Saint-Saëns planar- AKA SMJ-40- time for a project now?

[Johnloudb]

Sounds good Jon … I keep checking in here to see how things are progressing. Glad you’ve found time - I’m trying to squeeze in time for my audio projects as well. I look forward to seeing your build here progress … cool project!

[JonMarsh]

I keep falling back to the old "slow work takes time" quote from Dr. Tihanji in the early days (for me) at Siemens. But I'm pretty close to having the midrange - HF cabinet in testable condition, for some understanding of what might (or might not!) need tweaks in the crossover design.

Got a lot of plans for this week... lets see how they all work out, and hoping you and the other members have a great Thanksgiving break!

[letiennam]

Hoping you and the other members have a great Thanksgiving break.
You are definitely the one who knows best how fully prepared I am to pursue your project.

[JonMarsh]

Some further updates and alignment of CAD work and a physical sample of proposed TPL75 mounting panel are mostly complete- it does feel a bit weird having a hiatus on this since June due to family health issues, in-laws and wife- I wouldn't say I've lost track, but they keep updating my favorite CAD program, and the user interface has evolved unexpectedly! but significant progress yesterday. Today has been playing with smoke detectors with dying batteries- and one of them in a vaulted ceiling, rather a bit out of reach.

What the heck, just an opportunity to buy another ladder, right?

[JonMarsh]

So, this is an update with an image capture of the current MF-HF V4B3 drawing, which has some reconciliation with what I was last building, making some "executive level" decisions in fabrication which were not in the current drawings back in June!

Steve would probably make a more pithy comment about me just getting my "stuff" together...

I fabricated two possible versions of the tweeter mount panel, which is attached to the main MF-HF cabinet front panel using, (what else!) M6 Furniture bolts, I have both brass and stainless steel versions to play with, of course with RAMP M6 threaded inserts when I'm ready to install. (soon, quite soon). What's shown below is the version I'm going with.

The HF mounting panel for the Beyma TPL75 tweeter (or any alternate driver, such as GRS PT2522 with custom MOD3 rear enclosure) is fabricated from a layer up of 3/4" BB ply (bought a serious amount of that stuff right after the Ukraine invasion, so this is the real "Baltic Birch", not just "Birch" ply, with a top overlay of 3/8" solid maple board. Had some fun with the router table and drill press fabricating this; don't start without your Forstner bits, either!




I have the cabinet with mid sub enclosure with damping pads built, next step is some wipe on polyurethane for the tweeter plate, and installing the M6 inserts in the MID front plate. Second cabinet in a similar state except that I'm lacking the side panels; need to get more bamboo ply.

[JonMarsh]

Another thing I plan to try is splitting the upper cabinet into two pieces to make setup and tear down easier- getting the 100 lb cabinet with dual woofers and PR's up on top is not trivial, and I'm not getting any younger- I'm holding up well for almost 75, but let's be realistic!


So, here's a quick look from a few viewpoints, plus one render...









And, yes, I have two of the core inner sections glued up, need to cut the additional panel pieces now that I have it worked out and can create dimensioned 2D drawings.

[JonMarsh]

Distractions abound this year, and the last couple of weeks, but a bit more progress on the V3 MF-HF module test fabrication.

Here is a WIP drawing of the removable tweeter mounting plate for the Beyma TPL75. Not a final plan drawing, just documentation for Work In Progress.



This part was fabricated much earlier last year, in the early summer, before all heck broke loose. It's designed for using furniture style M6 bolts, as one can buy at ACE Hardware and many other places, for mounting to the main MF (Mid Frequency) enclosure.

To get a clean entry hole into the bamboo ply panel I used for the MF enclosure, I chose to use a 3/8" Forstner bit...


Due to the basic enclosure being already assembled, and the depth from the edge regardless of that, the best way to do that was with a high stability Rockler drilling mount, which gives precise angle control, and adjustable depth stops.

The upper edge holes in particular require some care...




This shows examples of M6 furniture bolts available locally- (Ace Hardware stores)

[JonMarsh]

Hmmm, once again, I have to say, "Rampa Rulz!" as this is still my favorite brand of inserts, here we see an M6 threaded insert installed for the mounting of the tweeter panel.




