Site Links
Howdy, Stranger!
It looks like you're new here. If you want to get involved, click one of these buttons!
Quick Links
Categories
In this Discussion
Able & Baker: My InDIYana 2025 theme project
Following the Trinity test, Operation Crossroads encompassed a pair of nuclear tests to determine effectiveness of detonations above and below water. Using two virtually identical 23 kiloton yield fission devices..
Test "Able": The first device was air dropped and detonated approximately 500 feet above water.
Test "Baker": The second device was suspended 90 feet under water for detonation.
Test "Charlie" was planned as a third, even deeper sub-sea detonation, but was deferred and rescheduled as Operation Wigwam due to baker's radiological impact.
The speaker:
A pair of Dayton PC105-8s sharing the same enclosure volume in a traditional .5 type configuration for baffle step compensation. Keeping things simple.
Enclosures will be .5cf flat packs I scored at this year's InDIY gathering. I really wanted to do a pair of ports out front side-by-side between the drivers, but sanity got the best of me and I think I've decided to rear port. Less weird baffle diffraction effects, also when using widebanders port resonances seem an inevitability. Maybe I'll sim a PR. we'll see.
For the circuit.. Calculators show baffle step for an 8.5" baffle is centered around 530hz. The impedance of the PC105 is pretty flat. It stays around 7ohm in the baffle step region.
For funzies I put ~500hz and 7ohm into the basic online 2-way calculators (you know, the ones never to use). It came up with 2nd order electrical values around 3mH and 33uF. I pulled the factory Dayton files into the sim and applied those cap and inductor values to get a rough idea of the interaction. It was surprisingly close. So I'll start out testing that combo.
So there we go. Super simple, easy and inexpensive. Maybe not the most exciting for you guys, but I'm excited to hear what the result is for such minimal input effort. Hoping for high juice:squeeze ratio. I can't wait to see the weird stuff you guys come up with!
I'll look to post some screenshots later.
Comments
If i end up using dual ports anyway i suppose i could add a divider to cut the volume in halves. Idk if there would be much real benefit. Would lose some total volume which id like to not do.
Since both will play bass in your case, the divider is unwarranted.
With what I'm planning, I'm hoping to keep impedance above 3 ohms.
InDIYana Event Website
One will obviously be dumping higher frequencies in the cabinet and the other will likely have an extra humped bottom end due to the 1ohm from an air core. So both will have different things going on in the same space.
If that's no big deal then that's cool with me.
Since they are the same woofer, it doesn't matter in either case.
Have fun, Drew!
InDIYana Event Website
Simming both, 8watts hits the 2mm xmax. 98db at 1m. Gotta subtract baffle step though
I'm sure they'll be giving all they've got playing in the big room.
Modeling them seperately to show the extra bump from the inductor resistance. Note the divisions are only .5db. Hard to argue that f3 for 4 inchers though.
Trying out the simple calculator values with factory data (no baffle step simulated)
Looks like it might tickle ~3.5ohm
I simmed a bunch of PR combos. Just gives up too much bottom end for my liking (~15hz or more).
First dust from the router table. Much less stress getting all the edges flush trimmed compared to handheld. Then tried a 1.25" roundover.
Just now realizing the holes are going to be awfully small to get damping material in and placed. doh. Probably would have been a good idea to at least pre-apply on the sides that aren't getting any holes cut before buttoning it up.
I've had good luck cramming open cell foam in without glue. I usually cut it 1/2 inch oversize for a good friction fit. I have been in builds that are 10+ years old and the foam was still in place.
For that cabinet I'd probably roll up wool batting and stand it up in the corners.
Thinking of trying an lpad pot on the .5 driver so i can adjust the bsc boost. Bad idea? Maybe ill just test it and see.
Then you can pad the other driver also. Normally with full comp designs, I still end up padding the upper range a tad.
InDIYana Event Website
I guess ill build what i want to build and you can tell me if it qualifies or not at the end.
I was trying to be supportive, and did not mean any offense at all. I was just stating from experience what happens for me.
InDIYana Event Website
@Wolf Ok, apologies. I read it rather different as if I was veering away from the theme rules.
My aim is to keep with the spirit of the theme. Trying to run with the main driver wide open and adjust the second driver to fit. Seems simplist that way, but maybe that will change once I get to listening and tweaking.
And FWIW, I don't think you are straying from what has been laid out. It is still well within the rules.
InDIYana Event Website
The PC105 pincushion frames give me old school vibes. That and the big baffle roundovers.. I'm thinking mahogany.
It is the Band-it brand stuff from PE. Perfectly usable quality, but it is not a high grade in the looks department. Lots of knots and a big color shift from end to end. Hoping I can manage to atleast get no knots on the front baffle areas. I might have to position a knot over a driver hole to pull it off though.
I like a knot here and there, its the cost of having good grain. Sometimes perfect grain is just too plane.
What he said. Gives it character.
Yep, normally id totally agree. But something about mahogany's bold but subdued grain makes knots a bit unsightly to me. Im not going to be able to totally avoid them so it is moot anyway.
I know it is something us modern woodworkers will have to accept. All the old big trees are probably gone and newer smaller growth is being harvested. Which is going to have less "clean" wood between blemishes. So the cost shoots up for the blemish free examples.
Some people pay extra for the blemishes.
I must have very valuable speakers. 🤣
The boring stuff.
Come on, everyone likes a nice rear.
I prefer a good looking front since thats the side that'll always be yappin at ya. Nice rear is just bonus points
... We still talkin about speakers right?
Because of the multiple bends. I tried the Titebond+Iron technique.
I find Titebond+Iron is amazing and awful. Way easier to do complex stuff like bends since you can align things perfectly without worry of pre-sticking. But it is very difficult to get 100% adhesion. Anyway, moving on.
I made a boo boo
I've never really been a fan of the 45deg tilt for the diamond shape effect, but it is an option. Or trim rings.
Great work Drew. Glad I'm not the only one working an Indy2025 theme already.
BTW... trim ring for the win. I don't care for the diamond look either.
Yup, trim it
IDK I might have to do the diamonds for the trigger value
The rings seem like they might be a slight PITA to implement. I'd have to clip the tips off the frame corners, and use super flush screws. Possibly come up with some sort of spacer to make up for the flange thickness otherwise I suspect warping of the flimsy ring may be an issue. Then rough em up and spritz with matte clearcoat. I'll probably run without for a while and add em later if it bugs me enough. Many months between now and Indy.