Sanity check sonotube sub DIY project

[ThomasW]

You better clarify because typically a 'bolt' of fabric is many yards long.

[HMenke]

I finally contacted them. Their web form doesn't work but their email does. A "bolt" is one yard and if you order (3) yards you get a continuous piece. Not a bad price.

What do you guys use to seal the MDF before painting? All the sealer-primers I found at HD were white. Seems like a clear or gray sealer would be better under black.

What are your thoughts on gluing the end plugs vs. making them a tight interference fit without glue?

[Paul H]

You can get them to tint your sealer gray or black, which could potentially save you a coat or two for the finished product.

Paul

[ThomasW]

What are your thoughts on gluing the end plugs vs. making them a tight interference fit without glue?

I use a round-over bit to ease what becomes the inside edge. The fit is snug. I grease the edge of the endcap with acrylic caulk to make it easier to slide it in place.

Once in place I use more caulk or liquid nails for final gluing by filling the notch created by the roundover bit between the edge of the end cap and the wall of the tube .

[HMenke]

You can get them to tint your sealer gray or black, which could potentially save you a coat or two for the finished product.

Doah! ops: I saw that some of the cans were labeled "dark tint base" but since they also said "white" it threw me off. Great idea Paul, thank you. I am going to try textured black spray paint as my finish. wrz0170 used it on his box sub and I think it looks outstanding. Only problem is that it seems to be out of stock at both HDs in my area.

I use a round-over bit to ease what becomes the inside edge. The fit is snug. I grease the edge of the endcap with acrylic caulk to make it easier to slide it in place.

Once in place I use more caulk or liquid nails for final gluing by filling the notch created by the roundover bit between the edge of the end cap and the wall of the tube .

I had an idea to use my 1/8" roundover bit to do exactly as you suggest. I like the idea to create a fillet of caulk or glue by filling the notch. Is this hard to do to the port (top) end? It seems the caulk has to be in place first because this area is inaccessible from the other end (55" away).

My Soundsplinter RLp-15 driver arrived by FedEx today! What a beauty! The quality of the build definitely exceeds my expectations. You have to see this thing to believe it! My wife thinks I need to be committed. I quoted Harrison Ford in his '55 Chevy from American Graffiti: "Baby, you'll be hanging on for dear life once I get this sucker rollin'!" :twisted:

I do have a question based on ignorance: what is the purpose of the rubber surrounding the magnet structure?

Another question: I bought this bi-amp terminal from PE:

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-304

I'd welcome suggestions on how to best mount it to the side of the tube.

I spent the afternoon making brackets for my Samson S700 amplifier. I am mounting it vertically on the wall in the corner behind the subwoofer. The primer is on it and the top coat will be applied later tonight. I'll post pics when done. I am also waiting for my solid state relay to arrive. I am going to split an existing duplex outlet in the sub corner and make one of the outlets switched by the relay to power the amp on/off with the receiver.

It has been raining in my area a lot. I need a nice clear day to go get my Sonotubes and MDF!

Henry

[ThomasW]

I do have a question based on ignorance: what is the purpose of the rubber surrounding the magnet structure?

Cosmetics, remember this driver was developed for car audio.

I use a pair of the single small terminals mounted on the end cap. Some go to all the work of installing a little box on the side of the tube. That's way too much work in my world..

Visual aid Home

Is this hard to do to the port (top) end?

Install the port endcap first, that way you can access the notch from back side with a caulking gun and long arms. Then install the driver endcap. That way you have the large opening to work with last.

BTW, you might want to use a 3/8"-1/2" round-over depending on how thick you endcaps are...

Visual aid Forum

[HMenke]

Install the port end first, that way you can access the notch from back side with a caulking gun and long arms. Then install the driver endcap. That way you have the large opening to work with last.

BTW, you might want to use a 3/8"-1/2" round-over depending on how thick you endcaps are...

Gives new meaning to the phrase "tunnel vision"! Actually that psychs me out a little because I'm somewhat claustrophobic! I may have to consume a couple barley pops before I stuff myself up inside the tube!

I am a little surprised that the port is not installed in your "visual aid". I had been thinking about making the entire upper end assemlby and then dropping it into place.

[ThomasW]

I may have to consume a couple barley pops before I stuff myself up inside the tube!

