The Satori MTA- a two way, but with a checkered past and lots of different DNA

[JonMarsh]

This is a project that you might say has multiple ancestors and source of design DNA, as far back as 20 years ago, and as recently as six months ago. And, just to get this out of the way, it's NOT another 6-1/2" two way, but rather, an upgrade? A 7-1/2" two way... and with well pedigreed parts.

And it's being driving partly by the desires of one long term HTG member, Darryl Glenn, and by my own speculations and itches.

So, what are the historical antecedents? (This is sort of like answering a question such as, "who in your family do you resemble?" Which can be very complicated, or obtuse, if who you resemble was never living when you were born, and a key example goes back to the mid 1800s, in my case). But no time span like this.

So, I'd list these items as being in the genetic soup of this project:

• M8ta, circa 2006/2007, for a roughly 8" two way in a tower format speaker similar to Avalons- too bad Charlie Hansen passed nearly 10 years ago, he could tell you about the prototype speakers I gave him when my development and business partner died from an aortic aneurysm when I was away at CES in 1980 scoping out the competition. Charlie was working for me in a small professional audio outfit in Boulder Colorado while attending school at CU. More than 45 years ago.
• NatalieP, also a two way, with smaller drivers, and an unusual crossover with a low turn-over frequency to get the most out of an Usher tweeter made for PE, the RS28a.
• SMJ Audio Calliope, with the SB Satori MW19P-8, and the Peerless DA25TX-008 Corundum dome tweeter. IN and Out of availability, never goes out of style.
• Ardent D, for overall enclosure concept, materials, and finishing options (possible to get a nice result with just golden Watco oil and wipe on polyurethane. Some modifications to dimensions and configuration, of course.
• Modula Magnifique, based on the concept of a Bessel fourth order high pass, given specific requirements for driver Qts, enclosure size, etc. are made. Complete analysis still pending.

So, I'd say the enclosure details are pretty close to being fully nailed down, with one special option set-

• for the more budget minded, a reflex port in the base
• For those favoring passive radiators, a pair of the new Dayton SS10's might be optioned... or the RSS265PR. The SS10's if you want a 4th order Bessel high pass. The RS265PR if you want options for a flatter measuring system, with a heavier low end.

For now, a few renders of the enclosure.


Just the facts, ma'am, as seen with basic visualization.



An X-Ray view of the ported version:





And a very basic rendering visualization:




For reference, this build will be done similarly to the Ardent D:

• Maple ply front panels, as used for piano tuning plates
• Maple ply top panel
• Bamboo board, not ply, the kind made with 3/4" wide strips, for the side walls and back.
• Back from combination of bamboo board and 1/2" Baltic Birch Ply, new old stock in my case.
• Internal bracing materials primarily from 1/2" and 3/4" Baltic Birch Ply.

[JonMarsh]

Well, a lot going on today, and I forgot to mention the drivers:

• Woofer: Satori MW19TX-08 Textreme woofer
• Tweeter: Peerless DA32TX-008

Of course, a pic...

[JonMarsh]

Yes, I get a bit of a buzz just looking at them and handling them!

[JonMarsh]

Let's talk possible low frequency alignments- something sexier than just sealed. Of course, this is an area where DIYW can always rule, but perhaps some examples will be useful.

I examined two types in detail-

• A downward firing double flare port
• A passive radiator setup- many possible variations, but I've been having fun modeling with the new Dayton SS10, I have four currently on hand; though truthfully, I think it is more suited to Evil Twin, as it has some interesting characteristics, but will lead you into a design that seems influenced by the Dark Side.

Let's start with the vented alignment-




The port diameter is a critical parameter- too small and the high air velocity results in compression and distortion at higher SPL; too large and port resonances at significant amplitude will occur in the working pass band.

Like this one:


With the 3" diameter port, things are fairly reasonable, if not quite perfect, and port resonance is fairly low and port air speed is within reasonable bounds.







This is for a port construction flared at both ends. ET says don't even consider not using flared ports..


Lastly, the LF impedance curve, it's almost like a smiley face...

[JonMarsh]

Now, with ET looking over my shoulder, I'm going to take a trip on the dark side- PR's on the back side of the enclosure, and to make the challenge even more interesting, let's consider one of Dayton's newest high value parts, the SS10. I ran through many alternative configurations, and even flirted with a full 4th order Bessel alignment, but in the end settled for something a bit more conventional... but given the parameters of the SS10, not without it's quirks. PR alignment quirks include the relatively large steps in MMP depending on how many weights one uses and how large each weight is; sometimes one might prefer smaller steps, and that is possible, but requires visiting your hardware store. Here, we're keeping it simple... sort of.



These PRs will always be loafing, but hey, so are many modern cars at legal speed limits, right?

Baseline tuning target for Fb is similar to the ported alignment, but there are no port resonances or similar issues. For various reasons, I wound up with a Fb of 30Hz.




This was partly to wind up with a similar max woofer excursion for the same input power limit at low frequencies as the vented design, and Qmp of the PRs is a factor in that choice.



Another smiley face impedance plot, sort of, this time with a bit of a wink and a nod...




Yesterday I also ordered the maple ply for front panels and top, and two more Dayton SS10's... glad I have all the other needed wood on hand!