JBL-NOT!! - DIY 4351 Studio Monitor

More pics

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Originally Posted by Mr. Widget

:rotfl:

So true!

Are these using original 4350 dimensions so they are approximately 48" tall?
How far from the floor is the center of the 2202?

Widget

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The center of the 2202 is about 37" off the floor. Original 4350 is 47 5/8" wide by 33" tall sitting on a base about 2" tall. These cabs are 48" tall on top of a 2" base and are 33" wide (dimensions of the 4355 cabinet).

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Originally Posted by riessen

The center of the 2202 is about 37" off the floor.

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That should work well. If you have well matched drivers and have the network set up properly, I would expect your vertical alignment to sound quite good.

Widget

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Originally Posted by riessen

Found some pics of the cabinet under construction. Although the end result looks good, one of my primary goals with these monitors was to have a finished baffle, kinda like the Westies. Something that looked real nice when the grilles were off. I decided to have an oak baffle finished in blue stain and satin polyeurethane. That way all of the grain would be highlighted, instead of the traditional JBL blue paint.

I intended to veneer either baltic birch or particle board in oak veneer. Was about to do that when I found some 1" oak plywood. Plywood would not be my first choice but since it was 1" thick and I braced it to the hilt I suspect there will be no problem. Anyway, I went to all this effort and then had no end of problems getting an even stain coverage on the baffle. Spots and irregularities everywhere. I finally gave up and painted it blue. BIG dissappointment since the stained blue baffle was a major goal. Will try again when I build the second cabinet. If I pull it off I'll take on the nasty job of stripping the blue paint on the first baffle.

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Even though oak is a hardwood, treat it as a softwood when it's a plywood veneer. The thinness, the shaving process, and the bonding process all serve to open up and crush the grain in spots, and also to distort it microsopically. This can result in blotchiness and a sort of cloudiness in places when it is stained.

To minimize this, use a traditional softwood sealer, which will have two effects: 1) to prevent excessive stain penetration into the porous areas created by the veneering process described above, and 2) to lighten the overall cast of the stain, since all the pores will be less receptive. You offset #2 by using a slightly darker stain if need be.

You've got some big scrap that you can experiment on to perfect your system. Read the softwood sealer directions carefully to see how you can vary its effects. I have used this method successfully many, many times on hardwood plywood that otherwise would have looked unsatisfactory. :thmbsup:

Good luck.

BTW your design goal with the stained baffles is a great idea and will be very sharp if successful. It will exceed anything JBL could produce for mass distribution and lend an air of class that no one else will have. :yes:

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Originally Posted by Mr. Widget

That should work well. If you have well matched drivers and have the network set up properly, I would expect your vertical alignment to sound quite good.

Widget

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Wig: Right now I have four 2231A's with new cone kits in them, two 2202H's, two 2440's with new JBL diaphragms, a mint pair of 2405's and a pair of NOS 3107's. This was my surplus stash and if I ebayed it I wouldn't see it again. To my ears the 2235H is a superior woof to the 2231A so now I go on the hunt for a quad set to replace the 2231A's. Since the 2441 has a better high end than does the 2440 I want to make that change too. In the 4355, what is the x-over point between the 2441 and the 2405?? After talking with Giskard I'm convinced that the x-overs will be the climax of the project. Thanx - Rick

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Originally Posted by riessen

In the 4355, what is the x-over point between the 2441 and the 2405??

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The crossover is at 10KHz which is similar to the 4350, but it is not at all similar to the 4350... it is a 3rd order network and is a significant step up over the 3107.

Keep going you will have a system that is superior to those 4350Bs!

Widget

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Originally Posted by Titanium Dome

Even though oak is a hardwood, treat it as a softwood when it's a plywood veneer. The thinness, the shaving process, and the bonding process all serve to open up and crush the grain in spots, and also to distort it microsopically. This can result in blotchiness and a sort of cloudiness in places when it is stained.

To minimize this, use a traditional softwood sealer, which will have two effects: 1) to prevent excessive stain penetration into the porous areas created by the veneering process described above, and 2) to lighten the overall cast of the stain, since all the pores will be less receptive. You offset #2 by using a slightly darker stain if need be.

You've got some big scrap that you can experiment on to perfect your system. Read the softwood sealer directions carefully to see how you can vary its effects. I have used this method successfully many, many times on hardwood plywood that otherwise would have looked unsatisfactory. :thmbsup:

Good luck.

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Thanx for the advise. Will keep trying. I used a cutout from one of the woofer holes and thought I had it right. I have never used water based stains before so this was a pilot effort for me. I asked about using a sealer ahead of the stain and they told me it wasn't necessary on hardwoods, but I can see from my failed efforts that they may not have been right. I hope to whip this problem as I would really like to end up with a stained blue baffle. Until then I'll have only achieved half of my intended goal. Regards - Rick

I got nuthin' new to add here, I just want it known that I am leering at your project. Very, very impressive, man.

I am floored with the attention to authentic detail, engineering and transducer assemblage.

Really well done, Rick! :thmbsup:

Here's a couple more pics. The second cabinet shell is sitting together dry just to check fit-up and square. Have a little trimming to do and will then start putting in the rest of the braces and the mid-base box. The other pics show the mirror imaged baffles after I had them done.

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Originally Posted by boputnam

I got nuthin' new to add here,
:thmbsup:

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Affirmative Will Robinson,


Just send him a tape measure you Dang Yankee...:rotfl:

Riessen, may I suggest you try a pair of Widgets wood horns on those new boxes (if the cabs are deep enough). Trust me, you will never go back to that short stubby JBL horn again. The 375's/2441's will smoooooooth out and won't be anywhere near as harsh. I know cause my 4350's had the same stubby horn (I forget the model number)and when I switched out to the longer horn with serpintine lens (same horn lens on the hartsfield) it was an amazing improvement.

Ken

That's a slippery slope...

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Originally Posted by Ken Pachkowsky

Riessen, may I suggest you try a pair of Widgets wood horns on those new boxes (if the cabs are deep enough). Trust me, you will never go back to that short stubby JBL horn again. The 375's/2441's will smoooooooth out and won't be anywhere near as harsh. I know cause my 4350's had the same stubby horn (I forget the model number)and when I switched out to the longer horn with serpintine lens (same horn lens on the hartsfield) it was an amazing improvement.

Ken

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Hi Ken: I've given some thought to breaking from my old habits on horns. I've thought about the smaller wood horns like some of the Westies use and also about bigger serpentine lenses. I have no experience with either and need some education before deciding what to try. These cabs "are what they are" with little ability to make changes without butchering the baffle. Inside cabinet depth is 15 1/4". Normal 4350 depth is 15 7/16" but I gave up 1/4" when I went to a 1" baffle. When these are complete I need to give my 4341's an overhaul. After that I want to start a new project, something less traditional. I'm sure I'll stick with JBL for my main drivers as I have no interest in TAD, etc. I am interested in learning more about some of the horn/lens options that will improve the high end. Will also look at improving the x-overs. I appreciate your comments and any suggestions in the future. Thanx - Rick

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Originally Posted by Lancer

That's a slippery slope...

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After looking at the photo's again, your right. The baffle does not have enough room where the horn hole is cut.

Ken