DIY Hawthorne AMT Project

[Gremrock]

So,

 

Big project begins for new speakers. I've sourced all the drivers, found someone to cut some steelwork & do welding, and organising a quote for some CNC work on MDF for the baffle. Also if anyone on here DOES cnc machining work and would be interested in helping with this project please let me know, as I'm currently looking through a local cabinetmaker who will outsource  the work anyway.

 

Big question for you guys here is, does anyone have experience with different brands/suppliers of MDF and are there better quality options (higher density, better smoothness for painting) and where to get them? Looking at 25/32mm.

 

Any opinions on best glue to use to bond the MDF to the Steel? Bass/mid driver will be mounted to the steel, the AMT will be mounted to the MDF baffle.

 

Any other suggestions for material over MDF? Had thought of maybe using hardwood of some sort but not sure where to get goo straight panels that are least 55cm x 150cm, or what to use. Also without going to crazy $$$

 

Anyone have experience with how bevel cut edges on a baffle affects sound in an open baffle speaker? Plan to have a small trim around the drivers routed to 45 degrees and similar on the top/sides of the baffle, but is there a limit to how far into the baffle it should be done, or angles that positively or negatively affect sound?

 

Probably shouldn't call it DIY, as 92% of the actual work will be outsourced, but it's not a commercial product so I suppose it counts?

 

 

Cheers

Dan

 

[mwhouston]

What about 5 ply. 

[Gremrock]

5 Ply as in something like Birch Ply with 5 Layers?  Not sure plywood will give the finish I'm looking for with all the angled routing.. Wouldn't mind the timber front but routing through the layers would require veneering, or painting, which will be much harder to finish well.. (I think, but correct me if you think I'm wrong..)

[Wozza_Lee]

Painting ply if you undercoat etc is just as easy as painting anything else

[mwhouston]

It does prickle where MDF doesn’t but may be a much better box timber. MDF is easier to work with but it all just enquires some smarts and skill. It also can be CNCed. 

Edited November 6, 2019 by mwhouston

[wen]

i think the plywood routed at 45 degrees exposing the layers would give the speakers an edgy look

[mwhouston]

There are various grades of 5 ply some with more expensive finishes. 

Edited November 6, 2019 by mwhouston

[bob_m_54]

There are various thicknesses of "5 ply" too. 9mm, 12mm and 15mm can all come in 5 ply structure. Maybe a seven ply 15mm or 17mm thickness would be good too.

[davewantsmoore]

18 hours ago, Gremrock said:

Anyone have experience with how bevel cut edges on a baffle affects sound in an open baffle speaker?

The shape (in all dimensions) of the baffle affects all speakers, however the size of the features on the baffle need to be significant with respect to the wavelength.

 

ie.  if you're talking about a <12mm roundover on the edge of a baffle, in most situations you may as well not even bother, it does nothing.    It useful for aesthetics only. 

18 hours ago, Gremrock said:

Plan to have a small trim around the drivers routed to 45 degrees and similar on the top/sides of the baffle, but is there a limit to how far into the baffle it should be done, or angles that positively or negatively affect sound?

How far away from the driver, and how big the 45 degree bit is are all relevant .... but by the sounds of it what you are doing will have next to zero effect.

 

18 hours ago, Gremrock said:

Probably shouldn't call it DIY, as 92% of the actual work will be outsourced, but it's not a commercial product so I suppose it counts?

Sounds like a "DIY design" to me.

 

[davewantsmoore]

18 hours ago, Gremrock said:

Any other suggestions for material over MDF?

If you're going paint, then stick with MDF (or ply, but use a high quality ply, ie. not 5)

 

If you're thinking of material for acoustic performance considerations.... then the shape of the baffle, and how its braced, etc... are much much much more important than the material choice (within reason),

[Gremrock]

So the first quote for custom cnc is coming out fairly expensive, does anyone on here have a contact who could cut something like this with 45degree bevel edges?

[Wozza_Lee]

Does that really need to be cnc'd?

That's easy enough to do with a jig/band saw and a router

[Gremrock]

Doesn't need to be just figured it would be easier to get both panels the same.   Happy if someone can do by hand.