And after installing all four inserts, and checking the mount, it's a good idea to double check the depth of the inserts and that they clear just below the wood panel surface, and a little clean up sanding due to wood expansion may be in order. With the bamboo, which is hard and doesn't like to give, I actually followed up with a 9/32" bit after the 3/8" Forstner bit.




And finally, the more "normal" view, with the MF cabinet oriented as planned for this implementation.

[JonMarsh]

Now I've started on the work of fabricating single woofer cabinets, for the upper modules- this gives a few different possibilities in final execution. The starting core is the same, either using the PE modular cabinet, with the back, bottoms, sides, and braces, but discarding the front panel pieces, or building from scratch as the drawing above in post Source Bleed shows.

After these pieces are epoxied together, some clean up is necessary, just like for the unitary dual woofer LF cabinet build, due to seepage while setting.

Here you can see typical seepage resulting in a hardened epoxy ridge on side walls...


And the typical kind of dribble at the base joints- this all has to be cleaned up before gluing on the additional wall lamination pieces, of course.



This can require several passes, as the initial follower roller trim can be bumped a bit by the first pass from the adjacent joint.

Most of you will understand this stuff from past work; this is just the "wires and sparks" guy possibly overstating the obvious...




Here's how it looks with things setup to get started, using my Bosch 1/2" router installed in a 1611 fixed base and set to the right height inside the router table I use (also Bosch).

After the multiple passes back and forth are completed, things are looking pretty smooth and ready for the next step- don't even need a pass with a sanding block!

[JonMarsh]

BTW, what's made getting out and working in the garage in the afternoon is the rather unusual winter weather we've been having here in Idaho- stuck in a high pressure inversion with stagnant air for over two months, now having higher temps in the afternoon, and no snow in December or January, and nothing in the forecast for a while- 50 degrees is OK to work in, in the afternoon, but I do gluing operations in a bedroom that is usually a crossover assembly room, so that I have the right working temperatures.

[JonMarsh]

Still in the slow work takes time, especially if you're using West System 109 epoxy with 206 hardener! (heh, that's a joke of sorts...)

The last step of getting ready to glue up the end caps (besides buying some more MDF and cutting them out!) is to fine sand the surfaces and deal with an glue drips that that old guy you had to settle for doing the last stage of cabinet assembly got on the enclosure walls!





I'm almost as bad about rotary sanders as I am about routers (dedicate specific models to specific tasks due to ease of use or other factors) and I do have a certain fondness for Makita as well as Festool and DeWalt, depending on the task at hand. But they all get loaded with various grades of Mirka Abranet, which is porous and allows air and sanded particles to just flow through into the sander and catcher bag or exhaust port.

Gluing the end caps is straight forward, the System West series is self metering, one pump of Resin to one pump of hardener, and this task just needs two pumps of both, plus short clamps on the open side, and some narrow clamps on the opposite side.

Note, this stage of work is only being done in the winter in my bedroom that is currently an assembly and crossover construction room. Far too cold in the garage, not practical to heat.




A few more comments regarding what I call the mono woofer cabinets-

• I'm using these just for the top, as I already have two dual woofer cabinets built. But note, those puppies come in at 100lb each.
• For some, building JUST these smaller cabinets, which have the same footprint for stacking, might be a lot more practical- whether you're 74 like me, or younger but of slighter stature. Stack them for the low side cabinet, stack for the upper cabinets. Should only be around 50 lb each.
• A lower budget alternative that some might want to consider, using the existing crossover design or what ever evolution occurs, is to use HO-8 woofers, 8 ohm, instead of 4 ohms, and just use one on the bottom, one on the top, and make a short stand to raise the effective tweeter height to whatever seated listening position you prefer, and then tweak the padding networks slightly. I will provide suggested values for that before we're done.
• In my own case, I may just use a single HO-8 cabinet on top. The upper cabinet and lower cabinet are wired in parallel to the output of the LF crossover network. The lower cabinets I built have two HO-4 connected in series, at the Cabling output from the 4 pole SpeakOn connector, just to remind you. Of course, this is DIYW, so you can chose whatever output connector setup you prefer, should you decide to build a version of this project.

[JonMarsh]

And, yeah, no, I do not sleep in that bedroom! 4 bedroom home, no kids!

[JonMarsh]

And here's a wireframe drawing that may help visualize how all the bits and pieces go together better than the basic CAD model images:

For reference, the next pieces to be cut out are the rear PR surface panel, on which the actual PR mounting hole will be routed before going further.

