Interesting Drivers

[tktran]

I wanna see peaks - in all of their ugliness - if they are there.

Do I understand you correctly Mladen? In the amplitude response or in the impedance response?

If in the former, we're not going to get any better than Erin's NFS. That thing has a measurement resolution of 20Hz, IIRC. A typical gated measurement, even a good one of 10ms, only gives a resolving power of 100Hz. Between the musical octave of 500 Hz and 1000Hz we're only going to 5 data points. With a typical indoor measurement with a window of 5ms, that 200Hz resolution gives 2-3 data points between this octave. :cry:

[Zvu]

Do I understand you correctly Mladen? In the amplitude response or in the impedance response?
...................

No, i meant what Yevgeniy at hificompass does.

THIS vs THIS - it's measurement for the same driver.

[5th element]

I find it very troublesome to see that 1kHz dip thingy with the 8" in Erin's measurements. Trouble is his measurements show large issues with the 6" aluminium cone too and around the same frequency range. Purifi and Hificompass disagree with these measurements quite significantly and it's the same with the paper and aluminium drivers that all three have measured. Purifi and Hificompass show flat frequency responses through the 1kHz region whereas Erin shows a dip.

Doesn't the Klippel system only use nearfield measurements with complex software summation? Whereas the other two are going to be gated far-field? Needless to say we have two measurements in agreement and one that isn't. Are there any other sources who've measured them we can add to the comparison?

The Klippel system does seem a bit plug and play and open to errors if you don't know exactly what you're doing. I've also noticed some gaps in Erin's knowledge that I was surprised about during his YouTube reviews. Such as not knowing/being confused as to where the 3rd order HD peaks come from in the SEAS C18 coax? I thought this was common knowledge. Either way we need more data to be absolutely certain because the Klippel isn't matching the others.

The Klippel estimated xmax for suspension linearity is perhaps questionable too but then who knows quite what's going on. If you compare Erin's measurements for the PTT6.5W04 (paper) and the 18WU4741 (paper) we can see that the xmax spec favours the Scanspeak but if you then look at the HD plots and compare the low frequency distortion the Purifi has better performance.

More concerning is that if you compare the Klippel soft parts results for all the Purifi drivers tested it would appear that there might be consistency issues between drivers. For example the soft parts in the PTT6.5W04 (paper) appear to perform quite a bit better than those in the aluminium 6" and the 8". To me this makes no sense. Surely the spider and surround in the paper and alu drivers would be the same? Maybe they are supposed to be. Either way it's concerning and underwhelming. The bass performance of the paper vs alu 6.5 Purifi's favours the paper even in the HD measurements. The Kms symmetry plots looks very different for the two. Did the original paper driver use a different suspension back in 2020? Or does it have a different suspension vs the alu version? Or does the paper version now come with the same suspension as the alu? Vance Dickason's Klippel measurements for the paper look similar to Erin's for the paper version.

Whatever is going on it doesn't inspire confidence considering the price of these drivers.

[JonMarsh]

I find 3rd party tests interesting and a reasonable guide for identifying opportunities, but there’s no substitute for one’s own test setup. Assuming it’s well put together- so far, I trust mine fairly well, and adding the Audio Precision into the mix the few times in the past (while still working) that I’ve had the time has proven interesting too.

I have both the 8” and 6.5” aluminum on order… throw of the dice. We’ll see how it works out.

Thanks for your inputs!

[tktran]

No, i meant what Yevgeniy at hificompass does.

THIS vs THIS - it's measurement for the same driver.

Ok I'm with you. I have WT3 too; I'll do zoomed impedance testing when my pair arrive and report to this forum

[Gerald Jansen]

Dear Folks,

I love the way you are searching for answers on issues to be investigated.

In the mean time -while reading your conversations- Albert King pops up in my mind; giving 'some advice' to Stevie Ray Vaughan :-)

I may be wrong that my interpretation of this 'Blues Expression' has nothing to do with the current interpretation of measured figures, or -seen otherwise- figures to be measured. . .

So, while trying not to grab too much attention, let me please suggest to listen to the following album:

https://en.wikipedia.org/wiki/In_Session_(Albert_King_and_Stevie_Ray_Vaughan_album)

More:

https://www.youtube.com/watch?v=4-apz26BfHY

https://www.discogs.com/master/297162-Albert-King-With-Stevie-Ray-Vaughan-In-Session

Better alternatives are welcome :-)

Enjoy!

