My build of ZaphAudio 2 cu.ft Dayton RSS 12" HF Sealed Sub
Hi There! I'm new here, and many would say I'm a speaker noob. But despite not having done a speaker project before, I feel very comfortable with all kinds of tools and techniques, and I've built plenty of electronic projects and pieces of furniture, so I'm jumping in to build a sub for HT/music.
I've been lurking here and there for months, planning My First DIY Project (tm). After much research and thought, and a little advice from PE Techs, I've landed on using the Dayton Reference Series HF 12" driver, and the 500 W Dayton plate amp to build the Zaph Audio 2 cu. ft. sealed sub. I originally wanted to try the Drake, but I was seeking a little lower extension, so wound up here.
And while I'm comfortable plunging in, I do have questions. I'm carefully adapting the design to use 1" MDF as in the Drake, and while comparing that to the pictures in the archive zip file, something is bothering me...
If you look at this picture, there clearly appears to be an MDF panel on the inside back, sealing off the amp cavity from the rest of the sub. The speaker wires are poking through it. This makes some sense to me, especially considering the Drake design.
However, I'm confused by the amp area in the schematic (the screenshot of the .pdf below). In the rear view, there appears to be a panel there that closes it off. But in the side view, there doesn't seem to be a piece that will seal the amp housing from the rest of the cabinet. For one thing, the depth of the amp housing (4.5") plus the back panel (3/4") appears to be the same as the depth of the amp itself (5 1/4"), allowing no room for a 3/4" panel to seal it off.
Is it necessary to seal the amp section off from the rest of the cabinet, as in the Drake design? If not, why does that picture seem to have it sealed off? And further, if it is sealed, that doesn't seem to be taken into account in the box volume calculations. Is this right?
John Krutke doesn't seem to be accepting email right now, and I realize I'm probably making too big a deal of this, but any insight you have would be appreciated. Thanks in advance!
Yes, the closed area would need to be accounted for in terms of volume. Yes, if possible, it's good to keep it closed. If I were you, I'd close it, as you're doing one heck of a build on it, it seems. No sense wimping out now! A sealed box, fortunately, doesn't tend to be as volume-critical. I'd just close it up, and finish as normal.
Should I adjust the design?
Thanks Badman. I agree that closing it off is the best idea, but I'm trying to decide whether I need to go to the trouble of adjusting the internal volume to compensate for the additional panel required.
Based on the picture of the sub and the design, I believe there's a minor error here; there is supposed to be a panel that seals of the amp cavity there and it isn't accounted for in the box volume calculations. Also, I believe I've found another couple minor errors resulting in a difference in the box volume:
1) As discussed, the amp cavity cover panel shown in the picture is missing from the design diagram and volume calcs. This equates to approximately 0.06 cu ft.
2) The front baffle brace volume calc is missing. The volume of the 1 1/2" x 3/4" pieces at the front of the cabinet equate to approximately 0.04 cu ft.
3) According to PE Tech help, the driver volume is 0.134 cu ft., not 0.06 cu ft.
This means that the real box volume is approximately 1.89 cu ft. instead of 2.07 cu ft.
This equates to almost a net 10% reduction in box volume. What effect will that have? Will I lose some low end extension if I don't adjust for this?
Or am I being too analytical about all this?
You're worrying a little too much. 10% will effect a relatively small change in a sealed box. With a vented box, tolerance is more critical to get effective tuning. But 10% shouldn't be noticable.
Re: Should I adjust the design?
2)Also deemed insignificant.
3)when I calculate driver volume, I basically calculate a cone, cyclinder (for the magnet) and throw in a bit extra for the frame. But note however that a good portion of this driver's volume has to be added back in because the baffle is 1.5" thick. Some of the cone volume taken up is inside the baffle, not to mention the hole through the baffle adds a little more effective volume.
All that said, this kind of volume calculation is way overkill and I just do it because I am a perfectionist bordering on a compulsive obsessive disorder. (or so my wife says) All you really have to do is get close and it's a maximally flat alignment, and even if you're off high or low, the parametric EQ can compensate.
(poof, I'm gone.)
Thanks for the help...
I understand why you don't accept email... and I don't blame you! With your experience and designs out there, I'm sure there's quite alot of questions out there that get directed your way.
