Are 24 x T60-LAB15s Enough? ;)

[Levi]

@Bruce

Thanks, Bruce! That makes perfect sense, and is definitely the easier thing to do. KISS.

For the record... It took me a bit to find it, but I think I found the source of this idea in my head. In theory, if the rate of cooling can be higher than the rate of heating, then it's a win. But only if that net cooling is more with the low voltage high movement option than with the it being completely off option.

https://ddaudio.com/tech-talk-smokeem-i ... smoky-sub/




@Bill

Thanks for clearing that up! Makes perfect sense!

[Levi]

@Seth

I love the organization! I'll try to keep it going!




Power/Wiring


Yes, choosing the cabling was a big project all on its own! The copper wire with THHN jacketing is much lighter and can withstand much more heat than the SJOOW. Also, the actual wiring is fewer strands but bigger diameter, which is better for higher ampacity. I can't remember exactly why that is, but I know that if there are different phases in a cable, the magnetic flux between them creates a lot of friction/heat. The higher amount of smaller wires ties into that as well, I just don't recall. Anyway, we will still use the flexible and heavy SJOOW, with the more strands and smaller diameter and lower ampacity, but only for that last little bit to wire into the Furman. This is because there is no way to bend the stiffer THHN into the terminals in that tight little space. Or maybe there is, but you need just the right tools, and exceptionally strong finger grip. Like, Alex Honnold free solo climber strength.

The run is probably going to be 100 feet from the Sparkle Box (aka the big military distribution box - which is hundreds of pounds and can fit probably two dead bodies in there!). The genny to the sparkle box is about 10 feet. I am going to make more cables to have all the runs to the rest of camp spider boxes be 100' as well. that way, the voltage meter on the genny can be more precise across the grid.

And yes, the cable is 5 wire. We took an old SJOOW 6/4 (6 gauge per wire with 4 wires inside), and just added a little 10 gauge wire on the outside for the ground. We then banded them together with velcro cable ties. Smaller zip ties kept breaking, and we didn't want to risk bigger ties for fear of severing some/all of the itty-bitty copper wires in the cable with over-tightened zip ties. Plus, all those zip tie nubs are a huge pain in the ass when rolling/unrolling the cable.


The Furman... HOLY SMOKES!!!

Thank you so much for looking into that! I feel so embarrassed I don't even know how our own equipment works! Ahhhhhh!!!

First, I guess we should get on the same page for a definition of power conditioner. That hunk of junk better help "regulate voltage, reduce noise, and filter out electrical disturbances", or I think we'll just throw it into the fire.

I guess I just guessed that it also had the ability to transform power. I mean "regulate voltage"... I assumed too much! But now I know better! It only splits the 3 phase source into its separate phases. Nothing fancy. Otherwise it would probably cost a lot more than it does! This is such a great awakening to have, especially since my amperage estimates, which were based on 208v, have been way, way off! Thank you!!!

Seth, listen. My mind was blown with that revelation...

But now...

Holy shit man!!!

This rewiring idea for inside the Furman... WOW!!! This is genius!!!

Lucky for us, we actually have 2 of these bad boys! So, now I can just completely rewire one for all 208v, and leave the other one all 120v! This is fantastic! Now, I just need to make a good splitter box to take the cable from the genny into both boxes.

Regarding the possibility of 16 cabs on one 20 amp breaker, it's certainly worth a shot!





Amplifiers


Man, those Admarks keep looking better and better! Not having to worry (or not worry as much that is) about so much AC to cool them with 8 total, that is a sexy, sexy thought! Savings on AC would help increase the amplifier budget! Maybe we could even get away with just fan cooling, not AC! Hmmm... I'm still going to plan on having at least some AC, though. If not for the amps, for the guy working around them!

Also, all of this makes perfect sense! Thanks for running me through it!






Limiters


Reading all this makes me think our shitty test was even shittier than how shitty I originally thought it was. Which was shitty.

I honestly can't remember all the details. At this point, it's probably better I just reread this whole section when we run the test again. And do it properly.

And sorry, clumsy language! Yes, I meant where the limiter kicked in. No clipping. Thanks for catching that!






T60 Deployment


Mono it is! Again, thanks for the knowledge!