[JonMarsh]

In the progression of slow work takes time....

• The PR back surface panels have been cut, 1/2" MDF as for the original dual woofer cabinets
• Below, a pic of the first one being glued up
• Next, these will be routed for the pass through hole of the PR, and M4 threaded inserts installed.
• Next step will be the PR Rebate BB ply back side pieces, which facilitate assembly processes without worry of damaging passive radiators
• Then the outside BB ply side panels, front panels last.
• A pair of RSS210HO-8 have been received for experimentation...
• More SLR26R are ready for mounting in test cabinets...

[JonMarsh]

Mad Max reporting in on Friday...

• PR back surface panels have both been glued up, ready for routing.
• Rough cuts and finished cuts of PR Back Rebate panels have been cut and are gluing up
• Side wall rough cuts are done

Working in the garage this time of year isn't exactly fun- this was supposed to be finished up last summer until other things "blew up"!

[JonMarsh]

2nd PR Rebate epoxied and setting up- just takes a little care as one tightens the clamp to keep the sides aligned.

Next will be routing the PR cabinet holes and the PR rebate holes.






BTW, I use cooking grade parchment paper all the time as a glue shield to make cleanup for an impatient guy like me fast and easy.

[JonMarsh]

This week has had a lot of distractions, (mainly health advocate education for various folks, stuff from hip joint replacement surgery recovery (got lots of first hand experience there, and high ratings from my orthopedic surgeon) to discovery of aFib and education on the issues and typical courses of action.


But some steady progress finding a bit of free time in the afternoons...

First, a reminder about my all time favorite by a mile router hole cut accessory:



The Perfect Circle indeed, infinitely adjustable. Just loosen the knob and put the center pin where ever you need it.

Of course, this is the right time for me to finish up some of the clean up sanding- my battery powered Makita is a favorite for this task, with Mirka Abranet abrasive.



I really love this Porter Cable router for hole cutting - two reasons- one is the cut step adjustment just by rotating a fixture plate that has some fixed and some adjustable setting posts.





Then setup carefully for the cutting radius- balancing both the data sheet and hands on measurement, I figured 4-5/8" was the optimum radius for my Seas SL26R passive radiators.




And, no, I do NOT get any "influencer" payments for mentioning these tools, but sometimes I get PM's from you guys about how they work out!

[JonMarsh]

Time to make more router dust...

After adjusting the depth stop offset, the bottom two cutting stops work out fine for the initial cut and the Final Cut, not all the way through, the last bit is cut with a saber saw and then the wall flattened with a follower bit in a DeWalt 1/4" router.



The other reason I love this combo is how effective the dust collection is- those few little bits you see on the surface is all that was "missed" by the router air path being cleared with one of those DeWalt canister vacs you can get at CostCo.





Then test fit the SL26R passive radiator - (in this case, the fit was so close it felt like a piston in a cylinder bore), and I used a standard Sharpie through the mounting holes to mark the center for each screw hole to setup drilling holes for inserts, and center punched the holes for precise drill bit location.

Speaking of drill bit location, the recommended drill hole size for these Rampa SKD30 M4 inserts is 7mm. Umm, you might have some trouble finding a 7 mm drill bit even at a local Ace Hardware- much less a normal Big Box store. But that works out to 0.275" "approximately", which if you convert to 32nd's, thats 8.8/32. So, if you search a bit, you should be able to find a nice 9/32" Milwaukee premium drill at your local Ace Hardware or other good hardware and tool store (have one in Middleton, much MUCH closer than the Woodcraft store in Boise).

And the results after installation with a hex tool (preferably metric, but in one of those lucky quirks of fate, the size used has a very close SAE equivalent at 5/32"; so either of my favorite DeWalt multi-hex wrench tools will work, the MM or the SAE.

[JonMarsh]

This is all so primitive compared to how Steve would do this, we both get a good laugh... but replacing my collection of tools that I'm very familiar with is a non-starter at this point in life!

[Steve Manning]

Time to make more router dust...

After adjusting the depth stop offset, the bottom two cutting stops work out fine for the initial cut and the Final Cut, not all the way through, the last bit is cut with a saber saw and then the wall flattened with a follower bit in a DeWalt 1/4" router.