Unless you're only 3' tall I think you can use a caulking gun and simply reach in....

I had been thinking about making the entire upper end assemlby and then dropping it into place.

Pete wanted a fancy oak top. I wanted to do that separately from the actual MDF endcap .So the oak top was was fabricated up, stained, and finished. Then glued down to the MDF endcap. The port was then glued in.







Obviously yours will be different since you're using the wood to make the flare

You could dado (rabbit?) the backside of the top and put the port in the dado from the bottom after the top is finished.

I attached a picture just for you...:wink:

[HMenke]

I use a pair of the single small terminals mounted on the end cap. Some go to all the work of installing a little box on the side of the tube. That's way too much work in my world..

I thought either A) people use a thick gasket or B) they make a little box. I think I will go the little box route - I don't mind making little stuff out of wood.

You could dado (rabbit?) the backside of the top and put the port in the dado from the bottom after the top is finished.

I'm planning to make a hole in the plug the OD of the port tube and a hole in the end cap that is the ID of the port tube. What I like about this is that I can get a good seal where the end of the tube butts to the bottom of the end cap.

I attached a picture just for you...

8O Excuse me while I phone my therapist! :lol:

[HMenke]

I see that the RLp-15 has another rubber ring all around the outer mounting flange that looks to be the main gasket. Do you guys use additional gasket material? Do you use the included rubber gasket at all?

I measure the bolt circle at 14-5/8" diameter. Is this correct?

[Bent]

my first RL-p's rubber ring didn't fit very well (the holes were not aligned well at all, so I couldn't make it fit on the enclosure), so I used a piece of 3/4 inch wide closed cell sticky back weather stripping stuck to th mounting surface of the friver - worked slick.

[HMenke]

my first RL-p's rubber ring didn't fit very well (the holes were not aligned well at all, so I couldn't make it fit on the enclosure), so I used a piece of 3/4 inch wide closed cell sticky back weather stripping stuck to th mounting surface of the friver - worked slick.

Yeah, I noticed that the holes on mine don't line up very well either. I can live with that, but the material seems a little on the hardside to make a good seal against MDF. I think the closed cell foam stripping sounds like a good idea. Maybe a high density foam is in order.

[Bent]

OMG, my spelling sucks!

(or my fingers are fat, or my keyboard is sticky...)

[HMenke]

Bent, should there also be some sort of a ring around the outside of the surround to take the pressure of the screws? It seems like there should be a positive clamping of the surround and it shouldn't just rely on glue and eight little screws to keep it in place.

[ThomasW]

The rubber ring can be rotated to align the holes.

Mark Seaton takes me to task for removing the rings.....

But I find them a PIA. So I pull them off and use closed cell neoprene weather stripping tape to seal the frame to the endcap.

it shouldn't just rely on glue

NO GLUE, NO CAULK or anything else with adhesive proprieties should be used to seal the woofer. Use 8 screws and foam tape. If you glue the driver in you'll regret it 15 min later..... 8O

[HMenke]

NO GLUE, NO CAULK or anything else with adhesive proprieties should be used to seal the woofer. Use 8 screws and foam tape. If you glue the driver in you'll regret it 15 min later..... 8O

Right, I was talking about how the rubber surround is factory-glued to the basket. Doesn't it seem like there should be a metal compression ring on top to "squeeze" the surround and clamp it against the basket? Or is the surround glue really that good that it can handle the pressure and movement of the woofer?

[Bent]

Yes, the surround glue is that good - but try to use the smallest head mounting screw you can get away with, as I've seen the screw heads "wind" the rubber or foam surround material up a bit and negate the effectiveness of the glue in that immediate area.

The hex socket head screws I use to mount the driver don't have a large shoulder at all, the unthreaded portion just fits, and the shoulder (flange?) doesn't upset the glued portion of the surround at all.

Image not available

my driver-enclosure seal is obtained with the closed cell foam.

[HMenke]

SoundSplinter RLp-15 driver CAD file

I drew a 2-D AutoCAD LT 2002 file of the SoundSplinter RLp-15 driver from measurements off my unit, but I can't upload here due to the filetype. I have included a .jpg of the CAD file here so you can see what it is. If you would like the CAD file, just email me or PM with your email address.