Thermometers added to my cart! I see they go to 140F outdoors... How hot do you think it gets in that chamber?

Also, this is all very exciting for orientations! So many possibilities!!!

That said, would it make sense to use bigger #10 than #8 driver mounting screws if they are going to be on their sides or upside down, yes? More shear strength? I have more questions on this kind of stuff, coming up in a bit!

Thanks, the placement rules now make much more sense! Now, about those submarines... What if they are feeling lonely down there, and just want someone to talk to?



.... . .-.. .-.. --- / -.. --- .-- -. / - .... . .-. . -.-.-- / -.. --- / -.-- --- ..- / .-- .- -. - / - --- / -.-. --- -- . / .--. .- .-. - -.-- / .-- .. - .... / ..- ... ..--.. / .-- . / .... .- ...- . / .--. .. -.-. -.- .-.. . ... .-.-.- .-.-.- .-.-.-



Damn, 45' x 22.5'? That would be quite the DJ booth!!!

Side note. With the current plans, one shipping container would be 50+ feet directly off to each side of the booth/subs, and two more about 30 or so feet directly behind, creating a 8'x40' wall. (4 containers in total.) Do you foresee any cancellation problems there? Would that mess with the low frequencies in front of the booth? We were planning on having an ambient lounge going on the other side of that wall, using it to help keep the roars of the main system to a minimum.





Sinewaves


Yet again, another head explosion! The perfect 208v sinewave now makes perfect sense! I made a shitty assumption that the slopes were parallel... They're not! There's an eyeball/almond shape in there, I see it now! Thank you!!!






Other


Yes, we will have Starlink out there! It usually works fine until a critical mass of people makes it into the city. Once that happens, all bets are off. We get it back after the man burns and the mass exodus occurs. Cell service works on the same pattern. We have an antennae/extender/booster thingy that goes up about 15-20' or so, but even with that, any type of service can be limited. There are a few places with big tall antennae to piggy back off of, but those are a ways away from our block.


This is great news on all these electronics working on 208v! Thanks for checking that out! Seems like we can plug the whole sound system into the 208v Furman. Then, everything else can go into the 120v Furman. Sweet!!!


And thanks for checking into the Furman again! Man, every single piece of this setup is wrapped in marketing hype! Every. Single. Piece. Thanks for helping to cut through it all! Oh, and yes, AD BE DF, those are all grouped together in the manual as well if it's set up for 3 phase. Otherwise, I think it's ABC and DEF on 2 phase. Or ABCDEF on single I guess!

[Levi]

Build Techniques



Choices, choices, choices... I'm guessing a lot of what I'm about to discuss here probably won't matter too much in the end. Pretty much all of this is coming from troubles we've had with our previous T60s. I figured I'd type it out here to avoid any silly pitfalls, though.


So, in no particular order...




Driver Mounting Screws


I see the #10 x 1.5" sheet metal roofing screws! Thanks for the link!

Before I go further, I'll say I've nerded out on screws with the McFeely's folks. Here's what I've gathered so far. I'll try to organize it from top to bottom.


Recess type - Robertson/Square drive is preferred by many woodworkers. They retain very well, and stay straight when driving them in. Very hard to strip out. Star/lobe drives like Torx and Phillips can wobble off axis. This can be good if you're trying to drive screws in at a slight angle, you don't need to be perfectly straight on. However, if you are off axis too much, you slip off the driver off the screw entirely. I can see why they're not recommended for our purposes, especially for driver mounting. It makes sense that hex head are great for the ratchet driver option, especially if you don't have access panels on both sides. And, no sharp points to damage the cone.

Head type - Flat heads area great for countersinking. Bugle heads help provide a little more clamping force than flat, a little harder to countersink. I messed around with both, and there's not too much of a difference. With enough torque, either can go right through the wood. Pan heads have more clamping force than bugle, but are more prominent. Washer heads provide the most clamping force. They will definitely strip out the bore hole long before countersinking, no matter how high the torque. Probably impossible to countersink these without a drilling beforehand. Neoprene washers are there to help keep water out.

Shank type - Partial vs full threads. Partial threads help lag the far piece to the near without drilling a larger gliding hole. Full threads will require repeated attempts and clamping because the thread grabs the near piece as well. You can also get the lag technique going with variable pitch threads.

