Tarkus Speaker design by Paul Carmody

[highfigh]

Home center "3/4" is more like 17.7mm. I have to shim it to make it match up to real 3/4".

I would have rabbeted the braces but the drop I had left wouldn't let me get both out of it if I made it for rabbets. The corners on the bass bin are already screwed with drywall screws. I just glue the braces in first and screw after unless the piece is a little loose. These braces only had enough room for glue and had to be bumped into place once glue was on them. Appreciate the tips.

I also use cabosil/epoxy for filler, than I saturate the enclosures with thinned epoxy. As the solvent in the epoxy dissipates, it returns to it's full viscosity gradually and I keep feeding it until it won't take anymore. I get about .25" penetration and it makes it to where the extra sharp corners needed for veneer, aren't so fragile anymore and it hardens the MDF substantially. Sanded, cleaned epoxy is a very good (if not the absolute best) primer for paint, solvent based adhesives like contact cement. It turns MDF into a sort of a phenolic type material with what amounts to extreme durability. All screws are set in epoxy as well and will never vibrate loose. They may even need to be heated with a soldering iron in some cases to get them out.

first coat of thinned epoxy on a set of baffles. 80 grit sandpaper on an RO is all it needs to get adhesive to really grab hold.

ETA: Since the window brace is trapped on all 4 sides, all the screws really need to do is keep it located. I epoxy seal the insides of the cabinets as well. These should last hundreds of years. I'll use leftover epoxy filler to make epoxy fillets on both sides of the braces. Best place to put it, rather than toss the overages when it starts to kick.

What brand of epoxy do you generally used? I haven't bitten the bullet for that at this point, but plan to because I want to build some things using fiberglass cloth that need to be stronger than polyester will likely provide. I know about West Systems, TotalBoat and others, but no longer have access to someone who has years of experience with it.

 

[MrBoat]

What brand of epoxy do you generally used? I haven't bitten the bullet for that at this point, but plan to because I want to build some things using fiberglass cloth that need to be stronger than polyester will likely provide. I know about West Systems, TotalBoat and others, but no longer have access to someone who has years of experience with it.

I have been using US Composites resin and cloth since 2003. Before that it was System3 or Mas. When you look deeper into it, there are only a handful of chemical manufacturers that make the resins for all the brands. Dow-Corning etc. So basically each product just thins it to their preferences. The US Composites has been on my wood boat for 17 years now.

ETA: Polyester/glass is pound-for-pound stronger than steel, but epoxy is a much better adhesive. Also, Epoxy goes to hell in temps over about 135F and needs to be coated with UV inhibitive top coats, even if that ends up being exterior varnish.

 

[MrBoat]

Shopping polyfil specifically on scamazon was expensive for what you get. 2 queen sized pillows are cheaper somehow with a lot more of the same fill. Again, amzon is rather expensive for cheap pillows. Walmart has them for much less and they deliver as well. This is twice now that I was able to get a better delivered deal than amazon and sometimes it is next day. The other instance was wrangler jeans. I haven't gotten in the habit of cross reference shopping walmart, because I have grown to avoid the actual store and their online shopping pages kind of remind me of the store, too. I will start looking there more, at least for household items.

 

[MrBoat]

Ports and backs today. Already have the foam pre-fit as well. Just waiting on binding posts, but that won't stop me from taking them for a spin around the block. I ended up mounting crossovers on the braces for serviceability. Probably long after I'm gone but maybe some poor soul that has to work on them in the future might feel the convenience. Also wrote design/date on the crossover boards. I know I have had to work on electric motors and found that the previous tech bothered to put nevr-seize on the thru bolts. I always did as well and it was like a common bond with qualified techs. It's the little things.

This is the best way, really. Using a piece of the exact material for a gauge, over just measurements.

I predrilled pilots for the screws before gluing the braces in. Side braces, and every other joint will have glue and screws. I sand all the glue areas with 60 grit just to scuff it up a bit. I used shoe goo for the pvc to wood. I had it on hand from my RC hobby. I sanded the pvc with 60 grit as well. The lacquer thinner based glue does chemically meld with the pvc a little, and more than epoxy. The trick is to glue both surfaces and make sure it is well rubbed in or that none of the joint becomes glue starved, due to the absorptive nature of MDF.

