A new small system for the Meditation module? Perhaps a new Modula

[Evil Twin]

The recent AudioXpress article about reflex alignments and a referral by Steve Manning to a new Italian speaker system, not for the impecunious (59,000 Eu for a pair of 7" two ways?) has me pondering possibilities, especially considering relatively recent passive radiator products in the last two years, and the heritage of the SMJ Calliope and possibilities for minor enhancements...

Key elements, then:

• A Bessel LF alignment, or as close as is feasible to achieve with woofers and passive radiators that seem to be in the right ballpark
• An improved MW19, the MW19TX-8, with a Textreme cone, a better optimized surround (no surround resonance at ~1100 Hz, and a slightly more optimized Qts
• Acquisition of a few more DA25TX-008, though it should be noted that Jonmarsh has offered BlieSMa tweeters on hand, NIB, to consider if needed.
• An intriguing esthetic developed by an Italian manufacturer, at a rather astronomical price, fit mainly for the Oligarchs which have seemingly risen to ascendency of late in the Terran sphere...

A reminder, the last factory data for the MW19TX-8; an enclosure has been prepared and ready for testing in the coming days for QNF driver evaluation...







Initial modeling results for the LF alignment:







And some renders based on initial cabinet concepts. The intent is to support the necessary Z axis offset for an LR4 style crossover, and a tapered rear construction, perhaps not as effective as Bowers&Wilkins, but aspiring to the same avoidance of rear wall reflections and internal standing waves.

The crossover will be mounted on the base plate near the front, easy access for modifications, and no interaction with acoustical pressure waves. Dual pairs of binding posts vertical at the rear of the base platform.

[JonMarsh]

After researching a significant number of 8" and 10" passive radiators, perhaps bordering on vast, but at least all inclusive of vendors selling in the North American Market, a preferred candidate for this application has been identified, with desirable parameters for Qms, MMS, and CMS, to achieve the target response profile (near Bessel) with the chosen primary driver and desired enclosure volume range.













And, of course, a key fundamental criteria has been met- black is back. And, as Mr. Manning is fond of saying, "Shiny".

Calculations with both VitiuxCAD and Unibox 4.08 confirm the usability in a 25L configuration with appropriate added weights:






Order placed for hardware evaluation, upon confirmation by Evil Twin.

[JonMarsh]

This is a very new series from Dayton Audio, priced very reasonably… for now.

[Evil Twin]

Some additional information regarding the Satori MW19TX will be shared- first measurements show that it is in compliance with some of the basic improvement claims, particularly the elimination of surround or cone or combined resonance at 1100Hz which shows up in the impedance curve of the MW19P, and slightly in the measurements of SPL.



I find this test result to be most satisfactory, for a driver which is not broken in at all.

Photographs show the differences in cone and voice coil to cone construction...

[Evil Twin]

A basic test enclosure is nearing completion for QNF and LF data.

[technodanvan]

Out of curiosity, I was wondering if you modeled a single PR of the same type for the Satori? I would think a single 10 from the Signature line would be sufficient for a Satori woofer - it isn't exactly a subwoofer! That said, I know you've been concerned with nonlinear function of PRs as excursion goes up, so perhaps you are using a pair to alleviate those concerns?

I wonder if there is a way to extrapolate linear function of a PR with a DATS LA if one were to construct two boxes and use a reasonably well-behaved long throw subwoofer for the test. One box would contain a pair of PRs tuned to a specific frequency and would be the 'baseline' configuration. The other would also be a PR box, but only one PR this time, since we want maximum displacement, tuned to the same frequency. Run the linearity test on the DATS LA for both and observe the differences in woofer behavior.

In an ideal world a Klippel would probably be involved along with a laser, but we have to work with the tools within our reach!

[technodanvan]

By the way, I'm a fan of the proposed cabinet design!

[Evil Twin]

The challenge is getting a PR setup with the specific Qms and CMS needed to achieve a Bessel transfer function. Two of the SS8 will not do this, and one of the SS10 will not do this. Dual SS10-PR will achieve the desired LF transfer function. There remain many details to work out for the cabinet construction, I am sure a number of hours will be required in Shapr3D- hopefully I can "incentivize" Jonmarsh to dedicate resources to that task... but at this point, it seems fairly clear that the basic goal is realizable with the drivers now on hand.
The cabinet concept is inspired by the Italian company Diapason, which reportedly has a number of Sonus Faber engineers.

[Evil Twin]

In an ideal world a Klippel would probably be involved along with a laser, but we have to work with the tools within our reach!