Thread type - Coarse, fine, hi lo, serrated/saw tooth. Coarse threads have a smaller core and fewer, wider threads. Good for soft materials. Fine threads have a larger core and more, narrower threads. Good for hard materials. More holding force, but only if the material is strong enough to take it. The McFeely's guy said modern coarse screws are just as good as fine threads for wood. I don't know, just parroting. The difference in core size would mean different shear strength, though. Hi lo threads like on the roofing screws offer a combination of coarse and fine threads, usually with a large core. McFeely's said in solid wood they would be better, but in plywood they are not as good as just plain coarse thread, though. Serrated threads have barbs on the last big that help cut through the wood fibers instead of pushing them out of the way. That helps for ease of insertion. As can dry lube coating.

Tip type - Self-drilling are pointy. Self-tapping have cutting flutes to tap the hole (Type 17 I think). These flutes are probably worthless unless there's somewhere for the cuttings to go, so you'd have to back the screw out to clear them. Or maybe they can compress in the material. Depends on the material density I guess.


With all that said, it seems like the the driver mounting screws, things have moved from tee nuts/inserts/hurricane nuts and bolts to screws. Screws with hex head to help with slip out. Washer head to provide more clamping force. Larger core diameter and hi lo threads for shear and holding strength. And the prevalent type 17 self-drilling, self-tapping tip.



Here's my line of thinking:

Go with as much #2 square drive as possible. Minimize switching bits on build and during maintenance. We've had to do a lot of digging in access covers and driving mounts over the years. It will be nice to do it with just one bit, especially at scale.

Washer heads where clamping force is the first priority. Driver mounts, rubber feet, access covers. Flat heads when countersinking, using a countersink bit just to be safe and not split anything.

Partial threads at all times. That said, shorter screws like 1" and below usually only come in full thread.

Coarse thread at all times. This was a bit of a tricky one. Talk to the lumber yard guy, and he classifies baltic birch as a hard wood, even if it's in plywood. Talk to the screw guy, and he says it is softwood. Maybe it's the hardest softwood there is, harder than pure softwoods even with all the glue. Anyway, I went with the screw guy's recommendation. Again, he said hi lo would grip better if it was pure wood not plywood, but because it is plywood, then coarse is the way to go. Go with as large of screw diameter that I think I can get away with if I'm concerned about shear strength. I'm not sure on serrated or not. Seems like if I predrill anyway, that won't matter. Plus maybe it leaves more of the wood fibers intact, and maybe that would increase holding power?

And type 17 tip. It's pretty much all there is, so why not.

***I will always use a drill with adjustable torque to insert screws to avoid any blow outs. (This has happened many times in the past - no bueno!). So far it seems like the "5" setting on the drills I'm using is just right.



Lock Washers

For the driver mounting screws, we also need to use lock washers to counter the vibrations. But which ones? More research. Internal tooth, external tooth, split ring, etc. All have their application. Lots of YouTube videos out there testing them. It seems like the undisputed king is the nord lock / wedge washer. It comes in pairs. More expensive. But it seems like the way to go.

If I get the biggest size screw head that the driver frame can handle (Depends on the screw, but I think #10 at just under 1/2 inch head diameter), with a matching nord lock washer, that just might be the ticket. No more vibrating loose, even with a week straight of rumbling bass! And easily removed and reinserted if the driver needs to be changed! No more loctite blue!

Thoughts? Does that construct sound like the bee's knees? Does anyone have experience with these washers?




Driver Spacers

Do you guys use them? The hard ones that come with the drivers? Or do you just mount with the driver gasket right against the plywood? It seems like the 1.5" length for driver mounting screws is perfect if I don't use them. But if I do, then I'd need to get 1.75" long.

Also, silicone anywhere as an insurance policy?




Leaving the Screws In

I know the plans say we can remove fasteners after the PL sets, but I'm a little timid to remove them. The cabs will definitely be stronger with them in there, yes? After a couple of years, some of our old T60s were coming apart at the seams, mostly near the mouth. We had to put screws in to close them back up. I feel like these cabs have to endure quite a bit more than your average bear. We are coming up with other ways to minimize the hardship, but it seems like all the little things we can do up front would be good.