Edit: I have made the CAD file available for download here:

http://home.insightbb.com/~henry.menke/RLp-15_driver_3_views.dwg

I did this because CAD is not available from SS and the measurements given on the website are fairly basic. I am using this CAD model of the driver to drop into my sonsub enclosure design to help me make the right cuts to mount it.

This drawing does not include the rubber ring that goes around the mounting flange. The rubber ring is kind of a pain because it doesn't line up with the mounting hole and also I find it strange that it touches the surround a bit in places.

[HMenke]

Yes, the surround glue is that good - but try to use the smallest head mounting screw you can get away with, as I've seen the screw heads "wind" the rubber or foam surround material up a bit and negate the effectiveness of the glue in that immediate area.

The hex socket head screws I use to mount the driver don't have a large shoulder at all, the unthreaded portion just fits, and the shoulder (flange?) doesn't upset the glued portion of the surround at all.

my driver-enclosure seal is obtained with the closed cell foam.

I see what you are saying: the small head just snugs down against the metal and doesn't even attempt to compress the rubber surround material - pretty clever! Thanks for the tip - I feel much better now!

Here is a picture of the mounting hole so others can see what we are talking about.

[ThomasW]

If the driver is a snug fit into a recess, then the stock rubber rings work fine.

DO NOT torque down the screws too much. The driver frame is cast aluminum and will crack when too much torque is applied ...... (been there done that... ops: )

[Bent]

good advice, Thomas.

[Jack Gilvey]

DO NOT torque down the screws too much. The driver frame is cast aluminum and will crack when too much torque is applied ......

I also like to tighten them evenly, going across the driver torquing opposite pairs a little at a time (as opposed to going around the perimeter sequentially tightening each one all the way).

And, as mentioned, don't even use caulk. That black stuff PE sells will not come off, gets everywhere. They make black weatherstripping, closed-cell stuff, that's perfect.

[HMenke]

DO NOT torque down the screws too much. The driver frame is cast aluminum and will crack when too much torque is applied ...... (been there done that... ops: )

Thanks Thomas for that advice - man I would be bummed if that happened to me!

Jack I saw that PE closed-cell foam and wondered about it. Glad to get positive feedback on it.

[HMenke]

Amp is installed and ready to go

Here is my Samson S700 wall-mounted in the corner and ready for me to get this sub built and connected!

[HMenke]

solid state relay remote amp on/off

Here is the AC input/AC output solid state relay that I will use to remotely power the sub amp on/off from a switched outlet on my receiver. It will be mounted in a metal electrical box near my equipment rack.

A two-prong plug wire will go from the receiver 120VAC switched outlet to terminals 4 and 3. A three-prong grounded plug wire will come from a 120VAC wall outlet. The hot leg will go to terminal 1. The neutral leg will be wire-nutted to the white wire of a piece of Primetime A/V romex. The black wire of the romex will be connected to terminal 2. Then ground wire from the three-prong plug will be bonded to the box along with the ground from the romex.

The romex, carrying the switched 120VAC, will be run to an outlet to power the sub amp.

[HMenke]

Well this is the first clear day here for a long time, so I just got back from picking up my "Sonotube". Turns out it is not the Sonotube brand but a generic type with no brand name. I ended up with 24" diameter as they didn't have the 22" I was looking for originally. Just means my sub will be 7" shorter than originally planned.

I was a little surprised at the wall thickness. I haven't measured but it looks to be only about 1/4". Is that sufficient? I was expecting maybe 3/8" - 1/2". If 1/4" is marginal, I may put in a circular bulkhead in the middle for reinforcement. Might attach it to the "free" end of the port and cut a pattern of holes around the perimeter of the bulkhead for air transfer. Such a bulkhead might have an added function to help support polyfill in the upper end of the enclosure and prevent it falling down toward the woofer.

[ThomasW]

All the concrete tubes are roughly 1/4" thick, and that holds hundreds if not thousands of lbs of concrete. So bracing isn't necessary

[HMenke]

Thanks Thomas, I feel relieved. I was wondering how I would explain to my wife that I just bought a big tube that I couldn't use after all.

