Want to build 2- 15" hidden Sonosubs - comments please!

[RandyMidd]

I need a reality check...do I have something here or am I a nut?

I want to (primarily) enhance the music experience of my DIY 3- ways.
I figure I can disguise a pair of 3.5 cu ft sonosubs as tables very much like the ones we have already in these pictures.

I'm excited because I got approval for the project...I thought I was going to have to build a piece of furniture for this...the Sonosubs will be way easier and plus they won't be committed to one spot...I'll have some leeway to move them around in the room for FR improvements. Another plus...their appearance can be changed to go with any room by changing the cheap table cloth! Finally...I like the idea of guests not seeing where and how that big sound is being made.

My questions are...

1) Can I realisticly expect a big improvement in music playback?
I'm a bit naive with subwoofers 'cause I don't have much first-hand experience with them.

2) Ported or sealed?

I see Ryan and others have acheived around -3db @ 20Hz with a similar sized sealed boxes and a BFD. Could I expect any more from a ported design?

Proposed goodies:
* 2- RLp15 D2 drivers (voice coil pair wired in series for 4ohms per driver)
* 2- Tapco J1400 pro-amps (1,400W @ 4 ohms) ---- or---- Can I do this to save $$$...
* 1-Tapco J1400 900W per channel @ 2 ohms with 2- RLp15 D4 wired in parrallel for a 2 ohm load per channel???
* 1- Behringer Feedback Destroyer 1124P
* 2- 20" Sonotubes cut to give 3.5 CF net

I appreciate all comments...Thanks!

[BobEllis]

Porcelain on glass on a sub => annoying rattles

Otherwise, for pure music you probably don't need flat to 20Hz. Typical room lift will make that sound boomy. You wil hear that unless you like pipe organs or large orchestral pieces, there isn't much information below 30 Hz. A four string electric bass open E string is ~42 Hz, and often mentioned as the reason for pop music. I disagree, the prevalence of 5+ string basses in pop music and don't forget the bass drum. The tympani is the reason that you will want something that goes deep for orchestral music. All told, a good sub adds a level of realism that you will not want to be without once you have it.

Without running the numbers on your drivers, I'll just speculate that you may need more volume than you have available if you try ported.

[RandyMidd]

Porcelain on glass on a sub => annoying rattles

Do you think my mother-in-laws ashes could spill from the urn??
That'd be terrible if she ended up in a vacuum cleaner :W .

Thanks for the comments...I need to feel confident I'm doing the right thing.

Let's say I cross these to the mains at 80Hz...so the new subs would be responsible from 80Hz to 20Hz of music...is there a decent amount of info in this range? I guess that's a bit vague of a question...are drums in this range?

Without running the numbers on your drivers, I'll just speculate that you may need more volume than you have available if you try ported.

The SS website shows a graph of this driver in my 3.5 cf enclosure tuned for 24Hz.

I seem to recall that people don't recommend using a small diameter vent for this driver...that being the case my vent pipe would be ridiculously long so a ported sub may not be practical unless I change the disguise to a cast iron stove with stove pipe.

WinISD says tuned for 20Hz I'd need a about 21" length using a 4" diameter...and I believe people 'round here say 6" or better for these drivers...comments please...Thanks!

[SteveCallas]

Could I expect any more from a ported design?

Yeah, you could get a lot more from a ported design, but that doesn't appear to be a legitimate option in your case. 3.5 cubic feet just wouldn't cut it, you'd want more like 9.5 cubic feet. In addition, with a 20" tube, there is no room for both the driver and port on the bottom cap, and you certainly couldn't port it on top with a piece of glass covering it. You'd have to attach legs to the tap cap and then build a top plate so the port could breath, but then you'd be reducing enclosure volume for a given height even more.

Basically you gotta go sealed

[---k---]

You can get a lot more OUTPUT from the ported design. But, like Steve said, since you are limited on space, go sealed. With two sealed boxes and enough power, you will probably have satisfing bass. Depending on your room, you can get good response down to ~20hz..

If you go sealed, I would recommend that you hold off on your BFD purchase. Depending on your room gain and all, you may not need/want a lot of additional low low end power. The BFD may get you where you want to be, but, if you decide you need/want MORE low low end, the Behringer DEQ is a lot more handy at that (but at more than twice the price). I really like what the DEQ did for me. I'm sure it is similar to the results Stevenn and others get with the Bassis. I get strong output down to 10hz now.

