggestions are sincerely appreciated!

Greg

PS -- '57: With as many driver choices as I have, your photos may have heightened my lunatic leanings! :eek: However, the 2311s are now revealed as an obvious gap in my inventory! :( :banghead:

57BELAIRE
09-28-2014, 05:02 AM
Hello Greg...here is another pic of the factory stock internal bracing and support for the 2440 in
the 4350. Everything else in the design seems pretty much standard oh, and then there are the
internal metal supports for suspending them from your ceiling :D as these sound dramatically better
from that position. All the best

cgregory4
09-28-2014, 05:48 AM
Hello Greg...here is another pic of the factory stock internal bracing and support for the 2440 in
the 4350. Everything else in the design seems pretty much standard oh, and then there are the
internal metal supports for suspending them from your ceiling :D as these sound dramatically better
from that position. All the best

LOL! Yes, I bought a pair of 4430s from the Dallas area and noticed the huge eye-bolts in the bottom! I have this mental picture of us hoisting them: The speakers stay where they are, as the block-and-tackle slowly 'reposition' our rafters to a lower elevation. :eek:

Thank you once again for the photos.

Greg

1audiohack
09-28-2014, 08:47 AM
It kills me when I see the ports broken out of 2350's like that. :banghead:

Barry.

Doc Mark
09-28-2014, 09:04 AM
Good Morning, Greg,

There is a ton of great information on cabinet design and internal bracing, right here at LH. Do some searches, and see what you might turn up. Also, the internet has myriad sites which list such info. Here is just one:

http://www.slideshare.net/guest806842/4345-cabinet-plans

Also, if you can find one of JBL's old Enclosure Design packets, you can see, pretty much, how JBL liked to do bracing, back in the day. Someone has copied the original kit plans, and is offering them here:

http://www.ebay.com/itm/JBL-SPEAKER-CABINET-ENCLOSURE-BLUEPRINTS-18-11-x-17-Pages-/261476236888?pt=Vintage_Electronics_R2&hash=item3ce132be58

And, as an example of what you can find right here at LH, check this out:

http://www.lansingheritage.org/html/jbl/plans/1970s-kit.htm

Hopefully, sources such as this will help you see what you are trying to learn about bracing, etc.. As an anecdotal story about the evils of using resonant materials for building speaker boxes, a musician I knew back in the day, built some lovely cabinets for his road band. They were a beautiful sight, and many of us envied him his talents in turning out such great enclosures. However, when we listened to them, they sounded horrible with some music, and just OK with other stuff. Turns out, he had skimped on the internal bracing, and as a result, you could smack your hand against a sides of these cabinets, and hear a loud "BOOM"!! Instead of being acoustically inert, his boxes were, in the truest sense of the words, "Boom Boxes", and colored music horribly!! In any case, I learned a great deal from his failure, and though he never made another cabinet, I made tons of them, all braced as they should be. Mine were never as pretty as his were, but mine sounded tons better! For what it's worth......

Take care, and God Bless!

Every Good Wish,
Doc

57BELAIRE
09-28-2014, 12:28 PM
It kills me when I see the ports broken out of 2350's like that. :banghead:

Barry.

Barry...if you're referring to the pic of the 4350...that port was removed with a gentle twist to gain access to the 2440
to remove it for inspection. The port was then put back in place. All is well ;)

1audiohack
09-28-2014, 07:06 PM
The 4350 pic was what cought my eye.

Should you you come up against that in the future and the port dosen't want to come out or you don't want to chance breaking it, the driver is smaller in height than it is in diameter and will come out with clearance.

I'm glad to hear that yours is not damaged.

Barry.