I recently picked up a nice K130 for my Vibroverb, but, turns out, the mounting screws in the amp are nearly 1/4 inch too short (the original CTS speaker is a thin, stamped frame, versus the heavy cast frame of the JBL). I certainly don't want to drill any new holes or drive in additional screws as this is a vintage amp. Anyone have any suggestions? Thanks, Steveokla
Steve,Originally Posted by steveokla
Make an adaptive mounting ring/plate to attach to the stock baffle screw studs, attach the K130 to the ring.
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
Is it possible (with the speaker removed) to reach your hand between the baffle board and the grill cloth, then tap the orig screws forward from inside the cab?
There are two theories to arguing with women, but...neither has worked.
That was gonna be my other suggestion. Try to put in longer screws through the original holes
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
There's a way to do this. I saw a kit on eBay about 9 months ago sepecifically for the purpose. Anybody remember how it worked?
Alternatively, I'd be trying to remove and replace the original studs....
You're going to have a hard time pulling the screws out the front of the baffle. The screws have large flat heads that pull up flush with the front of the baffle and are long enough to give you problems with pulling them out the front due to the tight grille cloth.
You may want to look for T nuts, sized to thread on to the existing Fender baffle-mounted screws, that can push through the holes in the JBL frame and catch the screws. Look for long necked T nuts and preferably the ones with the two flat sides without the bent-over prongs. You could, of course, bend the prongs back on standard ones. The question is if these T nuts will fit in the JBL holes and reach the ends of the screws.
I agree that you should try to avoid "modifying" the amp if possible.
Hope this helps.
Tom
Thanks, all. I've spent a good part of the day in hardware stores, then specialy supply places looking for T-nuts and similar hardware, as well as connectors to 'lengthen' the machine screws. Struck out.
Zilch--do you recall if the kit was a JBL product of somd kind?
Edge--could you elaborate a little on the additional ring--what material, etc.?? Thanks agains, Steveokla
Not JBL, it was offered by one of the guitar amp restoration/customization type folks.
I kinda recall it was a custom nut with a threaded female shaft, like sex bolts. Go here and put "sex bolts" in the search window:
http://www.mcmaster.com/
Depending upon the stud size, you may have to enlarge the woofer frame holes for the standard ones to fit.
See also "weld nuts," the type like T-nuts without the prongs....
Steve,
Here's a really, really crude sketch to show you my idea. If there's room enough in the Vibrolux enclosure, you could mount the ring to the original studs and secure it with the original nuts countersunk. You would mount new machine screws or studs to the ring exactly like the on the amp baffle board....only you'd place the new studs between the counter sink holes, and only use four studs to mount the K130.
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
Thanks much, Edge!
Oh man, I just re-read this and it sounds like I'm suggesting to pound the screws deeper into the baffle board. Well, that's about the last thing I would have in mind, my intent was to gently remove the orig screws and, if possible, replace them with longer ones.
But...I just grabbed one of my Super Reverbs, pushed on the grill, and it only had about ½" flex before hitting the baffle, so Tom looks to be right about anything coming out the front....
There are two theories to arguing with women, but...neither has worked.
Bad news. Given crowding in the amp, it will not accomodate the 3/4 inch stock for a false baffle board.
I've done a lot of searching under 'barrell nut', T-nuts. 'connectors', etc. I've found some, but none small enough--the studs/machine screws in the amp are 8-32.
I did check for play between the baffle board and grill as suggested but, alas, as someone pointed out, it's only about a half inch. Might be stretched another 1/4 inch safely, but I figure these machine screws have to be 1 1/2 or two inches--that's likely pushing it too far for safety.
Please let me hear any other suggestions or other specialty hardware. Thanks, Steve
Surprisingly, the holes in the driver are spec'd at 9/32" (0.281"). I didn't believe it myself, until I just checked. A 1/4" bolt goes through. You may want to confirm that on yours. I assumed they were sized for the #10-32 screws typically used to mount them, but, no, apparently.
Like you, I don't find headed binding barrels as small as #8-32.
However, standard 1/4" OD Female Threaded Round Standoffs are available in #8-32 in lengths from 1/4" to 2". Spin a stainless steel one of the appropriate length on each stud, then secure the driver with #8-32 screws.
They're fully threaded through in lengths up to 1". I'd use button-head hex cap screws, probably, plus washers, if required, to mount the K130.
Also available at the link I provided above in brass and aluminum....
Will that work?
Zilch--I think that will work--can you tell me where I might find the 'standoffs'? Thanks so much, Steve
My fault--in my excitement, I didn't see your reference to the site--I've found them there and will order up a couple different lengths and give it a try. Much appreciated! I'll let you know how it goes. Regards, Steve
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