When using thick adhesives like silicone, shoe goo, or epoxy, it is important to allow room for glue. Parts should be 'slightly' loose fitting.

I left enough room under the ports for the egg-crate foam. All IDs were/are sized with a flush trim bit after. The inner support is rabbeted for the pipe to sit in. It's sunk 1/2" deep. I worked it out with the math to allow for flares on both ends. I may have forgot to, if I had not taken notes on this build whenever I stopped working on it. I used to not do this. On the job, the delays between processes are shorter in duration. But walking away from a project for days at a time is a bit more prone to memory lapse. So, after 40 something years in the trades, I start taking notes.

 

[MrBoat]

Last of the construction. Will test drive them after glue is dry and then on to the hard part. These came out satisfactorily. All the parts were interchangeable from one cabinet to the rest except for the crossover boards. I eyeballed the screw holes for those. Added some glued-in screws. The cabinets ring solid.

Probably try them out tonight sometime. Top cabs are fully assembled with drivers and wired for sound.

ETA: Internal flush trimming and round-overs are very satisfying to do. I always end up wishing there were more of them.

 

[MrBoat]

Anytime now. Letting all the today glue dry some more.

 

[MrBoat]

They sing! These things can definitely rock and they sound really nice, even with the cheapie monoprice gimmick amp. I have some other amps I will try as well. . .just took the lesser care about amp for the hail Mary run.

 

[MrBoat]

Much better amp. DIY Icepower 200ASC, Starving Student pre/headphone amp. Very little volume knob needed on this one.

 

[MrBoat]

These speakers have made me a fan of Peerless drivers. The SLS 830668 woofer totally kicks ass. These really are a do-all design with enough bass and it will crunch you to your spine. I have spent a few hrs point blank between these speakers just throwing all kinds of music at them and they deliver a proper audio whup'n when called upon to do so, which is exactly why I built them. For listening to music with all the right balance without fiddling with EQ or music selection.

The bass guitar and lower frequency effects capabilities don't ask for much in the way of compromise from being able to do both. This amounts to what has been the largest 'ported' subwoofers in my home, and brings to light, what an ideal size sub would be in my humble space, or plenty of, at least, because these things will POUND.

Been listening to them with no EQ at all and I am impressed, to say the least.

 

[-Jim-]

Glad you are pleased with them. Now the fussy bit => Finishing?

 

[MrBoat]

Glad you are pleased with them. Now the fussy bit => Finishing?

Yeah but I'm in no hurry. That's a separate project. Just another way to stay amused, without eating it up all at once nd then having to dive into something else. They're kind of menacing looking and it sort of perplexes people how something so undone, can sound so good.

 

[MrBoat]

After putting these Tarkus speakers thru the paces for the last couple weeks, I have come to some conclusions. They are a great full room speaker. They are a bit shouty, point-blank tho. Bass is really nice. They can do it all and there are no mysteries to setting these up for stand alone 2 channel. The SLS woofers are really nice as implemented.

My biggest issue? Is that I own the Fusion-12 Tempests by Bagby/diysoundgroup. They are not going to be bested (or competed with, really) without spending some $ or upping the game level to the next realm, and even then, I'd just become the even weaker link in all of that. Tempests are just too good/powerful and will deliver incredible performance as near field monitors too. In other words, I am likely permanently spoiled by the F-12s with subs.

I own 9 pairs of speakers. What the situation is in my home is, Fusion-12s, and then everything else. Two other speakers I enjoy equally as well but for other reasons is the Paul Carmody Classx2, and the JBL S38/subs. If I didn't own, or know about the F-12s, I could stop at the S38/subs for extreme near field experience and be absolutely fine.

A good speaker for me tends to make me forget them. My best, I never really think about them until realizing that. . . holy crap, these things are 20 years old and beat! Also, essentially losing a decade or two of audio advances during and having to relearn it yet again. Oddly enough, audio has certainly become more complicated and redundant than I ever need it to be. All I need is double the headroom of my needs, low *audible* distortion and musical bass just into the 30s and no tiny damn woofers.

Next person that comes at me with a 5" woofer design is gonna get a wedgie, a wet willie, and maybe even a purple nurple if they are extra insistent.

That all said, I have a setup for the Tarkus in my shop for the time being. I may bring them to work, since I work alone a lot these days since we ran the phonetarded millennials off that could not be broken of their addiction to it.