[JonMarsh]

I can always use and appreciate musical suggestions like that!

[tktran]

Gated measurements no match for Klippel NFS

So I found out more about the Klippel NFS, in my curiosity, to purchase… errr… rent one,

A typical indoor gated measurement of 5ms gives a resolution of 1/0.005= 200Hz.

A outdoor measurement with a speaker 200cm above the ground and microphone 50cm from the speaker baffle will give the first reflection around 10ms later. Gating for this allows a measurement resolution of 1/0.01= 100Hz.

Getting high up, on a scaffold or crane, and lifting your speaker such that the driver is 3 metres above the ground (and ensuring no other objects surfaces within 3m of the speaker) and again measuring at 50cm allows for the first reflection to arrive 16ms later. That allows for a measurement resolution of
1/0.016 = 62.5Hz

You may be wondering where I’m going with this.

Hold up.
Going back to music, on the equal temperament scale, on which most modern instruments are based, there are 12 notes per octave:

Each octave doubles frequency.
So between 500Hz to 1Khz is 1 musical octave.
1000Hz to 2000Hz is another musical octave.

But between that same 500Hz to 2000Hz, that is a span is only 1500Hz (2000-500Hz)

If we want to take a measurement with a resolution of at least 12 points per octave between 500Hz to 2000Hz, that means we need a resolution of approximately 1500 / 24 = 62.5Hz (between C5 and C6 the actual semi-tone intervals vary from about 31-58Hz, because the span between musical notes is roughly logarithmic)

So an indoor gated measurement of typical 3-5ms is not enough to resolve what’s happening between 500Hz and 2KHz.

So to be able to measure with 1/12th octave resolution between the 2 octaves of 500Hz to 2000Hz, one needs to be outdoors; at least 3 metres above the ground; measuring at 50cm away.
If you want to measure at the standard 1m away; the speaker and mic needs to be 10 ft above the ground.

Reference:

https://mehlau.net/audio/floorbounce/

[tktran]

There is no discrepancy, only mic-roscopic dissection.

Here are some measurements between 500Hz to 2000Hz (2 octaves) on the horizontal axis, and 5dB on the vertical axis for each large division.

First the Purifi datasheet for the Alu 8.0X, 2 large divisions in the vertical axis represents 10dB span.



Here is Erin’s NFS measurement



Second is the Purifi datasheet for the Alu 6.5X. Again 500Hz to 2000Hz, but now 1 major division in the vertical, thus representing 5dB.



Here again is Erin’s NFS measurement.




What’s the difference?

The NFS has a resolution just under 2Hz!

What we used to think was pistonic, is not really pistonic. At least not to 1Khz. It’s all a matter of magnification.

[JonMarsh]

So I found out more about the Klippel NFS, in my curiosity, to purchase… errr… rent one,

A typical indoor gated measurement of 5ms gives a resolution of 1/0.005= 200Hz.

A outdoor measurement with a speaker 200cm above the ground and microphone 50cm from the speaker baffle will give the first reflection around 10ms later. Gating for this allows a measurement resolution of 1/0.01= 100Hz.

Getting high up, on a scaffold or crane, and lifting your speaker such that the driver is 3 metres above the ground (and ensuring no other objects surfaces within 3m of the speaker) and again measuring at 50cm allows for the first reflection to arrive 16ms later. That allows for a measurement resolution of
1/0.016 = 62.5Hz

You may be wondering where I’m going with this.

Hold up.
Going back to music, on the equal temperament scale, on which most modern instruments are based, there are 12 notes per octave:
[ATTACH=CONFIG]32253[/ATTACH]
Each octave doubles frequency.
So between 500Hz to 1Khz is 1 musical octave.
1000Hz to 2000Hz is another musical octave.

But between that same 500Hz to 2000Hz, that is a span is only 1500Hz (2000-500Hz)

If we want to take a measurement with a resolution of at least 12 points per octave between 500Hz to 2000Hz, that means we need a resolution of approximately 1500 / 24 = 62.5Hz (between C5 and C6 the actual semi-tone intervals vary from about 31-58Hz, because the span between musical notes is roughly logarithmic)

So an indoor gated measurement of typical 3-5ms is not enough to resolve what’s happening between 500Hz and 2KHz.