How much are those amps? The Behringeer EP2500 at ~$300 is everyone's current value recommendation.

[BobEllis]

Crossing to your subs at 80 Hz limits your placement options a bit. That's fairly high and you might be able to hear the subs as separate entities if they are too far from your mains or close to your listening position. Shoot for as low as your mains can handle unless your subs will be fairly close to the mains and not under your elbow as end tables.

Of course, now you are getting away from being able to use your receiver's crossover. Not that it is particularly difficult to build an active crossover (and you may want to build a Linkwitz transform anyway). Just food for thought. Not a show stopper.

That 3.5 cubic foot /24 Hz alignment is interesting. Not sure where they got that response curve. WinISD shows that as an EBS alignment that rolls off 3 db by 90 Hz with a small peak 8 db down at 28. Add a fourth order filter at 80 Hz and you've got response that rises 2 db between 60 and 28 Hz. Exactly the opposite of what you want for natural sounding bass. Not to mention that a 35 sq. in. port is 6.7" id and 42" long to get that tuning.

For hidden subs and that driver consider a 2 cubic foot net enclosure with a Linkwitz transform to 20 Hz. - That will give you flat anechoic response and around 108 dB from a pair. You'll need a fair amount of power - with full scale 16 Hz. pipe organ note it will demand 500W.

Room gain may make the Linkwitz Transform sub a bit tubby, an alternative would be the same 2 cubic feet and a peaking second order filter giving 6 db of boost at 20 Hz. This will give you a rolled off anechoic response that room gain will fill back in. You'll still get the same SPL, since it is sealed. Amplifier requirements will be less - 300 W each will do it.

[chasw98]

The BFD may get you where you want to be, but, if you decide you need/want MORE low low end, the Behringer DEQ is a lot more handy at that (but at more than twice the price). I really like what the DEQ did for me. I'm sure it is similar to the results Stevenn and others get with the Bassis. I get strong output down to 10hz now.

Ryan:
Are you speaking about the Behringer DEQ2496 unit? If not, what is the model number? Thanks.

Chuck

[---k---]

Sorry,
yep, the DEQ2496. http://www.behringer.com/DEQ2496/index.cfm?lang=ENG

The big differance between it and the BFD (for what we are using them for) is that it has shelf filters which allows the creation of an L/T.

For a while, whenever the BASSIS came up, Thomas was recommending one of these.

I got mine from Ebay used with the mic also for $290. So, not cheap, but less than a BASSIS.

[RandyMidd]

I'm going to re-read and carefully consider everyone's input above...but right now I need to figure out if I need one or two amps for what's shaping up to be two sealed RL-p15 subs. You see...I'll be working in the neighborhood where they pimp these babies for cheap tomorrow so I'd like to save 50 to 100 lbs of freight cost too!

From what I read 'round here there's no real disadvantage between using the D2 (dual 2 ohm) or the D4 (dual 4 ohm) driver...right? We should pick drivers that's best suited for our amplifier, I think I got that from Thomas. Well, instead of getting the D2 and wiring those in series for a 4 ohm load can I wire the RL-p15 dual 4 ohm voice coils in parallel to make a 2 ohm load? This way a single amp will have more watts available per channel... in my case 800 wpc vs. 450 wpc. If I can wire the voice coils like that, will one amplifier at 800 wpc be sufficient?

Thanks!

[Dennis H]

Randy, it's not quite so simple. 2 ohms or 4 ohms is just a "nominal" rating. Down low where you need the power in a sealed sub, the impedance may spike up to 40 ohms. So, you really need to model the specific amp/driver combo to see what's going on. You need to know the max voltage and the max current the amp will put out to do it properly.

http://www.linkwitzlab.com/thor_splmax.htm

http://www.linkwitzlab.com/dipole_spl_limit.htm

[RandyMidd]

Down low where you need the power in a sealed sub...

Isn't that opposite of what the article said...

"It should be clear from the examples that amplifier power is not an issue at the low frequency end of the subwoofer range, but at high frequencies."

Anyway, the voltage for my amp is unpublished (I own one already)...I can figure amps if I knew that...then I'd be stuck on modeling the driver...

