Building new cabinets for RTA 12B's
Michael8it
Posts: 192
If I wanted to go crazy with a winter project that is fun and useful, I am thinking about building new cabinets for by RTA 12B's? Why is a loonngg story, suffice to say I am interested in doing it.
The original sales literature touts that the cabinets are constructed with a "laminate shear damping technique". Ok, in English, is the just 80's MDF these are made out of, and if I did go ahead and build my own new cabinets, could I use MDF or would some other material be better for them.
Ok, so why am I doing this? The speakers I have are RTA12's. I picked up 12B crossovers from a member here, and lucked across 12" radiators in absolutely mint condition for cheap as well as 6600x drivers for $20 each. My speakers have the US made Peerless tweeters (which I am quite fond of). If I pick up a pair of tweeters, the only thing left..... is a cabinet. And since I have contemplated refinishing these in rosewood or some other nice wood ( I just hate laminate), why not just build cabs from the ground up?
Back to the question at hand - can I use MDF and build the cabs the same specs as the originals or is there really something to this laminate shear damping technique??
The original sales literature touts that the cabinets are constructed with a "laminate shear damping technique". Ok, in English, is the just 80's MDF these are made out of, and if I did go ahead and build my own new cabinets, could I use MDF or would some other material be better for them.
Ok, so why am I doing this? The speakers I have are RTA12's. I picked up 12B crossovers from a member here, and lucked across 12" radiators in absolutely mint condition for cheap as well as 6600x drivers for $20 each. My speakers have the US made Peerless tweeters (which I am quite fond of). If I pick up a pair of tweeters, the only thing left..... is a cabinet. And since I have contemplated refinishing these in rosewood or some other nice wood ( I just hate laminate), why not just build cabs from the ground up?
Back to the question at hand - can I use MDF and build the cabs the same specs as the originals or is there really something to this laminate shear damping technique??
Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
Post edited by Michael8it on
Comments
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Well after thorough examination with my keen professional eye, I see that the cabinet is made of 3/4 MDF, nothing fancy. There is an added panel glued to each side of the interior of the cabinet, with braces on the top and bottom in the center.
2 4 x 8 sheets of MDF: $62.00
1 4 x 8 sheet of cherry veneer from a local supplier: $62.00
Finish and shop supplies: $25
Speaker Grill Material: $25.00
Total Finished project cost: $175.
Hmm.......Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd). -
What you might want to do is to mount the mids in a vertical axis... That should give a better sound image, theoretically...
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What you might want to do is to mount the mids in a vertical axis... That should give a better sound image, theoretically...
The (2) mid-woofers in the RTA-12 don't play the same signal; that's why the speakers are labeled "right" and "left".
If you want them to sound like RTA-12's, leave them factory spec. If you don't want them to sound like RTA-12's, then why even use that cabinet design, or those drivers, or those tweeters, or those crossovers etc.
My point is, if you want to "tweak" the design, you might as well start from scratch and pick every component to your liking. On the other hand, if you think Matt Polk had something good going on when he designed the RTA-12, and you want to recreate it, then leave it factory spec. It sounds like that's what you're trying to do, and I think they can turn out great, even without the "laminate shear damping technique" lol.
Cheers, and good luck on your project.
Ben
EDIT: make sure to keep us updated with lots of good pics! :razz: I want to see that Rosewood...
EDIT 2: Lots of good real-wood veneers are actually laminates. What you hate is vinyl laminate. (where's the damn winking smily???)2-Channel: PC > Schiit Eitr > Audio Research DAC-8 > Audio Research LS-26 > Pass Labs X-250.5 > Magnepan 3.7's
Living Room: PC > Marantz AV-7703 > Emotiva XPA-5 > Sonus Faber Liuto Towers, Sonus Faber Liuto Center, Sonus Faber Liuto Bookshelves > Dual SVS PC12-Pluses
Office: Phone/Tablet > AudioEngine B1 > McIntosh D100 > Bryston 4B-ST > Polk Audio LSiM-703's -
Ben - EXACTLY - I hate vinyl laminate....
