Ardent D (aka Kurosawa Jr) Winter Camp

[Evil Twin]

The weather is quite pleasant at my secluded workshop...






Endor is so relaxing on the weekends...

[Scottg]

-beware of any little-people furry convention happening in the area. ..apparently they will (j)ump anything that moves. :P

[Evil Twin]

-beware of any little-people furry convention happening in the area. ..apparently they will (j)ump anything that moves. :P

That is indeed a wise warning, one I have been on the alert about...

And that is not even considering the coyotes and raccoons in the immediate area who at times are overly curious...

[Evil Twin]

More test cabinets in process

LF test cabinets are being prepared...

A design target has been set for 21L per driver... using an RSS265PR with 275 grams of mass







Of course, hardware verification prior to completing a cabinet build is mandatory...



Test cabinets were built, and holes for PR and main driver candidates (AS168, Anarchy 708) prepared this weekend....

The modeled configuration of 21L per driver, with a 275gram weight for the PR is fairly promising- here, showing the expected response with 40W of drive power.





A driver mount check for the RSS265PR...




And quick driver mount check for the AS168

[technodanvan]

Very curious of your findings with the Anarchy. I had a smidgen of of thought to use four of those with either a Seas MR18REX/XF or SB Acoustics SB16PFC25 in an attempt to make a 'value-ish' KEF R11-style speaker with matching center that could get by without a subwoofer. I'm about to begin my Ardent journey but those will be located in the master bedroom (if my wife agrees) and our living room is in need of some upgrades.

Of course, one of the reasons I never pursued this earlier was due to lack of stock for the Anarchy. If that continues to be the case, I'm a little afraid I'd drop the 'value' portion of this and move ahead with the Seas Excel C18EN002/A and four Wavecor SW182 woofers instead....assuming they can reach the potential of their larger brothers.

[Evil Twin]

708 are in stock, and I ordered 8 for Steve in VA for his stock.

I recommend spending sometime modeling combinations of drivers and PR's- you may be quite surprised about the limitations of some specific PR's considering the MMS and CMS versus Qms and achievable resonant frequency in some configurations.

Let me just say that some PR's are "more equal" than others in being able to address a wide range of applications. And there is also the matter of how they work in parallel, and how much Sd is usable with the lumped paralleled parameters.

I have found the following to be quite useful in a range of applications with various woofers:

• ScanSpeak Discovery 26W/0-00 10" PR
• Dayton RSS265PR
• Seas SL26R 10" PR
• Dayton RSS315PR 12" PR
• Wavecor PR223BD02 8-3/4" PR ( used in the Kurosawa)

[chrisn]

I love the smell of Porter Cable Routers in the morning...

New router? How does the Porter Cable compare with the Dewalt DW621?

[Evil Twin]

It compares very well, and may have a slight edge in dust collection. But the DW621 has a slightly smoother motor.

of course, there is a certain "esthetic" attraction for me...


Which do you think looks more at home in a Seinar Research Laboratory?

[dwk]

This correlates well with the extensive measurements I've made for the DA25. I am primarily concerned about how difficult it will be to control the ultrasonic resonance and minimize resonance amplification of distortion products- that has been quite successful with the MT test design for Steve.

Thank you for the link to the other measurements- it's my usual practice to test at 90 dB and 96 dB for a tweeter like this...

Well, last digression on this for the moment. If nothing else, posting that Dueland alignment got me off my butt and I actually ordered some stuff. I've been locked in analysis paralysis for a while now, getting no closer to clarifying my plans. I ordered RS225-4, SB15NBAC and DA25Tx (the 32 is out of stock). (NBAC over CAC for purely aesthetic reasons) This isn't a final platform, but should help with evaluating the main questions I have:

- wide baffle (SF Elipsa / Troels PMS style) vs more conventional Ardent style cabinet. Does the wide baffle fit the space, and are there sonic downsides?
- how much output do I need? It's a large open space with high ceilings. Probably 10000 cu ft.
- bass options. RS225 (really a proxy for the WO24p) vs RSS265HO/RSS265PR, potentially the SDX10 depending on how it goes.
- is there any magic in the Dueland alignment vs LR2 or ET's modified 3rd order concept. Should be able to hit the posted Dueland alignment, although maybe not at full output.

I have to say, having placed my order the RS225/SB15NBAC/DA25Tx strikes me as a remarkably high-value lineup. About $350 or so in drivers for what should be a very competent 3-way. I'll be using either a PC based DSP setup or a MiniDsp nano-digi for initial experiments as I come up to speed with VituixCAD.

