JE Labs Open Baffles for 12 inchers

[markus]

started (and practically finished) construction on a pair of JE Labs Spec'ed OB's that will fit most 12 inch drivers. I'll eventually make a spacer ring so anything smaller than a 12 inch woofer can be mounted. Check out the link :

http://members.myactv.net/~je2a3/open.htm

Anyone who has toyed with the idea of making a pair of these should GO FOR IT - they are a piece of cake :yes: I splurged on a GOOD sheet of 3/4 inch birch plywood - HOME DEPOT SUCKS ! - all their plywood was warped and smashed. I hit a local lumber place - Howe Lumber - if you buy from a mom & pop shop, you'll probably find a better piece of wood. I paid about $5 more for the sheet, but it is VERY nice . . . .

Tools:

Circular Saw
Jigsaw
Pencil
Tape Measure
Straight Edge
a pair (or more) of 'Quick Clamps' or equivalent
Wood Glue
Coarse Thread Drywall Screws

I'm countersinking my drivers about a 1/4 inch so they're flush, so it is taking a little longer than normal . . . check out the pictures for progress thus far. If I had a circle jig for my router, it would look MUCH better, but too bad for me :tears: I didn't even have a comapss to use to draw my circle, so I found a shelf bracket with the holes of the perfect length to use :thmbsp:

The following 12 inchers will be tested in these - both have a curvelinear cone (cross-section) which should help in the high frequency extension. I'll try 'em first without a tweeter, and then with just for shits and giggles.

RCA c. 1957 12 incher's found in many of their 'Orthophonic' line of consoles
these have been going for about $100 / pair on 'the bay', but if you snag a whoile console, you're sure to find them cheaper (like FREE )

Magnavox manufactured/ RCA labeled 12 inchers c. 1956. these have a vented dustcap, which should also help HF extension.

I've got oodles of other 12's, and smaller drivers to use, but these are the two sets I've been itching to try OB.

I'll update the thread probably tomorrow with more progress - glueing and screwing

I know this is *kinda* DIY, but that forum always strikes me as more amplifier and cabling in nature . .

 

[mhardy6647]

Should I bring a pair of EV LS-12's on the 23rd? And/or a (mismatched) pair of SP12B's? Or one slightly tired SP12 that I keep forgetting that someone wanted.

 

[markus]

that'd be coooooooooool : )

one of the links off the JE Labs site has a guy using EV 12trxb's and they're supposed to sound really good. aren't the SP12B's pretty much the same without the tweeter ?

The LS-12's are yet another 12 I've wanted to hear OB

 

[mhardy6647]

oh, I have a mismatched pair of 12TRXB's too, I think. I also have a pair of LT-12 coaxes, but they're ensconced in enclosures and a little too hard to remove (and a little too big/heavy to schlepp).

 

[markus]

wow - the home for lost electrovoice like I'm the home for lost KLH !

I think we'll have to devote a couple hours to 'JE Lab OB listening' :yes:

 

[mhardy6647]

You need some 8" OB's! That's where the fun is...


I have some, but they're tedious to move. If I can wrangle the Battle Van from my son that day, I might be able to schlepp them over.

 

[markus]

I do have some Motorola / Jensen 'Golden Voice' 8's I want to try . . . the cones are SUPER thin ( sun damage me thinks ) so I'm going to give them a coat of dammar to stiffen them up . . . . should be cool too, since I have yet to tyry dammar on any speakers

I've officially completed the OB's ! the cool thing is the little plywood nub on the top edge is PERFECT for a tweeter (if needed). I'll probably try my Jensen Rp103's, Radio Shack Lineaum Dipoles, EV T35's, among others . . .

I'm considering using some 3/4 inch birch veneer tape to finish the visible edges, and a couple coats of shellac to seal the wood (after some steel wool rubdown).

check out the pix

 

[SixCats!]

Hey hey Markus!

Veeery cool indeed! I can't wait to hear them!