Side note. Do you think squirting a little PL in the screw holes (not the driver or access holes) before inserting would help any screws from vibrating loose over time? I know some PL probably comes up through the hold from the edges, but just to be sure the whole screw bonds to the wood, not just a little bit.




Speakon Dish

We are planning on putting the dish straight back from the driver chamber, in the middle of the back panel. Do you guys mess around with silicone on between the plate and the plywood? Or have you found that it stays airtight just with its mounting screws? I will be getting that 3' tube to test, but I thought I'd ask anyway.




Joinery Options

Pocket screws? 90 degree screws? Dowels? Pins/brads?

I know there are many options. I am looking for the best balance between strength, aesthetics, and speed. Ideally, these cabs will be way, way, way stronger than our old ones. Also, they will look better - hopefully nothing but maybe some 23g pins on the top, bottom, and sides. And hopefully whatever method doesn't take us forever to do.




For the interior panels, it seems like pocket screws are the way to go when attaching everything (until the bottom panel 12) to side panel 1. Then, for attaching interior panels to each other, using washer head screws when possible, and flat heads or 23g pins when not.




I'm leaning back and forth for the exterior panels, though. Mostly because of aesthetics. Remember that we are not painting these. We will still use Duratex, but it will be clear.

Nails seems like a no. We used them last time. I probably wouldn't be annoying you guys with all this chatter if our old cabs were still going. We can use them along with other joinery, but not by themselves. For instance, the 23g pins in the pocket hole trick.

Pocket screws seem to be the weakest option. However, they allow for maybe up to 1/4 - 3/8" round over. Rounded edges will be nice for durability. Or at least I think so. How much round do we need? I don't know. They provide excellent PL squeeze out. Fast, too. However, pocket hole plugs would line the top and bottom panels, and the back panel. I could probably hide almost all of them if it weren't for the limited access after putting the last side panel on. Unless I'm missing something? Should I use clamps for the last side panel around the edges, pocket screws in the driver chamber, and 23g pins along panels 6 and 7? Would that be strong enough?

Dowels are stronger than pocket screws, assuming there are enough of them to outshine the pocket screws spaced every 6-8 inches. They are hidden, which is really great, but need clamps or screws to help with squeeze out... Plus they are probably slower? Now that I think of it, it's probably impractical. If I use 1/4 inch dowel, I can drill plenty far into the top and bottom panels, but only about 1/4 inch to the side panels. That might not work all that well from a strength perspective. Maybe I should have gone with dados. I guess I still can, but since we've already made the big rips, the cabs will be narrower than the full 20".

90 degree screws are the strongest. Basically dowels, but made of steel. This assumes that the 90 degree screws are longer than the pocket screws and engage more material. So maybe 1.25" to 2" or something. However, they would polka dot all over the side panels. Also, probably can't do too much of a roundover with the screws in there. Maybe only sanding. Trim head screws would probably work better, with the smaller footprint.




For braces, do you guys press fit, and then just toenail in brads? Assuming that you can fit your nailer where it needs to go.

[Levi]

Oh, and here's a few pictures of the old ones splitting. Complete with playa dust.

[Bruce Weldy]

Joinery Options

Pocket screws? 90 degree screws? Dowels? Pins/brads?

I know there are many options. I am looking for the best balance between strength, aesthetics, and speed. Ideally, these cabs will be way, way, way stronger than our old ones. Also, they will look better - hopefully nothing but maybe some 23g pins on the top, bottom, and sides. And hopefully whatever method doesn't take us forever to do.




For the interior panels, it seems like pocket screws are the way to go when attaching everything (until the bottom panel 12) to side panel 1. Then, for attaching interior panels to each other, using washer head screws when possible, and flat heads or 23g pins when not.

There is no reason for any screws in the cabs. You should be using only PL Premium. 1 1/4 brads are all you need to keep it together while the glue dries. The glue bond is stronger than any mechanical fastener. My early cabs had some cabinet screws that were taken out before finishing. Later cabs are all brads. Once you trust that the glue will do the job, it's a no brainer.

If your old cabs came apart, I'm betting that you didn't use PL Premium.

