Dual opposed Dayton rss315hf-4 subwoofer build

[Scareurpasenger]

So, first off this is my first build and I expect to build a few sets of speakers this year. I am also an amateur woodworker but plan on being more active as I finish building out my wood shop and have some more free time.

I started out with the intentions of building a single sealed driver sub using the Zaph design but decided I could get away with something bigger in the place that I was allowed to use. It will be located behind the couch and nestled under a table. I know location makes a big difference but this is what I have to work with. Using Unibox, I calculated out what the inside dimensions needed to be for 2 drivers to have a similar but better response as the single driver design. The amp will be external and I am considering using a 500watt mono block ice power amplifier. I hope it will be enough.

Now to the sawdust. Decent progress and some minor adjustments to how I want to finish it with recessed binding posts on the bottom, 1.5" radius corners, walnut veneer and grills to protect from the kids. Attached pictures show the progress so far. I am pretty close to the veneer stage but will need to join a few sheets together to get a full wrap.

Main box without baffles.

Baffles dry fitted.

Chamfering the back side and adding the nuts.

Glue up.

[technodanvan]

The presence of all those clamps suggest you're a bit past being an amateur!

[Carl V]

The presence of all those clamps suggest you're a bit past being an amateur!

8O and the machines in the background...table saw etc.,
regardless, looking good, keep us up to date.

[Scareurpasenger]

The presence of all those clamps suggest you're a bit past being an amateur!

Tools don’t mean much! Most of my work has been home improvement up until this speaker. I justified the tools by planning on building my cabinets from scratch. Not done yet but I might make some progress with upcoming time off work.

[jeanpher]

Great start, Good luck!!!

If you don't mind, can you please share the missing details, box size, frequency response, etc.?

[Bear]

The presence of all those clamps suggest you're a bit past being an amateur!

....and the interlocking joinery.

On a more serious note, the main mechanical stresses will be on the baffles. You might want to retrofit (if they aren't already coming) bracing to mechanically link the front and rear baffles together. It doesn't need to be a lot (2" strips are about the sweet spot), and they would work best glued perpendicular to the rest of the cabinet walls (i.e., like a lip for a shelf or a truncated I-beam).

The Dual-Opposed concept works very well, but a mechanical assist here and there is even better.

[Scareurpasenger]

So, being new at this, I never saved off my original calculations. I went ahead and recalculated based on what I had for dimensions and it may have exposed an issue in my original calculations. Unibox also doesn't seem to agree with the parameters Zaph had. It calculates the QTC lower than what his target was.

So here is the Zaph plots for a single driver unit that got this started.

This is what I had for the modeling result from Unibox for the dual driver configuration.

This is what I input for the parameters.


So, what to do next? Should I have gone smaller on the box?

[Scareurpasenger]

....and the interlocking joinery.

On a more serious note, the main mechanical stresses will be on the baffles. You might want to retrofit (if they aren't already coming) bracing to mechanically link the front and rear baffles together. It doesn't need to be a lot (2" strips are about the sweet spot), and they would work best glued perpendicular to the rest of the cabinet walls (i.e., like a lip for a shelf or a truncated I-beam).

The Dual-Opposed concept works better, but a mechanical assist here and there is even better.

Hmm, I figured being 1.5" thick, close to the side edges and having the extra lips glued in there it would be fine.

[JonMarsh]

Short answer, no. Possibly larger- it all depends on the amplification setup you plan, but lower Qts just means the transient response will be a bit better damped, and you may need a bit of EQ to "level things out".

Now, an interesting thing is that you are doing a dual driver sub, with the HF-4 version, whereas I have a system design that is more for a woofer with extended bottom end and output capability using two RSS315HFA-8 - this driver has somewhat different T/S parameters and of course, 8 ohm voice coils I can wire in parallel for a 4 ohm speaker load.

Let's look and compare with the Isiris build, in which the Daytons were chosen to replace Auradound 4 ohm woofers.


First, the working pane for the sealed design:



This shows that for these drivers, and the desired Qtc of 0.6, a "standard design" would need a box volume of 111.2L, and that's pretty close to the actual cabinet volume of 115L, and the other parameters are entered based on the "as built" characteristics, including heavy fiberglass fill.


And the calculated response profile:



This is the level produced with a total of 40W input power, calculated from the RMS voltage into a resistive load (which the driver isn't), and the calculated F3 is 38 Hz, pretty much on the money as with the Aurasounds, with a box Fb of 34Hz. Things are pretty much loafing along to produce 103 dB SPL, and there is headroom for a single cabinet to produce 110 dB at 30Hz at Xmax. But these are stereo speakers...