Based on what comes out of this, I'll either decide that just running with an Ardent-D variant is the best plan, or I'll dive in and finalize my own design with a hybrid active/passive approach using the MiniDSP SHD that runs our main system (passive M/T, active between M and W). I'm hoping to target mid-Sept to start that project in earnest.

[dwk]

Oh yeah - a 5th question is narrow(er) vs wide(r) dispersion in my room - with lots of clearance to the side walls, will narrower dispersion sound too dead? This is based on my Kef R3's sounding a bit dull in the space. Bare DA25Tx vs waveguided, potentially also vs something like the DXT. (knowing full well I won't actually make it through all these tests given available time)

[Evil Twin]

You are making clear progress, and if anything we have done has been a catalyst of sort, all for the better.

The bare DA25TX has wider and more uniform dispersion than typical of a lot of "direct tweeters", and I say this after buying and testing many tweeters in 2019... this was quite noticeable in testing the finished crossover design for the first SMJ MT, so I would suggest thinking about the tradeoffs- the SB15BAC has reasonable output capability, so reinforcing it's low end with a wider baffle is probably not really necessary- or useful. But in the end I suggest not taking my word for it one way or another, but since you have an active platform (planned? or on hand?) for concept evaluations, try it out, and go for real data using a lazy Susan setup (Woodcraft has bearing sets to build high capacity ones if you are inclined). You might want to take a look at the concept for the 554 driver- if you ponder a Duelund- the SB driver may work best with something relatively similar, not too much higher in center frequency or the off axis will suffer. However, you will have a more difficult time getting the HF phase aligned correctly, due to the difference in Z axis origins. For this, a waveguide loaded tweeter could help.







Yes, there are similarities between a three way composed of two LR2 networks, but the Duelund has higher ultimate roll off rates for HP and LP, and can work with a narrower midrange band pass. If implemented correctly, the Duelund will have all drivers in the same phase at least for levels down to -12 to -18 dB. The Duelund offers ease of calculating and implementing specific targets which will achieve a desired transfer function, and with dual LR-2 and "experimenting" one might have fun, but also wander in the wilderness, so to speak, not really reaching exactly the desired result.

But this is DIY, and if wandering in the wilderness suits your whims, why not?

[Zvu]

Oh yeah - a 5th question is narrow(er) vs wide(r) dispersion in my room - with lots of clearance to the side walls, will narrower dispersion sound too dead? This is based on my Kef R3's sounding a bit dull in the space. Bare DA25Tx vs waveguided, potentially also vs something like the DXT. (knowing full well I won't actually make it through all these tests given available time)

Kef R300 is also a bit dull sounding. I don't think it is a product of dispersion though. The way their woofer is made makes me wonder if it is the cause for that, i'd define it as highly damped, sound. No matter what i did, the mids always seemed a tad quieter than i feel it should sound. When i modify the crossover to compensate for what i think is lacking, it gets shouty. Finally, since the midrange-tweeter unit is operating flawlessly, in my opinion, i concluded that it has to be the woofer that has very mild acoustic slope and highish crossover point. It sounds a bit dull and messes with the midrange too much - but since it overlaps the midrange quite a bit it is hard to pinpoint what is wrong.

I might be wrong about the cause of dullness though, but this is my opinion based on living with those loudspeakers (in factory variant and modified) for over a year.

[Evil Twin]

Your feedback is welcome and seems to hit on key points... dull versus shouty can also be an indication of variation in axial response versus power response - lacking in power response off axis, but clearly showing a coloration if the level is boosted to compensate.


Other thoughts which floated to the surface last night-

The proposed RS225 + SB15NBAC + DA25TX should be a very high value combination- note the RS225 was used in a floor standing predecessor to the Ardent. Like many of the other RS series drivers, it works best in a large enclosure, too. As posted in the last 12 months, the WO24 has some very strong performance characteristics, but it is even more desirous of what I believe is termed "monkey coffins" in the colloquial slang of this sector.

Also, I have a developing plan to study the comparative performance of high BL Flux linearity drivers against other more "popular" types, especially with intermodulation tests, and I believe some components, such as the SDX10 previously mentioned and in my own plans for a special system, may outperform otherwise popular choices like the RSS265 variants. Only hard data will tell the real story, though.

This is why a similar IM spectra comparison is now also planned between the SB15NBAC/CAC and the Anarchy 554/558. Their frame diameters are conveniently equivalent, so test conditions will be quite well controlled. Both are actually 6" drivers.

