Group Buy for Mechano23 flat packs

[Fred H]

I sent Speaker Hardware (dot com, a/k/a SH) a Sketchup model of the Mechano23 speaker; I made three changes to @XMechanik's design in that model:

1. Omitted the terminal holes; I expect purchasers will be able to drill what they want.​
2. ¾” (19.05mm) Baltic Birch instead of 18mm BB (which SH doesn't use); keeping all outside dimensions and driver layout unchanged, this reduces volume by 3.3%, from 7.86L to 7.60L.
3. Increased the depth of the model by 7.6mm (0.30”), reducing volume loss to 0.02% at 7.86L.​

I have attached printouts of the Sketchup model in both millimeters and inches; they are identical except for the dimension change.

The 45mm port hole fits both the original MBR-35 and the 1-3/8" port from Parts Express (you may need to wrap the PE port with tape as it's slightly smaller). I expect that SH will be willing to omit the port hole for those who want other alternatives. Please note that the model doesn't include screw holes.

SH has quoted $225 per pair and $200 per pair if at least five pairs are ordered in the group buy. The flat packs will be bisketed for easier and more accurate assembly (the speaker is too small for pocket screws). Shipping is extra; they will ship anywhere except China.

Finally, I will email a copy of the Sketchup model to anyone who wants it and probably make requested changes. (If you register for a free 30-day Sketchup trial you can modify the model; if you use the free version you can look at the model by opening it as a "component".)

Edit 6/1/24 Replaced PDF's with higher resolution, otherwise identical. Added SketchUp model.

 

[Inertiaman]

You may want to confirm w/ the vendor that their 3/4" baltic birch is indeed 3/4" (aka 19mm). Since virtually all baltic birch is sourced from northern Europe and Russia, my perception is that virtually all of it is metric (12mm, 15mm, 18mm, etc). All the 12-ply and 18-ply baltic birch I've ever sourced has been 12mm and 18mm, respectively. I suspect - but could be wrong - that they may be sourcing 18mm material and referring to it "nominally" as 3/4" out of convenience.

If true, your dimensional adjustments would not be necessary.

edit/ps - thanks for doing the Sketchup work and inquiring about flatpacks!

 

[Inertiaman]

Should we consider having the edges of the front baffle radiused?
Seems like this has generally been considered desirable in the review and build threads?

With a biscuit assembly, I don't think a radius will be problematic during assembly.

 

[Fred H]

You may want to confirm w/ the vendor that their 3/4" baltic birch is indeed 3/4" (aka 19mm).

I had the same concern and asked him. Their BB is indeed a full 3/4"; 15 ply. He said that they had just received a shipment.

I've read those comments and looked around on the web. From what I read (and I'm certainly not an expert), I'm ambivalent about radiusing the front baffle as it shifts the diffractions rather than eliminating them. If it's the consensus I will ask them how much radius the biscuits will permit.

 

[Raxumit]

I just ordered drivers and parts. Should I contact Speaker Hardware now about ordering the flat pack, or wait for the word here? No rush, no worries, just unsure how to proceed.

 

[Fred H]

You are the only person who has said they would participate. The model is available for download in my original post. I think it’s reasonable to call the group buy a bust. Thanks for checking.

 

[mumpgod]

Just adding my interest, if a group buy ever ends up materializing.

 

[Fred H]

I don't think it will materialize, I've moved forward independently. But I've found some resources that might be of interest:

Baltic birch (18mm) source: Ocooch Hardwoods; the largest piece they supply is 23"x30", but this is large enough to cut all pieces for one speaker. Two of these with shipping to New England was $55.05. I've attached a PDF and Sketchup model of the layout.

I searched locally for CNC woodworking and found Machined in Wood. He (Mike) quoted $100 to cut and biscuit two speakers; he's going to do mine. A 2-speaker flat pack fits in 1 Large and 1 Medium USPS flat rate boxes, but I'm going to pick them up as they are just 45 min away. Mike will also glue ($25/speaker) and finish ($ depends...) speakers. But shipping would be more.

Edit 8/22/24: I found that the drivers were a very tight fit and I wanted to be able to remove them without prying. So, after modifying the flange diameters with a dremel I suggest increasing them by ~0.5mm. I also increased the tweeter hole diameter by ~1mm (dremel, again) and relieved its connection locations with a half-round file; alternatively, you could cut the tweeter hole diameter 4mm larger.

 

[mumpgod]

Ahh gotcha, thank you for following up with your process and the design files, super helpful! I've started looking for a local CNC guy, so hope to be able to make some progress this week.