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Mnemosyne-a new monkey coffin

edited December 2020 in DIY

I have now started another build, because Craig has completed 386 pairs of speakers this year and making me feel like a lazy bum. Thanks alot Craig! :) ;)
Anyway, excuses aside, Mnemosyne is the titan of memory and remembrance in mythology and this is a speaker that has the classic monkey coffin look that I fondly remember as a kid. The plan is for a 30 x 16.5 x 12.75 box covered in walnut,
The cabinet is constructed of 3/4" plywood, lined with 1/4" recycled rubber flooring, and then 1/2" MDF for an approximate wall thickness of 1-5/8". Ben deserves credit for turning me onto the rubber flooring product, thanks Ben. I am planning a front to back "dagger" shaped midrange enclosure as well as whatever I deem as necessary bracing. These are going to be fairly heavy, but small enough to be easily moved.

jr@macSilver1omoPWRRYD6thplanetGowarjj45joeybuttsJasonPDanPsquamishdrocand 2 others.


  • I've been half-assed planning another large speaker with a throwback look. I have that quad of 8" Rival carbon fiber cone woofers. The problem I have been running into is finding a mid that will offer the sensitivity I need. Parallel, the woofers offer about 95db, and baffle step losses will only offset that marginally since one of the woofers will be near the floor. le sigh, nice problem to have. Easily solved with any number of 6.5" pro audio mids, but then I need stout tweeter that also plays low enough to integrate with a large mid, so maybe that Jethro planar tweeter from Beston.

    Anyways, love the look and am looking forward to how it all plays out!

    I have a signature.
  • Thanks for the mention. That kind of product works very well.

    Have you looked at the PRV NDY models? I'm still planning on using them in my Francium project with the MHT12 and dual HM170Z18. They have the sensitivity and in a 5.25" size.

  • What about the Gradient Axis axp-06 6.5" MCM closeout as the mid?

  • Love the look of these and I'm happy to be your inspiration Nick :p

  • The PRV lose due to the dustcap. Mars an excellent choice.

    I might have a pair of the Gradient, I'll look.

    I have a signature.
  • This another build where I am trying to use up drivers that are on the shelf. All tent sale specials. B&C 12PS100, Faitalpro 6pr150, and Morel cat378. Of course these get grills to cover the ugly.

  • Kornbread is curious. Let's dig a little deeper into the wall construction.
    If you want to use the Gradient axp and clear some of your shelf space; we might work out a trade?

  • It's recycled tires melted into sport-flooring mats. You can get several different types:
    1- rolls, usually thinner and less dense.
    2- puzzle-edged, meant to be loose pieced together across your floor.
    3- thicker sheets, usually about 24" square.

    I used to get them at Menard's, and they were 23" squares, about 3/8" thick. Screw-them down, glue-them down, pressure-fit, whatever suits your purpose. It appears as though Nick is almost going CLD with it, box within a box. This stuff is heavy and dead, and works very well.

    Jeff turned me to this stuff (then called 'Tough Tile') likely 16 years ago now. I've used in a lot of builds. In the recent EMP, I placed it above the slot-port and damping on top to stop the column resonance.

    I've even glued it to the rear of tweeter cavities to deaden the plastic.

  • I'm thinking more like Nick (UglyWoofer?) with the exception of going to a thinner 1/2" ~ 3/8" ply for both inner and outer coverings and bonding both sides of the mat to the panels. It would be nice to have an inert cabinet, in both resonance and acoustic transmission, and not hurt my dang back every time I try moving it. When practicing TKD, we used the interlocking mat on the shed floor. I'm leaning to something more dense than that. I'll have a look next time we hit Menards.

  • edited January 2021

    I used loctite pl300 foam board adhesive on the rubber because it stays a bit pliable when dry. Check out the monster build thread on diyaudio. The rubber flooring is from Home Depot, as is the adhesive. I ordered 32 sq ft of flooring and a case of pl300. If I remember correctly it was about $150 delivered.

  • Menards only seem to have huge rolls costing a pretty penny. Is there any specific brand or product.

  • There is interlocking sport-flooring that is not tire-shreds as well. I know they make those in closed-cell-foam as well.

    This is close to what I used:

  • We use a proprietary adhesive at my job, "TES" (thermo elastic something or other) that I intend on using in future builds. When I was in AZ in early December, I was fairly impressed with the stuff. Extremely high adhesion to wood, paper, plastic, even ceramic. Maintain pliability even ten years later (they had a demo setup with the material aged out), it is extremely dense as well. When it is applied, it is extremely fluid but does not run. It takes a lot for me to be impressed with materials (I have used pretty much every commercially available adhesive, caulk, tape, etc in the last 20 years due to my line of work), but this stuff blew me away.

    Wolf: how do you intend to paint the dustcaps? I would be interested in that process. I tried painting paper cone material in the past with pretty miserable success.

    I have a signature.
  • Oh - the TES comes in the 20oz sausages so requires one of the special caulk guns, or open the sausage tube and have fun making a mess. I'll bring a few tubes to the next DIY I attend.

    I have a signature.
  • For adhesive, I'm thinking the ape snot we used to glue down vinyl flooring. It stays pliable, can be spread on with a putty knife, no smell, and readily available. If not that, I think the the local hardware store has pl300.

  • This is the part number of the rubber flooring that I used. #314339680 $93.00 for 32 sq ft

  • @jr@mac said: Wolf: how do you intend to paint the dustcaps? I would be interested in that process. I tried painting paper cone material in the past with pretty miserable success.

    I'm going to try a dopping foam brush and tape off the cone, likely a flat paint to match consistency of the cone. Shouldn't take much.

  • I cut the holes in one cabinet and did a driver test fit. The sides aren't bowed, it's a camera distortion.


  • The interior so far, I still need the mid enclosure and bracing, before closing up the back.

  • That should be a rockin' speaker Nick! If those B&C 12s are anything like the 18s I've used, you should be able to dump a ton of power into them when you're in party mode.

  • They're rated for 400w, but here's a sim with 200w, F3 40ish depending on how I do the final tuning.

  • I'm really looking forward to some measurements, the 6PR150 has an unusual "dust cap". Maybe I'm being naive, but it looks like some engineering went into it, not just a dome thrown on as an after thought. Oh well,I'll just have to wait and see how it measures.

  • It very well may function like one, but it looks a bit different, in that its only about 1/4" proud, the outer edge is attached, and it doesn't have a steeper profile, in fact it's about the same as the rest of the cone. It's almost like they took a section of the cone and raised it 1/4". It is a bit thinner than the rest of the cone though. There is nothing revolutionary going on here, but I am curious to see how it measures.

  • edited January 2021

    Did I mention, it's pretty damn ugly. Ugly woofer, nope ugly mid.

  • Dust caps make a difference no doubt about that. I wonder if this was a way to stiffen the cone and make the functional cone area go deeper into the voice coil.
    This driver is not going to be winning any beauty contest that's for sure.

  • Here's the mid enclosure, it's about 3.2l. It didn't need to be that large, but I wanted to to give the mid a bit of space between it and the dagger walls. Just for kicks I modeled it and the qtc is .54, not that it matters.


  • Yep, that's the tweeter hole.

  • Fancy👍🏻

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