It makes me inclined to simply look at others' real world results...I see Ryan is (or was) powering his sealed RLp 15 subs with 450 wpc and reported satisfactory results...the SS website says to use between 400w and 1000w. Aside from required wattage though...is it cool to wire the dual 4 ohm voice coils in parallel to get a (nominal) 2 ohm load?--Thanks for your input! :T

[BobEllis]

2 ohms is a difficult load to drive, and will result in lower efficiency in your amp. As Dennis pointed out, just because you call a load "2 ohms" doesn't mean that it never goes significantly above or below that. You are also drawing more current, so fatter cables become more important.

Realistically, 400 watts per driver should be plenty. However, as Dennis pointed out, ** to make the same sound pressure level at low frequencies as high in a sealed system requires more power because of the EQ required ** I can't quite figure what article you are referring to, but it seems to be looking at power requirements differently. There isn't as much energy in the lowest regions of audibility as there is higher, depending on music type may be what they are saying. Or they could be using power rating as a way of determining voltage swing available and planning a higher resopnant frequency.

If you look at the impedance of a sealed system near resonance (where a sub typically operates) you will see a large impedance rise. If you need 100W electrical input to make the desired SPL, and the impedance is 40 ohms your amp will need to be able to swing 63V to deliver 100W. That same voltage will produce 1000 W into 4 ohms.

If you can't quite afford two big amps, I would still use the 4 ohm version and plan on getting another amp when funds allow.

[Dennis H]

Sorry, those Linkwitz articles probably confused more than they helped. He's showing how max output is limited by different things at different frequencies and that was the point. But we don't want or need max output at every frequency. Rather, we want the system able to play the same output at all frequencies -- flat frequency response. As Bob noted, a sealed box is going to need EQ down low to get flat frequency response down to 20 Hz. So just figure how much power you need to reach Xmax at 20 Hz and you'll have enough at other frequencies.

[SteveCallas]

Down low in a sealed sub will put big demands on an amp. I'd get the D2 versions and either use one EP2500 to give them each 750 watts or perhaps two EP1500s and run each in bridged mono for each sub.

neighborhood where they pimp these babies for cheap

Which "babies" do they "pimp"?

[RandyMidd]

SteveCallas wrote about ported vs. sealed...

with a 20" tube, there is no room for both the driver and port on the bottom cap

Right you are...if I was going to port this thing I was thinking about having the vent exit near the top but not out the top, rather out the side...I'd make sure there was a hole in the table cloth that slipped over the vent pipe which may protrude a couple inches. Once inside the sonotube the vent pipe would 90 down then 90 over then 90 up...basically 90 around (if that's allowed) 'till I got my required length...this might be OK for a 4" x 21" long vent pipe but if I need to use a 6" diameter pipe then the length grows to around 49" ...the exercise is difficult not to mention I'd have little internal volume left over for the driver!

Ryan wrote...

go sealed....you need/want MORE low low end, the Behringer DEQ is a lot more handy...

I guess that really low stuff would be for movies, huh? That's cool I watch those too Thanks for explaining about the DEQ...and props to Thomas for mentioning it before...I just didn't "get it" then.

How much are those amps? The Behringeer EP2500 at ~$300 is everyone's current value recommendation.

At $300 shipped the Behringer remains the value champ, these are $200 (plus tax for me cause I'm in CA) so 8 watts per dollar vs 7 watts per dollar. The only place I found that sells them this cheap is Six Star DJ.

BobEllis said...

Shoot for [crossing] as low as your mains can handle

My mains go to -3db @ 40Hz according to WinISD...so the subs would only be responsible from about 40 to 20Hz for music? This will easily be the most expensive section of the music spectrum 8O !

...an alternative would be the same 2 cubic feet and a peaking second order filter giving 6 db of boost at 20 Hz.

I'm only familiar with Peking duck!

2 ohms is a difficult load to drive...

Yeah and plus I remember Thomas saying to shoot for a Qtc of .5 ...the D2 models closer to that target than the D4 for me so I'll get the dual 2 ohm drivers and wire them in series.

Dennis H wrote...

So just figure how much power you need to reach Xmax at 20 Hz and you'll have enough at other frequencies.

Is there an easy way I can figure that... not exceeding a 12th grade education? If not, I'll throw a little more money at the problem and make it go away.

SteveCallas said...