The Fb is shown with the impedance peak in the impedance profile:


And the calculated impedance profile:






And for comparison, the measured impedance profile:



Which shows the Fb is more like 32Hz than 34 Hz, which is what I was hoping for all along.

Do you already have your HF-4 drivers? If not, and if your driving arrangements permit, you might want to consider the RSS315HFA-8.

[JonMarsh]

BTW, I like the idea of push-push force cancelling subs! Good way to go for a sub build.


:T

[Scareurpasenger]

Yeah, I pulled the trigger on the 4 ohm version a while back thinking I would be doing a single driver. 2 ohms running parallel might not be an issue for the ice power amplifier I have but that is something I could experiment with. I decided to Mae it easy by exposing all 4 hookups externally.

[Scareurpasenger]

Where did go wrong with unibox? I can’t seem to get those numbers to work.

[Bear]

Hmm, I figured being 1.5" thick, close to the side edges and having the extra lips glued in there it would be fine.

You've got fairly extensive bracing on the side walls, but with a subwoofer that will likely be crossed <100Hz, you are looking at very little energy (3rd - 5th harmonic, at best) that excites the sidewalls. The bracing will help with the "knuckle" test, but in practice there won't be a lot of energy there from your content. In other words, you should hit the sweet spot for overkill there.

Your sub box is proportionately tall, though. If you are really looking at driving these things hard, then a 2" - 3" lip that is perpendicular to your top and bottom walls that connects your front and rear baffles with the rest of your bracing structure (looks like you'd need three sections for each wall) would get you to overkill by breaking up the length of unsupported baffle. If you are happy with your test fit, though, then go with what you've built.

As far as Unibox goes, you probably don't need the 0.2 ohms of resistance in the model unless you are running a long length of copper between the ICEPower module and the woofers. Given the applied power, I'm guessing that you've got a 1000ASP module? The Unibox model is showing 500W applied (the power is per driver) with the drivers wired in series. That's an 8 ohm nominal load, and it will affect the overall model a fair bit (so will the series resistance).

[Scareurpasenger]

I decided to pull the trigger on a crown xls 1502 since the price was right. That should be enough even at 8 ohms. I have enough msg to create some vertical trial braces but I am not sure how much it will help.

I guess I need to model a the 8 ohm version of the woofer just to see how it differs. I was thinking my calls were off but it looks like the 8ohm version models a bit better?

[JonMarsh]

Remember, all the different versions have somewhat different T/S parameters; the HO are nominally optimized for small enclosures (I think car audio when I hear that term) and the HF for larger enclosures. Interestingly, the HF usually have a longer throw VC... but cone mass and compliance vary too, and the HFA version is not the same as HF. HFA is a relatively newer part.

I like to use the verbiage that they model differently, and whether it's better or not depends on your usage case. Also, remember, a small amount of EQ can see you through in leveling out your LF response. And that can be as simple as something like an inline filter as described in the voicing filter thread, but adapted to low frequency by changing the capacitor and resistor values.

you've got options... take a deep breath, and just keep investigating.

[rick844]

I have a crown running my sub. I like it. Stays cool and very quiet.

[Scareurpasenger]

So, it looks like I made some notes on what my original input parameters were and they are quite different for the driver. The parameters from PE were not as accurate from what I recall and I seem to recall using DATS to verify.
This is the updated model.


As well as reviewing my modeling, I did pickup some walnut veneer to wrap the enclosure. Using a 1.5" radius round over router bit is a bit scary and barely fits into my router. 2 edges are complete and 2 more to go. I will also ass in some triangle bracing toward the baffle as sugested.

I also plan on creating some frames for the speaker grill that will attach via magnets.

I purchased some SVS subwoofer feet and self tapping inserts designed for mdf. In a couple experiments, it ends up splitting off some of the mdf upon inserting at several different predrilled hole sizes. How does one avoid this and do you you veneer and then add the inserts or add the inserts and veneer?

[technodanvan]

Yeah, those big router bits can get scary...I did the same thing yesterday. I really prefer using those large bits in a table router, but sometimes that just doesn't work. I also only did half the edges I needed to do as the router and bit were both uncomfortably warm (and my hands were tired).

[CADman_ks]

...

I purchased some SVS subwoofer feet and self tapping inserts designed for mdf. In a couple experiments, it ends up splitting off some of the mdf upon inserting at several different predrilled hole sizes. How does one avoid this and do you you veneer and then add the inserts or add the inserts and veneer?

