Holey crap. Sydney in Oz? Thornspawn (Ben) near Melbourne sells sets of FH3 flat-paks (each pair will use 1 sheet) in hoop pine ply for not much more than that so there has to be sources with better prices.
dave
Jon,
$230 for a single sheet is cruel...
A search yielded these options:
plywood sheets in Sydney Region, NSW | Gumtree Australia Free Local Classifieds
Not sure about the quality/reliability - but prices look more reasonable for the stuff listed.
IIRC 17-19 mm is what is recommended, you might be able to do a decent build with good quality 15mm ply with a good bracing scheme for your Pensil.
Thanks guys. For the time being, I'm going to keep my eye out for some cheaper 19mm ply - I'll take a trip to my local timber merchant at the weekend (I didn't get the quote from them.) Sounds like there are options though - my speaker building project kind of got derailed by that quote, and I think these options put it back on the rails!
Cheers,
Jon
Cheers,
Jon
Well I seem to have set myself a tricky task. I made some new 3-ways using MDF, quite thin (16mm) but with a fair bit of bracing. During initial listening tests I was happy enough, so set about looking for veneers only to find it very difficult to find where I live (> 1500km from a large city).
However what I could find was 2.7mm marine ply and decided to glue that to the MDF - a stain should look OK and adds some thickness to the panels too. Mitre cuts have been easy enough (via the router), easier than expected actually, but I glued the first sheet on tonight and it was a challenge. The sides all decided to warp away from the MDF and I was frantically looking for heavy objects to keep it flat. I will check it out tomorrow morning.
Has anyone done something like this before? Thankfully I had the wisdom to do the bottom panel first, so I've learnt my lesson on the least visible panel.
However what I could find was 2.7mm marine ply and decided to glue that to the MDF - a stain should look OK and adds some thickness to the panels too. Mitre cuts have been easy enough (via the router), easier than expected actually, but I glued the first sheet on tonight and it was a challenge. The sides all decided to warp away from the MDF and I was frantically looking for heavy objects to keep it flat. I will check it out tomorrow morning.
Has anyone done something like this before? Thankfully I had the wisdom to do the bottom panel first, so I've learnt my lesson on the least visible panel.
My material of choice is always high-density particle board. From cabinet supply outlets it can be found in sheets up to 5 feet by 10 feet, but 4' by 8' is more standard and manageable. The high density material works so much stronger and more workable than MDF. It is heavier and available in a range of thicknesses, up to 1 inch or more. I tended to use either 5/8 inch or 1/2 inch thicknesses, though in both cases I used internal bracing keeping all internal dimensions between baffles and braces less than 2.5 inches.
Sorry to dig this up now, but I have a question on this.
I was planning to make it removable using threaded inserts (or t-nuts) but I have recently read many comments in threads suggesting not to do so, and use plain wood screws. What is your experience on that?
I feel that if something goes wrong with the inserts, you don't have room for repair. But if a wood screw "eats" the wood, you can repair it some way - putty, glue etc.
Plus, the wood screws are stupidly easier to use. After all, I would like to be able to open the cab around 10 times without degradation. Do you think that wood screws would suffice? My brackets are pitch pine.
I've done both, in fact, I've done both on the same cabinet. I was rebuilding my DIY speakers which had large head wood screws, and as long as I was rebuilding, I converted over to large head machine screws and T-Nuts.
Both work. But I feel I can open and close the cabinet more times with machine screw without degradation using machine screws.
This also depends on the material. Plywood and solid wood will hold a wood screw better then particle board or MDF. Though there are product called Wood Hardener that works well on the exposed edges of particle board and MDF to make them hold screws better.
But keep in mind, wood screw or machine screw, it is not like you will be in and out very day. While the speakers are being built, you might need to get into the cabinets a bit more often, but once done, you are not likely to open the cabinet more than once every 5 or 10 years.
Buy the way, I didn't actually use Wood Screws, I used Sheet Metal Screws.
This is a common Wood Screw -
http://www.duplexfastener.com/image...-screws/screw-types-of-screws-wood-screws.jpg
This is a common Sheet Metal Screw -
https://www.belmetric.com/images/SLH4.8X32SS.jpg
Of course I replaced them with common Phillips Head Machine Screws -
http://www.usifaz.com/Web Site Pics/Screws/phil truss ms zinc.gif
I went for Machine Screws that had the largest heads I could find. I used large heads to spread the force out on the wood to keep the screw head from digging farther into the wood each time it was tightened down.
