A thought experiment - Wavecore Ardent II

[TEK]

Jup, and as you can see our house is in the middle of one of those steep hills (ref. the vertical christmas tree)

[JonMarsh]

Makes me want to move somewhere like Idaho Falls! :B

[CraigJ]

Hi Tek,

I've been in Minneapolis visiting my Norwegian in laws and have fallen behind. I tried very hard to find some exciting outdoor shots, but, between the 40 mph winds, thunderstorms, and a Cayote on the bay looking to eat our 5 dogs, I give you this;

[TEK]

Jon: That looks like a wonderful place.
Craig: is that a pet of yours?
I have some not as cosy pictures of simular creatures that I will save you from. It seems as if cats, goid hunders as they are, also have some strange interest of dragging mice and birds inside - and not nessesarly after killing them...

BTW: I found this nice one that seems fitting for you audophiles now after christmas:

https://www.facebook.com/eo.loeks/posts/10211277718921070

Some time to play :-)



And now the sun is peeking up and lighter times are coming (during the winter time there is only a few ours of light each day in the northern parts of norway).

[dar47]

Hum, this time I was in central park NYC with just a shirt on Christmas day!





All week was nice and I took in some great Jazz at the Standard with my daughter but I did get off the plane to 29cm of snow to shovel at home yesterday :E

[CraigJ]

Craig: is that a pet of yours?

My daughter had 28 babies and is now down to two after adopting them out. Yes, rats make excellent pets.

Regarding cats, got one of those as well and it also loves to play with its prey. Had to get a couple of bells for her to wear in order to protect the song birds.

Nice pictures Dar, and glad you had warm weather and a good time.

Craig

[JonMarsh]

I aspire to be the man my dog thinks I am.
Bones for everyone! maybe some catnip too. arty:
Ron

That's what I aspired to with Masha, too, not sure I made it. Probably had a little better luck with my daughter.

Seasonal pictures and a seasonal topic (more talk of Ardent variations going on)

One I favor would be your build, but with the Peerless DA25TX tweeter... and if we want to go back to the future, to the first gen Ardent, then it's your build (with the SS midrange), the DA25 tweeter, and a pair of the new Epique E180HE 7" drivers, combined with two RSS265PR...

Yes, I have enclosure design files already...

[dwk]

Very curious to see some measurements / design on the Epique woofers. They look rather interesting, but I haven't seem much discussion or measurements/designs. I'm a bit surprised that a pair will drive a pair of 265PRs, but I guess I shouldn't be - they have close to the Vd of an RSS265HO which pairs with 2xPRs very well.

[dwk]

Apparently not paying attention. Someone did some IMD tests of the Epique, and reported that it does almost as well as the Purifi on his IMD test. At 1/3 the price, that's very intriguing. https://www.diyaudio.com/community/t...2#post-6773354

Although, looking more closely at the results it seems that the Dayton is largely competitive only in the bass and less so as frequencies rise (if I"m reading the results right. something seems off with the labeled voltages)

[JonMarsh]

Yeah, I think there's some real potential there. Thanks for sharing the link from DIYAUDIO.

[DaveFred]

Another matter is the LF system- I would call it one of evolution, but I have simulated an alignment for another project, intended to be quite compact, which is interesting, using the SW223BD02 with PR's, and it is flat to 30Hz, with a nice controlled minimum Q roll off below that (essentially it looks like a classic QB3 ported alignment in the transition band), which keeps the driver out of trouble or unloading even with a fair amount of what is nominally out of band power. And it requires just 20L net. I first arrived at this with some SS PR's which are no longer in production, but which Solen has had some, but I also find I can tune a wavecor PR's to get the desired results, with the mass tuning they offer. And there is a vendor in Germany which has some of these in stock, that I have worked with in the past. May order some soon. And we can get something very close with 10" PR's, but the size could be an issue for a rear mount- have to check that. Maybe just two Seas SL26R...

Jon

Hello Jon,

Do you think the SW223BD02 could possibly be used in a two way crossed over at 1600Hz?

Thank you,

David.

[JonMarsh]

Funny you should mention that, I was going through some files looking for the most up to date Calliope stuff, and I came across what looked like a concept evaluation for that. The real question in my mind becomes what tweeter, and what optimum frequency? Especially considering suppression of resonance amplification of distortion products. Now, If you’re willing to consider something like an XT1086 CD horn and a good 1” compression driver (Peerless 2544, or Eighteen Sound NSD1024, then I’d say sure, it’s just a development question.

I’ll go have a look around again and see what it was I was thinking about way back. you do realize that SW223’s of any ilk are pretty rare, being out of production, near as I can tell .I have 4 on hand, enough for one set of Wavecor Ardents. Get back to you tomorrow morning

[DaveFred]

Hello Jon,

I already have a pair of SW223BD02 that I picked up from Solen a couple of months ago, and I am going to add the SS 26/0-00-00 as per your recommendation.

