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**JonMarsh** · 22 April 2023, 08:27 Saturday

It's also occurred to Steve and I that this might make an interesting though not terribly compact center channel at an attractive price point... could even make sense to consider the midranges in an MTM format. Availability of the "midrange" is the key issue, other than the fact that I have a box of them for building a line array that will probably not get built, due to other projects in progress.

**svenarajala** · 22 April 2023, 12:44 Saturday

Originally posted by JonMarsh View Post

It's also occurred to Steve and I that this might make an interesting though not terribly compact center channel at an attractive price point... could even make sense to consider the midranges in an MTM format. Availability of the "midrange" is the key issue, other than the fact that I have a box of them for building a line array that will probably not get built, due to other projects in progress.

That's an interesting proposal to use as an MTM... Funny what happens when you stop and reflect for a moment and then the ideas flood in. The fun of DIY and building is that it is endless. I don't think there is ever a floor or ceiling!

**JonMarsh** · 23 April 2023, 13:23 Sunday

Yes, very true, the key challenge being finding time to work on evaluating concepts and prioritizing time and resources for builds!

**Wayman** · 30 April 2023, 18:57 Sunday

With so much amazing work being done on the Saint-Ssens, I was wondering if conceptual framework could be adapted to this smaller build using the PT-6825-8?

Cheers, Wayne

**JonMarsh** · 01 May 2023, 11:45 Monday

Are you thinking about the PT6825 as a relatively low budget midrange, or seeing how well it would run from around 1kHz up to the top end? Granted, that appears to be limited to about 15kHz, but the reality is a lot of folks can't hear even that high....

This is another case where some experiments would be needed to figure out the optimum rear sub enclosure configuration- judging from the factory curve, it isn't as a dipole or in a large enclosure.

When you consider the factory response curves, my thought is that the PT6816 might be easier to work with and more amenable to some flexibility of application and sub enclosure size-

Just look at the dimensions of the driver- it's like a triple stack of the PT2522... the $64 question is, is it as smooth as the factory data sheet claims? The PT2522c is not. nor is the PT2522.

But, only one way to find out... as is normal, my bank account gets an injection on the first of the month, and I'm in a good mood, so I'm ordering two with front panel plates to find out!

**Wayman** · 01 May 2023, 21:36 Monday

I certainly didn't think it thru as clearly as you have. I did think since it's almost 1/3 the cost it might be suitable as a mid for a lower cost build. I also noted that like the PT5010, it has a rising response (if that proves to be real?) and thought with a similar offset it may do well & help shorten development time.

And yeah it does look like a triple stack! Good point.

Cheers, Wayne

**JonMarsh** · 01 May 2023, 21:50 Monday

Oh, I don't really doubt the rising response. Soon I'll know; four on order.

For reference, here is the PT5010 in a 15L enclosure, this is as close to IB open back as I've measured it.

Now, here is the exact same unit, but in 7.5, also with a careful damping configuration:

Differences are due solely to the rear enclosure volume and some slight tweaks to the damping setup- basically the same materials, actually! And the this is the same part, measured in two different enclosures that have identical front baffle configurations...

This is what one is up against to optimize the PT5010, and to a similar extent the 2522, and why I've tested 4 different configurations for each before saying, "Ok, I think this is about as good as we'll be able to do."

For example, here is 3.5 L, again, with an identical front baffle configuration:

**JonMarsh** · 01 May 2023, 22:10 Monday

And to give you an idea of where things can go with that 7.5L version, here's the POC bandpass crossover measured today, polars from 0 degrees to 50 degrees off axis.

This is nailing my target and hopes; no more tweaks until everything is put together in the full top module build, not just an MDF test enclosure. Nominal crossover frequencies are 450Hz and 2400Hz.

On axis with distortion plot:

**JonMarsh** · 02 May 2023, 09:52 Tuesday

Now, just to take the "thought experiment" with the PT6816 a bit further, I loaded up the provided FRD and ZMA data, ugly as it is, to see what might be done with a "brute force massage" in the crossover without going too crazy....

The selected target transfer function is an 800Hz LR3 high pass, an Eazy Peazy cross point for the RSS210HF if you wanted to configure a two way. In fact, the ideal would probably be a 2.5 way, so you only have the upper driver to consider with that high a crossover, as regards CTC distance.

This is working just with the factory supplied FRD curves- here's a plot of the driver response as measured by the factory, plotted out to 40kHz, but graphed just to 100Hz on the bottom end.

