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Discussion Starter #1
This design is a result of my search for a build that could deliver sub 20Hz frequency content at decent output levels on a budget of less than $500 including building materials and finishing.

After a lot of modeling and exploring different options, it is my opinion that there is no better budget sub driver out there than the Dayton RSS390HF. At $160 for a 15" driver with 14mm Xmax and low distortion I think it's a great deal. This driver has a very low Fs and therefore can be put in a ported enclosure that is tuned very low. It also requires very little power (relatively) to drive so amplification is cheap.

Here are the major design details:
  • 210 liters
  • 15 Hz tune
  • 250 Watts
  • 110 dB at 29 Hz
  • 104 dB at 15 Hz
Here are estimated costs:
  • Dayton HF driver = $160
  • 240-300 Watt amp = $150
  • hardwood plywood = $80
  • stain, paint, other finishings = $100
  • total = $490
The enclosure volume and port size may put this in more of a "quasi-LLT" category but I'll let the expert weigh in on that.

I used a 4" port because I haven't seen any 6" pvc available at the big box stores in my area. 4" seems to be the biggest they carry. It also allows the port length to be very manageable. Air velocity should be no issue above 20Hz. Could be an issue below there but I have a feeling I won't be able to hear it from the listening position. We'll see.

WinISD plots...

dayton15hfspl.png

dayton15hfexcursionl.png

dayton15hfvelocity.png
 

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Discussion Starter #2 (Edited)
Here are some pics from the box build...using birch plywood instead of mdf so I can stain without needing to veneer and to reduce weight

Box minus top with some of the bracing installed. Outside dimensions are 24"x24"x28".



Cutting out the hole for the driver...





Test fit of driver...



Here is with the port tube installed and bracing complete. Still no top. Amp will be contained in its own box separate from this one.

 

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Elite Shackster
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Your logic sound spot on, and Ive no doubt the end product will be fantastic value for money. Your build looks to be coming along well too :T

I'll be following with interest :yes:
 

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Discussion Starter #4 (Edited)
Gluing the top of the box on.... I wish I had more clamps. I used 8 but really needed at least 12. Probably not air tight but I will seal things up with silicone. That's 130 lbs on top to get the middle. Again, probably not enough but the results seems solid.



The top is on and the port hole is cut in the back...Notice the glue marks on the back panel that I failed to sand off. This will haunt me later when I go to finish. I've never done this before so it's a learning process :doh: At least its just the back panel.





Here is after the first coat of cherry stain. Now you can see how those glue marks are showing up.



 

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Discussion Starter #6
Nice job so far!! :T I really like your router template.

Matt
Thanks Matt,

Yeah, the funny part is that I had to drill like three holes before I got the one in position for the correct diameter. I kept forgetting to add half the bit diameter or something like that. Thank goodness I made test cuts on scrap before I went for the real cut! Other than that, the hole jig was super easy to build out of 1/4" mdf and a 1/4-20 bolt. I don't even have a plunge router and it works great. Just cut a little depth at a time and use a little vertical slop in the bolt.

Oh BTW, pics for your theater build are missing...
 

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Discussion Starter #7
Here is the box after a couple coats of Red Mahogany on top of the Cherry base coat. I'm going to start applying coats of polyurethane next and then I'll trim out all the edges so that the end ply is not visible and to give it an end table look.

 

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I like how it looks. I also like the concept. I'd been considering this design concept for some time. If I may be so bold as to ask for a cut list posted on the thread. I think this would be a wonderful option for our budget members.
 

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Discussion Starter #10
I like how it looks. I also like the concept. I'd been considering this design concept for some time. If I may be so bold as to ask for a cut list posted on the thread. I think this would be a wonderful option for our budget members.
Thanks, I'd be happy to post a cut sheet when I get the time to put one together. (and I wouldn't exactly call that a "bold" request :bigsmile:) I have some sketches on paper. Maybe I'll post those for the time being.
 

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Thanks, I'd be happy to post a cut sheet when I get the time to put one together. (and I wouldn't exactly call that a "bold" request :bigsmile:) I have some sketches on paper. Maybe I'll post those for the time being.
I appreciate it. I do suggest you try out the Dark Knight on your sub if you haven't yet.
 