The tweeter I am thinking about is the BZCQ66.

http://www.bzspeakers.com/ribbon66_en.html

The late Rick Craig was fond of this tweeter and used it in a number of his designs and I already have a pair.

From the tweeter maker, "1600Hz, -12dB/oct(2nd order) butterworth crossover is enough for CQ66", so I am thinking it could be crossed similar or lower with an LR4 combined with an LR4 on the subwoofer to avoid the nasties after 2.5KHz.

I am going to try it, just wondering if you have any advice...

Thank you,

David.

[JonMarsh]

Now, this is part of why I enjoy getting out of bed every morning, in the hopes of finding out about something new and interesting... and Bohzen speakers comes under that category-

The late Rick Craig was fond of this tweeter and used it in a number of his designs and I already have a pair.

The last 5 words in that sentence are probably the most critical, because from what I can tell, there's nowhere to buy them at this time.

They have a very interesting construction, using a multi-fin structure to support the ribbon on a regular basis, so it's not just floating in space.



Now, looking at the results, their BZCQ66 is certainly promising....







But the asymmetric bump at 1700 Hz is definitely unfortunate, and as Voice Coil mag states, a crossover at 2,000 Hz is probably the best approach. Have you measured yours? Maybe their samples were atypical.



Now, the newer part (relatively) the CQ76, seems to be more lust worthy...





And I believe would work fine in the frequency range you need. Especially since after reviewing my past measurements, I'd say that I'd probably want to shoot for a 1400 Hz crossover (more about that in the next post).


Now, If someone was holding a gun to my head, and said, "Jon, your do or die assignment is to develop a wide range high performance SW223BD two way Mach Schnell, using available off the shelf parts (apart from the woofers), I would likely go with the Beyma TPL150 AMT, which I'm considering for another "Top Secret" SMJ three way project, which, ironically, COULD be turned into a two way fairly easily, as the woofer's HF breakup mode is at nearly 5kHz, and I already have nice PR alignments worked out using the RSS265PR.




I'd still consider the SW223BD in a two way as a bit of a stretch goal, and I'd seriously consider a 1250Hz LR4 crossover, even with the Beyma.

If you're got your heart set on a two way with the Bohzen tweeter, consider the RSS210HF-4 woofer instead.

If you've got your heart set on using both the Bohzen tweeter and the Wavecor woofer, consider turning it into a three way, and use a carefully setup GRS PT5101 as the midrange between, say, 450Hz and 2kHz.

This graph is representative of the current state of development investigation for optimal rear loading of this part; the next step should be further improved.




Note the differences between the above and the "factory" response curve.








I believe that with the right loading design, this driver can be fairly useful over a two octave range, with enough response beyond that for well controlled crossovers.

[JonMarsh]

OK, this follow on is just to confirm/post previously measured stuff for the SW223BD, as regards SPL response and LF alignments.

First, using the SS PR, quasi NF and more "normal" measurements of the SW223BD on axis:








Keep in mind that for the far field LF response, a long window has to be used to get LF data, and so of course room acoustics and position has an impact on linearity. The Quasi NF measurement is far more telling regarding the basic driver behavior in a typical room- what the room does to it afterwards is the responsibility of the owner!

The Quasi NF response has some artifacts above 1,000 Hz due to size of the radiator and distance from the mid, but it's reasonably faithful to the purpose of crossover potential, and shows the same breakup peak as factory data sheets.

Another interesting/surprising data point, checking with our main distributor for Wavecor, is that it looks like these will be back in stock here in the US around the end of this December!!

Another option for the PR that is usually more readily available these days than the Scanspeak is the RSS265PR.

Using three weight disks:

[JonMarsh]

And for reference, this is an on axis measurement I did of the RSS210HF-4. The target design will use two or 4 of these in different versions.

[DaveFred]

Hello Jon,

I should have pointed out that this build is an InDIYana 2023 theme build, where limits are max 1.5 cu ft, min woofer 8", max tweeter 4.125", two way.

Since I already have the subwoofer, tweeter and PR's, I am going to at least make a test box and measurements to see how it works out.

If it does not work out, other =>8" woofer options I already have in inventory (too many drivers!) and can try are Ciare HWB200, Seas U22REX/P-SL, SB29NRX-00, SB23NRXS45-8, Eton 8-412/C8/32HEX and HiVi LK8A.

Thank you,

David.

[JonMarsh]

Dang! You must have the kind of inventory storage issues I do!

