sixstringer wrote:Has anyone tried this cabinet from Hermida Audio?
One forumite bought one and was quite unhappy with the cab due to ghost frequencies in the bass region. It turned out that the back panel is way too thin and vibrates at higher volumes cousing the bass trouble.
Guess it can be fixed with additional wood inside the cab.
I was worried about that too, the back panel on my cab is 1/2" birch ply, way thicker than I've used on other cabs. With plenty of screws to hold it tight. BTW, the new cab sounds a little dark with the EV Force installed.
A JBL D120 is going in this week.
The cabinet is 10" deep (same as the head cab) with an interior depth of 8", subtracting the depth of the 3/4" baffle and 1/2" back panel + the set back of the baffle to allow for the grille cloth and piping. The Ports are 1/4" walled ABS, recessed 3/8" into the baffle with 4" extending into the cabinet.
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sixstringer-
After trying all the speakers I listed in the previous post, I have settled
on one of my red frame JBL D 120Fs in the tl806.
It sounds tremendous!
The D120 is my favorite speaker anyway, so no surprise there, but the tl806 brings out its best. Very full sounding. Real low end thump.
I find one of the best things is the amp bass control can be run quite low,
so you're not using all the amp watts to push low end out. You've increased the efficiency of the speaker's low end reproduction. Now the amp watts are available in the other tone bands-mid and high.
Will use it on a gig this week and report more.
It's a thumbs up project so far.
George
I think we have opposing sciences in the acoustics of speaker cabinets for guitars.
On one hand you have the old combo cabinets made from pine that resonate, hopefully in a good way with the guitar.
Or the open back speaker cabinets like the 212's.
Then you have the sealed and or ported cabs where I would think you don't want excess resonances because the boxes are tuned to the speakers specifications.
In between those you have the cabs with the oval ports in back in sort of a semi-closed back design.
So in a ported cab perhaps the thickness of the back is not as critical as say in a sealed cab such as a Marshall 412.
Because in a ported cab you are allowing pressure to leak out of the tuned ports.
However in a sealed cab such as the Marshall it would seem that you would want that cab rock solid with little flex or resonance as possible to direct the sound forward.
Tom I see your train of thought, and I agree with your reasoning.
The tl806 and other Thiele designs from EV are specced for 3/4 inch
plywood. I used that and it is solid.
Quite a chunk of building material.
The designer clearly did not want resonance from the cabinet itself.
George
Hmmm.. What I don't see on the ! x 12 cabs in this thread are the 1" vertical cleats (spelling) that attach to the back panel of the ported box. Many years ago (over 10 years) I had a photo of an opened dumble ported box ( same as Guitarman18 post) which clearly showed 1"x 1" timber cleats spaced 1" apart ( glued and nailed?) across the back panel. I build a cab for a friend and it sounds great. Plenty of depth for a 7 string. I guess it's the increased surface area that makes the difference, I don't really know I just blindly follow.
Anyone have a photo of that back panel? Has anyone A/B'ed the plain and ribbed backs? The Thiele TL806 building instructions allow for a wide margin in interior volume. Perhaps the ribbed back offers some acoustic variation beyond adding increased surface area. Adding the ribs would reduce the possibility of vibration from the back panel so perhaps lighter construction materials could be used without sacrifice. In fact, why only rib the back, why not rib all the surfaces on the interior? Just a thought.