So to be able to measure with 1/12th octave resolution between the 2 octaves of 500Hz to 2000Hz, one needs to be outdoors; at least 3 metres above the ground; measuring at 50cm away.
If you want to measure at the standard 1m away; the speaker and mic needs to be 10 ft above the ground.

Reference:
https://mehlau.net/audio/floorbounce/

Good points, EXCEPT that my typical indoor gated measurements for woofers are 100ms to 200msec, with the ability to adjust and reduce when I want to focus on higher frequencies only. Heck, I don't even measure tweeters at 5msec!

Right now, I'm setting up for quasi-near field measurements on relatively large baffles with a semi-outdoor approach. Not sure how it will all work out. But I do routinely use relatively near field measurements (6", 9", 12") and I'm very curious to see how the new parts hold up, and where the issues lie.

Now, consider that a "lowly" part like the Dayton RSS210HF-4 has it's breakup mode up around 4500Hz, I'm going to be looking at it with a microscope below 2kHz, but at most only plan to use it up to about 400Hz- same as for the PuriFi's.

Just have to see how it all works out!

:huh:

[5th element]

[QUOTE=JonMarsh;641429]Good points, EXCEPT that my typical indoor gated measurements for woofers are 100ms to 200msec,

How do you manage this without any reflections getting in the way?

[JonMarsh]

Environmental control, and large rooms.

And reviewing/sweeping impulse function, to identify reflections and their impact, by adjusting gating and gating filters.

For example, this measurement of one of the Isiris updates has lots of reflections and only 1/48th octave filtering. But it is reasonable for understanding the overall balance at the listening position.




But then I also do quasi near field measurements, typically at 12", occasionally six inches, just to see what it looks like with direct sound swamping out reflections. That's more often done for individual driver evaluations, to identify driver issues apart from room stuff.

For example, let's look at the Eighteen Sound 6ND430. Here's a far field polar set done on a specific baffle, to get an idea of the polar coverage- not necessarily the fine points of the driver response.




OTOH, this graph is for the same driver, mounted in a different cabinet, ported, and a near field measurement was done to get a feel for the driver radiation as modified by the port on the bottom of the enclosure. This response is fairly representative of the driver for an outside infinite baffle measurement. You can see the expected dip in the driver radiation output due to the port loading.





These kinds of near field tests are good at identifying driver related issues, like the surround resonance in the relatively recent Dayton RS542 dome midrange production, which did actually correlate with the impedance plot. The parts I worked with years ago didn't have this issue- I know, because I have a couple of samples still! It's pretty crappy when a manufacturer's production process changes and they don't catch it or fix it or will even acknowledge it (yes, I contacted Dayton audio about this issue back in 2021).

[JonMarsh]

These arrived earlier than quoted- not 4 weeks, more like two weeks exactly!




I can't wait for the move out from the rental to be finished and to have some time for projects again...

[tktran]

Looks like the 6.5X054-NAA. Did you get 8 of these as well?

Be interesting to see if we can see the dip just over 1KHz.

I mean, Purifi's datasheet has a scale of 60dB in the Y-axis, the screenshot I took has the NFS having only 5dB vertical scale, and Røde's Fuzzmeasure uses a scale of 80dB and stretched 10Hz to 40Khz- you might not be able to catch it.

[Scottg]

Linearity below 5.5 kHz isn't good, but multiple ways to work it into a design.

Horizontal Dispersion is rather good, and predictably vertical is not.

https://audioxpress.com/article/voice-coil-test-bench-the-u80w-air-motion-transformer-from-mundorf

[Scottg]

[QUOTE=tktran;641427]So I found out more about the Klippel NFS, in my curiosity, to purchase… errr… rent one,


If you want to measure at the standard 1m away; the speaker and mic needs to be 10 ft above the ground.

[QUOTE]


You know, provided you have enough room (including height) - and it doesn't have to be that large of a room, It's very possible to suppress enough output down to just below 100 Hz with enough absorptive material (..multi-layer *panels on ceiling, floor, and surrounding the loudspeaker - with it lifted off of the floor to place it mid-point vertically).

