But still no need to worry about that 8 Ohm resistor!!
It only have to dissipate 1/28 of the CONTINOUS power you put in to the speaker.
So even if you CONTINOUSLY put 280 Watts into the speakers, only 10 Watts will need to be dissipatede in the resistor.
It only have to dissipate 1/28 of the CONTINOUS power you put in to the speaker.
So even if you CONTINOUSLY put 280 Watts into the speakers, only 10 Watts will need to be dissipatede in the resistor.
Very true and I didn't say otherwise.
My point was that the rating of a chassis mount resistor is often misleading. Perhaps 100w resistors being mentioned may have sent things in the wrong direction.
I didn't consider trimming the driver flanges themselves. But doing so would allow me to easily fit 28 drivers. What do you mean about gluing the drivers down? No screws at all? Whtat kind of glue? How would you remove for service if need be?
Glue vs screws achieve two things:
1 - Mechanical separation from baffle/enclosure
2 - A good seal
Downside is the added hassle if one need to remove a driver obviously. A knife usually does the trick.
http://www.diyaudio.com/forums/full...tc9-line-array-cnc-cabinet-2.html#post4981999
The glue they used is intended for making a cylinder head gasket, there are however plenty of glues around that are strong enough to make a proper bond.
1 - Mechanical separation from baffle/enclosure
2 - A good seal
Downside is the added hassle if one need to remove a driver obviously. A knife usually does the trick.
http://www.diyaudio.com/forums/full...tc9-line-array-cnc-cabinet-2.html#post4981999
The glue they used is intended for making a cylinder head gasket, there are however plenty of glues around that are strong enough to make a proper bond.
Ah yes, I did see that thread but I didn't realize that they removed the screws afterwards. It would be so much easier (and prettier) not to have to drill the mounting holes. It would be easy enough to just glue and have a weight on the drivers to keep them in place while the glue cured since I'm mounting from behind the baffle. I had originally planned on mechanical separation with the o-rings both on the face of the driver itself as well as on the screws and nuts that would hold them in place. But this idea gets the driver isolated from the baffle and also a little closer to the baffle as the thickness of the o-rings is not insignificant.
I'll look into good glue options. Ease of application seems to be important here as well as the proper bond! I may need some sort of location fixture too to make sure things stay centered.
I'll look into good glue options. Ease of application seems to be important here as well as the proper bond! I may need some sort of location fixture too to make sure things stay centered.
Last edited:
With that build they used a sandwich construction. The mounting board is recessed slightly to account for the thickness of the gasket then the front baffle is fixed down on top providing some force to keep the driver floating in the sandwich.
Trying to glue it on the back of the baffle without support would require some very strong glue that would not be elastic. You could use some sort of magnet support to apply force from the back to keep the drivers in place. The glue then doesn't have to take the weight of the driver by itself.
This thread had a complicated support structure not quite the same but might give you some ideas.
http://www.diyaudio.com/forums/multi-way/288784-tc6wd-pe-buyout-line-array-lessons-learned.html
Last edited:
Interesting... I had not seen that thread. It did worry me a bit to simply rely on the gasket to hold the drivers in place by themselves. Let's spit ball a few other ideas... no claim these are good ideas, but maybe they'll spur on better ones!
1. Use the gasket adhesive around the circumference and then use 4 dabs of something stronger (like liquid nails or 2 part epoxy) at the mounting holes. Simplest.
2. Use the O-rings I already bought and liquid nails or similar at the mounting holes. Almost as simple... but drivers sit farther away (~1/8") from the baffle.
3. Use the gasket adhesive or the O-rings with some ~8" bands that can hook to the edges of the baffle with some clips and apply force to the drivers against the baffle. (Looks like I can even get them in fun colors!) 😛 I don't know if these bands will maintain tension over time though. I guess they could be metal springs or some other reinforced material? I like this concept, but not confident that I can find the right material.
4. The "spine" idea from dynomike's thread is interesting. I can't execute that with my design, but I could potentially use 2 screws from the back sides to apply pressure to the drivers. It's really complicated and would make the damping difficult to execute as well.
1. Use the gasket adhesive around the circumference and then use 4 dabs of something stronger (like liquid nails or 2 part epoxy) at the mounting holes. Simplest.