The other reason I love this combo is how effective the dust collection is- those few little bits you see on the surface is all that was "missed" by the router air path being cleared with one of those DeWalt canister vacs you can get at CostCo.





Then test fit the SL26R passive radiator - (in this case, the fit was so close it felt like a piston in a cylinder bore), and I used a standard Sharpie through the mounting holes to mark the center for each screw hole to setup drilling holes for inserts, and center punched the holes for precise drill bit location.

Speaking of drill bit location, the recommended drill hole size for these Rampa SKD30 M4 inserts is 7mm. Umm, you might have some trouble finding a 7 mm drill bit even at a local Ace Hardware- much less a normal Big Box store. But that works out to 0.275" "approximately", which if you convert to 32nd's, thats 8.8/32. So, if you search a bit, you should be able to find a nice 9/32" Milwaukee premium drill at your local Ace Hardware or other good hardware and tool store (have one in Middleton, much MUCH closer than the Woodcraft store in Boise).

And the results after installation with a hex tool (preferably metric, but in one of those lucky quirks of fate, the size used has a very close SAE equivalent at 5/32"; so either of my favorite DeWalt multi-hex wrench tools will work, the MM or the SAE.

For those crazy odd ball sizes, McMaster Carr is still one of your best bets.

[JonMarsh]

Very true, Steve, but when you want a solution TODAY, not in a few days, since I don't have a local McMaster Carr, needs must, guys gotta do what a guys gotta do!


And, just between me and you and the rest of the forum, I know the reason for your secret love of McMaster Carr!

Solidworks 2022, Parasolid, and STEP files for over 700,000 of their products!


https://www.mcmaster.com/cad-models/

[JonMarsh]

Whatever happened to the idea of Sunday Day of Rest? Or Sunday Funday? Seems like I'm on a tight schedule, but got a little shop time in, plus ordering bits and pieces and some tooling accessories.

So, the PR rebate panel through holes have been cleaned up on the router table using my favorite do everything top follower bit:




Some inner fine sanding, then round over work will be next.

But you know, at the pace this is going, it reminds me of an old three stooges skit (let's not talk about how "mature" someone must be to remember stuff like this....)

[JonMarsh]

All this open loop work, probably should be time for a quick fitment test, especially since I didn't use the main cabinet as a routing template for edging the PR rebate plate...

So, time to stack them up along with one of the SL26R passive radiators these will use!



I'd like to say I'm getting good at this, but I'm probably just getting lucky... nice flush fit all the way around, no leveling issues at all on the sides where the additional BB play panels will go!

[JonMarsh]

So, before knocking off for the day, gluing up one cabinet, using the West System 105 + 206 (slow hardener) in the pump cans, just one squirt from each for this small job:

The key thing is to keep the panel edges lined up after slowing increasing the clamping pressure; the one Bessy clamp is key for that.




This is done in the indoor workroom where temperatures are very epoxy friendly, not out in the garage shop where it won't setup!

[Efalegalo]

All this open loop work, probably should be time for a quick fitment test, especially since I didn't use the main cabinet as a routing template for edging the PR rebate plate...

So, time to stack them up along with one of the SL26R passive radiators these will use!



I'd like to say I'm getting good at this, but I'm probably just getting lucky... nice flush fit all the way around, no leveling issues at all on the sides where the additional BB play panels will go!

Jon - why such a deep recess?

[JonMarsh]

That's so one can install the PR, then lay the cabinet on its' back to install woofers. And to have another "safe side" to set it down. A single 3/4" panel isn't quite enough- the phone photo distorts the perspective. . And I bought quite a few sheets of BB ply when the Ukraine war started, anticipating supply problems with the usual vendors. Which have come to pass, but not for me.

The point behind this cabinet version is to have more compact lighter weight LF module to experiment with - one could use two with 4 ohm drivers for the upper set, and it's much easier to lift, being only about 55 lb instead of 100 lb for the dual driver module. But with an 8 ohm HO woofer a single driver up top might work well also. Will be time to experiment soon.

[JonMarsh]

I checked the actual clearance on the built dual woofer cabinets; it's 1/2". Now, if a PR like the new Dayton SS10 PR were used instead, with its physically compatible diameter (both 236mm), then the deeper surround roll would reduce the clearance further.