The place I bought the tube had a neat cutting jig. It was a "V" bed of rollers so you could lay the tube down and spin it. Then underneath was a circular saw that could be raised up until it cut the tube. Once the cut was started, they just spun the tube to make a straight cut. I went ahead and had them cut the 24" to exact length, but I bought 4' of the 8" port tube so I can decide later what exact length I want for it. Total cost for both was $40.

[ThomasW]

That's the standard way to cut the bigger tube. And yep those saws are nifty.... :T

As I'm sure you've discovered the larger diameter tube is a bit on the flexible flyer side when unsupported. It will stiffen up significantly once the endcaps are in place.

The 'Achilles heel' of the tube is that it can 'bruise' from an impact. That's one reason I opted to use real carpet for Tube-Zilla. The thickness/density of carpet makes the tube much less susceptible to impact damage.

[HMenke]

You're reading my mind! Yes the tube seems to flex more than I expected. My perspective may be affected by the 5" dia. shipping tubes we use where I work, easily 1/2" thick to remain stiff even at lengths out to 20 feet. But...they are heavy!

This tube I bought for the sub looks to be wax coated. I imagine that should be removed with solvent or by sanding prior to wood gluing and caulking?

I read your comment in another thread about your preference for carpet and I agree it sounds like the way to go. I already ordered 3 yds 72" wide "speaker carpet" for $10 / yd. The circumference of a 24" dia. tube is about 24*3.14 = 75" or about 2.1 yds so I should be good to go. Do you think the carpet has any additional function to dampen the tube?

I'm now thinking that I can probably cut the 8" port tube nice and square, almost the same way they did at the supply house, on my table saw.

[ThomasW]

The inside is usually coated with a very thin plastic film so water isn't absorbed. I just leave it alone, others have peeled it out. The solvent based Liquid nails adheres to it without problem. I've not seen a wax coated outside, but that wouldn't surprise me.

Once you have the endcaps in, you'll find the tube is inherently self damping and surprisingly 'dead' of resonances.

[HMenke]

sonotube is in the house!

OK, will do!

Now the sonotube is actually in the house, and all members of the family are filled with a mixed sense of foreboding and awe...yes, Dad really is a lunatic!

[J-Dub]

ahhh... I love that feeling!...

[J-Dub]

If you want to "peel" out the plastic coating you can do just that...

start at the top grab a little corner with your fingernails and PEEL it all the way to the bottom.

At first I did it for the same reasons you are thinking. Then Thomas said it wasn't necessary so now I just do it for fun! It's kinda like one of those little stress relief balls where the eyes pop out of socket 8O :B

[SteveCallas]

...yes, Dad really is a lunatic!

:B

It looks like in that last picture the edge of the tube is a bit frayed. To help get the end caps in easier and not risk smashing the edges anymore, I found wrapping strips of tape from the inside to the oustide, over the edges, compacts them and makes endcap insertion easier.

[HMenke]

Steve that is a great idea. I was looking at the end and the layers aren't really all that tightly bonded. I tell ya, $40 just doesn't go as far as it usta...

Between taping the end and Thomas' idea to use a roundover bit on the plug to ease the starting, everything should go smoothly. My next task is making a circle cutting jig for my router. I also need to go get a 1/4" upcut spiral bit - all I have at the moment is a straight cut.

I'm like a bad little kid - I pulled the plastic layer off the inside. It was like once I started messing with it I couldn't help myself! :lol:

Can't decide if it is worth the trouble to recess the woofer, what do you guys think? It's pretty much invisible under there, and recessing it removes material that would otherwise provide additional stiffness.

My teenage daughter is the only one in the house who "gets it". She said, "Dad, you just might end up with the biggest subwoofer in the tristate area - how cool is that?" She is going to make a fine HT wife someday - there'll be no SAF problem with her! At school she had fun with a boy in Art class who drew a big screen TV with little tiny satellite speakers. "You call those speakers? Those are pathetic!" How bad would that be for a girl to think your woofers are too small? ops:

[HMenke]

update

Well all my parts are finally here so I should be ready to start cutting up MDF this weekend. The black speaker carpet from Speaker City got here. Looks really good, almost like a heavy black felt but a little shiny. It's about 1/8" thick and easy to manipulate so it should cover the sonotube without too much work or fuss.

