Interesting Drivers

[kevinlin1013]

Wow a dome driver with 180.2cm² SD is really impressive!

[JonMarsh]

Peerless has done some big ones, but not that far... OTOY, the rear resonance issue is not very impressive, and really limits the application area for the part.

[duvixan]

A cheap alternative to Bliesma's 3" dome perhaps?

https://www.parts-express.com/HiVi-DM-7500-3-Soft-Dome-Midrange-Driver-6-Ohms-297-470?quantity=1

[technodanvan]

I don't know why, but a big dome just speaks to me this morning. Maybe coupled with an Epique 7" and the baby RAAL in a standmount with RSS210-PR(s)?

[duvixan]

An attempt on another forum

[JonMarsh]

A cheap alternative to Bliesma's 3" dome perhaps?
https://www.parts-express.com/HiVi-D...470?quantity=1

Ok, I think I'm getting cynical enough that sometimes I start thinking like ET- or maybe it's just my experience with the Dayton RS52 and the last project I considered using it on, and had to do an about face?

Let's take a brief look at some of the data...



Now, manufacturers will often soften up the SPL plot with substantial smoothing, but it seems they rarely think about the impedance plot (fortunately), which is what I FIRST look at for a new driver...

Those wiggles at 900 Hz and 1500Hz might be diagnostic of resonances in surround or other areas, or standing waves in the cavity. Or might not. Hard to say. But a data sheet lacking so much basic information REALLY doesn't give me a warm fuzzy... Xmax anyone?

OTOH, this plot gives me fairly good confidence in just what we're getting...



Of course, we're paying for that information as well as for the performance.


I do intend to update my Ardent D's with these when some of the other stuff is done and there's a bit more spare change under the sofa cushions...


Now, if I really wanted to try to low buck it, maybe I'd consider the Visaton DSM50 titanium dome midrange- I know where I can get these for under $90 each, and I'm more a hard dome than soft dome kind of guy.




But I'd be cautious about this part, too, and how low I'd try to run it.

The thing about three ways, and midrange drivers, is the crossover cost goes up quite a bit. Doesn't mean it's not worth it, but all the issues need to be considered carefully - like, would you get more bang for the buck putting the money somewhere else?

And at this point, for a high tech midrange driver, I'm really itching to hear the GRS5010 in a good setup before trying other parts.

[duvixan]

I've been wondering why the SMJ-40 project took priority over the Isiris (or, at least, I got that impression)
Is it the PT5010 that makes it so special?

[JonMarsh]

The Isiris is nearly complete, may have some minor tweaks yet for the midrange crossover, and I do mean minor.

As explained briefly previously, this system concept with 4 LF drivers was started some time ago- originally conceived with the Epique E180HE-44. The reasoning was several benefits from a "mini" line array-

• Narrow front width with smaller diameter drivers and baffle step moved up in frequency
• Larger vertical source minimizes floor bounce response effects- often this is sought after by careful positioning of two woofers, but experiments have proved to me that that is just part of the way there. Four are better.
• A 4x series parallel array will have the same impedance as one driver, but will have an efficiency gain of 6 dB. These concepts were being investigate for the Saint-Saëns NALA two way line array.

However, having bought 4 E180HE-44 and tested them, I found that though the motor was very low distortion at 100Hz and below, as others have reported, the HD3 steadily rises above that, most likely due to inductivity modulation, as the actual cone excursion is decreasing with increasing frequency.




This "disqualified" it for a woofer to low midrange application, in my opinion. At that point I shifted to the RSS210HF after evaluating quite a few other 7" and 8" woofers.

There were several other potential candidates for the midrange, besides the GRS PT5010, but I had established in my mind that I wanted something as free of resonances impacting the lower frequencies and their distortion behavior, especially after working on the Isiris and beating the 6.5" Purify Midrange into submission. Some Faital and Eighteen Sound drivers were under serious consideration.

Then, Steve sent me the YouTube video about the introduction of the PS Audio FRS30, and at that point I figured I'd better take a closer look at the GRS planar drivers derived from the technology obtained from B&G. I hadn't been initially terribly thrilled by the data sheet information.

Key point for the PT5010 and PT2522 is that the achievable performance is very dependent on the rear enclosure volume, and I conducted multiple experiments with both before finding a configuration with the PT5010 that I was really happy with.

Around that time, the HiFi News test report came out for the FR30 system. They are a sister publication to Stereophile, owned by the same holding company, and now using similar testing procedures. The results in the presence region and top end did not exactly thrill me...



But they didn't surprise me, either, given the results I'd had with 4 configurations for the PT2522.


For another project, I'd been evaluating the Beyma TPL75, and I liked what I was seeing, and of course, unlike dome tweeters, there is no upper end resonance to speak of to induce resonance amplification of distortion projects.

With my 4th effort for the GRS PT5010, I was able to get the bandpass characteristic I wanted with fairly low distortion...




