Home Brew Cabs

[bowtie427ss]

MDF/HDF requires some of it's own design and structural considerations, but can be a perfectly satisfactory loudspeaker cabinet material depending on the overall goals of the design.

I agree that in many designs the cost effectiveness of MDF/HDF is a factor, sometimes a major factor.

However, in many designs the use of more expensive void free hardwood plywood vs MDF/HDF in cabinet construction would yield sonic differences so miniscule that to say "exceeds the point of diminishing returns" would be a gross understatement. I don't think my Altec 9849's, model 17's or Westlake BBSM-10's would benefit in their cabinets having been constructed of any type of plywood vs the MDF their manufacturers chose, important to note these speakers share the common thread of heavily braced and heavily damped cabinets.

OTOH, i understand that there are designs that rely on the resonance of their plywood cabinets as part of their sonic signature. I can surely understand how replicating these kinds of designs with MDF would yield a comparatively dead or lifeless sounding speaker.

There is also the numerous variations of densities and core compositions in all sheet stock whether it be ply or composite.

At the end of the day, i'm not comfortable with saying one material is better than the other as a blanket statement, in a word it "depends".

[Altec Best]

I, like GM, believe the only reason cabinets are made from MDF is cost. If you have had the chance to listen to identical speaker systems in different cabinets, I bet you will never build a speaker from MDF again. I agree one of the objectives of the cabinet is to remain as inert as possible and at no point should it impart a signature of it's own but having had the opportunity to listen to 3 different systems side by side I cannot suggest that MDF is a good cabinet material. It simply sucks the life out of the speaker. Kind of like a crossover with too many components.

+2 I'm with you (Cal & GM) on this one ! MDF is garbage and the only reason it was ever used is for COST period.The minimum wood that should be used for a medium to large cabinet is 3/4 ply and only Void Free ply preferably Baltic Birch ply IMO.

[zelgall]

I just checked my factory 620 cabinets and my model 19s. Around the ports they both look like particle board with veneer facing. I've had the 19s apart and if I remember correctly the whole cabinet is particle board. MDF that I'm familiar with is of much finer composition than this.
Kyle.

[Cal Weldon]

That particle board is likely K-3. It was used a lot for cabinets of that era before MDF became popular.

[westend9]

MDF/HDF requires some of it's own design and structural considerations, but can be a perfectly satisfactory loudspeaker cabinet material depending on the overall goals of the design.

I agree that in many designs the cost effectiveness of MDF/HDF is a factor, sometimes a major factor.

However, in many designs the use of more expensive void free hardwood plywood vs MDF/HDF in cabinet construction would yield sonic differences so miniscule that to say "exceeds the point of diminishing returns" would be a gross understatement. I don't think my Altec 9849's, model 17's or Westlake BBSM-10's would benefit in their cabinets having been constructed of any type of plywood vs the MDF their manufacturers chose, important to note these speakers share the common thread of heavily braced and heavily damped cabinets.

OTOH, i understand that there are designs that rely on the resonance of their plywood cabinets as part of their sonic signature. I can surely understand how replicating these kinds of designs with MDF would yield a comparatively dead or lifeless sounding speaker.

There is also the numerous variations of densities and core compositions in all sheet stock whether it be ply or composite.

At the end of the day, i'm not comfortable with saying one material is better than the other as a blanket statement, in a word it "depends".

+1, it depends on the design criteria.

In the example of the Model 19 clones, hopefully, there isn't an issue with voids or delamination. I use a pretty fair amount of sheet goods through my business and was thinking that plywood had improved through process technology and new adhesives over the last 30 yrs. or so. The advent of more veneered goods also seemed to be an indicator of quality increase. That assumption is proving not to be the case. More of these sheet goods are being imported and even the domestic makers seem to fail on quality, on occasion. I have returned more plywood in the past year than the previous ten.

[cradeldorf]

Are there Model 19 Cabinet plans available somewhere?

[LICORNE]

Are there Model 19 Cabinet plans available somewhere?

Yes at this site.

Model 19 Shop Working Prints

[cradeldorf]

Yes at this site.

Model 19 Shop Working Prints

Thanks Licorne :2thumbsup:

[scharron]

Hi guys,
I always thought that Altec went to MDF both for cost and the fact that most of
their cabs, specifically A7's were going into permanent installs ie theaters, skate
rinks, indoor stadiums etc. they didn't have to endure the rigors of set up and
breakdown or truck pacs so they built them that way. I am sure cost came into it
too, but lots or permanent install cabs are MDF or particle board. I had an old
Earth guitar amp that had a large cab with 2 15's and man that thing was heavy!
it was all particle board. I saw stuff like that shattered on a pretty regular basis.
just my .02
scott in nc

[Captgonzo]

"Intended application" is definitely the key phrase here. Properly constructed, damped, and braced, I've never heard much difference. But I believe you really don't want MDF for portable professional applications. Cheap MDF boxes do not like to be dropped off a truck or stage--even a little. Seems a lot heavier, too. I've seen really cheap MDF that seemed to dissolve in a light rain shower... I'm sure the good stuff is better that way. If some wanted to post some info or a good link or two about how to identify "the good stuff" (plywood and MDF) that would be very helpful to some of us.