[ergo]

It seems you are planning something more advanced with IMD measurements. Would be interesting to hear more

Klippel has also some interesting new approaches like
3D Intermodulation Distortion Measurement
and the prior multitone method
Multi-tone Distortion Measurement
Getting the 'current into speaker' spectrum should be doable also with the tools I have, but I'm yet to get around to attempting that. The data it produces looks interesting though.

[Evil Twin]

Thank you for the links- I will review this evening... I have having my 3rd Monday for the week, and the schedule for tomorrow appears very similar...

[dwk]

Kef R300 is also a bit dull sounding. I don't think it is a product of dispersion though. [...]

I might be wrong about the cause of dullness though, but this is my opinion based on living with those loudspeakers (in factory variant and modified) for over a year.

Very interesting. The R3s are my desktop speakers (I have a big desk), and in that role I find them terrific - not dull at all. Moving them into the main room with RSS210 woofers was where it was apparent, particularly when casually listening around the space (living room /kitchen/dining room). Hence my initial thought that dispersion may be a bit narrow.i'll have to see if I can find some more time to do some more listening/comparison at some point.

[dwk]

You are making clear progress, and if anything we have done has been a catalyst of sort, all for the better.

The bare DA25TX has wider and more uniform dispersion than typical of a lot of "direct tweeters", and I say this after buying and testing many tweeters in 2019... this was quite noticeable in testing the finished crossover design for the first SMJ MT, so I would suggest thinking about the tradeoffs- the SB15BAC has reasonable output capability, so reinforcing it's low end with a wider baffle is probably not really necessary- or useful.

To be clear- in this case the wider baffle is purely an aesthetic consideration. My design target is the SF Elipsa.



This may make some of my questions/investigations a bit more sensible - will they fit in the space? how much woofer volume can I squeeze out of this form factor? Is there any detrimental impact on imaging from the wide baffle? etc. Thus the effort to create a test mule using relatively modest cost drivers to investigate (which will effectively be Troels Poor Man's Strad http://www.troelsgravesen.dk/PMS.htm)

But this is DIY, and if wandering in the wilderness suits your whims, why not?

Well, maybe I have my thread title for this effort :-)

[JonMarsh]

Maybe you should look at these Sonus Faber Stradivari, too?

Have been very popular with some folks, seems right up the same alley esthetically...

[Bear]

SF knows how to finish a cabinet. I keep coming back to the Strad's/Ellipsa for inspiration.

[Evil Twin]

It is rumored that they take 4 weeks just to cure the lacquer finish...

[dwk]

The Strad is definitely impressive, but I actually prefer the design of the Elipsa - I think the single woofer looks more balanced. The opposite of the Avalon style designs - I think they look much better as dual-woofer designs that single woofer.

But both are definitely very pretty, though. The obvious potential flaw in my grand plan is that my woodworking skills may not be anywhere near good enough to do justice to the concept.

There is actually a pair of Elipsa for sale 'locally', but for some reason the wife is balking. https://tmraudio.com/speakers/floors...ecial-edition/

Getting back to the driver discussion, I'm very interested in seeing the IMD testing progress. I've always thought that the 32-tone AP multitone IMD test is pretty much the best 'one picture summary' for the preformance of an electronic component, and I'm intrigued by the idea of applying something similar to speakers. The Purifi certainly seems poised to do well on the test

If I go with the Elipsa style design I think there's a pretty good chance that the SDX-10 will prove to be the best fit - it models very nicely in 40l (as long as you have a bit of power), which is the volume Troels managed in his PMS. I'm not sure whether it'll reach high enough for a Dueland, but it does seem to stay pretty flat up past 1kHz according to the datasheet. Still, very interested to see what the measurements say vs the WO24 and other candidates.

[Evil Twin]

I plan as a starting point to do tests with a two frequency IM setup like HiFi compass has posted- the combination of 30Hz and 255Hz can be very revealing for larger drivers, as well as integer multiples of this frequency set for smaller drivers to examine their linearity.

This is why the interface electronics for the test setup have been updated, and in order to accommodate Thunderbolt 3 and USB-C, the laptop needed a refresh to a 2018 MacBook Pro also.

[Steve Manning]

To be clear- in this case the wider baffle is purely an aesthetic consideration. My design target is the SF Elipsa.



This may make some of my questions/investigations a bit more sensible - will they fit in the space? how much woofer volume can I squeeze out of this form factor? Is there any detrimental impact on imaging from the wide baffle? etc. Thus the effort to create a test mule using relatively modest cost drivers to investigate (which will effectively be Troels Poor Man's Strad http://www.troelsgravesen.dk/PMS.htm)



Well, maybe I have my thread title for this effort :-)

I've always thought this would be a cool build to try.