I don't recall what feet I used when I built my sub, but the inserts that were provided with them did bulge up the edge right around the insert. Luckily for me, I had predrilled the holes in the panels before veneering, so I was able to simply sand or chisel off the area that bulged up.

I wouldn't worry too much about it though, since the foot will cover up all that area. I think that the key is to just get it flat, so that the foot is sitting on a flat plane...

[Bear]

Using a 1.5" radius round over router bit is a bit scary and barely fits into my router. 2 edges are complete and 2 more to go. I will also ass in some triangle bracing toward the baffle as sugested.

You're undoubtedly already doing it, but definitely step into the big cut. For mine, I use a 3/8", 5/8", and 3/4" before bringing out the big guy. I am almost exclusively using LBL these days, so I have a fair bit of tear-out to "fix in post" (aka sanding). I have tried a few different patch methodologies, but sanding, sanding and more sanding seem to provide the best remedy. Make sure that there aren't any bumps or divots where your bearings will ride -- especially divots -- or those will telegraph to the machined edge.

For MDF, tear-out is much, much less of an issue, but you do have some risk for delamination -- but that risk is largely due to handling the cabinet. Be sure to have enough table surface to properly support the cabinet, and definitely use a table mounted router, rather than freehand. For freehand, I'd go with "scary" as the right descriptor.

[Scareurpasenger]

Yeah, I have been stepping up the round over size for each pass and even raising it a bit for each pass when bringing out the monster. I also am not going to the edge. That should reduce tear out enough. The final profiling is done on the face of the cabinet with a flush trim on the edges to match the round over profile. I already made the mistake of trying to get to the absolute edge and had to do some patching.

I guess I will add the threaded inserts first using a jig for perfect placement that I can use again to go through the veneer later.

[Steve Manning]

Another "trick" is to cut a 45 chamfer on the table saw prior to using the router. That way you remove the bulk of the material and the router bit is just doing clean up duty.

[Scareurpasenger]

Yeah, that is a good trick! I just need to build a decent outfield table so I can handle larger items. I tried to use the router table but this box is way too big for that!

On another note, I am very glad I picked up a couple sheet of baltic birch earlier this year. Prices have finally gone up on it. I paid $55 a sheet and it is $115 now!

[CADman_ks]

...

I guess I will add the threaded inserts first using a jig for perfect placement that I can use again to go through the veneer later.

While a jig is not a bad idea, you just really need to know what the location of the insert is from the outside of the box. I just measured in say 1.5" (I don't recall the exact dimension I used) from the edges, put a mark there, and then I used an X-Acto knife to trim out the veneer so that I could get the threads for the feet in. Once I had it trimmed up, I used an oversized bit by hand to put a finishing chamfer on the veneer.


As long as everything in that area is flat, and your feet cover it up and trimming that you do that might get out of hand, it will never be visible...

[rick844]

Curious, how is the build going?

[Scareurpasenger]

Threaded inserts added for the feet. Used the jig and glad I did due to not using brad point bits. It wanted to wander a bit. I am slowly replacing all my harbor freight bits with better ones but the size needed was unusual.

Round overs complete as well. I had to rework the edges on half due to the trim router base being so small and the bit not staying perpendicular to the front edge. Using the router table on those may be harder but is far more accurate.

Bracing added top and bottom. Glued in and pin nailed to hold it as it dried.

Next up will be more cleanup from the patches and giving it a nice smooth surface to prep for the walnut veneer.

Being new to woodworking, I am learning to dial in the tolerances and some of the issues when using a router.

Finding time and waiting on the patches to dry has taken some time. I can’t blame it on the 1.5 month old

[theSven]

How is the build going? Were you able to complete this build Scareurpasenger?

[Scareurpasenger]

Still need to add the veneer and wire it up. I misplaced one of the threaded inserts so I may have to correct that section. Home project take priority and I have a laundry room remodel underway. Moved the washer and dryer, knocked out a wall and put down new tile. I need to build some cabinets and install the sink/countertops.

[theSven]

Still need to add the veneer and wire it up. I misplaced one of the threaded inserts so I may have to correct that section. Home project take priority and I have a laundry room remodel underway. Moved the washer and dryer, knocked out a wall and put down new tile. I need to build some cabinets and install the sink/countertops.

I can relate, it took me 3 years to get the dedicated room for the theater. That required moving the washer and dryer to the other side of the basement, plumbing changes, electrical changes, and I still need to finish the drywall where the washer and dryer ended up.

Thanks for checking in though, and enjoy the woodworking time with building the cabinets. That is something I have wanted to do, but will most likely order cabinets from Lowes. It's always time these days. As JonMarsh tells me, slow work takes time 😂.