THT LP Build for 2 channel horns - high wall mounted

[Tom Smit]

Oh, for testing leaks....Bob's suggestion is good re the use of the flexi pipe...but this will only test the outer cabinet walls...not certain sections of the internals...eg near the horn throat. How do you know if ALL of the internal pieces are free from leaks?

Test with a light as you go. IOW, install a panel and let the adhesive cure. Then use a light to check for leaks. One could also install several panels, check all the bottoms and end joinst before the panel is closed in by the next one.

[Atilsley]

Oh, for testing leaks....Bob's suggestion is good re the use of the flexi pipe...but this will only test the outer cabinet walls...not certain sections of the internals...eg near the horn throat. How do you know if ALL of the internal pieces are free from leaks?

Test with a light as you go. IOW, install a panel and let the adhesive cure. Then use a light to check for leaks. One could also install several panels, check all the bottoms and end joinst before the panel is closed in by the next one.

I like it...nice and simple.

[88h88]

Assuming this all works out for you, just how are you planning on mounting that beast to your wall?

[Atilsley]

After all the (partly justified) stress re glue, ply...the mounting is the easy part.

Firstly, I'll take the advice of forum members re testing the sub on a temporary basis to make sure good room loading. If ok, I'll build three or four sturdy wall brackets, plus ceiling supports. Studs I wall are metal frame, so sturdy. I will also be building a ply decorative front panel to cover the whole job.

[Atilsley]

OK - update on my test.

Pic shows the earlier glued job test, using the Sellys poly glue. It had dried for 24 hours.

Repeated battering with hammer would not dislodge it.

I pried open the joint with a large screw driver, being hit heavily with hammer....4-5 blows.

You see the screwdriver mark as it drove in.

The glue completely pulled the top laminate away, plus a thinner layer of the ply substrate.

Conclusion - very strong!

[Atilsley]

OK, now I tapped into my mate's experience...as he's a design engineer for Selly's here in Sydney. He supplied me with a stack of lab products...all of the poly range, mega bond, moisture trigger etc. (It is the competitor product to Locktite's RL.)

So, you see we're back on track with this product.

Foamed up in seconds.

Will test for strength after 12 hours.

[Michael Ewald Hansen]

OK - update on my test.

Pic shows the earlier glued job test, using the Sellys poly glue. It had dried for 24 hours.

Repeated battering with hammer would not dislodge it.

I pried open the joint with a large screw driver, being hit heavily with hammer....4-5 blows.

You see the screwdriver mark as it drove in.

The glue completely pulled the top laminate away, plus a thinner layer of the ply substrate.

Conclusion - very strong!

Funny how I would have come to another conclusion.. If you had made that joint with regular ply and PL you wouldnt even be able to get a screwdriver in between the two pieces.. And as the laminate just broke off, it only confirms its not the right material to use..

The problem is, you think we're attacking you, but we're not, we're merely trying to help you use the right tools for the job.. Sometimes you just gotta realize that you didn't choose the right tool and cut your loses while you still can!

[Atilsley]

OK - update on my test.

Pic shows the earlier glued job test, using the Sellys poly glue. It had dried for 24 hours.

Repeated battering with hammer would not dislodge it.

I pried open the joint with a large screw driver, being hit heavily with hammer....4-5 blows.

You see the screwdriver mark as it drove in.

The glue completely pulled the top laminate away, plus a thinner layer of the ply substrate.

Conclusion - very strong!

Funny how I would have come to another conclusion.. If you had made that joint with regular ply and PL you wouldnt even be able to get a screwdriver in between the two pieces.. And as the laminate just broke off, it only confirms its not the right material to use..

The problem is, you think we're attacking you, but we're not, we're merely trying to help you use the right tools for the job.. Sometimes you just gotta realize that you didn't choose the right tool and cut your loses while you still can!

So, what about the end joins that will now have the proper glue, plus all the panels being heavily screwed in?

[88h88]

Concern is with those large panels there's far more leverage on those joints, if you have to use it then I'd back it up with a million screws mainly because that veneer won't be bonded as strongly to the ply as the ply will be to itself.

Also for anyone else new thinking about building speakers this is why the plans state what they do, it is far easier to just buy the right stuff than to piddle about testing a stack of other options.

[Gregory East]

Looks to me like the screwdriver took a dive into the first layer of ply, as you'd expect. Something has to give when you bash a screwdriver.

Correct me if I'm wrong but the phenolic finish is some kind of resin paint isn't it? It looks like the screwdriver took a whole layer of ply not just the shiny surface?

If that foaming stuff goes as well I'd go with it.

[Atilsley]

Looks to me like the screwdriver took a dive into the first layer of ply, as you'd expect. Something has to give when you bash a screwdriver.

Correct me if I'm wrong but the phenolic finish is some kind of resin paint isn't it? It looks like the screwdriver took a whole layer of ply not just the shiny surface?

If that foaming stuff goes as well I'd go with it.

Yes, Greg, finally...a hint of acceptance that we can recover this...and the 'thou shalt not' brigade can take a breather.

Our Danish friend thought only the thin black layer was removed...but not so.....the glue pulled up fibres and ply as well.

[Bill Fitzmaurice]

OK, now I tapped into my mate's experience...as he's a design engineer for Selly's here in Sydney. He supplied me with a stack of lab products...all of the poly range, mega bond, moisture trigger etc. (It is the competitor product to Locktite's RL.)

So, you see we're back on track with this product.

Foamed up in seconds.

That result is similar to what you get with Gorrilla Glue, and indicates that it's the wrong stuff. PL Premium is a construction adhesive, applied with a caulking gun. It expands by about a 3:1 ratio, taking a few hours to do so. Since it is available in Oz there's no reason not to get the right stuff.

[AntonZ]

For now, with the ply you have on hand, have you given thought to routering dado's (dadoes?) where you would otherwise glue a panel to the sleek laminate surface? That would probably make your joints a lot stronger. It's a bit of extra work, but I'd feel much more comfortable about the strength of the finished result.

[koturban]

Is it worth experimenting outside the plans with what appears to be a semi-permanent installation?

After all the time, effort, and money I put into assembling two of them, and all of the planning and money I've been putting into their final finish, I'd be , if I had to start over.

Just my two bits.

[Atilsley]

Spent a very easy and pleasant arvo working on the horn.

The panels have all been angled via my bench saw. All internal widths are 490mm (approx 19 inches).

I've used the stronger adhesive for the panels to the black surface, as I've already assessed the strength of this glue.

For joins where ply ends are meeting each other, I have used the fully expanding adhesive.

ALL joins have now been further sealed at the edges - on BOTH sides for added security.

There is positively NO GAPS anywhere....everything is working well.

All of the multiple two inch rough course screws have been fixed using mega bond thread to avoid any loosening.

I have purchased standard ply for the remaining panels...so will ensure we get that additional strength/seal.