My experience with this family of drivers shows the similarity of behavior to similar parts like the big Magneplaner drivers; in that, the low frequency diaphragm resonance will produce a Qts related bump in the output level- for the Magnepans/Magneplanars, this is how they get their LF dipole EQ to produce something reasonably flat in room. This bump is generally followed by a dip in the response, then a climb up to a higher level until the upper frequency limit from mass is uncounted. My experience is that you get the best results pushing that resonant frequency up just enough to fill the dip somewhat, and adjusting that and the damping to get the smoothest response through the desired passband.

Just compare the published data for the PT2522 and the PT2522c with the rear cup and you have a clear, if not optimum, example of this.

Those with sharp eyes will note that the response plot from the FRD file is NOT as flat as the published SPL sample, for example, compare the rise between 2kHz and 5kHz for the two.

So, mainly as an experiment and intellectual exercise of sorts, I put together a crossover to see what could be made of this "as is". In practice, I would/will spend a fair amount of time on sub enclosure experiments, though given my experience with the PT2522, I think a variation on my MOD3 enclosure may work best. Time will tell. The parts on order should get here Thursday, but very early Friday I'm leaving on a storage run to CA, so these will have to wait until some time after I get back.

Here's the result..

And the result with off axis data 0-15-30-45 deg:

This is a brute force approach, and not what I'd recommend, but it gives an idea of what is possible. The right way is to address as much as possible with the acoustic loading of the driver first, IMO.

Note, there is no actual data above 20kHz in the FRD files provided by PE for this part; it's just a straight line extrapolation based on the recent real data.

**JonMarsh** · 02 May 2023, 10:30 Tuesday

For further explanation and illustration, I'm going to plot the FRD files that are provided for the PT2522 (dipole version) and my own "MOD3" of that, which is closer to the optimization that might be needed for the PT6816.

First, the factory 0 Deg SPL file directly plotted in VituixCAD, then the polar 0-15-30-45 plot.

Now, data recorded for the MOD3 update for PT2522, both on axis with distortion, and 0-40 deg polar in 10 degree increments, not the 15 degree used for the PE supplied data:

Note, this is REAL data above 20kHz, not a nonsensical extrapolation. You can see how the Fs has been pushed up, and there is less dip in the center.

Now, this is MOD4, note, still only 1/24th octave smoothing (I.E., minimal):

As you can see, this is quite a long ways from the base FRD performance in full dipole mode. I show these examples to highlight the challenge of working successfully with these parts, and the necessity for acoustic solutions for acoustic problems. The MOD4 is targeted for operation with a crossover frequency of 2.2 to 2.4 kHz.

**JonMarsh** · 05 May 2023, 06:17 Friday

The PT6816's arrived yesterday, I'd post pictures but server issues are preventing me from transferring pics from my phone to the computer.

An interesting thing is that the stamped panels look "crisper" and cleaner, as if from different tooling design than the 2522's I have.

It will be interesting to see how they measure- I'm getting the impression that however the FRD files are created for PE for some of these drivers, the measurement setup isn't very good- results are rather "dirty" (as in acoustic reflections) compared with my own test setup.

Now, an interesting question- should this move forward, especially if it does as a two way, is it really an Ardent, or another Natalie P variant? If done in a two type configuration with PR's, then it definitely would move into the "love child" category between the two...

**Evil Twin** · 24 May 2023, 22:54 Wednesday

Once again I am detecting a serious disturbance in the Force, and the likelihood of Rebel spies plying their craft...

Though deliberate misdirection has been used in this topic post as to the true goals and intent, nonetheless it seems that key aspects of the development direction behind the minor revelations in this topic have been discerned by a well known commercial firm...

In this case, I am referring to the "early" oblique disclosure of the "FR10" loudspeaker system from PS Audio...

There can be little doubt that the intended upper range driver complement is based on the well known PT2522 for HF, and a derivative or exact usage of the PT6816, revealed and discussed very briefly earlier in this topic...

It is also most curious that the passive radiators mounted on the enclosure rear would "appear" to fit the form factor of the SB15SFCR which were sourced at our facility many months ago for the development of this more diminutive member of the planar driver family....

Though there is another dual woofer system in development consideration, that uses the PuriFi PTT8.0X04 woofers and the high end complement of planar midrange and AMT tweeter.

