Open baffle

[tezza10]

Anyone see any issues with using a 10mm thick steel plate for the baffle plate (laser cut for drivers and pressed for side wings and base plate). Also just how much low end can I expect from 2 x 15" woofers each side (fs=47, Qts=0.55, Xmax= 4.1, Vd=3505, Sensitivity claimed 97dB)?

 

[deicide67]

I think, at 10mm, it is still going to ring like hell.

Ever knock on a military tank?

I know my 4 X 15" drivers will hit with authority.

The bases are 2.5" thick.

Blair

 

[tezza10]

Very nice! Are they solid timber baffle? And good point about the tank. I was just trying to get a bit creative seeing as I have access to a fabrication shop.

 

[deicide67]

The bass panels are cabinet grade ply. The tops are solid mahogany.

I think the steel would be awesome, but you need to sandwich it with a deadening layer in the middle of two 10mm pieces.

Blair

 

[studiotech]

Very nice! Are they solid timber baffle? And good point about the tank. I was just trying to get a bit creative seeing as I have access to a fabrication shop.

Well, if you've got access to the stuff, then do it. Just make sure to brace the back side AND use a liberal amount of Dynamat or other similar material.

 

[tezza10]

Would filling the gap (between the two layers of steel) with sand provide the damping needed?

 

[Melo theory]

Peanut butter works best.

 

[deicide67]

I would use Masonite or something similar layered to get the speaker driver gasket thickness. Sandwich the speaker between the steel plates.

 

[ashok]

My long standing plan was to use sand filled panels like what G.A. Briggs did a very long time ago.
I haven't yet completed testing my prototypes which use farily thin MDF. If everything goes according to plan , the final version will be with sand filled baffles. These can be a pain to make. I have experience making many sand filled baffles and stands in the past.

 

[tezza10]

Peanut butter works best.

It would be eaten faster than I could fill the baffle plates !

 

[DeonC]

Hi Tezza

Can you get hold of balsa wood? Someone told me years ago that balsa was used in the space program for vibration damping. Don't know how true that is, but it might be worth a try. That or maybe a thick layer of cork, if you can get hold of a reasonably thick sheet. I'd say 5mm up to 10mm thick ought to be good.

Would filling the gap (between the two layers of steel) with sand provide the damping needed?

Sand won't work IMHO. It does have vibrational damping properties, but I don't think it will damp the ringing enough. It works between layers of wood, but the resonance properties of wood is different to that of steel. I'd still say go for it with the steel, but use something more solid than sand as the constrained layer inbetween.

Enjoy,
Deon

 

[Abbiendi]

Hi Tezza,

NaO-Mini, wood and steel plates. MR/TW section is original. H-Frame dipole is with AE IB15. Total 112 Kgr per side. No ringing.

Regards,
Claudio.

 

[Silent Screamer]

I think 10mm plate is overkill. Don't get me wrong I'm all for over-engineering but think about the application... Open baffle doesn't vibrate anything like a closed or vented cabinet.

 

[SprockeT1597]

what about using Sikaflex between steel sheets?

 

[deicide67]

Hi Tezza,

NaO-Mini, wood and steel plates. MR/TW section is original. H-Frame dipole is with AE IB15. Total 112 Kgr per side. No ringing.

Regards,
Claudio.

Nice build! When someone says open baffle, I assume no H or support frame like the NaO. Of course, the box like structure around the metal will deaden it.