And yes, I am simply trying to recreate the original. We'll see if I proceed or if other things in life are more pressing.Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd). -
To restate my insane logic: After buying these I realized there were significant differences between the 12's and 12B's. I was able to get all the 12B components to convert these to 12B's in the cabinets of 12's. So my next thought was: Why leave a bunch of vintage components in a box in the basement.... build new cabinets, put all the 12B components in the new cabinets, reassemble the original 12's and sell them so someone else can enjoy them. IFI can get $150 - $175 for them, I break even, have fun building some cabinets, and someone else gets a nice set of vintage speakers......Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
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Michael8it wrote: »To restate my insane logic: After buying these I realized there were significant differences between the 12's and 12B's. I was able to get all the 12B components to convert these to 12B's in the cabinets of 12's. So my next thought was: Why leave a bunch of vintage components in a box in the basement.... build new cabinets, put all the 12B components in the new cabinets, reassemble the original 12's and sell them so someone else can enjoy them. IFI can get $150 - $175 for them, I break even, have fun building some cabinets, and someone else gets a nice set of vintage speakers......
Gotcha. I didn't realize that you had enough components for (2) full sets of speakers. And, yes, it sounds like a great idea to me. DO IT!!!2-Channel: PC > Schiit Eitr > Audio Research DAC-8 > Audio Research LS-26 > Pass Labs X-250.5 > Magnepan 3.7's
Living Room: PC > Marantz AV-7703 > Emotiva XPA-5 > Sonus Faber Liuto Towers, Sonus Faber Liuto Center, Sonus Faber Liuto Bookshelves > Dual SVS PC12-Pluses
Office: Phone/Tablet > AudioEngine B1 > McIntosh D100 > Bryston 4B-ST > Polk Audio LSiM-703's -
RTA 12's are real time aligned so I'm not sure how you mimic that without some semi-sophisticated measuring equipment, software and a little know how. If you don't know what time alignment is, then I suggest you rethink this project, unless you don't care and are just messing around. I have no idea of your speaker building, testing, trouble shooting skills or the test equipment and software you use.
Time alignment comes from the x-over but also how the drivers are mounted in/on the baffle, etc.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
H9 - I would be making copies of 12B cabinets to the same specs - I don't think I would change anything, except wrapping them in some nice wood......Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
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Michael8it wrote: »H9 - I would be making copies of 12B cabinets to the same specs - I don't think I would change anything, except wrapping them in some nice wood......
New cabinets without changing the driver alignment, xovers, etc. sounds like a good idea. The 12B/12C's are special and create an amazing stereo image when set up properly. As falconry said, the speakers do have a dedicated left and right cabinet.
When set up accordingly they produce a stunning, wide & spacious image. MP accomplished this in part by having the two MW's play different parts of the audio spectrum.
But if you accidentally reverse the speaker cabinets and put the left one on the right, etc., the image sounds like crap! Ask me how I know. . . :redface:
Do you plan to upgrade the Xovers?"Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer -
I already got a set of 12B xovers. At some point I will recap them, that is assuming I am not satisfied with the sound as is. If I like them as is, Ill leave them alone.Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
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Well discovery number (I lost count)... Had a friend over who works in a shop building countertops, among other things. The cabinets are not MDF, they are 3/4 particle board. I wonder how building these out of MDF would affect them sonically.... I know the purpose for the bracing was to stop vibrations, and MDF is a higher density material than Particle board. But that also means I would need to mount the drivers with t-nuts. My friend was very clear that MDF would not hold a screw (the particles are too fine) so Ill have to consider that. It is also $10 per sheet more than Particle Board. The saga continues.....Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
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On another note, hats would be too hard to make for these. I am thinking of a wood cover for the crossover, with a mounting plate for the tweeter, and then a grill to cover the tweeter. The wood housing would need anti-vibration inside it (I think) and I would angle the sides back away from the tweeter to keep the open sound of the tweeter.Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