I'd get the D2 versions and either use one EP2500 to give them each 750 watts or perhaps two EP1500s and run each in bridged mono for each sub.

I like your thinking...I can live with either of those.

Which "babies" do they "pimp"?

The amps I was going to use... Tapco J1400 .

I went to this pimpin' place today in beautiful downtown L.A. set in my mind to just get two 1400W amps and they were out! That's what I get for not calling ahead. This area is filled with Tijuana-like audio shops for blocks. I thought I drove into a worm hole and was transported to a third world.

Your input...moocho appreciado!

[SteveCallas]

Right you are...if I was going to port this thing I was thinking about having the vent exit near the top but not out the top, rather out the side...I'd make sure there was a hole in the table cloth that slipped over the vent pipe which may protrude a couple inches. Once inside the sonotube the vent pipe would 90 down then 90 over then 90 up...basically 90 around (if that's allowed) 'till I got my required length...this might be OK for a 4" x 21" long vent pipe but if I need to use a 6" diameter pipe then the length grows to around 49" ...the exercise is difficult not to mention I'd have little internal volume left over for the driver!

Using bends in ports is not recommended, as it can cause turbulence in the air flow. Even if you were able to somehow get the port situation adequately solved, for the enclosure size you are considering, I still wouldn't go ported. As much as I love to tout a great ported sub design, in this case, you clearly should go sealed.

[RandyMidd]

Here's where I,m at so far...subject to change based on your suggestions...

Drivers
2- RL-p15 dual 2 ohm voice coils to be wired in series. - Ordered!

Amp(s)
2- J1400 or their equivalent 2- EP1500 or 1- EP2500

Enclosure
2- 2.1 cubic feet, sealed sonotubes

EQ
Need Suggestions!

Room gain may make the Linkwitz Transform sub a bit tubby, an alternative would be the same 2 cubic feet and a peaking second order filter giving 6 db of boost at 20 Hz. This will give you a rolled off anechoic response that room gain will fill back in.

My room is sorta big...about 700 square feet which is always open via three doorways (one big two regular size) to another 700 square feet...so 5,700 cu ft plus another 5,700 cu ft.

What device can accomplish this peaking second order filter?

Given my room size now, should I just plan on using an LT?
or...
Do I hold off purchasing like Ryan suggests?

Ryan, did you mean hold off purchasing any EQ or hold of purchasing a BFD in favor of a DEQ?

My existing 10" drivers in my 3-ways model lower than these 15" subs do without anything to force them lower. :sos:

I'd sort-of like to buy everything I need in advance but I guess I don't have to.

I'm going to stuff my enclosures with 2 lbs. of fiberglass each, any experience on how much that'll increase my enclosure size...10%....20%?

Comentarios por favor!


----Randy

[ThomasW]

Buy the EP2500, the Behringer DEQ2496, and the ECM8000 microphone.

You can create the LT circuit or the peaking filter, or almost anything else with the DEQ2496

To hook up the DEQ you will need a set of special cables that have RCA on one end and XLR on the other.

Here's a link to one supplier, there are hundreds of other suppliers

http://www.markertek.com/Product.asp?baseItem=XLM%2DP%2D3&cat=CABLESCONN&subcat=AUDIOCAB&prodClass=ARCAXLR&mfg=&search=0&off=

A set of standard XLR to XLR will be needed to connect the DEQ to the EP2500

Here's an article that talks about how much damping changes the box size.

http://web.archive.org/web/20041027051204/http://www.integracaraudio.com/caraudio/resources/fiberfill/

[chasw98]

Here's a link to one supplier, there are hundreds of other suppliers

http://www.markertek.com/Product.asp?baseItem=XLM%2DP%2D3&cat=CABLESCONN&subcat=AUDIOCAB&prodClass=ARCAXLR&mfg=&search=0&off=

C'mon Thomas, this is DIY. Steer him towards the Neutrik connectors with the gold plated pins and the canare star quad cable. BTW, the Neutrik RCA connectors are very nice. :T

[SteveCallas]

With that large of a room, you won't be getting much pressurization....I'd place the subs as close to the seating position as possible.

[---k---]

Ryan, did you mean hold off purchasing any EQ or hold of purchasing a BFD in favor of a DEQ?


----Randy

Sounds like you are getting there.