Assuming the mic remains in the same place - cepstral editing can handle the low-end.

I think that makes it very possible to get a good repeatable measurement in-room withOUT any gating at all. While the panels won't be cheap - they just have to be a LOT less expensive than a Klippel NFS.


*I'm thinking DIY absorbers about 2+ feet in thickness (varying the density with air-gaps between panels).

[tktran]

I've read about this Scott, but does it really work? Sounds like hard work... like.. building an mini-anechoic chamber... type of hard work.

I recently did the whole ground plane measurements for some twin woofers. Well that was a bloody waste of time, because it just verifies what one can do with nearfield and baffle diffraction compensation. Well at least within +/-0.5 dB; which is close enough because the room swamps everything in real life. You don't have to put your hand into the fire to know it's hot, except if you're crazy (where we probably are, a little)

Anyway, I'd be interested to see some actual before/after measurements of anyone who's done this, and their experience before I go off and acquire over 10 cu ft of fibreglass and polyester wool and foam and start lining my living room in it. :roll:

My spouse already hates the fact that our stereo is in a constant state of flux. So I say:
"Can I buy the KEF LS60.. it's a wireless bluetooth speaker. Only 10,000 Australian micro-pesos, and I promise I won't fiddle around with it; it'll just WORK, like an appliance!"

"Does that mean I can finally play my CDs again?"

"Errr..."ops:

[JonMarsh]

Looks like the 6.5X054-NAA. Did you get 8 of these as well?

Be interesting to see if we can see the dip just over 1KHz.

I mean, Purifi's datasheet has a scale of 60dB in the Y-axis, the screenshot I took has the NFS having only 5dB vertical scale, and Røde's Fuzzmeasure uses a scale of 80dB and stretched 10Hz to 40Khz- you might not be able to catch it.

Just two to evaluate for now. Took just 14 days, not the quoted 4 weeks- ordered on June 6, received on June 20th. Pretty good result. I’m very curious to setup and measure once we get the move out finished and a few other things taken care of- and I have to find the bin with the measurement gear! A lot of stuf stacked up on shelves here and not fully organized.

[Scottg]

I've read about this Scott, but does it really work? Sounds like hard work... like.. building an mini-anechoic chamber... type of hard work.

Interestingly, you don't need higher density material as you increase panel thickness - this makes it a LOT cheaper (and is contrary to what I expected).

Basically it's a 2" cotton rebond in "front" of a 12" Fiberglass (that's about 0.8 lbs/ft³). The cotton rebond is broader-band and the fiberglass is for lower freq.s. (though the rebond can help with that range below 500-250 Hz). I'm not even sure if you need the rebond - but I have seen inconsistent results with "panel" fiberglass above 4kHz or so. A poly batting "wrap" (used for blankets) to the fiberglass panel would likely work just as well at higher freq.s and further decrease the cost. You would still need something "structural" for the panels though, like framed open metal grating.



Really, I thought it would be more complicated than this. ops:

[JonMarsh]

Still not trivial, but interesting, and dovetails with what I've been thinking about doing- wouldn't be hard to just make a "floor" panel like this, to control floor bounce. Imagine doing this 6-10 ft out from an open garage door... certainly worth an experiment. And, I've got lots of ATS panels around, different types, wouldn't be hard to some up with a few multi-layer ones that could be used in concert.

[Scottg]

That lower density with thicker material result explains why (when I've done loudspeaker measurements to get rid of floor bounce) that lots of pillows surrounding the base of the loudspeaker (and all the way to the mic.) do such a good job - it's about perfect. 8)

[5th element]

Environmental control, and large rooms.

Yeah there's nothing I can do to get that sort of measurement with long gates in the environment I'm in. I'm still surprised you manage to get such clean results.

I had assumed there was some post processing trickery involved but it seems not.

[PANDINUS]

Tang Band 3" Textile Dome Midrange is back under the heading 75-1558 SH

http://www.tb-speaker.com/products/75-1558sh

[morbo]

Tang Band 3" Textile Dome Midrange is back under the heading 75-1558 SH
http://www.tb-speaker.com/products/75-1558sh

I think this is actually a new version of the old SE, somehow different. The performance measured in the latest VC seems impressive!
Unfortunately, I can't find any vendor that has it yet.