Not all of us are as well equipped for fabrication as Mr. Manning... Some of us must use the "old ways|"

And although Mr. Manning is not fond of passive radiators on side walls of enclosures, considering the design and finish, even he might resort to one of his favorite quips...

"Shiny!"

[Steve Manning]

Not all of us are as well equipped for fabrication as Mr. Manning... Some of us must use the "old ways|"

And although Mr. Manning is not fond of passive radiators on side walls of enclosures, considering the design and finish, even he might resort to one of his favorite quips...

"Shiny!"

Now, now, I'm fine with side PR's in moderation of course. As for fabrication .... when ET is happy with with a design, I have some tweaks to the concept drawing he's done to take advantage of said fabrication equipment! 😁

[Evil Twin]

Now, I can report a favorable early product reaction by Mr. Manning, after having received the first SS-10 PR examples for evaluation, and shared a photograph with him.



He agrees that they still are qualified for the initial rating based on the factory supplied image:

"Shiny"


A more pragmatic evaluation was made of the packing concept, using multiple layers of a celled cardboard structure, and while it does not qualify for the appellation of "Shiny", the packaging and shipment support seems quite protective and should pose no problems for high G earth to orbital transition or the opposite. The box design is quite literally "stellar".

[technodanvan]

The signature series is a really good looking line. No argument from me!

[Evil Twin]

One must be careful to choose the parts with satisfactory acoustical and electrical parameters, but first indications are most promising...

Not obvious from these pictures is the quality of frame design and construction, and the implementation of gaskets on both front and rear of the mounting rim.

[JimS]

Maybe should have waited on ordering the RSS PRs, these sig series sure look pretty 🤩. Good thing Steve agreed to keep them on the back where I won’t notice 😜

[Evil Twin]

Indeed... out of sight, out of mind.

[Evil Twin]

Maybe should have waited on ordering the RSS PRs, these sig series sure look pretty 🤩. Good thing Steve agreed to keep them on the back where I won’t notice 😜

However, do note that the parameters for the SS8-PR are not as favorable for your application, and three of the RSS210PR with one disk work out very well- note the analysis post on your build thread. Passive radiators are just as variable (or more so!) in acoustic parameters and predicted performance as conventional drivers, and generally seem to be less well understood.

[Evil Twin]

Many structural details have been added and refined... given the lack of orthogonal oriented components referenced to the coordinate system, this has been a more exacting process than typical... short cuts and techniques employed that Mr. Manning might not approve of, given his professional background...







Some of the specialty wood products for fabrication of a prototype have arrived, but much remains to be obtained...

[technodanvan]

What is the approximate width at the front and back? Seems like a pretty aggressive taper and I'd be concerned about stability, depending on weight.

I'm also a tad concerned about the relative lack of black...

[Evil Twin]

Perhaps you do not realize this, but inside my meditation module I am assured of freedom from high winds or small children and animals running around...

With out any footer assemblies (that are under consideration, similar in concept to the original Ardent D) the front width is ~17-1/2". With some footer concepts being considered for the front and rear, this would increase by at least 10".

I believe that will suffice. Do you?

Now, "home decoration" is an interesting concept- with a meditation module mainly in black, I have a somewhat similar condition to Jonmarsh's home, which I have seen, which unlike modern decorating trends is NOT painted with a variety of strong primary or pastel colors, but with a neutral very light gray.

Instead, the background fades away and the attention is taken by the photographic artwork on the walls, from highly detailed images he has captured in his travels in Europe and Antarctica. It is an interesting contrast- it is thought that these speakers may achieve a similar contrasting esthetic impact, one perhaps suited for an aesthete desiring an environment with characteristics similar to the Scandinavian ethos.

[Evil Twin]

Keep in mind, this is not just another 6-1/2" two way, but rather, a 7-1/2" two way. Unquestionably a different level of expectations...

[technodanvan]

That seems sufficient! For this particular design, I wonder if two feet very wide on the front would go well with a single foot to the rear? I've been thinking about a 'tripod' set of feet for one of the other Ensemble builds that are pending.

[JimS]

However, do note that the parameters for the SS8-PR are not as favorable for your application, and three of the RSS210PR with one disk work out very well- note the analysis post on your build thread. Passive radiators are just as variable (or more so!) in acoustic parameters and predicted performance as conventional drivers, and generally seem to be less well understood.

Yes, I failed to look up actual parameters until after I posted because shiny object (ducks to avoid long distance force choke-hold….)

PS these look great 👍

[Evil Twin]

Shiny black objects often are most impressive.... but they must also be infused with the right Force...

[Evil Twin]

Compliment accepted... as you know, details matter...

