After perusing what would be an nice compliment to my [main speakers], and satisfying all criteria for movie and music listening for subwoofer duty given my apartment, I've decided to give the 20Hz TH a shot. I've built a couple cabs of Bill Fitzmaurice design (with excellent results), but this DIY project is most appropriate shown here in this forum. Test fitting and assembly is under way! More photos to come...
-Radian
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-Radian
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Now this is interesting.
Have you by any chance built the Bill fitzmaurice THT? I would love to see your comparisons between it and a tapped horn using the same driver.
ATM i'm sitting here with the BFM plans for the THT but i have two of the drivers used in these plans so i would like to see how a 20hz tapped horn compares.
Have you by any chance built the Bill fitzmaurice THT? I would love to see your comparisons between it and a tapped horn using the same driver.
ATM i'm sitting here with the BFM plans for the THT but i have two of the drivers used in these plans so i would like to see how a 20hz tapped horn compares.
I'll be going with the 3015lf. I'm trying to keep it light weight, as the sub will be parked in front of a small door that provides maintenance access to our furnace. The filter gets changed every six months, so I wanted the cab light enough that the GF can shuffle it out of the way if need be.
I've not had a chance to build the THT yet. Although, I have the drivers on deck to do so when that time comes. I have built several AT's and a Table Tuba. With thanks to Ultra Fidelis and a visit to DSL, I've also had the pleasure of hearing all sorts of high-zoot commercially available subs the like of SVS, TH50, DTS-20, JL...etc.
My desires were for a DIY cab with minimal horizontal footprint, was horn loaded, went down to at least 25hz with some authority for movie watching, and had good prints to work from.
You simply can't go wrong with the THT if you have the space for it. It's insane (just check out youtube). The Table Tuba I built for my parents' HT setup is crazy and it's a third narrower than the THT.
I've not had a chance to build the THT yet. Although, I have the drivers on deck to do so when that time comes. I have built several AT's and a Table Tuba. With thanks to Ultra Fidelis and a visit to DSL, I've also had the pleasure of hearing all sorts of high-zoot commercially available subs the like of SVS, TH50, DTS-20, JL...etc.
My desires were for a DIY cab with minimal horizontal footprint, was horn loaded, went down to at least 25hz with some authority for movie watching, and had good prints to work from.
You simply can't go wrong with the THT if you have the space for it. It's insane (just check out youtube). The Table Tuba I built for my parents' HT setup is crazy and it's a third narrower than the THT.
Alright, first brace glued into its dado and side panel cleats glued on. These cleats stiffen up the side panel as the span from the baffle to the outer panel increases along the length of the cab. Was this a must? No, but it sure makes for a rock solid cab when working with 1/2" ply. Will it affect performance? Not enough for me to fret over, and not over any frequencies that I'd care about.
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This is exactly what i would like to build. Do you have any cut sheets of this design? My HT front wall is 14' across, i thought i could lay 2 of these end to end on their sides. I didnt know the dimensions?
Would you have the port ends adjacent to each other or opposit in the corners? Should they face out or back into the walls/corners?
Thanks for any help.
Would you have the port ends adjacent to each other or opposit in the corners? Should they face out or back into the walls/corners?
Thanks for any help.
I did the similar project...with 12-inch Visaton. Certainly large volume of rich bass....running high pass filter to roll off around 120Hz....but ideally, this could be lower, eg 70-80Hz. Earlier 600-watt plate amp with 96dB driver was complete overkill.
The shape of the pine box means my wife doesn't need to invest in a coffin...
...hence the love note I stuck on the front door prior to her returning home after it was built.
Note the size compared to the Big Fun Lowthers....no small units either.
All fun though....
The shape of the pine box means my wife doesn't need to invest in a coffin...
...hence the love note I stuck on the front door prior to her returning home after it was built.
Note the size compared to the Big Fun Lowthers....no small units either.
All fun though....