[Tom Smit]

Matthias Wandel has used bamboo skewers to strengthen joints.
I have had a strip of plywood come loose even though the surfaces were clean, misted with water, and PL applied.

[Seth]

The Furman

...That hunk of junk better help "regulate voltage, reduce noise, and filter out electrical disturbances", or I think we'll just throw it into the fire.

Some of the Furman products do offer voltage regulation. This is not one of them. But, don't shit-can it! It's still an amazingly clean solution to breakout three phase service into individual 208V single phase circuits and outlets. Even in it's standard 120V configuration, it's a nice, clean, rack mountable distro. It would be a project all it's own to come up with a home baked solution in it's stead.

...It only splits the 3 phase source into its separate phases...

Slight distinction here. In it's stock form and intended use, it splits three phase power into it's separate 120V Legs. Leg hots to neutral would be L1, L2, and L3.. Phases would be leg to leg, 208V. Where L1 to L2 is PH1, L2 to L3 is PH2, and L3 to L1 is PH3.

...we actually have 2 of these bad boys! So, now I can just completely rewire one for all 208v, and leave the other one all 120v! This is fantastic! Now, I just need to make a good splitter box to take the cable from the genny into both boxes.

That's a great plan!

Regarding the possibility of 16 cabs on one 20 amp breaker, it's certainly worth a shot!

If you wire one Furman for 208V, just put each amp on it's own Furman circuit breaker.

Limiters

Reading all this makes me think our shitty test was even shittier than how shitty I originally thought it was. Which was shitty.

I honestly can't remember all the details. At this point, it's probably better I just reread this whole section when we run the test again. And do it properly.

And sorry, clumsy language! Yes, I meant where the limiter kicked in. No clipping. Thanks for catching that!

You're cracking me up, Levi. Please, feel free to call/text/WhatsApp me when you guys are doing this stuff. If I'm available (I usually am), I'm happy to walk you guys through it.

If neither amp was clipping, it should have sounded the same on either amp when the limiter engaged.

T60 Deployment

Thermometers added to my cart! I see they go to 140F outdoors... How hot do you think it gets in that chamber?

That's a really good point, Levi. To be honest, I haven't the wildest idea. But, if it stayed under 140ºF, I don't think I'd sweat it at all and just continue to pound the piss out of them. And if it was more than 140ºF, I'd consider a wireless meat thermometer instead. But, you wouldn't know that until afterward. Hmmm. (scratches head, strokes chin)

That said, would it make sense to use bigger #10 than #8 driver mounting screws if they are going to be on their sides or upside down, yes? More shear strength? I have more questions on this kind of stuff, coming up in a bit!

I'm pretty sure (although, not positive) the link I posted was for the thicker #10 screws. Honestly, with eight of them per driver, either will be completely sufficient. The smaller #8 might even give you a little more wiggle room without being too close and breaking out into the edge of the driver cutout when securing the drivers.

Thanks, the placement rules now make much more sense! Now, about those submarines... What if they are feeling lonely down there, and just want someone to talk to?

Hahaha... too funny. A bunch of nearly adolescent young men alone in a phallic shaped tube under the ocean for extended periods of time... they'd probably want a little more than conversation. LOL

Side note

With the current plans, one shipping container would be 50+ feet directly off to each side of the booth/subs, and two more about 30 or so feet directly behind, creating a 8'x40' wall. (4 containers in total.) Do you foresee any cancellation problems there? Would that mess with the low frequencies in front of the booth? We were planning on having an ambient lounge going on the other side of that wall, using it to help keep the roars of the main system to a minimum.

Containers aren't going to block much sound. What comes out of the tops won't wrap around and emit much from the back and what comes from the subs will just pass over. As far as reflections and cancellations, if you inverse the formula to find wavelength (the speed of sound (1125fps) / frequency) and divide the speed of sound by feet, you'll get the frequency that has the wavelength of that many feet. 8 feet is the wavelength of 140Hz. Not likely to cause any issues. Are you able to post a drawing or rendering of the proposed layout plan?

Other

And thanks for checking into the Furman again... ...and yes, AD BE DF, those are all grouped together in the manual as well if it's set up for 3 phase.

Yup yup, you're welcome. The blacks should be where you need them and you'll just have to relocate the white's.