And the polar behavior was very satisfactory in the nominal operating range:





A POC system crossover with adjustments to the Z axis location produced very good results, with very deep reverse null behavior, and an early test of the POC crossovers for just the midrange and tweeter in a very non-optimum cabinet configuration confirmed the basics:





So, this system and the CC Supreme are the ones receiving current development and build efforts- in the case of the Saint-Saëns Planar, the cabinet designs are being refined and parts in the process of being fabricated.

The CC Supreme test cabinet is finished, the initial asymmetric minimum phase low group delay midrange (PuriFi 6.5" midrange) to tweeter Beyma TPL105H AMT) crossover has been built and tested and performed as expected based on VituixCAD simulation, and the LF crossover is being fabricated. This system could also be converted to a tower three way with larger cabinets for the PuriFi 8" woofers and passive radiators. A test build is planned in the future, presuming the CC works out as expected. This will probably be called something unimaginative like the "PuriFi-Beyma Ardent Supreme". Clever names aren't my forte...

[JonMarsh]

I continue to find "goodies" in my CA long term storage- one box in particular from Parts Express caught my attention, because it was about the right size for an 8-10" woofer, but didn't weigh nearly enough...



Hmmm, interesting... now, if only...




Voila!!






Vintage NIB (New In Box) RS52AN dome midranges!

So, is my memory correct, and they didn't have the big surround impedance bump that the ones bought in 2021 had? Last time I used these in a successful system design was the NeoD CC center channel...



That system as measured with an updated test setup, there is no evidence of the midrange resonance aberration of the 2021 samples...





The quick "acid test" would be to measure and compare the impedance curves...


The VNIB RS52AN, measured this morning:






One of the 2021 samples:





I'd say that's a smoking gun...


Well, I'll need to make a test baffle and test the SPL response for one, and verify all as regards impedance curves, but this opens up some possibilities:

• In moving my Ardent D's, the EM1308, which have no protective grilles, have been damaged, that is, the dome deformed. It should be some relatively simple crossover changes (removing a notch filter, possibly adjusting level slightly) to sub these in.
• A small HT mains had been under consideration as a follow up to the NeoD CC, but upgrading from the HiVi D6.8 to the Jantzen JA-6012 3" voice coil 6.5" woofers. As hoped for, those turned up too... to make that system a "old home reunion" week project, I should use the Visaton KE 25 SC ceramic tweeter with the Visaton W148R waveguides, right? Blast from the past?

The possibilities....


🤣

[duvixan]

I'm thinking about a scaled down version of SMJ-40 (for our small euro apts), with PT6825

https://www.parts-express.com/GRS-PT6825-8-8-Planar-Mid-Tweeter-8-Ohm-272-126?quantity=1

and maybe 6-7" midwoofers? Would the PT6825 allow to skip the need for a tweeter perhaps, and keep it very simple?

[JonMarsh]

We discussed the PT6825 and PT6816 in the "Dayton Ardent PE?" topic, and I suggested that the PT6816 might be a better choice due to it's overall more linear behavior. Physically, it's like three stacked 2522's, and using the FRD data provided by PE, derived a crossover that could deliver a reasonably usable 900Hz crossover point. Even so, that's limited to about 15 kHz, but with moderately decent off axis response compared with typical dome tweeters.

[technodanvan]

I'm thinking about a scaled down version of SMJ-40 (for our small euro apts), with PT6825...

...and maybe 6-7" midwoofers? Would the PT6825 allow to skip the need for a tweeter perhaps, and keep it very simple?

If you're looking for a very scaled down variant there is someone on Javad's Facebook page making one based on an 8" GRS mid (unknown part, though I'm pretty sure it's the 6816), along with a GRS tweeter and the Dayton ND140 as the woofers.

Edit: I wonder if the SIG series may have been a better direction to go in over the ND140. They'd cost a bit more but maintain that clean look. They probably came out after this project started though.

From Facebook (my understanding is it will use PRs but they haven't been cut yet):

[JonMarsh]

The SIG180-4 would have it beat on both Xmax and Sd. But I bet this is pretty compact, and that does look like the PT6816 based on driver cut out sizes.

[technodanvan]

CSS has replaced the SDX-10 with a new XBL^2 version. Price has gone up, as has weight (by 10 pounds!). Curiously, I only noticed it based on their recent sale flyer - I didn't see anything advertising this change, though I had noticed the SDX-10 was out of stock for some time.

https://www.css-audio.com/online-store/CSS-SDX10-10-XBL%5E2-Subwoofer-p579780762

Based on the SDX-12, I would wholeheartedly recommend the 10" variant if someone needs a compact subwoofer.

[Evil Twin]

The image is impressive, most impressive...

Looks like an early release note- "full spec sheet coming soon"

With a claim like this, I would expect it is mandatory before expecting customers to commit credits.

While the SDX10 produces high quality deep bass, it's not completely relegated to subwoofer duty. Thanks to the low inductance motor design, the frequency response has a wide and flat usable bandwidth. This makes the SDX10 suitable as a woofer in a 3-way or even in a 2-way with a waveguide!