About the amps. I was temporarily satisfied with 400W/ch. I felt to play them at the "impress your friends and scare your neighbors level" I needed more power. Someone with a smaller or sealed room may not need more. So far, the EP2500 has been great, no complaints.

About EQ. It really comes down to your budget. If you can afford the DEQ, I would get it in a heartbeat. Being able to do a L/T really gives the low low end for movies, and will make you jump.

If you can't afford the DEQ right now, then get them built, enjoy them without eq for a while, measure your in-room response, post it, and well help you decide if you can get by with a $100 BFD or try and talk you into the DEQ then. Adding the DEQ later can be a great way to scratch the upgrade itch.

[RandyMidd]

Thanks for chiming in ...

Thomas, thanks for the stuffing link (mmm stuffing)...I saved the page on my HDD, good info has a way of disappearing off the WWW after time.

I ordered the DEQ2496 today and it was CHEAP! So much so I doubt they will actually ship it ...more on that later.

I want to order the EP2500, the ECM8000 and cables from Parts Express all at once... so I'd like to verify something before I place my order with respect to what cables I'll need.

How does the DEQ connect to the receiver???

I ask because I need to plan my connections to include my existing pro-amp to drive my mains. This pro-amp is already connected to the receiver by a set of those XLR x RCA cables.

[ThomasW]

How does the DEQ connect to the receiver???

Use your existing RCA to XLR to connect the sub out to the DEQ. The use XLR to XLR from the DEQ to the power amp.

[RandyMidd]

Use your existing RCA to XLR to connect the sub out to the DEQ. The use XLR to XLR from the DEQ to the power amp.

Your losing me...I need to keep those cables where they are to drive my mains...

I'm going to take a stab at this...from the receivers LFE preamp out to an RCA Y splitter into two RCA x XLR to the DEQ2496...is that right?

FWIW... pictures of the back of a DEQ2496 and my receiver follow...

[ThomasW]

I'm going to take a stab at this...from the receivers LFE preamp out to an RCA Y splitter into two RCA x XLR to the DEQ2496...is that right?

Yes...

[RandyMidd]

I'm an air conditioning service guy so things are busy with work this time of year but I'll do my best to make regular progress with the project...in any event I'm committed now!

Here's what's been ordered...

Equipment

2- RL-p15 drivers, dual 2 ohm voice coils to be wired in series.
Vendor: Sound Splinter. Cost with shipping (& CA sales tax for me) $541.25.

1- Behringer EP2500 Pro-audio amp.
Vendor: Parts Express. Cost with shipping $300.

1- Behringer DEQ2496 Equalizer/Processor.
Vendor: Ebay auction (brand new). Cost with shipping $247.83.
Note, if you're patient you can get these for cheaper (I missed one today that went for waaay less $)....apparently I'm not patient.

1- Behringer ECM8000 Measurement microphone.
Vendor: Parts Express. Cost with shipping $51.62.

Cables & Adapters
1- Male x female x female RCA adapter (this turns one RCA jack into two, it goes on receiver LFE preamp out).
Vendor: Parts Express. Cost (shipping cost for this is covered by mic cost) $3.95

2- RCA male x XLR male cables, 3 ft. (goes from RCA adapter to DEQ2496).
2- XLR male x XLR female cables, 3 ft. (goes from DEQ2496 to EP2500).
Vendor: Markertek.com. Cost with shipping $43.96.

Total so far $1,188.61.

The remaining stuff will be relatively cheap, sonotube, misc hardware, glue, insulation, paint, MDF board...some of which I already have laying around.

Questions remaining

It crossed my mind that because my sealed sonotube enclosure will be so small that maybe I should go down to 18" diameter...
Has anyone put these drivers in a 18" tube?

I want to omit the (usually standard for sonosubs) very bottom MDF plate....
Is there a significant disadvantage to having the drivers downfire into carpet?

The girl below says she loves DIY home audio guys especially the ones who make subwoofers...either that or she has absolutely no relevance to this thread and it was a pathetic attempt to make it look as good as others.

[RandyMidd]

.....girl below...

[RandyMidd]

I ordered the DEQ2496 today and it was CHEAP! So much so I doubt they will actually ship it ...more on that later.