2. Use the O-rings I already bought and liquid nails or similar at the mounting holes. Almost as simple... but drivers sit farther away (~1/8") from the baffle.
3. Use the gasket adhesive or the O-rings with some ~8" bands that can hook to the edges of the baffle with some clips and apply force to the drivers against the baffle. (Looks like I can even get them in fun colors!) 😛 I don't know if these bands will maintain tension over time though. I guess they could be metal springs or some other reinforced material? I like this concept, but not confident that I can find the right material.
4. The "spine" idea from dynomike's thread is interesting. I can't execute that with my design, but I could potentially use 2 screws from the back sides to apply pressure to the drivers. It's really complicated and would make the damping difficult to execute as well.
The magnet is fairly heavy for it's size and the weight being un-supported, gravity will always want to pull it down, away from the baffle and weaken the glue joint. I doubt even epoxy would last for the life of the cabinet.
If the drivers are to be mounted frame to frame or even have a little shaved off you could epoxy the plastic frames together to form a rigid spine and reinforce it with some thin aluminium or acrylic then find some way to apply pressure to that at key points.
If the drivers are to be mounted frame to frame or even have a little shaved off you could epoxy the plastic frames together to form a rigid spine and reinforce it with some thin aluminium or acrylic then find some way to apply pressure to that at key points.
Their arrangement was not a sandwich as in baffles clamped between mounting board / front baffle, the front baffle is for estetique reasons alone.
The glue gasket as the sole fastener the drive frame is isolated mechanically from the baffle provided it is allowed to flex (somewhat)
Any rigid media (screws , epoxy) will allow mechanical force to travel to the cabinet making the purpose provided by the gasket void. There are glues that are incredibly strong whcih will never fail provided they match the surfaces they are intended to bond to. Spacecrafts have gone to space using glues, airliners are bonded with glue/resins etc etc 🙂
Weesayso used rubber between his mounting plate/front baffle to achieve this, so no firm material connect driver to cabinet.
That may have been their intention but the front baffle will provide some assistance to keep pressure on the whole construction whether they realised it or not.
The problem in this case is that there is very little surface plastic for the glue to bond to and dissimilar materials tend not to bond so well.
A super strong glue is also likely to be stiff and not elastic which kind of defeats the purpose.
To me a small surface bond high stress and no support is not a good recipe for success. That being said if you engineer it to cope with all of the above it would be a good idea 🙂
1 - The TC09 have a soft foam gasket glued onto the frame (as they are intended to be mounted from the rear) so the front baffle rest against that. As long as the compression isnt too high or hard materials actually touch eachother a level of isolation is maintained.
2 - That is only a problem if it is not taken into account during the planning/material selection stage. But I understand your point.
3 - I dont believe that to be true 😉 There are plenty of really tough formulaes around that maintain flex yet give a really good bond.
They did add a gasket (black ring) glued to the wood with contact glue to act as a adhesion surface for the glue (and to increase mechanical separation)
Have you ever seen koldby's solution?
http://www.diyaudio.com/forums/multi-way/193015-stupid-cheap-line-array-21.html#post2890230
http://www.diyaudio.com/forums/multi-way/193015-stupid-cheap-line-array-21.html#post2890230
I'm not saying that you can't get a strong bond with some flex.
What I don't think you will get easily is a strong enough bond to hold the TC9 driver to a baffle with no extra support and have enough flex in the glue to make isolation a reality.
If the driver was being mounted face down then gravity would help keep it in place, as it is being mounted at 90 degrees the weight of the driver will be trying to force the glue joint apart, add flex and movement into that and it is a tough ask of any adhesive.
I am happy to be proven wrong if someone can make it work 🙂
Any ideas for specific adhesives that would have a strong bond (driver to aluminum) and remain pliable?
As I was reading through the comments (thanks by the way) I thought of a couple other options.
1. Use metal clips to hold the drivers down near the mounting holes. The clips themselves could be epoxied down and the driver could simply slide under them for removal/installation. This probably makes more sense with the o-rings vs. an adhesive.
2. Instead of my idea with the rubber bands, I could use a piece of wood (or aluminum) that would hold the drivers down along the frame where two would mate up and the ends of the wood would be clipped to the edges of the baffle.