Of course, you can use flat washers under the screw head to spread the force out, or you can use something known as a Countersunk Washer -
:|:| Countersunk Washers at Factory Price|:| Countersunk Washers Manufacturing India
The Countersunk Washers work especially well with Wood Screws, though they will work with just about any screw.
You can get screws in either a gold/brass like finish or in black. I think these look better than Silver colored screws. At the time, I simply could not find Brass colored screws, so I painted the head on mine with gold paint.
Which is more likely to fail, a Steel Nut or soft wood? Both Machine Screws and Wood Screw will work, but, if you are not careful, you are more likely to strip wood.
Also, T-nuts are attached from the back and held in with cleats. If you strip one, simply pry it out and put a new one in. Though in my case, I put a small dab of glue between the T-Nut and the wood, but I think I could pry them out if I had to, though I don't anticipate doing so in my lifetime.
On the other hand, if you are careful, wood or sheet metal screws will work fine. On the speakers I rebuild with machines screw, they originally had sheet metal screws for about 25 years.
The Machine Screws / T-Nuts was just a suggestion.
Steve/bluewizard
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Driver fastening
Driver fastening is a matter that ultimately depends on how often one expects to need access to the cabinet through the opening. The approach that I fixed upon was to use hardwood splines glued to the high-density particle board front baffle, with one situated behind each fastening hole. To avoid splitting, the hardwood splines are pre-drilled to receive a wood screw. I prefer using round head Roberts (square drive) hardened self tapping screws, as these work well in tapping the pre-drilled hardwood and do not experience cam-out behavior that could lead to damage of the driver diaphragm. I also lubricate the screw with bar soap, usually Nutrigena or a similar glycerine type of soap. When removing and then reinstalling a screw, always carefully hand twist the screw to make sure that it is following the same threads cut from prior installation to preserve holding power.
I used to use a sealing material from Dynaudio, but I haven't found that lately so I use a hot-melt glue with low adhesion around the rim of the frame that can pretty easily be removed if needed.
Driver fastening is a matter that ultimately depends on how often one expects to need access to the cabinet through the opening. The approach that I fixed upon was to use hardwood splines glued to the high-density particle board front baffle, with one situated behind each fastening hole. To avoid splitting, the hardwood splines are pre-drilled to receive a wood screw. I prefer using round head Roberts (square drive) hardened self tapping screws, as these work well in tapping the pre-drilled hardwood and do not experience cam-out behavior that could lead to damage of the driver diaphragm. I also lubricate the screw with bar soap, usually Nutrigena or a similar glycerine type of soap. When removing and then reinstalling a screw, always carefully hand twist the screw to make sure that it is following the same threads cut from prior installation to preserve holding power.
I used to use a sealing material from Dynaudio, but I haven't found that lately so I use a hot-melt glue with low adhesion around the rim of the frame that can pretty easily be removed if needed.
Then no.
The basic idea behind a "baffle" (literally) is to separate front and back waves, which are out of phase, and for that, said baffle must be rigid.
Even 2 cm thick real wood or chipboard/mdf/etc. is not rigid enough, it vibrates and changes frequency response, imagine flimsy thin cardboard.
You *can* measure "something", of course, but it will be useless.
Unlikely. Cardboard tends to be acoustically transparent, particularly at lower frequencies.
Most pros use utility grade MDF boxes.
The measurements that you want to make are Thiel/Small parameters first and foremost.
Could you add a little more context to that question. What do you mean by "Cardboard" and what do you mean by "Response Only" and what do you mean by "Test Boxes".
There are several kinds of Tests one could perform. There are several interpretation of "response", though one more obvious than others.
Are testing individual drivers? Full speaker systems? Crossover accuracy?
As other have indicated, cardboard mades decent shipping boxes, but it is structurally a bit weak for a speaker box.
Generally, any movement of the box is lost movement to the speaker.
So, potentially, something could be done with cardboard, but it would be a very minimal thing at best.
So, if you can be more precise in explaining what you intend to do, then we can be more precise in our evaluation of how well it will work.
Today, there are various software programs that will simulate speaker boxes, that should give you a fair indication of how the driver and box will respond in the bass region.
Linear Team has a couple of FREE Bass Box simulator and modelers. These are not quite complete, but they do get the job done.
Linear Team - WinISD -
LinearTeam - WinISD
Linear Team - WinISD Pro -
LinearTeam - WinISD Pro
These files are not exceptionally large and you can install both programs.