[kevinlin1013]

With the Bliesma/Scan Speak/TB it seems we have the renaissance of big mid-domes!

[Bear]

Tang Band 3" Textile Dome Midrange is back under the heading 75-1558 SH
http://www.tb-speaker.com/products/75-1558sh

Vance's measurements are now available for us mere mortals. It looks like a great product.

https://audioxpress.com/article/test-bench-tb-speaker-75-1558sh-high-end-home-audio-3-dome-midrange

[tktran]

Release of the 8" Subwoofer from SEAS Extreme line.

http://www.seas.no/index.php?option=...ticle&id=604:e xtreme2-08-l22roy-2&catid=97&Itemid=603

I suspect the exclusivity agreement with Ex Machina Soundworks has lapsed...

Ex Machina Pulsar MKII 3-way 8-inch Active Studio Monitor Review (erinsaudiocorner.com)

[AJINFLA]

New boss, same as the old boss? It took like 15 years to come up with a new color it seems.

https://www.parts-express.com/brand/HiVi/promodisplay/N

[technodanvan]

Black HiVi? Say it ain't so!

[JonMarsh]

It is so. But not much else different...

Last time I used a HiVi driver was around 2001-2002.

[JonMarsh]

Now, TECHNICALLY this isn't a driver, but a passive radiator... however, it is LONG overdue, IMO!

Two of them sitting in my lab, but obviously, I can't post a frequency response plot, per se!


https://www.parts-express.com/Dayton-Audio-RSS210-PR-8-Aluminum-Cone-Passive-Radiator-295-499?quantity=1





And I could tell you all about the secret project they're going into, but then Steve would have to fly out from Maryland and kill me, and he gets cranky these days if he has to get on an airplane!

[dansan69]

Interesting new coax tweeter / mid

http://wavecor.com/html/tw045wa01.html

[technodanvan]

That IS a really interesting little guy! I'm a little curious though...I think I only see one set of terminals, as well as only one pronounced peak on the impedance graph.

Edit: Confirmed, there is only one voicecoil. It appears the tweeter is somehow bonded to the cone and they act together. No internal crossover, other than the mechanical aspects of the driver. Still interesting to me at least. Unsure what I'd do with them but I may try to source a pair.

[PANDINUS]

Coaxial tweeter ? I think it's a fancy name for a classic cone tweeter. Instead of a paper cone and canopy, there is a ceramic cone and a fabric canopy. So it's a modern high-tech version of a classic cone tweeter such as the VISATON TW 6NG or MONACOR HT-22/8

[tcpip]

What will someone do with the Wavecor mid-tweeter which one can't do with a good "normal" SB29 or Wavecor 30mm tweeter? The frequency range does not extend any lower than a normal good tweeter. The only thing I saw in the spec which was unusual was the huge power rating. Am I missing other unique features?

[technodanvan]

I mean, it has pretty bad off axis response. If you're into that...

[technodanvan]

Check this thing out, I'd normally not post such a weird thing but the high-ish price caught my attention. Low sensitivity but good off-axis response when oriented vertically. However, that response has a heckuva downward tilt to it. Trying to come up with an idea for them...skinny desktop computer speakers maybe when paired with a small flange tweeter of some variety? Curious about the modeled bass response too - 30 Hz f3 in just 0.35 ft3? I suppose that corresponds with the sensitivity...

https://www.parts-express.com/Dayton-Audio-RC180-55-2-x-7-Res-Core-Neodymium-Woofer-4-Ohm-295-248?quantity=1

[Evil Twin]

Given my general reputation, I trust that no one will be troubled if I should make some pointed and acerbic comments regarding this "device"...

After a cursory and then more detailed review of the data sheet, my initial thought is that some engineer had what he believed was a clever idea and was able to get a relatively inexperienced marketing person to sign off on a development project.

Alternatively, I might merely opine that it appears to be a solution in search of a problem of unknown characteristics....


As an aging Sith, I believe that no one should hold a few pointed observations against me, and if they do, it will not trouble me....

