A happy ending in the back of a cab...tone porn content

[212Mavguy]

Have enjoyed the sounds gotten of this particular cab design, it is not super heavy duty, for size it is light in weight  The ply is half inch, and the tolex is half the thickness of what I'm used to seeing, the corner protectors are made of thin metal, careful handliing has kept them working perfectly for years.  Here's what they are, and where to get them.  I look for the lowest price one of a given model, the discounted ones arrive with sloppy hole cutouts and incomplete speaker fastening hardware.  A bit of time with hand tools was always worth the discount, and personally selecting and installing the kind of hardware you want to mount the speakers delivers a personal advantage.  One of the auction pics displays the back baffle clearly, it is helpful to glance at it before reading on...

http://www.ebay.com/itm/Seismic-Audio-212-GUITAR-SPEAKER-CABINET-EMPTY-12-Cab-2x12-Tolex-/382219815054?epid=1400466129&hash=item58fe13888e:g:8twAAOSw4kVZrvXI

I had a mixed pair of Lansing designed ceramic and alnico speakers in one identical to this cab, the alnico 417C  has a metal dust dome that imparted a slightly excessive crackle to the edge of the distorted tones where something smoother and glassier would sound more appropriate.  Both of the speakers together had strong, but not overwhelming bass response out of this cab.  The ceramic was a JBL MI-12.  I had a couple of his big brothers...JBL G125-8's.  I knew from using them with other amps how they would basically sound, but mainly had run them in 1/12 applications.  When I put them in and ran them they were fantastic except that they became unusually and excessively bassy in this cabinet.  This speaker is a secret weapon, out of production but can be had, often for nearly double this example went for.  They sound great clean and particularly nice dirty, have a great feel to play through,  and are very, very durable with their power handling.

http://www.ebay.com/itm/JBL-G125B-8-12-034-speaker-8-ohms-works-superb-with-no-issues-/263226675518?hash=item3d4988513e%3Ag%3A1iEAAOSwvGZZx73l&nma=true&si=%2BsjGVfvm1z9Ns2My1EH4Q6i1i4U%3D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

I started playing through the cab after unscrewing the back, with it set on end for a vertical speaker arrangement, and experimented with moving the back to one side a bit at a tine to see how increasing the size of the back baffle opening effected tone, well, it did, and the effect was huge.  The more open, the less overwhelming the bass was.

I have a total of four of these cabs, so decided that none of them were sacred, at all, so I got out the 18 volt circular saw, adjusted the blade depth and went hacking.  The first cuts were to divide the back into equal halves, but the cuts were made more towards the kitty-corner direction rather than straight down the midldle.  That way one end had more opening than the other, and that bigger opening would be toward the bottom side when conventionally placed, or when positioned on end the more open end of the back baffle could be placed top or bottom depending on what the player wants to hear.  Each cut area had a narrow second pass to leave a narrow gap between the segments, no rattle against each other during loud playing.  in addition, the cut placements allowed fasteners from the cab's bottom and sides to hold each segment in place with significant rigidity.  The half that did not have the jack was cut again into two, one part roughly twice the size of the other by design.  With the smallest chunk of rear baffle removed, the opening doubled in area.  The next chunk when removed left the jack's half remaining, resulting in about two thirds of the cab back open, and for those speakers it turned out to be just about perfect.  

But what is perfect for an indoor venue with a wall a couple inches to a foot or so behind an amp will result in a thin and nasty tone set when the same setup is used for an outdoor gig with no wall or anything else for a "sonic backstop" is present...That is where the missing chunks get put back in, the cab can be quickly tuned on the fly with one or both missing chunks replaced, the screws are left torqued down some distance into the holes so won't get lost, a driver drill gets the job done in less than two minutes tops, hand tools... five.   If I did not use these speakers I would not have had enough bass on hand to be able to get away with modding the cab to its present versatility.   They are part of a small, heavily researched secret tone weapon JBL speaker family few know about, G125 in 12, G135 in 15 inch, long out of production because the herd did not want to pay what they cost $$-wise new at the time.  The build quality is insane in a good way.  Either of them can handle a hundred watt tube amp dimed all day and laugh, yet can be driven with less than one watt to surprisingly loud and great sounding volumes.  The amp tone knobs don't need to be touched going from soft to loud, either.  

This cab is driven by my '74 Hiwatt DR112 PA head as first choice, that amp is reminiscent of a huge cathedral's  pipe organ through it,  but that same cab surprisingly does Fender, Marshall, and Dumble circuit tones, what ever is playing through it, all exceptionally well, each tone set comes through with a fullness and clarity like nothing I've ever played through before.  This speaker, this cab, and this simple back baffle mod came out with an unusually cost effective and incredibly useful (for me at least) result!  

The cab itself is very light weight for the dimensions, but at over 13 pounds each, these speakers are not.  The amp heads it is primarily intended for tend to be heavy also.  It's a lot more compact and lighter than any 4/12, though, with the capability to dial in the kind of huge, full, bottom to top tones and rodent killing volumes reminiscent  of the bigger, heavier cab type.