[JonMarsh]

A further comment- as Seas reveals in an earlier spec sheet, the SL26R was designed to have a frame and mounting compatible with the popular Peerless 830481. The new Dayton SS10PR follows in those steps- all three have a 236mm through hole spec, and appear to be compatible for mounting requirements. OTOH, the depth of the surround roll can vary, the SS10 PR having the deepest. If you've seen pictures of that passive radiator, then you may REALLY wonder if there isn't some actual commonality in the manufacturing tooling.

[JonMarsh]

And just for fun, a picture of that original Peerless PR...

[JonMarsh]

Ya'll gotta be getting a little bored of these cabinet gluing pics by now, but I gotta keep posting so Sven knows I'm not just goofing off in retirement! And as we all know, slow work takes time!

this is the side panel glue up for the first side of the enclosure, covering over the PR rebate, and aligned carefully with the front wall edges, where the front panel will be mounted before long (as soon as I get THEM cut up and routed!). This West System 105 plus 206 hardener has a nice working time, but takes more than 12 hours to fully harden.

[JonMarsh]

And just to clarify a bit, this view of the top of one of the dual woofer LV CV3 enclosures shows how the various pieces layer up, so to speak. The dual BB ply PR rebate on the left. Maple ply front panel on the right.




A time consuming construction method, but boy, these enclosures are super stiff, and produce a flat response curve very close to the computer simulation, unlike the first style made like the PS Audio speakers.

[JonMarsh]

This next post is a combined public safety announcement and my usual reporting in to avoid a "goofing off" demerit!

First, the mono LV3 cabinet front panel have been cut to size from maple ply, and the bevels cut per the dimensional drawing-

The public safety part comes in where I probably shouldn't show this and tell you to do it this way unless you have a SawStop table saw with electronic touch detection and automatic brake. I'm in no risk on this saw cutting these bevels this way, but my DeWalts? Fuggetaboutit!





Now, there as also been a lot of detail sanding to line up the edges to where you can't detect them by touch, and to smooth the finish of the BB play and MDF panels and joints. I don't usually talk about this stuff, BUT! there's a bit of a weird story going on here. Well, weird by normal person standards, maybe not so unusual by mine?

Point is, I have a number of different random orbital sanders, and a common link between them is my use of Mirka Abranet disks, which are suction transparent over the whole surface, and can work with any sander's hole layout. And the sanding job they do is fairly decent...

This, though, is where a story comes in with a rather delayed return on investment, so to speak...

In November 2016, I ordered a FESTOOL Pro 5 Ltd 125mm diameter, 3mm orbital sander... from the Tool Nut. And I guess half the guys in the US did also, because it became immediately backordered by many months- it was a very friendly price, one of those things companies due to lure newcomers into the brand. Ahem....

I received notice that due to overwhelming demand, FESTOOL ran out, and they would do their best to ship by March 2017. My recollection is that they missed that date, I don't recall by how much.

Now, one issue with the sander I received is that there was no dust connector adapter included, or dust box. Much horsing around, and I eventually found an adapter for a different model that would plug into this one- but it was designed to only work with FESTOOL dust collectors... My my...

By this point, Steve Manning has probably got a smirk on his face and is nodding gently... I know the look, have seen it before...

well, recently I found an outfit that has some of the old dust collection boxes made for this model still in stock... yeah, that's kind of like still having a muffler in stock for a '69 Rambler. But it's on its way to me, and I've found some generic adapters that may allow me to hook this puppy up to my DeWalt dust extraction.

So, I have been playing with it, and using the "original equipment" GRANAT sanding pads... hmmm. Maybe the wait will be worthwhile none the less! Best disk sander I've ever used? Quite possibly....

[Scareurpasenger]

If only you knew someone with a 3D printer to make whatever dust adapter you needed... Seriously, this is a problem that 3D printers are great at, since there is no standard.

[JonMarsh]

The insider of the cable adapter is molded rubber, to get as dust tight a connection as possible, I think.

[JonMarsh]

OK, getting some practical work done with the new configuration, tie wrap air hose and power, on-off control via power draw of sander.

It's working exactly as hoped and expected, and not a hint of dust leakage from the sander to the air hose, and the noise is fairly reasonable - won't toss out my over the ear protection, but it does take things down a bit even when using them!

[JonMarsh]

Best 10 year old sander setup I have!

