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

[JonMarsh]

Well, I must have been fast enough, because the last can of the Watco Danish Oil Golden Oak shipped yesterday! I'd been looking for it at other places that carry Watco products earlier this week, and no joy...

Woo Hoo!

😎

[JonMarsh]

Are you running out of denim fill as well? I have a giant box of it that I'll probably never get through if you want some.

No, but for the Diapson "klone" I have been doing experiments with the help of ET, and he's sworn me to secrecy- but the R23 is being investigated more thoroughly, and it's a LOT easier to bend around a corner... in these chaotic times, a little experimentation is OK, yes?

Been a busy morning with shopping errands and other tasks, but still making progress...






SL26R installed; M4 hardware on the back. After lunch the woofer installation will be finished, and some testing initiated.





These have 8-32 inserts and bolts on the woofer side, just because the Rampa vendor sent me the wrong part, but the screw diameter is nearly identical...

You know, I really like the Dayton products from Taiwan and many other items from Taiwan... I'd be really disappointed if the current batch of geopolitical nonsense gave Xi the idea he can invade Taiwan without consequences.

[technodanvan]

With thoughts like that I might have to take advantage of that 15% off sale after all.

[letiennam]

Everything seems to be going very well. Your picture reminds me of Wavecor Ardent. I actually can't find that Acousta-stuff kind.
I usually use both combed and uncombed natural sheep wool to line the four walls of cabinet. For sealed speakers, I sometimes have to use sheet wool.
I currently have about 3kg.

[technodanvan]

Acousta-stuff is getting harder to locate...

Just a note for those in the US, Parts Express now stocks 'Acousta-Fill'. Uncertain about changes to the stuff, but it's from a different vendor.

https://www.parts-express.com/Acousta-Fill-Nylon-Polyfill-5-lb.-Bag-Speaker-Cabinet-Damping-Material-260-331?quantity=1

[JonMarsh]

Well, we know who they should be targeting, it's just a matter of how close it gets. BTW, last time I looked (fairly recently) Madisound did have Acousta-Stuf.

[JonMarsh]

I can't believe it's 4 PM and I'm just getting to where I hoped to be by 1 or 2, but a lot of comms going on, and double checking some connector details and pondering how I plan to interface with the last generation crossover check.

But there is some real progress, and tomorrow morning should be getting SPL measurements - for now, just updated impedance for this cabinet. Things are looking spot on, but then, that's what Unibox and VituixCAD are for, is taking the mystery and guess work out of things!









Looks like the impedance curve is matching up very closely to the dual driver cabinet. but, believe you me, the ~60 lb is a lot easier to pick up than the 100 lb! With past L5 back surgery and two artificial hips, I need to exercise some care about not over doing things just because the muscular strength still seems to be there!>


The 2nd cabinet is close to finished, then I need to get back to the new design MF-HF cabinet and recheck stuff, plus look at some basic finishing. Which brings up, the Watco Danish Oil Golden Oak DID arrive today- Need to hustle getting at least one of the lower dual driver cabinets finished!


Then, it will be time to check, tune and tweak- with a bit of effort, I hope to match the transfer function of the last rather tall version in a more compact package!


Being a 2 meter in room measurement, there's a fair amount of boundary interaction, which will just require some judicious use of AST panels in room. The QNF measurements were very smooth.

[JonMarsh]

OK, fired up Fuzzmeasure and the gear, remembered how to configure the OS audio for measurements (it's been more than just a few months!) and turned off all the other noise sources except HVAC, got decent measurements to confirm the basics.

QNF measurements, combining woofer and PR; of course the PR has a lot of reflected output from the woofer, but shows the important area clearly ....




And another QNF measurement just including HD2 and HD3; for a so called subwoofer driver, I really like the way the RSS210HO and HF were designed. This is the 8 ohm HO. Note smoothing is just 1/48th octave.




The RSS210 has no evidence of inductivity modulation or increase of distortion with frequency, as is so, so common in long travel woofers.

[Efalegalo]

Are the RSS265s just as clean?

[JonMarsh]

Well, the issues come down to impedance rise, motor design, and cone breakup.
Only one RSS265 part is in the running, IMO, and that's the RSS265HF-8. Both have a triple shorting ring motor for lower HF distortion. Impedance is similar, both close to 1.5 mH. And Xmax is similar, at 14.3 mm (RSS265HF-8) versus 12 mm (RSS210HO-8).

But cone breakup is another matter- the 265-HF has a lower mass cone than others in that series, at 131 grams, but first breakup is at about 2.35 kHz. The RSS210HO, the higher mass version of RSS210, is rated 99.3 grams, and though there is suspension stuff going on below that, the cone peak appears to be at 5kHz, and this is confirmed by the measurements above. So, that's about a 1 octave margin. It's certainly solid for a crossover point below 1kHz, something you can't say for most 8" subwoofers.

[JonMarsh]

Most of us are familiar with this phrase from Ralph Waldo Emerson:

“

A foolish consistency is the hobgoblin of little minds

”

It is often even misquoted as simply "consistency is the hobgoblin of little minds" (or even more sloppy approximations like "conformity is a bugbear of small-minded people", etc.).


HOWEVER!!

Consistency in the execution of speaker builds is quite another matter, I believe!

😆

To whit, the impedance check on the V3 8 ohm mono cabinet test build #2:




I'm a few screws short of a full deck, so after the hardware store opens tomorrow, I'll remedy that and get the powered SPL tests done also.

[JonMarsh]

OK, 2nd cab basic measurements completed- no surprises.


Two separate measurements combined into one graph...


And a distortion plot as for the previous cabinet, with the typical expected cone resonant amplification of distortion products:





Next, I'm getting back to the rough prototype V3 MF-HF cabinet, need to do finishing work and mount up and collect data, and see how well it works with the last crossover build.