This system was defined as a more "budget" oriented solution, hence the reference to "Dayton Ardent", as the woofers will be a Dayton model, selected for synergistic performance at a very manageable BOM, and like the classic Ardent configurations, wired in series.

It might seem that this is merely a "curious coincidence", but in my long experience in the Imperial sector, I have learned, sometimes in painful ways, that there is no such thing as a "coincidence"....

At this point, there is no reason to withhold this level of information regarding the project which has been code named "Scarlatti", after the well known Italian family of composers and the singer Rosa Scarlatti.

Of course, in fairness, Giorgio Scarlatti, the Italian Formula One driver should not be overlooked, either.

**Evil Twin** · 25 May 2023, 10:44 Thursday

Of course, now that PS Audio has "revealed their hand" with the FR10, there is no drawback to to revealing the current state of development here, as it would soon be reported in any case by the Rebel spies among us.

It should be noted that while a higher sensitivity design with the SB15SFCR-00 passive radiator was considered and evaluated internally, it's performance characteristics versus enclosure size were believe to be left wanting... certainly not suited to the SMJ family. This decision was based on linearity characteristics with excursion of both the main driver and the passive radiator candidate.

Instead, it is believed a more satisfactory solution will be arrived at by using the LF drivers from the SMJ-40 concept, but just 2 of them, and using the recently introduced and acquired RSS210PR passive radiator, a component of fairly sophisticated design characteristics and far greater linear excursion capability:

SMS™ (Sandwich Mass System) permits greater linearity by minimizing angular torque
Durable yet compliant suspension provides substantial linear travel and mechanical stability - 20mm
Rigid cast aluminum frame with thick black anodized aluminum cone
Cosmetically identical to the popular Reference Series subwoofer lines and RSS210HF-4 used as the primary woofer

These will be mounted on the rear enclosure wall, and due to T/S characteristics, only one PR per woofer is required to achieve a satisfactory response characteristic in a total of 60L for two woofers and two passive radiators. With boundary lift, extended performance to the low 20's can be realized.

**Evil Twin** · 25 May 2023, 10:57 Thursday

Note, this plot below is for 2 drivers and 2 PR's in a 60L enclosure; the above plot is a POC evaluation for just one driver and PR.

This plot is for probing the upper boundary of SPL capability... at about 75% of woofer Xmax.

**Evil Twin** · 25 May 2023, 18:06 Thursday

Now, for a "worst case" study for the PT6816, assuming that a custom sub enclosure and damping configuration cannot improve on the factory dipole configuration (a most unlikely case, based on experimentation to date), this is an example of a bandpass configuration from 600Hz to 2500Hz using my preferred LR3 configuration.

while I would not term this first design pass "optimum", it clearly hints at the potential to be realized from this driver in a more optimized enclosure configuration.

**JonMarsh** · 28 May 2023, 11:20 Sunday

Well, ET seems to have the midrange design well in hand, and the Chancellor has agreed to his participation in that area, but for now we are investigating more wallet friendly low frequency solutions. It is quite conceivable that there could be a Scarlatti, and a Scarlatti Supreme, the latter using the RSS210HF-4 woofers.

But, for now, there is an interesting new value option for the low frequencies that will be investigated, the Dayton SIG180-4. Two of these would be wired in series, in "traditional" Ardent style, for an "easy" LF load.

The SIG180-4 appears to be very easy to work with, and is reputed to have careful Kippel optimization and edge termination, and uses a concave one piece aluminum cone of careful design.

T/S parameters are reasonable for a variety of enclosure alignments.

My current "favorite" is with two RSS210PR without added weights, with a slow roll off extending the low end to near 30Hz, and working best in a Cardas style layout with boundary distances chosen for LF lift below 60 Hz.

With 3 PRs in the same size enclosure, a flatter response but with higher cutoff is possible:

With this alignment, a power of 20W per woofer (40W at 8 ohms) will results in an SPL of 106 dB per cabinet, at just below the 82% BL force Xmax rating.

**augerpro** · 28 May 2023, 15:21 Sunday

Can't wait to see 3rd-party measurements of the Signature series. What they've done with the breakup in the 5" and 6" is amazing.

**JonMarsh** · 28 May 2023, 18:06 Sunday

Yeah, me too. But in my case, I'm waiting for 1st party measurements!

Ordered 4 today.

Haver a couple of possible projects in mind.

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Dayton Ardent PE?

Dayton Ardent PE?

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