In commercial software, Bass Box Pro and X-over Pro are popular and reasonably sophisticated.
BassBox 6 Pro/X-Over 3 Pro Software Set CD-ROM
BassBox 6 Pro Software CD-ROM
X-Over 3 Pro Software CD-ROM
Also, here is True Audio Speaker Testing and Speaker Design software -
https://www.trueaudio.com/rta_abt1.htm
https://www.trueaudio.com/win_abt1.htm
https://www.trueaudio.com/ild_abt1.htm
Again, we aren't quite sure what you are trying to do, but generally, the circumstance where cardboard would be acceptable would be very very rare.
Steve/bluewizard
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Also, if you are trying to measure the Parameters of a DRIVER rather than a speaker, here is a device for that -
Dayton Audio DATS-V2 Audio Component Test Software -
Dayton Audio DATS V2 Computer Based Audio Component Test System
Generally the only way to be sure if a speaker is doing what you want it to do is to test it. You really can't depend on your hearing. The things you need to hear are too subtle.
There is a good FREE program called REW (Room Equalization Wizard), which is meant for testing room, but is versatile enough to also test speakers.
Room Equalization Wizard -
REW - Room EQ Wizard Room Acoustics Software
It does have some hardware requirements like a Microphone, but these can be had for about $50.
Though costing a considerable amount, there is a Speaker Test System that included a Microphone -
Dayton Audio OmniMic V2 Software -
Dayton Audio OmniMic V2 Computer Based Precision Room Measurement System
There are many hobby speaker designer out there that are using the FREE REW and WinISD/WinISD-Pro. That means you would only need perhaps $50 to $100, to have a complete design and test system up and running.
Because REW is so popular there are on-line tutorials, YouTube videos, and discussion groups dedicated to this software.
Just a thought.
Steve/bluewizard
Dayton Audio DATS-V2 Audio Component Test Software -
Dayton Audio DATS V2 Computer Based Audio Component Test System
Generally the only way to be sure if a speaker is doing what you want it to do is to test it. You really can't depend on your hearing. The things you need to hear are too subtle.
There is a good FREE program called REW (Room Equalization Wizard), which is meant for testing room, but is versatile enough to also test speakers.
Room Equalization Wizard -
REW - Room EQ Wizard Room Acoustics Software
It does have some hardware requirements like a Microphone, but these can be had for about $50.
Though costing a considerable amount, there is a Speaker Test System that included a Microphone -
Dayton Audio OmniMic V2 Software -
Dayton Audio OmniMic V2 Computer Based Precision Room Measurement System
There are many hobby speaker designer out there that are using the FREE REW and WinISD/WinISD-Pro. That means you would only need perhaps $50 to $100, to have a complete design and test system up and running.
Because REW is so popular there are on-line tutorials, YouTube videos, and discussion groups dedicated to this software.
Just a thought.
Steve/bluewizard
Foundational information advised
Cardboard might be useful in combination with other rigid materials, where the cardboard might aid in the absorption of back-wave energy. It is not normally used even for this purpose.
I would further recommend the review of the Loudspeaker Design Cookbook, by Vance Dickason. This would help provide a broader context for box design considerations.
Cardboard might be useful in combination with other rigid materials, where the cardboard might aid in the absorption of back-wave energy. It is not normally used even for this purpose.
I would further recommend the review of the Loudspeaker Design Cookbook, by Vance Dickason. This would help provide a broader context for box design considerations.
Wow, finally slogged through all 90 pages. Has really been enlightening to read.
I see the last post was only a few months ago, so I hope this isn't thread necro, but I had a question regarding metal enclosures.
I work for a toolbox company, and have access to large amounts of scrap ali, both checkerplate and plain, in 1.6, n and 3mm varieties, with the occasional thicker sheet come through.
I also have the ability to make ali holey braces and access to welding.
Would a speaker made out of 3mm ali, braced and welded be a reasonable speaker to consider (subscribing to Dave's philosophy of driving the box resonance as high as possible)? What potential hurdles might I face?
I see the last post was only a few months ago, so I hope this isn't thread necro, but I had a question regarding metal enclosures.
I work for a toolbox company, and have access to large amounts of scrap ali, both checkerplate and plain, in 1.6, n and 3mm varieties, with the occasional thicker sheet come through.
I also have the ability to make ali holey braces and access to welding.
Would a speaker made out of 3mm ali, braced and welded be a reasonable speaker to consider (subscribing to Dave's philosophy of driving the box resonance as high as possible)? What potential hurdles might I face?
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