This clarifies the boundaries of your design choices quite a bit! Good luck, and keep us informed if you want to kibbutz a bit on the crossover…

[JonMarsh]

One thing useful to keep in mind about PR’s- look at the suspension closely and if you can find test data, how linear CMS is with cone travel. Relatively narrow surrounds like the SB29NRX often hint at CMS nonlinearity which results in change in the effective tuning with excursion, which means a change in the transfer function and, obviously, distortion. Seas and SS have both put a fair amount of work into that, and the Dayton parts are surprisingly good, too.

if you have the means to test LF linearity at different output levels in the region where the PR works, I’d definitely do that, or just evaluate the amplitude transfer function at different output levels. If the SPL dB curves don’t basically overlap closely, there’s a problem.

[tktran]

JonMarsh,

What do you think of the value equation of the RSS210HF-4 vs SW223BD02?

I do like my PTT8.0X, Scan 22W8851, but I'm looking to use 8" in multiples from 40Hz to 250Hz, so as things scale up, so do costs.

Prices have gone up across the board, so despite the RS225 now costing ~US$90 I think it's still a value leader. RSS210HF is now US$140, and SW223BD02 is now US$300 from PE

Down down here in Oz. the RS225 is ~US$110, the RSS210HF-04 $175, and SW223BD02 ~US$220

As costs go up, one starts to wonder whether twin 10" or 12" is a better idea (it is) but you still want to keep the cabinet slim or smaller.

I think Vd really is king under 100Hz, but I need something from 40Hz to 250Hz...

Have you used the Peerless 830667 or SB23 midwoofers?

[DaveFred]

Hello Jon,

What are your thoughts on capacitor loading the Wavecor woofer?

Here are my results with 330uf to 1650uf, in a 1.5 cubic foot sealed box.

[JonMarsh]

JonMarsh,

What do you think of the value equation of the RSS210HF-4 vs SW223BD02?

I do like my PTT8.0X, Scan 22W8851, but I'm looking to use 8" in multiples from 40Hz to 250Hz, so as things scale up, so do costs.

Prices have gone up across the board, so despite the RS225 now costing ~US$90 I think it's still a value leader. RSS210HF is now US$140, and SW223BD02 is now US$300 from PE

Down down here in Oz. the RS225 is ~US$110, the RSS210HF-04 $175, and SW223BD02 ~US$220

As costs go up, one starts to wonder whether twin 10" or 12" is a better idea (it is) but you still want to keep the cabinet slim or smaller.

I think Vd really is king under 100Hz, but I need something from 40Hz to 250Hz...

Have you used the Peerless 830667 or SB23 midwoofers?

I have checked out quite a few Peerless and SB Acoustics woofers (as in purchasing and testing them) but not those two- the unusually high Qts of the Peerless part would eliminate it from many configurations for me.

This is your "money quote", as some would say, in my opinion:

I do like my PTT8.0X, Scan 22W8851, but I'm looking to use 8" in multiples from 40Hz to 250Hz, so as things scale up, so do costs.

Having bought 8 of the PTT8.0X03 to get the best price possible, I can totally relate. But then, as you well know, there are other factors besides price.

It's an open secret that I've been working on a system design that seems derived from the PSAudio FR30- what is not well known is that it had been underway for some time BEFORE I heard about the FR30, and originally I'd hoped/been planing on using the 4 of the Epique E180HE, with Dayton PR's, until I got my hands on it and like many others, discovered the less than stellar midrange performance above 200Hz. But as you allude, there can be many reasons to prefer multiple smaller drivers, some not as well known as the basic esthetic benefit of a slim cabinet- such as net efficiency coupling gains, and vertical directivity changes.

But then, too, one must consider things like the design of the driver as regards T/S fundamentals, and what size enclosure is suitable... the PTT8.0X04 is rather a different beast from the earlier 6.5" woofers, and is more monkey coffin like than anything previous from PuriFi. A relatively optimal configuration for two with PR's requires 75L (F3 of 38Hz) to 95L(F3 of 33.7Hz), depending on the PR type and your LF target curve, whereas 4 of the RSS210HF-4 in 130L with RSS265PR appear capable of an F3 of 26.4Hz. And while the RSS210HF-4 is not the driver that first comes to mind for 100Hz to 1500Hz linearity, as the measurement above shows it's quite credible and beats a lot of 6.5" and 7" woofers. A well designed stiff cone is a key point, along with a fairly well controlled impedance rise up to 2kHz.

I agree with you that the RS225 is a high value part, and I think that was a key factor (besides nostalgia) for its selection for the Obi Wan project. But again, tradeoffs between sensitivity and the number of drivers desired and swept VD versus enclosure size all come into play, plus top end linearity. Some fun things could be possible... imagine an RS225 based NatalieP, with the Beyhma TPL150 AMT as the tweeter.