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Discussion Starter #12 (Edited)
Attached is the cut sheet I used during construction. All panels should fit on one 4' x 8' sheet. I messed up one of my cuts so I had to buy another sheet to finish the panels. Cut all panels oversize except one so that overhangs can be trimmed flush with a router bit. See Collo's building techniques for help. Labels for BOTTOM and BACK panels are reversed (i.e. BACK should read BOTTOM).

View attachment cut sheet.pdf

Cut bracing from scrap. I basically made a windowpane looking brace out of six 3" wide pieces cut to appropriate length. Then I added additional eight more 3" wide braces that span from the windowpane out to the front and back panels.

For the port, I cut a hole in a piece of scrap that the pvc fits into. Then I glued the scrap piece in place inside the box so that the hole is in the appropriate place. Then I used liquid nails to glue the pvc outside diameter to the hole in the scrap piece and along the edge that sits against the enclosure panel. I positioned everything so that the port rests against the inside of the windowpane bracing and placed a couple dabs of liquid nails on the contact points so that the windowpane acts like a port brace. The last image in post #2 should help.

I haven't listened to this sub yet. I can't wait! Polyurethane is finishing up and then I've got to apply trim to the edges and install the connection terminal. Hopefully by this weekend I'll have this thing up and running.
 

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Discussion Starter #13
Well, sub is now 99% finished and I've got it in the house for some listening! This sucker goes so low it's really amazing. Of course, I'm coming off of a 10" sub tuned to 25 Hz so not a surprise that I'm amazed. I wasn't expecting a big SPL gain over my previous sub but this thing is just way louder. The ultra lows in LOTR are shaking everything hanging from the walls and I haven't turned it up to my normal listening volume yet because we have a new baby in the house.

OK, here is the finished product. Things that still need to be done: paint inside of table legs because I forgot that and some other minor touch ups. Overall it doesn't look too bad. Looks better in pictures. Definitely not pro quality. Plus I know where all my mistakes are and they really nag at me.



Here is the sub in my setup. It is so much more powerful than my "mains". Need to do a lot of tweaking to integrate correctly.



I plan on running REW as soon as possible and posting some graphs here. I'm really interested to see the kind of LF response I think I'm getting. Amazing what you can do with a large enclosure and a "large-ish" woofer for cheap!

This sub cost me about $400. I was able to use the plate amp from my previous sub. An Onkyo unit from 1994 that apparently has no HPF (from my listening tests). I had to spend a few extra $$ on wood and stuff because I made mistakes but this build is a real bargin.
 

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Discussion Starter #16
Cool trimming! Didn't expect that. Looks great in your place:T

The effects of increasing enclosure and driver size on bass production cannot be overstated.:hsd:
Thanks Glen, just got some molding from Lowes and slapped it on with a brad nailer. Like I said, not a real professional piece but the few people that have seen it in person were fairly impressed.

I played the first bombing scene from "letters from Iwo Jima" today. Impressive!!
 

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Discussion Starter #17
Here are a couple REW graphs to show the in-room frequency response. 1/3 octave smoothing on both graphs.

First, subwoofer only. I have a huge room mode at ~28 Hz, and this is after equilization.

avg couch meas 20100418.jpg

Next, out to 2kHz showing integration with my LR speakers. Nay too bad. I ended up turning up the gain on sub a little after this measurement for extra emphasis.

avg couch 15-2k hz 20100418.jpg
 

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Discussion Starter #19
Looks great for a budget build! Do you have any EQ device to get rid of the 28hz peak? Like the BFD, AntiMode?
Thanks! I have the BFD and the curve I'm showing is after equalization, believe it or not. I only had time Sunday to give it a go with REW's initial suggested settings. Can't remember the filters off the top of my head but I know there are some -12 dB ones in there already. I'll have to play with it more but not sure the peak bothers me that much right now. I want to set up a house curve as well in the future...
 

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Discussion Starter #20
I also need to try moving the sub a bit. I can't really change the location much but maybe rotating it 90° will do something. This weekend I might have time.
 
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