[Bear]

I've always thought this would be a cool build to try.

It would work very well as a translam model. We'll just ignore the amount of waste that it would take...

[Evil Twin]

It would work very well as a translam model. We'll just ignore the amount of waste that it would take...

Not particularly concerned with "sustainable" manufacturing I imagine...

Truly, you are strong in the Dark Side!

[dwk]

My personal thought is semi-translam. A sequence of ribs to define the structure, a solid front baffle (and possibly back - not sure yet), but the curved sections created by laminating up something like 1/8" hardboard onto rebates in the translam ribs. This makes it pretty natural to reproduce the horizontal divisions, and reduces the veneering work to a bunch of small panels which is less intimidating. No idea how to handle the sides, though.....

I have a small cnc (a 6040) which can just barely handle the translam ribs for this, and that is indeed my intended direction - I wouldn't ask it to handle the volume of a pure translam build, but ~12 per cabinet seems viable.

[Bear]

My personal thought is semi-translam. A sequence of ribs to define the structure, a solid front baffle (and possibly back - not sure yet), but the curved sections created by laminating up something like 1/8" hardboard onto rebates in the translam ribs. This makes it pretty natural to reproduce the horizontal divisions, and reduces the veneering work to a bunch of small panels which is less intimidating. No idea how to handle the sides, though.....

I have a small cnc (a 6040) which can just barely handle the translam ribs for this, and that is indeed my intended direction - I wouldn't ask it to handle the volume of a pure translam build, but ~12 per cabinet seems viable.

To my simple mind, the point of the translam would be to avoid the issues for side adornment. If you are looking for side pieces (cheeks??), then a traditional build using kerf cuts may be the easier route. Steve's process, but with ~6" rib sections would most closely match the SF original. I could see the piano black ribs, white spacers and bamboo baffle/end caps being attractive here.

[Steve Manning]

Here's an idea for you, not so much as go out and buy it, rather, the concept. https://www.curvomatic.com/

I made these out of layers of 3/16" hardboard. There very strong with very little spring back during the glue up process. Getting the profile you need shouldn't be to crazy to do. Use your CNC to cut ribs, top and bottom and away you go.




If you have a band saw, you could laminate some wood together and cut the profile on the saw.

[Zvu]

Your feedback is welcome and seems to hit on key points... dull versus shouty can also be an indication of variation in axial response versus power response - lacking in power response off axis, but clearly showing a coloration if the level is boosted to compensate...

My thoughts exactly at the time. Then i did measurements 0-90 degrees and averaged them. This was the result:



Averaged:



That's when i started to look at other directions to search what may be the problem. I even wrote something about it here:

https://www.htguide.com/forum/showthread.php?44139-Some-measurements-of-Kef-R300-drivers&p=631866&viewfull=1#post631866

I should take R300's back for a revision. I've found some midwoofers that could work in smallish volume in the meantime.

[Evil Twin]

In the meantime...

This thread has languished for some time, not due to lack of activity, but due to priorities- continuing construction activities. It will be updated in detail showing the phases of efforts for those interested.


For those who enjoy a fast glance at an advanced stage of construction, this picture may be interesting...





Setup and the work steps leading to this will be posted soon in an organized fashion...

[Scottg]

I plan as a starting point to do tests with a two frequency IM setup like HiFi compass has posted- the combination of 30Hz and 255Hz can be very revealing for larger drivers, as well as integer multiples of this frequency set for smaller drivers to examine their linearity.

-while not Mac software:

http://aplaudio.com/conc2/products/tda-im/

[Evil Twin]

Thank you for the link to investigate. My current plan was to use measurement and acoustics functionality in my Audio Precision analyzer, but this looks interesting, depending on price and configuration.

Interesting that you need to download a MatLAB runtime for running their software under Windows.

Also, it seems that they provide a reasonable amount of introductory information about the IM distortion analysis, which seems to be a separate add on, but it is quite unclear from the online material how to actually order or trial it, unlike the other products. There is a strong focus on system equalization and time delay correction as needed for live sound and car audio...

But as I have a "spare" LG 17" laptop, the trial version or individual versions seem like something worth investigating.

[Evil Twin]

Hints at what is to follow

I find this interesting to ponder...





This is the smallest Ardent style project as regards external physical dimensions, but the weight per enclosed volume seems to set a new benchmark.


There are many additional steps before they will produce music, but it is most satisfying to see this stage realized at last.

