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building my own speakers

Void free 3/4" Baltic Birch plywood is preferred by DIY speaker builders but it's expensive costing several times more than 3/4" MDF.

I do like the density of MDF and it's heavier than plywood but it's dust is toxic.
 
Wow, I like your chances for having the biggest, heaviest speakers in the county - possibly even a state record. I'm less optimistic of them sounding particularly good compared to what you could simply have bought. But this is diy, and I understand the allure - I just think that for the best diy results you should consider going with a proven design, from drivers, to crossovers to cabinets, for this level of commitment.
 
sawmill said:
Bowtie427ss, Can you share more information on the different bracing techniques necessary with plywood use?
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It's really a case by case matter, and for many DIYers it is a hair splitting exercise that when considering the rest of their signal chain is probably fruitless. For those of us looking to wring out the last couple % of goodness, it's mandatory.

It's very difficult to make a box that won't have some panels with resonant characteristics, but it's not so hard to tune those resonances to a frequency outside of the range of the driver operating within

While it might be possible to make some basic predictions, the only way to really do it right is to prototype the box, load it, and subject it to a routine of acoustic analysis. The main difference is that instead of analyzing the speaker system, we are going to aim our test mic at the side and rear panels in various locations for the purpose of pinpointing resonant hot spots, and then damp them to an acceptable minimum, or brace the "hot" area to swing the resonant frequency out of the pass band of the woofer(or whichever driver's enclosure we are analyzing).
 
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musichal said:
Wow, I like your chances for having the biggest, heaviest speakers in the county - possibly even a state record. I'm less optimistic of them sounding particularly good compared to what you could simply have bought. But this is diy, and I understand the allure - I just think that for the best diy results you should consider going with a proven design, from drivers, to crossovers to cabinets, for this level of commitment.
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Sage advice here. Quoted in bold for emphasis.
 
I use to built very large speakers for clubs and bars in the 1970-80s. Some larger than 18 cubic ft. I used 1" plywood and 2x4 bracing. These were not things of beauty but functional. We rented special lift devices to get them into place. I could not move them by myself. Most were 3 to 5 cubic ft and weighted 100-150 pounds.
Building such big boxes is hard to do physically. I used a huge table saw to cut the pieces.
 
EddyR said:
I used a huge table saw to cut the pieces.
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You fellas make cutting panels more difficult than it needs to be.

You cannot do better than a quality hand held circular saw with a SHARP plywood blade, and a straight edge clamped to the panel you are cutting.

Yes, it takes time. But, most DIYers have plenty of that, and the reward for doing it ALL yourself with your own tools is priceless.
 
Poultrygeist said:
I do like the density of MDF and it's heavier than plywood but it's dust is toxic.
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bowtie427ss said:
You don't want to breathe Urea or Phenol, trust me on that.
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Thanks for posting some safety factors with MDF, not many people know or care to research that some of the products we use have toxic stuff inside. I have heard of a hospital grade MDF that is a safer products than normal MDF. Good luck, cant wait to see your progress!

Thanks,
Scott
 
srm51555 said:
I have heard of a hospital grade MDF that is a safer products than normal MDF.
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It would be interesting to see the MSDS disclosure on this hospital grade stuff.

My wager is that the only difference is the hospital grade stuff will have a fungicide on board that is probably no less toxic to humans than the adhesive components.

It may or may not have a lower Formaldehyde content, or may have gone thru an additional process to force off-gas some of the Formaldehyde during production.
 
First off +1 for separated enclosures for each driver. Stops resonation and a whole slew o issues associated.

I would like to know where you are getting 18 cu ft for that subwoofer driver, the fs is 20hz which means a 18 cu ft sealed wouldn't even work.

And if its ported that puts you around tuning of 10-15hz with little ability to play above that. That would be a true HT tune IMO to feel the 7hz explosions and such in movies.. It would be far from musical

That tang band midbass driver is nice, but if you are actually tuning that sub as such it wouldnt be linear enough in the real bass 30-80hz to "bridge" between itself and the sub. You will have an extremely nonlinear freq response in the bass and it will show. I recommend running the sub with at least an f3 of 40-45 so that the tangband has a chance to pick up where the sub leaves off....


Also that subwoofer for the money is nothing great IMO. If you truly want undeniably clean low end I would go for stereo integritys HST-18 which is around the same price or even the Dayton ultimax 18 is very impressive, and much cheaped

Its all about the implementation of the box. Ported vs sealed and the size catering to your needs. Assuming you care about fidelity and linearity the best course is to get a low fs subwoofer with a large sealed enclosure (4-8cu ft) for extremely flat and clean response.

I literally have spent the last year or so doing continuous research bow to get the best LOW bass for my dedicated listening room. I run stereo integrity 18"s in 6 cu ft sealed boxes tuned to 27hz. The drivers fs are 16hz so they really can extend.

Be noted sealed boxes can be nearly 2x as inefficient as ported boxes, but they drop only 12db out of their playable range opposed to 24db for ported.

I'm a diy subwoofer guy feel free anyone who is venturing into this world to pm me. I am EXTREMELY happy with my setup I think the bass is the cleanest and deepest I could get without going off the deep end with pricing.

pSMT82h.jpg
 
sawmill said:
JoeESP9, The woofers and mids are long throw open back and I have no idea about the tweets . I will be veneering in old growth wood I generate here, not sure what species yet. When I say composite ,I'm thinking carbon fiber and foam /epoxy as it would be extremely rigid and save some weight. This is my first speaker build. Rob
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While the woofers will take advantage of the cabinet size and tuning an open backed midrange ideally should be in its own enclosure. Anything large enough to seal of the midrange is sufficient as you're not tuning the enclosure to the speaker. The same applies to open back tweeters.
 
kirk57, You are correct. Greg at PE advised me to use two woofers , so that's 16 cu ft, plus 1 cu ft for each of the mids. He said the tweeter didn't require any air space so that is where 18 cu ft came from.
motorstereo, The bracing thing is what I'm researching right now along with alternatives to MDF. It is possible to build in place at this point but not desirable , and subset casters are certainly a thing to think about. This will likely be my last music set up unless I decide to go a little further and branch out into speakers as a business. I posted a purpose built "music wall " a couple of months back at the start of my quest.
Alobar, Let's just cut to the chase,,,,,,,Please invite me up to fish , hunt , and dig clams in your front yard.
 
JoeESP9, Point taken, a separate box for the mids will allow me to "wrap " the speakers around the wall a little better as to aesthetics . The gentleman at PE was not clear about multiple chambers (boxes) when questioned by me.
 
18cuft is big but not huge. My double 18" subwoofer box is 20cuft. Its only 3/4 the size of my fridge:). I say if you have the room then go for it!
Good luck with the project
 
elitopus, Thanks.I do have the room and want to build two of these as the main music speakers.But because of the overall size, materials for construction bear review ! Just looking for thoughts "outside " the box LOL
 
sawmill said:
elitopus, Thanks.I do have the room and want to build two of these as the main music speakers.But because of the overall size, materials for construction bear review ! Just looking for thoughts "outside " the box LOL
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I'm sure with the input of PE guys and the AK guys you can build some nice speakers.

What do you have planned for crossovers? Maybe it has been mentioned and I missed it
 
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