[Evil Twin]

Some more refinement and updates, some visible from the outside, some not.
I actually had to learn some new commands... somewhat humbling for an aging Sith...

[technodanvan]

From my understanding, learning well into your later Sith years is a great way to keep the many varied brain degeneracies at bay. I'm sure this has a direct impact on Force ability.

[Evil Twin]

This clearly seems to be the case- at the Emperor's medical facility I so intimidated the medical staff recently that they completely forgot the idea of giving a cognitive or memory evaluation, as my initial conversational gambit threw them far off balance. That, and the books and notebooks of recommendations I gave the principal doctor in attendance. For some reason, he was rather reluctant to engage in discussion... but he did follow up on some suggestions I made as a matter of course.

Of course, he may have little experience with the bionic enhancements that have been necessary for my continued existence...

Interesting... most interesting.

[Evil Twin]

But, on a more relevant note, additional design investigations have proceeded, and given those results, plus having drivers on hand, a significant driver change is being pondered carefully...

As a technical graph is worth a thousand words...

[Evil Twin]

Identical enclosure volume and PR tuning.

[technodanvan]

But is the value proposition present? While the TX is certainly expensive, a Purifi is....a fair bit beyond that.

[Evil Twin]

Value proposition is a ratio consisting of both costs and rewards. It is most unfortunate that the current pricing of the PTT8.0X04 has risen so much compared with the NIB parts I have... but this project was always undertaken with the concept of improving on the performance of the original Italian inspiration which uses a 7" woofer custom built by Scanspeak, a custom designed cloth dome tweeter built by ScanSpeak, and a very expensive cabinet design, coupled with full balanced crossovers.

The PTT8.0 results in a substantial increase in both Sd and Xmas compared with the Satori 7.5" woofer, yet can do so and take better advantage of the 10" dual PRs, and all in the same enclosure volume and fundamental design. And this is not even considering the documented intrinsic motor linearity advantages and surround design of the PuriFi woofers.

These are the issues which I deem desirable to explore with appropriate design tools in the early stages of project development, before the first particles of sawdust are generated. A next step will be using past measurements to further explore the crossover concepts and possible results

I find that giving this stage time and coming back and re-examining initial assumptions can be most rewarding.

Obviously, this will not begin to approach a cost of 59,000 Eu per pair of speakers. Examined in this light, the difference in woofer cost is nearly a rounding error.

And consider- per a recent comment you made, there will be more black... with larger woofer cones.

[Steve Manning]

Value proposition is a ratio consisting of both costs and rewards. It is most unfortunate that the current pricing of the PTT8.0X04 has risen so much compared with the NIB parts I have... but this project was always undertaken with the concept of improving on the performance of the original Italian inspiration which uses a 7" woofer custom built by Scanspeak, a custom designed cloth dome tweeter built by ScanSpeak, and a very expensive cabinet design, coupled with full balanced crossovers.

The PTT8.0 results in a substantial increase in both Sd and Xmas compared with the Satori 7.5" woofer, yet can do so and take better advantage of the 10" dual PRs, and all in the same enclosure volume and fundamental design. And this is not even considering the documented intrinsic motor linearity advantages and surround design of the PuriFi woofers.

These are the issues which I deem desirable to explore with appropriate design tools in the early stages of project development, before the first particles of sawdust are generated. A next step will be using past measurements to further explore the crossover concepts and possible results

I find that giving this stage time and coming back and re-examining initial assumptions can be most rewarding.

Obviously, this will not begin to approach a cost of 59,000 Eu per pair of speakers. Examined in this light, the difference in woofer cost is nearly a rounding error.

And consider- per a recent comment you made, there will be more black... with larger woofer cones.

A couple of sayings come to mind ...... in for a penny, in for a pound, which rolls into, if your gonna do it, do it right! 😁

[Evil Twin]

Now, in consideration of exploring the issues and potential, and pitfalls for this design change proposal, it is does not require powers in the Force to use the data which PuriFi supplies (if you know the right people to contact) and get their measured IB small box on axis SPL data as a starting point, plus impedance.

Then, using the VituixCAD diffraction tool, model the driver's position on the appropriate size baffle to get a first order approximation of the raw response in the proposed system configuration... Note that this plot is at about -10 dB of nominal driver 1m behavior, due to the difference in theoretical measurement distance.



Of course, challenges exist because of the rising on axis response and the high frequency cone breakup modes, as well as the baffle step requiring compensation.


However, initial calculations targeting an LR4 crossover at 2kHz show reasonable promise of reaching the desired transfer function, and with reasonable sensitivity. But, of course, with a 4 ohm nominal driver and an effective crossover filter, this will not be driven with a light weight triode amplifier design.