• The size, at 2" by 7", is not suited it would seem for some possible compact applications where relatively low SPL capabilities might be acceptable...
• With a half plane sensitivity just under 80 dB, the 4pi sensitivity will be about 74 dB with 2.83VRMS. Due to the low impedance, (about 3 ohms) this translates to an input power over two watts. Let us be charitable and say just 2 watts. With an RMS power capability of 35 watts, this is 12 dB greater than the 2.83VRMS rating, which would make the 4pi space SPL capability about 86 dB. Certainly not deafening- those wishing to avoid excessive SPL will find this to be most satisfactory....
• The Xmax is 4.7mm; this and the Sd of 56 cm2 put it in the category of typical 4-1/2" mid woofers. The Qts is quite high, at 0.89, meaning that only a sealed alignment is reasonable, and that will not be close to critically damped. These are all factors of the T/S parameters that result in such low sensitivity but relatively extended response, albeit at very low SPL. Consider that with this cone surface area, the cone excursion for lower frequencies increases rapidly- Unibox will tell the story. Perhaps if one used 9 of them together, like a Bose 901...
• However, a conventional 4-1/2" mid woofer, such as the Wavecor WF118WA07 has a half plane sensitivity 6 dB higher, flatter more extended frequency response, and a flatter impedance curve, indicating the possibility of lower inductivity modulation and lower midrange distortion. However, it is round, not just 2" wide. But it is not seven inches long, either. And it would require porting or a PR to extend the LF output without EQ. But with EQ, it would be able to play just as loud as the RC180-55.
• The Wavecor is $25.67, while the RC180-55 is $54.

[JonMarsh]

OK, it's a slow Sunday before Memorial Day, but Dhar brought a mid woofer to my attention about a week ago that wasn't actually available at that point, and the specs seemed confused, but now it seems to be sorted out, if still a bit puzzling...


Nice open back...


It was originally listed in the Pro sound section of drivers, which didn't really make sense to me either.

But to get to the gist of things, key features:

• Extensive Klippel LMP and LSI testing to optimize Bl symmetry and parameters
• Indexed cone/surround junction for smooth transition/frequency response
• Polyimide formers and aluminum sleeve for improved inductance, damping, and frequency response
• One piece concave black anodized aluminum cone
• Vented former and elevated spider for improved air flow
• Open aluminum cast frame for improved heat dissipation

It does look like they've paid some extra attention to the cone-surround junction, but you know, that was never a problem with the RS series drivers like the RS180 or RS225. OTOH, this effort is not on the order of PuriFi or even some Eighteen Sound drivers.







Concave aluminum cone, like some HiVi parts I used in the dim mists of antiquity...




And the frequency response looks very easy to work with...




But the high sensitivity comes with a certain drawback- Xmax is only 5mm. But the Qts and Qes are in a range I like to work with, especially for PR systems, and it's quite amenable to sealed operation, too.


I should try to find some time to work it up in Unibox, but there's a lot of high priority stuff on the plate right now... I'm thinking possibly pair it with my new favorite Dayton PR, the RSS210PR.



Now, for a more "standard" kind of two way, the fairly new Visaton DSM25FFL titanium dome tweeter could be interesting...






But you know how the world is always complaining that we don't need another 6-1/2" two way, right?


But, at this very reasonable price, maybe this belongs in a Scarlatti Jr., two in series, with those RSS210PR on the back... increase the output capability and minimize the impact of Xmax. This would likely reduce the form factor compared with the "full size" Scarlatti, and of course, lower the cost, further- oops, silly me, I forgot to mention that they're pricing these at under $50 each...


Of course, there may be a good reason for that...


The factory distortion plot, something not usually included with Dayton driver Info...




But with a 600Hz crossover, I think I could stomach that.

Now, I do often have a bad habit of blaming others on sending me down some primrose path of development- just recently Steve and I were discussing the outcome of his sending me the video about the FR30 introduction. Ahem. It's all on you, Steve... just remind Danny and Sven about that!


So, I'm going to "credit" (blame) Dhar on this one... regardless of how it turns out!

🤣

And of course, we need to keep it on the down low that I just ordered a pair this weekend to test.... I'm thinking a Scarlatti Jr. could be just the thing, avoiding some of that midrange distortion rise, and not being just another 6-1/2" two way, ya know...


One never knows what will turn up on your Sunday morning...