Oh...I almost forgot...that one was for sale at Amazon for $35...the transaction went through...they charged my credit card...then they sent me an email later saying they cancelled the order because the price was mismarked...meanwhile I missed out on a fantastic buy on ebay...I suppose I deserved that! :lol:

[ThomasW]

It crossed my mind that because my sealed sonotube enclosure will be so small that maybe I should go down to 18" diameter...

Stay with 20" tube

[RandyMidd]

I hope Thomas doesn't rap my knuckles like Sister Mary Saint Thomas did in first grade, but I really like the slenderness of those 18's... they'll fit and blend into my room about anywhere...they grow to 21" diameter with the table top on and still look good...any bigger is beginning to look a bit portly...at least in my room.

I'm hoping he was trying to steer me clear of issues arrising from limited space to place the feet or possibly felt the baffle strength was compromised from the reduced material between the ID and OD cuts...if so I have some work arounds...

For the feet, I made Rocket Fins (see pic)...they only contact the baffle 3/4"...I sketched these then made a template on 1/8" plywood then traced onto kiln dried 2x4 pieces...and cut with jig saw....used a table saw for the straight cut, but it can all be done with a jig saw.

The baffle appears to be stout enough but for good measure I'm placing three stringers inside the tube...not coincidently at the same location as the rocket fins...so the fins will be screwed to the stringers, the stringers will butt against the baffle and top cap (not table top) where they'll be screwed and glued.

In the picture below all that's glued right now is the driver baffles...the rest is just set in place...the rocket fin feet need sanding/finish work.

I was surprised at how thin these tubes are...I'd seen some on construction sites that were 1/2" thick (larger diameter) but mine is only .190" ...I could have gotten the "thick" one if I was willing to drive for it, but it was only .250".

To add some mass, it turns out I have just enough bitimen laying around to cover the pair...so instead of carpet or a slip over cover I'm applying torch-down roofing material on the exterior, I'll then use a latex primer to keep the rocks from shedding off, then shoot it all flat black, the color doesn't really matter since it'll be under a table cloth.

[RandyMidd]

Oh yeah...for driver mounting I found these pipe clamps (see pic) after wandering the aisles at Lowes looking for something suitable...once I chop off some length they'll be pretty perfect...

I'll use 1/4" screws and tee nuts for fastening...these clamps move the required driver mounting holes and tee nuts away from the fragile edges and will allow for quick removal of the driver since the screws need only be loosened, and finally I don't have to remove surround material which is covering the holes on the driver's cast frame....thanks to Thomas for the idea.

I'll probably make binding posts from screws and lugs from the electrical dept at H Depot.

Tip: Lowes MDF appears better than H Depot but Lowes Bosch router bits don't last...and for the little use I got from one, projects would get very expensive, H Depot's Diablo bits are the same price and last way longer.

[Owen Bartley]

I like what you've done with the legs, Randy, I don't think I've seen a design like that before.

[JonW]

Oh yeah...for driver mounting I found these pipe clamps (see pic) after wandering the aisles at Lowes looking for something suitable...once I chop off some length they'll be pretty perfect...

Just to make sure... You know where the surround moves, right? You don't want any of your clamps to contact the surround, or it will wear out over time. And you might want to smooth down the metal after you cut, so as to avoid wearing the surround. Sounds like you know, but I thought I'd check.

I really like your rocket fin legs. :T

[RandyMidd]

I like what you've done with the legs, Randy, I don't think I've seen a design like that before.

I wasn't sure how much of it was builder's pride...but I really like them too. It took longer to come up with an appealing design than to cut them out...I'd be happy (honored?) to see more of them made and actually make a contribution around here...that's hard to do.

You know where the surround moves, right? You don't want any of your clamps to contact the surround, or it will wear out over time. And you might want to smooth down the metal after you cut, so as to avoid wearing the surround.

Any comments to keep me out of trouble is appreciated...yeah, those pipe clamps, found in the electrical aisle at HD or Lowes in case anyones interested, are going to be cut short, they'll only contact the raised cast lip of the driver's frame.

Lastnight I went shopping for materials and just cut plywood circles using a hole saw and installed tee nuts in them.

Can anyone explain why speaker wire is so expensive as compared to say landscape wire???

Example, 250' 12 AWG speaker wire about $165 and 500' landscape wire 12 AWG is about $140. The speaker wire may have more strands and may be slightly more flexible but it's hard to tell...the landscape wire has a black insulation the other is clear...I bought a lifetime supply of landscape wire.