This shows enough potential to justify continuing on this development fork as a possible alternative.

[Evil Twin]

A couple of personal messages asked basically, "why bother with the PTT8.0x04 over the first choice MW19TX-08?"

A few simple points easily elucidated:

• The PuriFi PTT8.0 has 50% more Xmas
• The PuriFi PTT8.0 has 50% more Sd, due to differences in the surround design and frame.
• The PuriFi PTT8.0 has a well documented highly linear BL force over the total Xmax- this is due both to the magnetic structure and the nonlinear winding of the voicecoil.
• The PuriFi would be less sensitive, but makes up the difference due to the 4 ohm nominal impedance. Lightweight triode amplifiers need no apply.
• The PuriFi DOES have exactly the T/S parameters desired for this alignment, including a Qts of 0.34.

And, the icing on the cake, a well executed set of 3D models in various formats, including my preferred one.

[technodanvan]

Having CAD files available is super helpful! Wish that was a standard.

[technodanvan]

By the way, have you evaluated the DX32TX from Peerless?

[Evil Twin]

By the way, have you evaluated the DX32TX from Peerless?

Do you mean the DA32TX-008? I have a pair new in box, and have confirmed the impedance plot.

It is also difficult to source, next availability at Parts Express MAY be in three weeks.

It is an interesting "dark horse" candidate because of the lower Fs and greater Sd; the upper breakup mode suppression network may be more problematic.

[technodanvan]

That's the one! I might be a reason PE is out of both models....

[duvixan]

The French connection has just restocked a lot of DA25/32TX...

[JonMarsh]

That’s interesting and welcome news! Maybe PE will get parts in December.

[Evil Twin]

The French connection has just restocked a lot of DA25/32TX...

Component stock for "interesting" parts has been verified; it should be noted that there may be some blocks in place on conventional CC transactions to the US; a order attempt was then made wiring funds from my galactic banking sector...

[Evil Twin]

To expedite early data collection from potential drivers, some cabinet components have been selected from storage...

First, an early basic subwoofer cabinet formerly sold by Madisound, if my recollection is correct. This is a useful volume for actual testing the PTT8.0x04 woofer and two SS10-PR, and the front panel width is 17", so baffle step will be in the expected frequency range.




The base needed to be re-attached, but that was a simple task with my preferred BSI slow cure epoxy for detail work.

A fixture used for testing a large Beyma AMT driver and horn can be relieved of the horn and a new test baffle installed for measurements of the Tymphany DA32TX.




And to think that some of the rebel scum believe I am a hoarder...

"Waste Not, Want Not!"

[Evil Twin]

Do you mean the DA32TX-008? I have a pair new in box, and have confirmed the impedance plot.

It is also difficult to source, next availability at Parts Express MAY be in three weeks.

It is an interesting "dark horse" candidate because of the lower Fs and greater Sd; the upper breakup mode suppression network may be more problematic.

One other note worth making, is that the DA32TX does not include the magnetic assembly outer diameter, and it is most definitely larger than the DA25...

[duvixan]

My calculations point very strongly to 100mm diameter magnet

[Evil Twin]

My calculations point very strongly to 100mm diameter magnet

My measurement points to 100mm diameter also.

Additionally, test baffle components for the tweeter evaluation fixture have arrived, and binding posts for the text fixture interconnects are due in today. The next days should start providing some useful measurement information.

[Evil Twin]

The French connection has just restocked a lot of DA25/32TX...

And the French Connection has initiated a shipment to my sector with the desired product- converting from galactic credits to Euros is more "taxing" than in previous cases.

[Evil Twin]

Distracting issues have delayed completion of setup of text fixtures, but on the other hand, additional cabinet materials have been located in the local warehouse and a Bamboo ply panel received... progress all in all.

[Evil Twin]

And, in a test of current logistical networks between my corner of the local galactic arm and key vendors in the e European Union, there is a certain success to report, not a rapid transit, but seemingly a Tariff free one... obtained through a trusted intermediary

Most interesting...

An additional set of fully contemporary DA32TX are on hand... verified recent production.

[Evil Twin]

An additional $26 duty fee was levied after the delivery by FedEx.

[Evil Twin]

A basic test fixture was fabricated from an older device test fixture (TPL150H) and some quasi near field tests accomplished after a system re-calibration. This is one of the new parts recently received, serialized in June, not the 2021 parts.

This was a small test baffle so measurements were done quasi-near field; it is usually the middle range of off axis measurements that are most useful as they do not have the stack up of baffle edge border reflections. I find that 10 deg to 40 deg measurements will correlate well with subjective impressions.