Thanks for taking the time to school a newbie on this... Obviously I too, lean to the obsessive regarding these types of calculations. I wondered about the how the driver volume calculations were affected by the baffle width, so that's interesting.
I guess I'll push ahead, and start making sawdust! I'll continue to use this thread to post my progress and results.
Build progress update 1
Hey all... I've made some progress on my build:
Over the last two weekends, I
1) cut and laminated my 1/2" mdf pieces to create 1" thick oversized blanks for the sides.
2) cut out the braces and the amp cavity pieces
3) cut the side pieces to final size; I'm using miter joints all the way around, so this design had to be modified slightly for the joinery.
I also glued up the back panel with the amp cavity pieces and cutout the amp recess.
After a short delay I'm now planning the best way to glue up most of the cabinet, cut the driver opening, and complete it.
I'll post a few more pics tonight.
good luck, and don't forget you are obligated to post pictures when you are are finsihed ;)
Build Progress 2
Hi all, I'm back, and I've had a fairly productive weekend...
Some say I'm way to OCD for most people, but I will admit to being an obsessive planner. I spent a long time thinking about the glue up of the subwoofer cabinet, figuring out the best clamping arrangement to allow me to do it 1) accurately and 2) without any help.
I'll remind you that the cabinet is mitered on every edge, so this makes the glue-up extra involved... The way MDF develops a fuzz on a cut edge makes it extra "grabby" so it doesn't always go together right. Add to that the fact that you need two hands to close a clamp, and I was envisioning having a very hard time getting six panels to go together right and not have a glue soaked mess...
I'm happy to report that I figured out what I think is the best way to do it.
Normally I wouldn't go into this detail, but since I spent so much time on the net trying to find details of construction for speaker building, I feel obligated to share my experiences. Here's my (reasonably) brief description of the process:
1) Beginning with three panels (back panel with Amp housing, bottom panel, and the top panel), dry fit them together. Set the Top and Bottom panels in place over the Back panel lying on its back. Clamping the top and bottom panels against the Amp housing braces creates the right 90 degree angles to avoid having to clamp up all panels at once.
2) Glue only one of these two panels along one edge (bottom to back, or top to back) and against the Amp housing braces. Clamp against both panels to get the best possible fit and confirm with accurate squares and measurements. When dry, glue the other panel the same way.
3) Now dry fit the rest of the panels to ensure they will fit properly. Once satisfied with the fit, glue only one of the two side panels along three edges (against the top, back, and bottom). Keep the remaining two panels in the glue-up (front baffle, and one side) dry to ensure they all fit properly. Use painters tape on the corners where three panels meet to prevent glue seepage from sticking. Use a couple pieces of tape around an edge as handles to pull the front panel out when dry. When dry glue the other side panel the same way.
4) Remove the front baffle, and seal the interior joints with polyurethane. Seal the amp housing joints the same way. Add the cabinet bracing.
Next on to the routing of the front baffle to accept the driver!
I've taken pictures most of the way through, but still have to convert them down to a smaller size, and host them so please bear with me...I'll get there.!! :)
All right everyone... I promised pics and here they are. I've spent some time getting them hosted and posted... I've always wanted more details when searching for DIY projects on the web, and I like how-to's with lots of pics, so I hope I'm not boring you with my simple noob subwoofer cabinet build, but I wanted to document it as I go...
On to the pics!!
Panels cut to rough size.
...cleanup that workbench! My design tweaks call for an 18.5" cube on the exterior, with 1" thick panels. Beefy!
Laminating the panels and braces.
The panels are two 1/2" pieces of MDF glued up. I had only 3/4" lumber to work with to make braces, so had to laminate pieces together to make them 1.5" thick.
More panel laminating.
Panels cut to final size, with mitered edges.
I'm very happy with my table saw...once I ran a couple test cuts, I had a perfect miter joint. It does a great job.
Gluing the amp housing to the back panel.
Prior to gluing, I used the table saw to cut up through the back panel, and finished up with a hand saw to cut the square opening for the amp cavity. The top and bottom of the H-brace will be glued against the top and bottom panels. This will make it much easier to align the miter joints and get good, square joinery.
Panels ready for glue-up.
It took me a long time to figure out the best clamping arrangement, and alot of dryfitting, but it was worth it when you look at the final product...
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