As expected, managing some dimensions with regards to the visual character of the design is tricky- looking at this picture, you will most likely think that the upper facet bevels are longer than the lower, because of what the driver arrangement does to the eye/brain interface, as well as perspective- but the lower facet bevels are 2" longer.

[ergo]

Looking good and nicely angular indeed.

[theSven]

The enclosure looks great. Looking forward to see what components are gonna be used from all your testing. How much does that enclosure weigh, >50 lbs?

[Browncoat]

Agreed, that looks fantastic. You've really got your cabinet making skills dialed in, 'cause those went pretty fast. Any other Ardent cabinets nearby for a side-by-side comparision?

[chrisn]

The enclosure looks great. Looking forward to see what components are gonna be used from all your testing. How much does that enclosure weigh, >50 lbs?

I'm going to wager a guess of 125. I wonder what prize the winner gets:roflmao:

[Evil Twin]

I'm going to wager a guess of 125. I wonder what prize the winner gets:roflmao:

You are far closer to the current value, without base, crossovers, or drivers, but you are a bit on the high side.

[JonMarsh]

Agreed, that looks fantastic. You've really got your cabinet making skills dialed in, 'cause those went pretty fast. Any other Ardent cabinets nearby for a side-by-side comparision?

No, as my Wavecor Ardents have been owned by a colleague at work for several years now- this is where Ergo heard them, in fact. It was necessary to find a new home for them when the family room needed to be converted to more of a home care area due to the pancreatic cancer- the stereo had to go.

However, I should be able to prepare some simple profile drawings from the original CAD files to illustrate the differences, once some time can be freed up on the weekends.

[Evil Twin]

Some progress is being made...

In a project like this, there is much detail work- at times, the hardest problem to solve is finding the time for this work when Imperial matters keep intruding...

But complaining does not solve problems, or build speakers.

Operations such as basic side wall clean up and sanding are easily completed...






The only real "trick" involved here, since no veneering is planned, is that enough material must be removed so that the surface seepage of epoxy into portions of the wood is completely removed...






Specialty tools are advised for operations such as leveling the sidewalls to the rear panel...






The results prove most satisfactory...





Whether the matching of LBL and Maple ply will be esthetically acceptable is a judgement call, but it is deemed adequate for a rarely seen part of what is essentially a design study, not a finished product.






For only two hours of work, the results are acceptable...

[Bear]

If one is careful with the machining, especially roundovers, and one likes the look of the bamboo, it can be surprisingly cost-effective compared to MDF+Veneer. And one gets to stay away from MDF.

[Evil Twin]

More progress has been made, to the point that one cabinet is nearing completion...

Certain trim operations and the PR mounting holes have been completed, along with a fine sand with 120 and 240 grit Arabnet disks...





After completing a base trim operation and sanding to 120 grit, the PR mounting holes bracketing the back center brace must be prepared.





The cut depth is to the full capability of the router on the edges near the cabinets side wall, but is restricted in the center so that the disk is still supported by a small amount of the BB ply material- then this is cut with a saber saw, and the overall hole must be cleaned up with a follower bit.




A test fit confirms the required 1mm clearance was implemented correctly...





After sanding to 240 grit surface, the cabinet was placed back on it's mobile work base to return to interior storage and the next steps in detail work (installing threaded inserts, etc.)





Regrettably, the pictures do not convey the solidity and surface polish that the construction now possesses....

Nor the remarkable strength and solidity due to the construction materials that were chosen.

Satisfactory... very satisfactory.

[ergo]

Very nice progress! This one promises to become a very good looker also from visual shape and balance point of view. With the wall thickness and the materials in use it must be a close to "rock solid" indeed.

[Evil Twin]

I have been curious to get an early impression of how the wipe on polyurethane will work with this build-

So after finishing the second cabinet mechanicals to the same stage as the first one above, I indulged myself slightly... by applying a fast test coat of Minwax wipe on polyurethane.







While it must be remembered that the primary point of a design study is utility, it is useful if the esthetic results are not an eyesore...





The initial results indicate some promise, with a very simple application process... the key to productivity in a design study.

[dar47]

Well it's bin a while since I have posted, I have to remark your A game cabinet has grown to an A+. Although I will continue my admiration of my Wavecor's I look forward to your comparison of this new verses old. The new Nat P's is a build I would be interested in and look forward to that fine work.

As a note I have went through 2 years of weekly vertigo but am now in remission with my Meniere's disease and only have 5% hearing in the left ear. Was contemplating passing along all my gear but glad I didn't as even with 1 good ear low distortion sound is great! Glad to see your back with a vengeance Master.