Thanks for the suggestions! I removed the screws today. Everything looks OK. Also cut more sides of the rest of the sheet. I`ll do some experimentation with screws and white glue on one of the next side layers first, as it was quick to do. It seems that it will not be that hard to make it fit nicely on to the first layer. I think I should predrill to avoid pulling up small dents around the screws between the layers.
Yes, good idea. Could use a screw to cut a thread into the wood, then apply a chisel or a razor blade to slice away any burrs raised up around the screwholes. These little details of technique all seem to add up to make a successful build.
ToS
Not very, unless you add wide vertical baffles to extend the floor's mirror image to compensate for the height offset. FWIW, 'boxing' them into the corners with removable baffles to create a false wall corner of sorts and toss in some big rolls of wall/whatever insulation to damp any hollow sounds like I did with a previous horn system really pumps up the low end through the mids. FWIW, I used industrial grade Velcro to attach them, worked great for both tghe big 70 Hz horns/dual 15" bass bins and an earlier room where we 'boxed in' modded Altec A7-500 VOTTs all the way to the ceiling, which really transformed its low end output.
True and why I did a ~70 Hz flare frequency to get it down to 100 Hz; IOW tune ~ a 1/2 octave below desired low gain corner frequency.
GM
Your sim goes a bit lower in frequency, but the horn is also a bit longer. What are you looking for when choosing the different cone lengths? Since I already have the thin ply, I`ll do a first attempt building up the curved sides with 5-6 layers. The ply is 4mm thick.
Read an interesting article here, see part #2 of 9 , where damping around the mouth is discussed. Seems like good advice
See my previous response.
Wasn't aware of this one, thanks! I learned about this while still a kid when exposed to some Acoustic Research AR-1 speakers that the owner had added a thick felt baffle cover and after a 'before/after' test convinced me that if it could make so much difference with these big cone drivers it had to work really well on horns since what's a horn, but a complexly folded up baffle mounted driver.
GM
See my previous response.
Wasn't aware of this one, thanks! I learned about this while still a kid when exposed to some Acoustic Research AR-1 speakers that the owner had added a thick felt baffle cover and after a 'before/after' test convinced me that if it could make so much difference with these big cone drivers it had to work really well on horns since what's a horn, but a complexly folded up baffle mounted driver.
GM
Well, you never know until you try. You might have more success with cling film and a wheelie bin bag connected to a vacuum cleaner.
This could be that the screws have threads all the way to the head. You may try to pre drill in the ply that is not yet glued to the form, and use a screw that has a thread-less shank near the head.
I think ToS' idea of cling wrap and sand bags will work very well. You could also use ratchet straps/rope with some wooden wedges. I've used this technique several times on similar builds and it can work very well.
The cling wrap is also an awesome tool. With a spool and handle you can generate a good bit of pressure, rather easily. The glue also tends to not stick to the cling wrap too well, so cleanup is nice and easy.
I'm going to be building some similar mid-bass horns in the next year, though larger, and will likely use a similar method.
Good luck and keep up the great work.
Cheers,
Gable
The 'industrial' stuff they sell in rolls is awesome. Incredibly strong.
http://a.co/d/apGtdQy
Cheers,
Gable
FWIW I used discarded pants belts modded by a leather hole punch + hammer as required for all my curved projects. Also works great for holding my 'curb queen' pressure washer assy. to a super cheap yard sale hand truck/dolly [depending on how it's configured].
Hmm, never occurred to me to try this with my 'curb queen' electric central heating blower motor + belt + Datsun 240Z air conditioning compressor vacuum pump assy. for 'pulling a vacuum' on A/C systems.
Actually, since it can pull as near a perfect vacuum as these systems can achieve [great way to find an internal leak], I wonder if it would be too powerful, i.e. need a bleed valve of some sort?
GM
That's a good question.
Might be some clues here:
Vacuum Bagging Basics for Veneer Work
He has loads of info on vacuum bagging for woodworking.
Cheers,
Gable
Indeed! I learned this the hard way when I put it along the entire perimeter of a large, relatively heavy gauge, plastic poster to a fabric covered false wall office divider. Nobody, even the biggest/strongest out in our manufacturing plant could pull it off years later when doing yet another room rearrangement.
So, be forewarned that you don't need a whole lot of overlap for it to stay stuck even under a heavy [shear] load.
GM
Yes, I`m aware of this. I may try again and predrill holes that are larger diameter than the screws. But I think a little bit thicker glue would be better also. Maybe "liquid nail", or similar?
Yes, would probably work very well, but I need at least 5 more layers of ply, so I would be a valued cling wrap customer
Not sure how much is on a roll? Here in Norway I have only seen the small rolls that you use to wrap food in. Or maybe you are talking about some other product?Also, vacuum bagging would be interesting to try. My only experience with it so far is using a regular vacuum cleaner to pull my pool liner into the corners and sides of the pool. I saw a tv-program here in Norway, where they made a camping trailer collapse with a (very) large bag and a regular vacuum cleaner!
But I can`t leave the vacuum cleaner on until the glue sets, so if I try this I need some equipment.
Hopefully my horns are playing happily by then
Last edited:
Yep, I was puzzling over the same thing. I mean if Cyberkul wants to do 5 layers of 1/4" ply then it's his prerogative. It certainly is doable, but like you say, it won't necessarily make the music sound any better. Maybe it would be best to stop now as it is, and clean it up in readiness for the next stage of 'sonic treatments'.
As a seasoned builder GM, I'm sure you know exactly what I mean by that
ToS
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.