Tonight I wired up my solid state remote amp power relay and tested it out. It works perfectly so I can go ahead and install it. Here are some pictures of how it is connected. The brown two-prong plug goes to a switched 120V outlet on the receiver. The switched outlet can't power the amp directly because the amp is near the sub and also because the the current rating of the switched outlet is too low. Therefore the main current comes straight from a wall outlet via the black three-prong plug and the relay. The white Romex carries the switched power to the outlet where the amp will be plugged in. Here are some pictures in case anyone wants to do something similar.

[HMenke]

Making headway

Started the day with a sheet of MDF and ended up wih a big pile of sawdust and a lot of circles! This is a lot of fun!

[HMenke]

Port

Here is the port. I thought this would be the hardest part and it was! I made the hole in the end plug about 3/32" too small for the port tube to fit. What a pain to enlarge it. But it is assembled and looking good now.

[SteveCallas]

Looks great! Better to start with too small a hole then too large a hole :T

I put a fine bead of caulk between where the edge of the sonotube port meets the MDF flare, then used my finger to smoothen it out - when it dries, it's basically one smooth surface.

[HMenke]

Looks great! Better to start with too small a hole then too large a hole :T

I put a fine bead of caulk between where the edge of the sonotube port meets the MDF flare, then used my finger to smoothen it out - when it dries, it's basically one smooth surface.

Thanks, you should know your sub was one of the inspirations for me tackling this project.

I'll probably do the caulking too. I bough some black caulk. I got a very nice fit between the MDF flare and the inside diameter of the port tube and the caulk will complete the smooth transition.

[HMenke]

More progress + question about acoustic fill

More progress today. Here are some photos showing the acoustic fill stuck all over the port and then a view inside the tube with the port end installed. This fill is Acousta-stuff from PE. My wife says it looks similar to or the same as regular polyfill from the fabric store. I told her, yeah, but this polyfill has the special extra-cost magic speaker ingredient.

I bought the big bag but as you can see, I still don't have enough to cover the lower part of the tube. Does this matter? Have I achieved enough damping with what I have done on the port end?

Installing the port into the sonotube was "fun"! I had a few moments of abject panic when it appeared that the plug wouldn't go in. I was actually up on a ladder stomping on it when it finally popped into place. A sledge and a scrap piece of wood were needed to coax it the last 1/8" home. Whew! Thomas, that sucker is sealed and glued tight, so I will not be claustrophobically "tube diving" to apply caulk on the inside! :B

[ThomasW]

You're coming very close to 'stuffing' this tube with what's called 'heavy fill' and that's not the goal with a ported design. A layer of material around the inside of the enclosure is all that's needed. There's no need to put any damping material on the port itself.

Acousta-stuff is a 'crimped' polyfill, so yes it is different than what's used for pillows.

[SteveCallas]

I'm definitely no expert of stuffing, but I have to agree with Thomas that that is quite a bit for a ported sub. I just lined my walls with a couple layers of batting and my port with a few as well, nothing major. Mine was more of a solid sheet of the stuff as opposed to clumps.

If you've already sealed your top cap in place, how do you plan on applying a finish to the top cap?

I sealed my bottom cap in, my top cap is just jammed into place. I did that just in case I ever wanted to change the length of the port for a different tune.

[HMenke]

Alright, thanks for the caution Thomas. The directions that came with the Acousta-stuff are apparently bogus. Does too much stuffing in a vented sub inhibit necessary air transfer? What I can do here is pull the looser pieces off and re-apply them to the lower part of the tube and hopefully that will suffice.

Steve, do you mean how am I going to apply spray paint inside the house? Probably won't; I'll just haul it outside when we get a nice day. Having the end cap in place on the tube actually provides a nice stable work surface with access to the whole top surface. At any rate, I'm not big on elbow grease and lack the patience to apply it, so I'm not going for piano gloss. The top cap is going to be spray painted with textured black and then most of it will be covered by a large-diameter DIY grille made from a donut of MDF and some black speaker grille cloth. Thus I don't need to worry about finishing most of the top surface area.

I was surprised that the Acouta-stuff is clumpy. It's weird but not really hard to work with. For this application I think batts maybe would have been more straightforward. That's a good idea to be able to pull the port and change it, but I don't think I'll be changing anything on this dude once it is up and running. An interesting thought for "next time" would be a flanged port assembly that bolts in like a woofer. Unbolt it, pull it out, put in another.