[JonMarsh]

Life is what happens while you're busy making other plans...

Well, back to the original plans! It's crazy how much other stuff keeps coming up- NOT the retirement I planned on! But enough!

Working on the mono woofer front panels- some specific goals/tweaks in mind:

1. tighten up the inner cutout for the woofer, to reduce any "wiggle" and optimize the room available for threaded inserts. set to 3 - 5/8".
2. Adjust the woofer mounting plane further into the cabinet- let's say 0.625" from the front surface, to minimize exposure of surround. That's 1/2 of the thickness of the front baffle.
3. Tighten up the outer pass through hole diameter to the mounting plane reduce to 4.25" radius, 8.5" diameter.

Of course, I'm using my all time favorite routing combination for driver holes- my old Porter Cable with the Perfect Circle hole jig- infinitely adjustable, fast and stable. Can actually do quite small holes, too.



This is setup for the mounting plane work with a 3/4" outside diameter fluted carbide bit. Maple ply can tool very nicely, but I find one should treat it gently for routing operations, so I plan to take several passes increasing the depth each time.




This is after the first two cutting passes, including an additional sweep around to suck up the wood dust:




All of the dust pickup has been done by the router with its air paths and the DeWalt vac connected.


Here, the final depth cut is just completed. Yes, it really is that free of dust in the work area. Love this setup.

[JonMarsh]

Next step is cutting the inner pass through to the 3.625 diameter. For this I use a 1/2" solid carbide plunge bit. as a friend in Bahstan would say, "Vewy Vewy sharp!" Handle with care!


Here I stopped briefly to show how this cut partially overlaps the other, because we're taking away some of the 3/4" width of the initial mounting plane cut.



The variable depth adjustment plus free floating depth rod with locking screw makes setting up the maximum depth easy, then working down to it a few steps at a time.





I take the inner route cut to a depth of 1", leaving 0.25" holding the center in place while making routing operations.




then I drill a couple of large pilot holes on the inside of this inner route cut, so I can cut the center piece out with a saber jig saw. Yeah, this is the point where all of you guys with CNC setups are chuckling and nodding... maybe drifting off to sleep?





But us Poh retired folks must make do with the tools we have!


Next up is flush current the inside of the pass through hole using a follower bit on my ancient Bosch router table...




And here's what it looks like when the circle is complete...




Final check of course is a test fit of the RSS210PR I keep around for any type of RSS210 driver work, as a frame size check.



Next up is getting installing threaded inserts; I got shipped some RAMPA 8-32 instead of M4 by mistake, but those are usable for this application.

Then the biscuit jointer and assembling the front panels on the two cabinets.

[JonMarsh]

TGIF! Made some time this morning to get the Makita and some biscuits out and get ready for gluing one of the front panels to a cabinet- only have room in the assembly work room in the house to do one at a time, can't do it in the garage due to working temperature required for the Bob Smith Epoxy.




First I markup the lateral locations for both the cabinet and front panel, 4" centered from each side (arbitrary choice)




And cut the slots, reference to the bottom and top edge, and relying on the precision of the fabrication process to date that they will mate up properly...

Here, moved into the assembly room inside for gluing, and biscuits installed...



Yes, this may be a crime against woodworking, using Porter cable biscuits with a Makita tool...

But, as you can see below, the fit is "perfect", because of the tight tolerances in the cabinet construction.

[JonMarsh]

For gluing, with Bob Smith 30 minute epoxy, the cabinet was flipped on it's back, and some scrap pieces of maple ply used to space off the bench level- note the parchment paper to collect any epoxy dripping that might occur (though hopefully not, if I've done things correctly).




Yes, the front panel edges were previously sanded to obtain a smooth flush surface for mounting the front panel. Is that cheating? I'll leave that call to you...




Everything clamped up and wiped down- when they say 30 minutes working time, this means you can take your time putting it together and lining up... but the full setup takes a while- this is 30 minute Slow Cure version, which has the highest strength of bond of all their epoxies, but must be used at 70F or higher. Darn, I knew there must be a reason I have the thermostat for the house set at 71...

Full cure in 6-8 hours, working the joint, like cutting or drilling, in 24. My favorite for joint work, of course, YMMV!

[technodanvan]

Looking really nice Jon, can't wait for some numbers and graphs!

[JonMarsh]

Me neither! though, technically, I already have them from earlier research cabinet, just MDF, same components.