In the end, it comes down to the mix of your personal desires and targets. And the budget. Note that PS Audio uses 8" woofers of the same lineage but different T/S parameters in the FR20 release, with a somewhat smaller (shallower) enclosure. I've had in mind the same idea, but with the PTT8.0X04 woofers.

For the time being, though, after having measured one RSS210HF4 with RSS265PR, I will remain on realizing a system with that 4x configuration as the initial solution.

I've been more concerned about the rear loading of the planar midrange, but believe after several iterations I've about dialed in on an approach that linearizes the frequency response and should be quite usable - an seems quite different from PS Audio, based on their enclosure cutaways. But a complete POC system build needs to be done, and see how well all the pieces go together. Do note that it is curious that they actually have the planar tweeter mounted forwards of the midrange, and I do rather find the short waveguide structure they use on the midrange something of a head scratcher, so I'm sure I have more to learn...

[JonMarsh]

Hello Jon,

What are your thoughts on capacitor loading the Wavecor woofer?

Here are my results with 330uf to 1650uf, in a 1.5 cubic foot sealed box.

I'm not 100% certain of the configuration you're talking about, but at first blush it sounds like the configuration I used with SS 26W12867's, with a series capacitor creating an electrical interaction with the sealed resonance impedance.

https://www.htguide.com/forum/forum/mission-possible-diy/35515-modula-xtreme-follow-up/page5



This can certainly reshape the response curve to a degree for a given sized sealed enclosure; both parameters need to be adjusted or modeled to get an optimum result.

What it does not do is improve the output capability and reduce cone excursion at low frequencies. But it that isn't of concern, it does make it possible to use the woofers in a smaller enclosure for a given LF cutoff, in most cases. The original Wavecor Ardent is 40L for two SW223BD02. That's actually a bit under the 1.5 cu ft limitation you mentioned based on the contest parameters. Are you planing on one or two per cabinet?

For comparison, here's an RSS210HF4 with 1 PR in 28L. A bit larger wouldn't hurt, but at the time I was targeting what could be done in 1 cu ft net. Of course, you'd need more actual volume for it to be net. Maximum excursion is a bit over 60% of rated Xmax.

[DaveFred]

Hello JonMarsh,

These sweeps don't look promising for a two way...

[DaveFred]

Duplicate...

[JonMarsh]

Nice quality of measurements. Not surprised though. You'd need a steep notch filter, and probably a 6th order network around 1250Hz. That's why I was nudging you towards the idea of the RSS210HF-4

[DaveFred]

Nice quality of measurements. Not surprised though. You'd need a steep notch filter, and probably a 6th order network around 1250Hz. That's why I was nudging you towards the idea of the RSS210HF-4

Hello Jon,

I will pick up a pair of RSS210HF-4 to try.

Having modeled both the 26W/0-00-00 and RSS265-PR to go with the subwoofer, I think the RSS265 with it's lower MMPR is a better choice.

Funny how PE, who like to over state everything, says that the sub is only good to 1000hz.

David.

[DaveFred]

Nice quality of measurements.

Forgot to mention, I did the same measurements yesterday for, Human Pro 8, HiVi LK8A, Ciare HWB200, Eton 8-412/C8/32 and Seas U22REX as I was trying to decide which one to use.

I can post if you would like to see them.

[JonMarsh]

Yeah, why don't you do that? I'd certainly be curious, and others too. I'm thinking maybe we should start a new topic for your project, if that's OK- even if for now it's just about driver evaluations. I could do that and copy all of these recent discussions into a new thread- what do you think?

[DaveFred]

Hello Jon,

I will pick up a pair of RSS210HF-4 to try.

Having modeled both the 26W/0-00-00 and RSS265-PR to go with the subwoofer, I think the RSS265 with it's lower MMPR is a better choice.

Funny how PE, who like to over state everything, says that the sub is only good to 1000hz.

David.

Hello Jon,

I will start a new thread tonight and then you can move the messages over.

Any comment on what I quoted above?

Thank you,

David.

[JonMarsh]

Well, the Dayton/PE comment could sometimes hit home, BUT, I have to say they have had some pretty good people working for them or as vendors for many products- many of the subwoofer and woofer products definitely deserve respect (particularly the passive radiators, as they're a lot better documented and easier to setup than many many competing parts from well known vendors. I agree with your opinion regarding the RSS265PR- the Scanspeak is one of the better competing commercial parts, but the parameter set is not as optimum (IMO) and suspension linearity not quite as good. This is something most folks don't talk about much- for example, Seas pulled a whole production lot of SLR26 PR's because of issues they found with that, and that's actually a pretty well designed part, IMO.

If you start a new topic thread where you want with the title you want, then I'll get things copied over.