Regards,
SixCats!

 

[Urizen]

 

[mhardy6647]

what!?

 

[Zilch]

what!?

"What" what?

The open baffle itself, the array of drivers under test, the cone painting, the efficacy of the nub, the potential tweeter in exile, or what to bring?

 

[mhardy6647]

just puzzled by the invocation of the feared 'popcorn' graphic...

 

[Urizen]

just puzzled by the invocation of the feared 'popcorn' graphic...

Feared?

I thought it meant lurking.

I'm interested in the thread. Someone pass the butter.

 

[brainsmasher]

I have had these open baffle mounted norelcos for some time and while they sound good my preference is for another speaker ( I am very biased ). The horns dont work on either baffle so if I ever get around to fixing/ replacing them my opinion could well change. Ugly as hell, yes but still not ugly enough to part them out.

 

[JimJ[VT]]

Some good photos and reading, I've been thinking about doing something like this...

 

[Dan ʕ•ᴥ•ʔ]

Feared? I thought it meant lurking. I'm interested in the thread. Someone pass the butter.

It used to mean lurking. Nowadays it's being used to represent bystanders watching an argument. :thumbsdn: So, I don't use it anymore.

 

[markus]

I have had these open baffle mounted norelcos for some time and while they sound good my preference is for another speaker ( I am very biased ). The horns dont work on either baffle so if I ever get around to fixing/ replacing them my opinion could well change. Ugly as hell, yes but still not ugly enough to part them out.

I'm surprised the Norelcos need a tweeter at all - arent those supposed to go pretty high on their own ? :scratch2:



Once my daughter went to bed last night, I was able to rreeeaaallllyy listen to these. Listened to some Miles Davis, Dave BRubeck, ozzy, Jimmy Smith, Paul Simon, The Who, and a little Bach just to round out the experience :thmbsp:

ME LIKES :huge:

bumped the bass up a couple clicks for the Ozzy and I could feel it in my chair! the RCA's are a little beamy, but once seated they really sound nice. I'm going to swap in the Magnavox 12's with the vented dustcap to see how they measure up.

I also have a pair of Heppner 12's from some Bell & Howell projector speakers that I'll try. the intersting thing about the Heppners is I did a little mad scientist surgery - cut off the dustcaps, and added a styrafoam ball phase plug thingy. Some Lowthers benefit (or so I've heard) from this, so I figure I'd mess around with it. I epoxied a wood shaft onto the pole piece so I can theoretically swap on different phase plugs.

 

[markus]

it's happened again . . .

I've reached another layer of detail / resolution with my 'audio chain'

I had a little AK Day on Saturday:

http://www.audiokarma.org/forums/showthread.php?p=1218089#post1218089

and the ever-kind mhardy lent me his 1st generation Bottlehead Paramours to play with for a while. I hooked them up to the RCA 12 inch FR / JE Labs OB's last night and all I can say is WOW :huge:

amazing detail - all the little nuances of the music were coming through - string plucks, fingers dragging on the fret board, percussion was unreal . . I could go on !

The funniest part is, I was using my laptop's CD drive for a source - hardly ideal. imagine the level of purity I can reach with a REAL (good) CD player!

These JE Labs OB's are no joke. This has pretty much convinced me to do a flea powered 2a3 / 45 power amp . . .

 

[mhardy6647]

Build a version of Gary Kaufman's 45/46/300B "convertible" (essentially Gordon Rankin's "Bugle" 45). Go for a more normal P/S, though, unless you like power supply design and troubleshooting as a hobby
http://www.the-planet.org/Ragtop.html
I am supposed to... some day.

 

[markus]

yup - that is one I was looking at . . the other is the JE Labs 45 / 2A3 . . .

yet another, which I can't find used (if you can believe it) EL84 (PUSH/PULL :yes OPT's - I wish I could find that page, since it's right up my alley - i.e. unconventional & I have almost all parts on hand . . .