[Seth]

And... ah hem!

Progress update? Pics?

[Seth]

I've had this same joint (bottom of mouth) separate on two of my cabs. TAT and T39. PL premium used on both. Both were also constructed with 5 ply Douglas Fir. Maybe the lumber used? Maybe I didn't clamp the 2nd side on with enough clamps? I'm really not sure. However, will make sure it doesn't happen on any future cabs. I like the idea of bamboo skewers. Although, I'm not above just securing those corners with a countersunk screw.

[Levi]

@Bruce

Thanks! What gauge brads do you like to use?

We only used PL Premium in the old cabs. And we plan to use it for the new ones as well. Following the plans!

Also, it's not that I don't trust the glue bond. I absolutely do! However, given the splitting of our old cabs that only used brads (either 15g or 18g I think), I just feel like we need more holding power for these circumstances. In more common applications, brads and PL are probably just fine.






@Everyone


I've been thinking on this a bit. I wonder if the failure is more in the wood than the glue. As in, the glue is just fine, it's not separating. However, the wood that it is adhered to fails and splits. This is something to consider, yes?

We used 9 ply Baltic birch on the old T60s. The plywood had an interior grade adhesive between the layers. We used brads and PL. We stained them with Sherwin Superdeck. That construct has failed.

Where was the failure(s)? I'm not sure exactly.

Maybe an exterior grade adhesive between layers would've help keep them together with higher tensile strength? If yes, that is good to know. However, it is a moot point now, because we already have the interior grade plywood for the new T60s.

If the veneer is splitting and failing, or the plywood glue below the veneer, then maybe screws are the only way to help hold it down? Because they help hold it down to deeper layers/fibers? Brads with heads might help a little, but probably not as much?

I believe in the strength of PL. But I think mechanical fasteners can help secure the joints more deeply versus just on the surface of the plywood, in case the surface bond, or just underneath the surface bond, fails. Does that seem plausible?

Here is a video of some tests. Granted, it's not necessarily indicative of the forces that these cabs will be subject to, but I think the general principles apply.

https://www.youtube.com/watch?v=f1xnU6DE9y8

The first tests he does without glue help show that longer 90 degree screws are better than pocket screws. He does an advertisement in the middle, so skip past that. In the last part of the video, he uses wood glue. It's not PL, but I think the general concept is clear, that both screws and glue are better together than either one is individually.

That begs another side note. How much stronger is PL than wood glue? In tensile, shear, compression, etc. I'll have to look into this, see if I can get a good comparison. Not that I'd ever use wood glue on these cabs. I won't. But it would be interesting to know to put that video into perspective.

Here's a video where he tests dowels. Skip to the end, about the 12 minute mark. It's a different test, but shows that they are strongest.

https://www.youtube.com/watch?v=2NOx8F91AaA&t

Again, this matters to me because our old ones failed. It's easy to see the splitting on the exterior joints. Obviously, I can't see most of the interior joints, so who knows what's going on in there.

Maybe it's just as simple as that we didn't have the proper building techniques down last time... Maybe we just needed to use more clamps, and leave them on longer. After all, given our arid climate up here, PL probably takes more like 48 hours or more to cure.

Anyway, the big point here is that, if I take a little more time up front researching and building, and do everything up to or even past spec, then hopefully I don't have to worry as much about repairing cabs later on. That is pure gold to me!!!

That said, I'm not committed to any techniques/constructs yet! Just exploring what might be the "mega" option that will survive the extreme conditions. Open to any and all ideas here!







@Tom

Hi, Tom! Great to hear from you!

Matthias seems like the real deal! I found the skewer video, and loved every second of it! Thanks for the suggestion!

https://www.youtube.com/watch?v=CUPkudnw9X4

What a great trick these would be! Seems like they are right on par with maple dowels.

If I dowel, I can go halfway into the side panels, yes? No benefit going further than that?

Or maybe going all the way through would be good? I would need to figure a way to keep the panels compressed for the PL to dry. Just a lot of clamps? That'll slow things down a bit...

I suppose if I go all the way through with the dowels, I might as well just use screws and plugs. Hmmm...








@Seth


The Furman - Yes, we will keep them! They became much more valuable with your rewiring idea! Again, genius!!!