And here, is a summary of 0 deg to 40 deg...







And last, HD2 + HD3 for the 10 degree measurement.

My conclusion for now is that the results are sufficiently satisfactory to consider fabrication of an evaluation prototype with 4th order 2kHz crossover.

[technodanvan]

Does this software allow you to compare two different tweeters in one graph? It would be interesting to see the difference compared to the DA25TX.

[Evil Twin]

This is possible with this software, but it would require having two new test baffles, preferably much larger than the one setup for this quick check, of identical outside size, but sized correctly for each tweeter- the DA32TX is larger in diameter for the magnet assembly and the mounting plate.

The main drawback to this test setup using a relatively small test baffle with a fixture originally designed for the TPL150H horn + AMT driver, is that directly on axis with the DA32TX mounted in the center, diffraction reflections stack up and cause modifications of the 0 degree on axis response that would not be present in a larger baffle or with offset mounting. As the off axis measurements eliminate that effect, the main usefulness of this test is evaluating response and distortion from 1kHz to 10kHz.

Now, for reference, here is the full expanded scale measurement of the 0 degree on axis response for comparison to the factory measurements and previous measurements.



The roughness in the 2800 Hz area seems to be due to this diffraction effect and recombination time delayed with the primary signal.

It should be noted that the SPL response extends flat considerably lower than the DA25TX samples I have measured, or the factory curves, and the distortion stays lower longer before rising in the low end. Surprisingly on this sample, the HF breakup behavior is more like a DA25TX than older samples of the DA32TX or factory measurements.

[Evil Twin]

Jonmarsh has donated a new in box Madisound sub enclosure for fabrication of a test enclosure to check the LF alignment design.

This has been proven to be interesting for more than one reason- the MDF used in this cabinet exhibits different characteristics from that readily available in some prebuilt cabinets and in cabinet kits. It would probably not be called cabinet or shelving grade MDF at this time, as the particles making up the panels are coarser than normally encountered at this time. But, most interestingly, it is also harder and stronger material- one suspects a different base wood was used for creating the MDF material.

Regardless, fabrication is proceeding and an evaluation test should be feasible in the near future...

[chrisn]

Jonmarsh has donated a new in box Madisound sub enclosure for fabrication of a test enclosure to check the LF alignment design.

This has been proven to be interesting for more than one reason- the MDF used in this cabinet exhibits different characteristics from that readily available in some prebuilt cabinets and in cabinet kits. It would probably not be called cabinet or shelving grade MDF at this time, as the particles making up the panels are coarser than normally encountered at this time. But, most interestingly, it is also harder and stronger material- one suspects a different base wood was used for creating the MDF material.

Regardless, fabrication is proceeding and an evaluation test should be feasible in the near future...

Zooming in, it does look more like "particle board" than mdf, but more dense...like a hybrid. Interesting...

[Evil Twin]

Exactly. I have not seen material quite like this in some time...

[Evil Twin]

Further measurements have FINALLY been completed- too many disturbances and distractions in the Force for optimum productivity...

But the test cabinet for basic measurements has been assembled, and some preliminary measurements completed- enough to report some basic details.


Note, this Unibox calculation of the expected basic LF response profile IF a fully stuff cabinet is used. That option was chosen for this test, as the internal cabinet configuration is nothing like the proposed design, and it is easy to calculated how this modifies the target LF response, without being concerned overly with the impact of a flat rear baffle wall on midrange response.



Of course, this still predicts an Fb for the enclosure in the 32Hz region, and the desired Bessel response is modified by some additional downslope due to the full stuffing.

For the test cabinet, as a matter of expediency and availability, Dow Corning Pink Next Gen R13 fiberglass roll material was used, with the backing stripped, a total of 6 - 13" x 14" pieces.

The measured impedance curve indicates an Fb in the expected range, just very slightly lower...





Of course, of more interest, but harder to secure a definitive measurement in a residential environment, is the measured SPL response to evaluate potential suitability. With no optimum placement options for test, a basic QNF test is a useful first check, though it will under estimate the PR contributions.





As noted in the Unibox analysis with a fully stuffed cabinet, there is an additional soft roll off below 100Hz...



But in general the response profile appears quite usable, and at this output level, with 2.83VRMS input, distortion is quite low, and dominated in the LF area by 2nd order.

Checks off axis at 1 meter show that the PTT8.0NAB output may be usable well off axis with a crossover point of 1500-1800 Hz.

The next step will be further crossover modeling and evaluation of necessary Z axis offsets.