Upcoming project - SubOptimus

S7910

I'm finalizing driver selection for some of next years builds to use up some old inventory and first up is a 3 way monkey coffin. I'm calling it SubOptimus because of the drivers involved.

10" Dayton Series II woofers - not a bad driver, just NLA

HiVi K1 - Measures better than it performs, IMHO

Random Focal mid - not good enough to make the cut in anything else and needs to get off the shelf

The idea here is a '70s - '80s style three way floorstanding "bookshelf". The crossover should be a fun challenge come spring.

jr@mac

Seconded on the K1.

Do I know the Focal drivers in question?

jr@mac

Also, awesome build. The world needs more monkey coffins.

S7910

Yep, you know the Focal drivers in question. I've lost count of how many build ideas I've had them penciled into and then promptly removed them from because there were better options to track down.

jr@mac

I sent measurements along with them, right? 

S7910

not that I recall.

I've measured T/S to figure out what I need volume-wise for a mid enclosure. The rest I'll deal with when I pull out the Planos of XO parts.

jr@mac

Check your PM, sir. I sent snapshots of in-box response of the Focal.

S7910

Had some time to figure out the mid chamber.

Which yielded this in 1L sealed...

jr@mac

That should be very agreeable to work with.

Wolf

Is this a 4" mid? Or is it a 5" with 4" width surround-peak to surround-peak cone?

Only reason I ask, is that the driver has a 5 in it in model, and most 3-4" drivers are in the 80-82cm^2 range. I would have expected the Sd to be larger.

S7910

IIRC it's a 5" with 4" width surround-peak to surround-peak cone. I'll try to verify that this weekend when I have some free time.

S7910

Here ya go Ben.

S7910

Got the Series II broken in and measured,

Plugged things into UniBox,

.... and that's not gonna work out based solely on the SPL @ 2.83 Vrms 1m as compared to the Focal. I forgot these were that sensitive, so back into the stash they go.

Enter their replacement ...

measured

and modeled

gives this in 3.5 cubes. Little bigger than I expected at the outset, but still very doable.

S7910

Now that it finally warmed up enough to work outside, time to get these moving again.

Internal cabinet dimensions are going to be 36" x 18" x 10", and takes into account the volume needed for the mid enclosure (.23 ft3), bracing, etc.

I'll be using 3/4" ACX plywood from Menards primarily due to personal preference and familiarity with working with the medium.

S7910

Been making slow progress, but progress none the less. Both planters cabinets have had basic glue up. Bracing will be added after I route the baffles and build the mid chamber so I can test fit the various parts to make sure they aren't interfering with each other.

kennyk

Monkey coffins are COOL! I need to brake down and build one. 🤔

rjj45

Digging the monkey coffin, but that's one big monkey!
Got a pair coming in my near future with the Dayton PN395 anchoring the bottom.
Tentatively planned for wide baffle.

6thplanet

I might have to jump on this bandwagon, the new garage need some monkeying 😝

S7910

rjj45 said:

Digging the monkey coffin, but that's one big monkey!
Got a pair coming in my near future with the Dayton PN395 anchoring the bottom.
Tentatively planned for wide baffle.

It's a big monkey, but since the coffin isn't big enough for a gorilla ...

S7910

Making some more headway on these.

Baffles routed

Gluing first mid enclosure

S7910

Quick mock up:

I added the port, and then realized I didn't leave a good place for a window brace.

After some contemplation on the likelihood of these being used for anything remotely resembling critical listening:

rjj45

You could have tied some bracing into the mid enclosure, and you actually still can. Really just need 2 3/4x1 sticks at 90 degrees. 

S7910

rjj45 said:

You could have tied some bracing into the mid enclosure, and you actually still can. Really just need 2 3/4x1 sticks at 90 degrees. 

Good thought. I'll see what I have for scrap lumber in the stash.

S7910

Been a while since I've done much with these that's noteworthy (fill, sand, repeat), but it's time for an update.

I started on the crossover a week ago after getting back from Grand Rapids. Started Monday evening and had things finalized Wednesday night. Parts count is not quite what I expected from the published FR measurements of the drivers used, with three parts on the woofer (one resistor) four on the mid (two resistors for Lpad) and one on the tweeter. I have some accompanying photos for when the uploader is working again.

S7910

@jr@mac : thanks for convincing me to do this before spray bombing them. The woofer was a nice snug press fit as it is - if you look closely "Look ma, no screws!" - I threw the musical gauntlet at them and they have yet to pop out on me.

Now I just need my XO order to show up in time to bring a stereo pair to IOWA.

PWRRYD

Are those the 15" you got from me?

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PWRRYD said:

Are those the 15" you got from me?

Yes they are.

jr@mac

That is serious monkey coffin action, my friend.

Tom_S

Holy Carp - those are huge! Can't wait to hear them in a few weeks. Glad I don't have to beast them out my basement.

S7910

Ran into a slight problem. I made a slight tweak to the crossover and am short a resistor. Does anyone have a spare of this resistor?

I dug through my parts stash and somehow this is the only 1 ohm resistor I own.

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Tom_S said:

Holy Carp - those are huge! Can't wait to hear them in a few weeks. Glad I don't have to beast them out my basement.

Hey Tom! Look forward to seeing you in a few weeks. These will just be in bare plywood finish, but they'll be there.