Limiters - Thanks! The curious thing was that the lower-powered Macrotech 2400 was the one doing the "wah-wah". We probably did something wrong. To be continued...


Thermometers - When we do our big dress rehearsal, it will be interesting to see whether we need to jump up to a meat thermometer! I mean, at the very least it would be good to know when the drivers are medium rare, yes? Just my opinion, but I think that is when they are most delicious!


Layout - I've attached a shitty drawing. (Our Sketchup guy will be back next week I think.)


Progress Update/Pics - Not a whole lot on the speaker front. Just lots of general prep. That doesn't sound like much, I know, but it's been a lot. For instance, it's a huge project just to get all the parts and what not in one place! That said, space is a little tight, especially with all the other projects going on. We will hopefully have the shop addition completed this week or next week, though, which is VERY exciting! That way we can have the room we need to get into full cranking mode! I don't mind the delay too much now, though. Gives extra time to get all the details dialed in. And annoy everyone here in the process.

[Levi]

Driver Spacer Ring

This is probably a stupid question. I feel like I should ask it, though, before I do anything stupid.

Driver spacer ring. Or at least that's what I think it's called. It comes with the drivers, not attached though. See the photo.

It seems like the LAB12 would be just fine mounting directly to panel 3. With the screws and lock washers, the foam gasket that's already on the driver frame will compress nicely to create an airtight seal. Right?

This would also correlate with using 1.5" mounting screws, because that distance matches up.

However, I am not completely sure of this, because in the T60 plans, page 3, second paragraph:

"The only rule that can't be violated is that every joint must be absolutely airtight. This includes the woofer joint with the spacer, where a potential leak source is gaps in the woofer gasket on the front of the frame. To prevent leaks there fill any gaps with acrylic latex caulk, smoothing the caulk flush to the gasket face with a wet finger."

So do you use the spacer ring? Because it gives a little more room for driver excursion? But you have to be sure to caulk it where it meets the plywood?

[Seth]

I don't have any personal experience with LAB drivers. It appears there's an open cell foam gasket already glued on the cone side of the mounting flange. I wonder if they just put the other one in there to keep the box/packaging from pressing on the surround while the driver is boxed up during storage/transport.

That loose driver gasket is a one piece deal. Some of the driver gaskets are composed of 3 separate pieces, each covering 120º of the circle. I always thought that advice about caulking the gasket meant to caulk where the multi piece gasket ends meet together.

It's difficult to tell in the photo, but if you feel the gasket that's already on the driver flange will be air tight, I'd just go with it. If you feel it won't be air tight, I'd carefully scrape it off with a razor blade and apply standard weather stripping tape with the butting ends cut at a sharp angle.

Maybe one of the other guys here can better speak to the gasketing needs of that specific driver.

[Seth]

I've found a few photos of your camp and speaker configurations over the years. I really like the vibe.

Some of the configurations look not too bad and others that would make sense to the average person, but are glaring mistakes to those who have a good grasp of the fundamentals of speaker deployment. None of them ideal.

I think you guys are going to be in for a big treat this year.

[Strange Kevin]

Lab12 extra gasket,
I understood it was for when you want to back load the driver if not using it in a horn cabinet.

Keep that gasket though, as it is a perfect template for marking out your driver cutouts on the baffle and mounting points.

Cab construction.
PL and 18ga Brad's is the way to go. Clamping as you go to keep everything as tight and square as you can, especially on the last side panel at the end.
I do use pocket screws occasionally on one side of some inner braces. Ex panel 2/8 brace, put 2 or 3 pocket screws from brace to panel 2 then Brad panel 8 the the brace..


My thoughts on the bottom/ side pannel corner (front) failure, it's the farthest joint from another suport. Allowing those panels to flex a little more than any other part of the cab.
1- Adding another cross brace or 2 out on the edge of the mouth could help.
2- framing in the mouth and adding a steel grill.
3- adding a 1/2" strip or some 1/4round molding along that inside edge to give the joint more surface area to glue to. Additionaly, this method would give you some room to screw the 2 panel together and still roundover the outside edge.

[Rich4349]

After all of his contributions and calculations, I hope Seth gets a statue at Burningman! OR at least a great big plaque mounted in plain sight!