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I downloaded the plans off of Volvotreter's tapped horn website, then made the appropriate external dimensional adjustments for the plywood. I kept the internal throat dimensions to spec, and I didn't want to mess around with the volume of the return side so that's why I used 3/4" ply for the baffle. It's very close in dimension to the MDF he spec'd out. Because of the plywood, the cab is a little narrower, a touch shorter, and a helluva lot lighter. I don't have cut sheets, but I could list the dimensions adjusted for the ply wood if you think that'd help. The problem with plywood is that it's sanded to dimension, not cured like MDF. That affects the dimensions here and there as not all plywood is of equal thickness all of the time.
If you're planning to build two to run together as a pair, the port ends should be placed together to avoid cancellations. If the cabs are lying down, stacked, the mouths can fire out into the room. You can get a little extra loading by firing the port ends at the wall, but you have to pull the stack away from the wall quite a bit (30cm or so) to keep them happy. That would take up some of your room. If you have the space for it though, I say give it a shot as this also would help filter any remaining harmonics from the driver.
More pics coming soon..slowly but surely.
P.S. -I don't recommend building cabs out of ACX plywood anymore. Use Baltic Birch, it's so much easier to work with in every way.
Rework is a PITA
That's what I get for blowing through a dry fit too quickly. My bracing on this side wasn't in far enough. When clamped down and adhered, the whole panel sat about 1 cm too narrow. I tried to spread it out to match it up to the side panel, but doing so fractured the glue seam about 10cm from the end of the bracing before even coming close to dimension. The solution was to "unzip" the bracing to relieve the stress, reposition the panel correctly, patch each cut in the brace, then re-glue the fractured seam. Acoustically and structurally the patches function as if the brace was never cut but it made for some tedious rework. It didn't help that this panel was warped about 15 cm end to end. It's all good now...waiting for cure, then I can move onto the side panel.
That's what I get for blowing through a dry fit too quickly. My bracing on this side wasn't in far enough. When clamped down and adhered, the whole panel sat about 1 cm too narrow. I tried to spread it out to match it up to the side panel, but doing so fractured the glue seam about 10cm from the end of the bracing before even coming close to dimension. The solution was to "unzip" the bracing to relieve the stress, reposition the panel correctly, patch each cut in the brace, then re-glue the fractured seam. Acoustically and structurally the patches function as if the brace was never cut but it made for some tedious rework. It didn't help that this panel was warped about 15 cm end to end. It's all good now...waiting for cure, then I can move onto the side panel.Attachments
It is PL Premium. That's why I almost crapped myself when I heard it snap. I thought I broke the panel knowing darn well how strong this adhesive is. Fortunately, the glue hadn't cured all the way through the joint. It was just the outer skin letting go near where I was clamping (where the panel was distorted the most). I figured something was amiss after that step when the side panel wasn't lining up at all down by the hatch opening, so I started to shuffle the joints before it was rock solid. Two or even three extra hours care getting it right before glue-up would have saved me the last three days work.
Repairs complete, back on track. Now it's onto getting the hatch framed in and securing the side panel (which is cupped beyond all belief ). Did I mention this thing is going to be feather weight? Even though it's measures in at a touch under 2.5 meters, it can't tip more than 15kg right now. 
FYI- Those patches on the braces are 1/16" 3 ply baltic birch...very stiff when it's orientated and bonded correctly. It's the type used for building RC airplanes. Awesome stuff. I'd build the whole cab out of hobby wood, but what a price tag that'd be.
). Did I mention this thing is going to be feather weight? Even though it's measures in at a touch under 2.5 meters, it can't tip more than 15kg right now. FYI- Those patches on the braces are 1/16" 3 ply baltic birch...very stiff when it's orientated and bonded correctly. It's the type used for building RC airplanes. Awesome stuff. I'd build the whole cab out of hobby wood, but what a price tag that'd be.
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The shape of the pine box means my wife doesn't need to invest in a coffin...
...hence the love note I stuck on the front door prior to her returning home after it was built.
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