I want to attach a plinth to my Seas Thor speakers in original Madisound-supplied cabinets. See pic. My plan is to use 3/4" mahogany lumber extending slightly past the edges of the Thors. See pic of JMLab speakers for the general idea. Figured I'd attach with six, or even eight, screws into the veneered MDF. Do builders feel I need to use threaded inserts (EZ-Lok style) or could I just screw straight into the MDF? Seems to me that would likely be secure enough; but would love to hear from those more experienced. Thanks.
That is what we did, some scres into the base. Our bases were MDF, the cabinets birch plywood thou.
Have you seen this thread: https://www.diyaudio.com/community/threads/clarity-on-seas-thor-kit.64799/
Your drivers could benefit from a better box. The stock Thor turns out to be bass shy (Joe made a number of mistakes).
dave
Have you seen this thread: https://www.diyaudio.com/community/threads/clarity-on-seas-thor-kit.64799/
Your drivers could benefit from a better box. The stock Thor turns out to be bass shy (Joe made a number of mistakes).
dave
Thanks, Dave. Good to know; although agree that plywood is a different case. Yes, I have seen that thread, and been through most of it. Very interesting. Moving to a different box probably not in the cards for me at this point in life; for better or worse. The bass is OK for 98% of what I listen to; although in my room (which is far from perfect) I have an upwards bump at 50 Hz; about 5 dB louder than 60 Hz. My guess is that's the room, but who knows.
I'd use 3 per side, (9 total) but I'm hard on gear when moving it around..
I was fortunate to have been able to access that area in the cabinet when I was building cabinets. In that case I used T-nuts. It worked perfectly. But now, in your case, I would make sure and drill a pilot hole just the right size for the threads to set tightly but of course, not over tight. If you can find a beefy threaded insert that might work too, but MDF isn't known for holding strength of threads (especially the shorter length threads on an insert), so the longer screw threads would be advisable.
And it sounds like you were thinking, straight into the MDF, correct? I was thinking of going in about an inch, which may line up with what Ixnay says. Weltersys, the footprint is 9"x14.25". So if I use 8 screws, starting 1" from a corner, I get 6" intervals with 3 screws on the long sides, and 3.5" intervals with one centered at front and one centered at rear. I could go to 10 screws, with 4" intervals on the sides. That might be overkill?
+1
While you're at it, you would perhaps also like to interpose a layer of vinyl glue or - maybe better - a sheet of butyl.
https://www.globalselfadhesiveproducts.com/product/sound-deadening-butyl-sheets/
Excellent. Thanks, Weltersys as well as Ixnay and ulogon. I should clarify that the bottoms of these speakers are fully open; just the four walls coming to a stop. Weltersys and ulogon, still trying to understand "three screws per side, nine total." Do you mean what I show in attached sketch? As in, three across top, with three on each side below those?
Thank you, very interesting. If a sheet of butyl, is that mostly to eliminate potential vibration between box and plinth, or for sound deadening within the box? If the former, I could maybe use butyl tape; which could be more straightforward to apply? I was hoping to apply the finish to these plinths before attaching them. Is the stuff at link below what you have in mind for "vinyl glue"?
https://www.acehardware.com/departm...-glues-and-adhesives/glues-and-epoxy/1563279?
It would be handy if they were, because then I could re-use the boxes they came in. Certainly has bearing on the idea of using butyl or glue. Thanks.
Yes, and making the coupling more "deaf".
Sure.
https://www.amazon.com/Sealant-Camper-Repair-Trailer-4In-50FT/dp/B09WZWP2MQ
Yes, PVA (Polyvinyl acetate)
https://www.pattex-adhesives.com.au/en/strong-ideas/pva-glue-for-the-carpenter-in-you.html#B1
To be honest I didn't know the "homopolymer" form described in the link you provided.
Personally, if in doubt I would use the ancient formula which is more than sufficient and can certainly be diluted (and removed before it dries) in water and once dried it is more resistant than the wood itself.
Of course the above is valid only if you want to make a permanent and non-removable assembly, otherwise the butyl stuff seems perfect to me.
OK, great, thanks. Understood. This is pretty much my 8 screws plus one in the middle (which I can't do because the speaker doesn't have a bottom).
Ulogon: Yes, and making the coupling more "deaf".
Ulogon: Sure.
Ulogon: https://www.amazon.com/Sealant-Camper-Repair-Trailer-4In-50FT/dp/B09WZWP2MQ
Thank you. Butyl tape seems excellent for this. What do you think is a good thickness? The Camper-Repair-Trailer stuff from Amazon that you link to is supposedly just 1mm, where the sheets from Globalselfadhesiveproducts are 2mm.Most of the other tape I'm seeing is 1/8" thick, i.e. about 3.25mm. There is some 1/16" stuff, not easy to find at the retail level. I'm sure the tape will flatten out considerably once plinth bolts get tightened...
Had I understood your cabinet was built with no bottom, I would have suggested you simply follow the Thor cabinet design for attaching the base..
Many thanks. The cabinet as supplied in Madisound's kit does not (did not) exactly conform to those drawings. Which has some bearing on the question. Will post more once I put some files together.
@Ecaroh Please note that since English is not my first language, sometimes it happens that I'm not perfectly able to visualize what is being described and may be this also happened with regards to the description of the bottom of your loudspeakers since probably from what you said recently some doubts arose in my mind...
However the thickness should be proportionally related with the presumable difference in the flatness of the two pieces of wood that are to be coupled.
The thickness, however, should not be excessive since the butyl (which also has the characteristic of a "filler") in this case should act more as a "gasket" than as a filler (if you know what I mean) and I believe that 1 mm should be sufficient if the two pieces are flat enough (as I guess and hope).
Please note that about the link I provided from Amazon it only had the function of illustrating the generic product, not of establishing an optimal thickness.
However the thickness should be proportionally related with the presumable difference in the flatness of the two pieces of wood that are to be coupled.
The thickness, however, should not be excessive since the butyl (which also has the characteristic of a "filler") in this case should act more as a "gasket" than as a filler (if you know what I mean) and I believe that 1 mm should be sufficient if the two pieces are flat enough (as I guess and hope).