As I was reading through the comments (thanks by the way) I thought of a couple other options.
1. Use metal clips to hold the drivers down near the mounting holes. The clips themselves could be epoxied down and the driver could simply slide under them for removal/installation. This probably makes more sense with the o-rings vs. an adhesive.
2. Instead of my idea with the rubber bands, I could use a piece of wood (or aluminum) that would hold the drivers down along the frame where two would mate up and the ends of the wood would be clipped to the edges of the baffle.
Last edited:
Yes, I saw that. A very nice piece of work. That and dynomike's spine are what prompted my idea in post 307 around screwing from the rear to press against the drivers, but I would have to do it from 45 degrees from the other side of the walls given my corner layout. That in itself makes the idea daunting. And the deal breaker is that the wall on the right side is an exterior wall so going through that is not a great idea. But I like the creativity and I'm still noodling on other ideas that this spurs. (#2 from the previous post for example.)
The Loctite website recommends this via their product finder:
Technical specs here.
The specs indicate a peel strength of 12 lbs/lineal inch or more (depending on the material) which seems pretty strong for this application. No spec on durometer or anything... but it claims it remains flexible with age.
Technical specs here.
The specs indicate a peel strength of 12 lbs/lineal inch or more (depending on the material) which seems pretty strong for this application. No spec on durometer or anything... but it claims it remains flexible with age.
It does list a lot of plastics as not recommended. I'm not sure of the type of plastic that the basket of the TC9 uses.
The only way you will know if it will work is to sacrifice a couple of drivers and test it out.
If I tell you I don't think it will work another says they think it will doesn't really matter, someone will need to be the guinea pig and settle the speculation 😀
PS If you aren't prepared to test it I would concentrate on thinking of a solution that involves some support to take the weight.
Yes, I agree. The other thing that I'm not sure about is whether the adhesive will work better or worse with the foam gasket. Any other suggestions for adhesives to test out? I have enough drivers that sacrificing a few won't be an issue.
I'm still considering actual support too. Even if the test works out, it will not be easy to predict how things will perform over time with vibration and other things like humidity and temperature changes.
Two other ideas:
1. I could make two shallow (~3/32") saw blade width cuts at a 45 degree angle along either side of the driver holes from top to bottom. Then slightly overfill the grooves with the adhesive before positioning the drivers. That will provide some mechanical force as well as more surface area for adhesion.
2. I could stay with my o-rings and "super-glue" the o-ring to the baffle and then the drivers to the o-ring. No problem with guessing as to the flexibility of the o-rings. Super glue is pretty ridiculously strong. Could be another glue too.
I'm still considering actual support too. Even if the test works out, it will not be easy to predict how things will perform over time with vibration and other things like humidity and temperature changes.
Two other ideas:
1. I could make two shallow (~3/32") saw blade width cuts at a 45 degree angle along either side of the driver holes from top to bottom. Then slightly overfill the grooves with the adhesive before positioning the drivers. That will provide some mechanical force as well as more surface area for adhesion.
2. I could stay with my o-rings and "super-glue" the o-ring to the baffle and then the drivers to the o-ring. No problem with guessing as to the flexibility of the o-rings. Super glue is pretty ridiculously strong. Could be another glue too.
This looks like an interesting tape
Attachment Part Mounting - Adhesive tape solutions for the automotive industry
The same company has a lot of mounting adhesives.
Something like scotch red mounting tape holds really well and has some isolation as it has a foam component. Add in a small amount of mechanical support to take the weight and that could work. A thin ply spine with fingers that reach out to support under the magnet might work. the same tape can be used to isolate the spine from the driver too.
Long term reliability is always going to be somewhat unknown with any adhesive that is not also supported or kept in place with pressure.
Attachment Part Mounting - Adhesive tape solutions for the automotive industry
The same company has a lot of mounting adhesives.
Something like scotch red mounting tape holds really well and has some isolation as it has a foam component. Add in a small amount of mechanical support to take the weight and that could work. A thin ply spine with fingers that reach out to support under the magnet might work. the same tape can be used to isolate the spine from the driver too.
Long term reliability is always going to be somewhat unknown with any adhesive that is not also supported or kept in place with pressure.