Well, the 2nd front panel got glued up this morning.




Next steps are the SpeakOn connector and wiring, plus the threaded inserts for woofers. I'm going to double check there are no issues using 8-32 with the RSS210 chassis, before installing those- got sent RAMPA 8-32 by mistake on last order, instead of M4. I have enough M4 on hand, but might want them for other things in the future.

[JonMarsh]

Recall that the intent behind this new LF cabinet configuration was to remove the rising LF response that appears to be due to standing wave behavior in the older 4 driver cabinet design. This behavior would benefit the Peerless drivers used in the FR-30, as they have some roll off, due to T/S parameters before reading Fb, but this doesn't work well with the RSS210 series, which is essentially flat.

The dual woofer version of this still uses individually sealed enclosure spaces, with two 4 ohm drivers wired in series. This configuration is a single 8 ohm driver. Same PR for each driver, the Seas SL26R. But in a near field measurement, one doesn't really capture the PR on the back of the cabinet output.

What I have found is that the closest approximation to calculated T/S behavior, as calculated, say, by Unibox, occurs with the smallest possible dimensions cabinet, with depth, width, and height nearly equal to each other.


This is from this enclosure concept with the 4 ohm drivers.



With appropriate adjustment of the distance from boundary walls, an LF lift below 60Hz is obtainable- I have it on reliable opinion from ET that the results should be "most satisfactory".

This is a Unibox calculated SPL with the SL26R and just 20L volume, fully stuffed.



Time will tell the story soon, unless some other sequence of family health catastrophes (not mine) occurs like last summer.

[JonMarsh]

some more progress... RAMPA 8-32 inserts for the woofers installed,




And finish sanding well under way...




And Steve has bestowed on the "wires and sparks guy" (me) (not a wood working champ) a new nickname... "Sparky!"

Maybe because I've had the time to be showing a bit more energy and work progress?

[JonMarsh]

Getting the input connectors ready- using SpeakOn again for the small footprint. It has to be mounted in a corner, and considering the thickness of the side wall panels, the location spacing is critical.



The center point for the 15/16" Forstner bit is at 2-1/4" from each edge. I drilled down through both layers of the PR rebate offset panel, to accommodate the deep body of the SpeakOn connector and the connection tabs, then use a smaller bit that is large enough to accommodate just the 4 conductor cable I've been using on this project from AudTek. .

[JonMarsh]

Of course, if you try this build, the connector can always be "DIYW", and then the details are up to you!

This is AWG 13 cable. Full schematic details will be provided once everything is sorted out and tested.

[technodanvan]

Sure doesn't leave much room there does it?

[JonMarsh]

It's just the same as the dual woofer cabinets- which are actually two independent volumes in one overall cabinet structure, keeping the same minimal dimensions and relative freedom from any standing wave issues.

Oh, and I didn't mention, the mounting screws for the SpeakOn connectors are #5 flat head wood screws, 3/4" long. Picked up more of those yesterday.

The overall goal was to have a very stiff well braced cabinet shell at relatively low cost and complexity to the builder by starting with the PE cabinet for the RSS210-HO woofer series. Lots of lawn work this weekend, but I should find some time for finish sanding and some wipe on poly to tint and seal the wood. But the FESTOOL Granat P220 disks aren't scheduled to hit the dock until Wednesday, so that's a built in logistics delay. I'll be tempted to load drivers in at least one cabinet sooner and get some measurements, but obviously, given the relationship to the dual woofer/dual PR cabinets, I'm not expecting any surprises there! However, from Unibox work, I've decided to test a heavily lined version first, not stuffed.

[JonMarsh]

well, surprise, surprise! The P220 FESTOOL Granat disks came in two days early, so I was able to get the finish sanding on joints and gap patch up as well as all the panel sanding before Minwax wipe on stain and wipe on poly completed! I'm working on the cable and connector sets now, and figure I should be doing some checks and testing before the weekend.

[JonMarsh]

Multi-tasking is the word of the week- but that included setting up for some experimental staining work, this time Minwax "Golden Pecan". When the backs are also done, it will be followed up with a few coats of satin wipe on poly.



Remember, Steve just calls me "Sparky"; no splendiferous examples of wood finishing to be seen here on this project! I just want to get some finished cabinets ready to test!