[JonMarsh]

Just returned from my transport trip, a lot of boxes waiting for me, which is nice! A lot of items on the agenda this week, but not so much that I couldn't take a peek at the SIG180-4 and do a quick impedance and open air parameter check... and a couple of pictures, too, the ones on PE's website are not very clear...


Nice frame design, looks like good flow through on the back side, and a wider mounting flange than typical for a 180mm driver.




Looks like a pretty careful junction design of the surround to the cone... my only "quibble" is that it's not very wide, and I'm curious to see what 3rd party Kippel measurements reveal about Cms linearity. Of course, the Xmax is just 5mm, not a deep bass driver.


Along the same lines as pictures, the SIG180-4 mech drawing:




Now, something that was "interesting" about the Mech drawing PDF, is that it was actually the mechanical drawings for a number of drivers... including two larger ones, a 225mm (8") and a 270mm (10")








So, I suppose the appropriate advice would be to "stay tuned".



The factory DATS curve seems to be for a well broken in driver, or perhaps, a "golden sample"




Note Fs is 40Hz.


This is what I measured on one of my samples, fresh out of the box this morning. Note, Fs is 50Hz.

I should put this part on a function generator for a while and see how it looks after a day or two...





There are some curious differences worth remarking on, I think...

• Factory Fs of 40Hz, measured of 50Hz; this is a bit more percentage wise than one normally sees for the difference between a new driver and one "broken in" with some usage.
• Qes factory measured (remember, using the same DATS test system as I do!) of 0.4285, versus 0.47 for my own- implies a possible difference in motor BL, note Re are close to identical
• Factory L(e) measured at 1kHz at 0.4833mH is higher than my measurement at 10kHz, of 0.3615mH, and that is rather odd- it goes up with frequency, not down.
• Factory Qms (mechanical Q) of 5.738 versus my measurement of 10.57- this is a LARGE difference, and hard to account for. The difference in Fs may be a factor, but this implies a significant difference in the ratio of cone mass versus compliance. Curious. Dayton doesn't include the Rms resistive loss in specs, so this may be where the difference lies.
• For the factory specs of Qms, Wes, and Vas, the Qts should come in around 0.38, not 0.43 or 0.47. I plan to generate a Unibox Model based on these updates to the driver, out of curiosity.

My temporary conclusion is that using factory data for enclosure design may not be as reliable as I would hope/expect.

Like the old saying, goes, "In God we trust, all others we verify".


I have a test cabinet assembled, just need to route a mounting hole and connector. Expect another report back in a few days.

BTW, the DATS sweep tone was both loud and smooth sounding. THAT was a good start...

Frankly, I'm almost thinking this would be a could candidate for a new Wilson Audio clone of some sort... for the midrange... and...

Guess who brought back from climate controlled storage a pair of vintage NIB Focal TC120DX2?





It's going to be interesting measuring these with modern gear... but that will have to be later... much later, after current projects are completed!

[JonMarsh]

using my own measured parameters, the Unibox behavior changes significantly, a good PR design is 30L for two drivers wired in series, with 4 RSS210PR with minimum MMS, of 185 g. Produces an F3 of 43Hz with an Fb of 37Hz, with a quadi-Bessel LF roll off (low Q).

[duvixan]

So, I suppose the appropriate advice would be to "stay tuned"

https://www.diyaudio.com/community/t...5/post-7363068

[1Michael]

I like the TC120DX2. I used it in a Watt Puppy clone in the past that sounded pretty good. The only issue I had with it was the power handling.

[JonMarsh]

Yeah, I had to pay attention to the crossover point, that helped a bit. In the X1 SLAMM Klones, things worked out pretty well, and the overall distortion was so low that you could wind up playing them at ridiculous levels even on stuff like Michael Hedges, and realize later that the ears were on the verge of ringing- it was defiantly a new milestone for me for low distortion at higher SPL.

[duvixan]

Bliesma M142A-6

https://www.soundimports.eu/en/bliesma-m142a-6.html

[JonMarsh]

I've been spending too much time in the workshop, I supposed, didn't even know that part existed. Well, that's an interesting looking critter, but it seems to have similar issues as the Accuton C90-6-724, as regards the 1kHz area response. The BlieSMa goes lower, but not as high... I'd be inclined to say the useful range might be 200-800Hz. But don't pay any attention to me...