[RandyMidd]

Lastnight I drilled the baffles and glued in my tee nuts.

The chop-saw made short work of resizing the pipe clamps.

Can anyone explain why speaker wire is so expensive as compared to say landscape wire???

Forget about that...I think it's stranded differently and oxygen free...neither from what I've read matter much...there's a lot of marketing garbage out there on wire.

[RandyMidd]

A few more things done the last couple of days...

The first picture, cut and glued rubber to the driver hold down brackets. The drivers will be isolated from the tube with rubber, foam rubber and in case of the baffle cutout where the driver fits in, elastomeric sealant.

Second picture, getting ready to apply the bitumen roofing material, the torch was purchased at Harbor Freight for about $15 and that's an old propane tank from a BBQ.

Third picture, you can see that for the ends I simply let the material overlap, I worked the torch and my kid rolled the tubes, he's being careful to check the splurge factor at the tube ends and adjusting his downward pressure accordingly.

Fourth picture, I used blue tape in the areas where my feet where to be installed prior to rolling the tubes. Now I scribed the outline with an ice pick, of where my tape is to remove the rocks before cutting material with a razor knife.

[wkhanna]

Wow!
that's really slick!
But I must have missed something along the way.
What is the prupose of the bitumen?

[RandyMidd]

You didn't miss anything in this thread, it wasn't discussed.

I decided to put bitumen on the outside of the tubes because...

I was told that it was pretty standard for the DIYer's across the pond back in the day to line their speaker boxes with this stuff... this sort of jives with my understanding that the material was first available / more prevelant in europe.

I had just enough laying around...and I wanted to finish the outside at least a little better than they were...

The walls of the sonotube are only .190" thick, so the bitumen substantially increases the wall thickness...

In my case, the extra weight is welcome.

The material is compliant...if there were to be any vibes on the sonotube walls it's supposed to help dampen them...though not as well as CLD.

:T

[wkhanna]

Cool.
I think the texture of the bitumen on the outside would have interesting/different look when the color is applied.
I am looking forward to seeing these puppies when you’re finished!

[RandyMidd]

Some progress to report...

1st picture, I originally made the baffle openings tight to fit the driver but later decided to have a elastic coating applied to the baffle ID so I used a couple files to open the holes up a little, being careful to not chip the edges or to lose my nice round lines...this worked very well, there's no need to fret if you ever cut your circles a bit too small.

2nd picture, I made these cool stringers that get screwed and glued to the top and bottom caps. They serve the purpose of providing an attach point for the legs, (I've caulked around the screw zone for the legs as you can see to prevent air leaks) as well as to structually tie the end caps together and provide a rigid abuttment for the top braces as you'll see...

3rd picture, Stringers temporarily clamped in place...

4th picture, glue in top caps and screw/glue to stringers. Also seen in this photo is the elastomeric material on the ID of the baffle.

5th picture, made these really cool tri-braces for the top cap that interlock with themselves...once in place and butted against the stringers they would stay in place without glue...but of course glue is needed to secure the top cap to them...

[RandyMidd]

1st picture, Glue in top braces, if you note that the glue is already dry , pretend it isn't for purposes of maintaining sequence.

2nd picture, weigh down recently glued table top (not pictured) and braces and let sit overnight.

3rd picture, close up of feet, this is the only thing I used the foam glue (gorilla glue equivelant) on. Because I used a jig saw to cut these, they aren't perfectly machined to the mating surface, foam glue stays in place better and expands several times before it cures, filling any small gaps. I only used one screw that also served to provide clamping pressure to hold the legs in place.

4th picture, I filled the area where I cut away the bitumen (so that I could attach the feet) with Glenkote, an elastomeric sealer whose texture resembles the bitumen. I used a chip brush to make help blend the textures.

5th picture, I applied a very small caulk bead underneath the table top to close the gap between the bitumen and the table top..tedious but not as bad as welding.

[Martyn]

[QUOTE=RandyMidd]

Can anyone explain why speaker wire is so expensive as compared to say landscape wire???
QUOTE]

...because we live in a free market economy. As long as people will pay more, businesses will charge more.

[Owen Bartley]

Looking good Randy, I like the tri-braces a lot.