Kurosawa Koncept System

[Evil Twin]

Bad news, good news...

Materials logistics are continuing to move forward, but not without some compromises in efforts. The imperial treasury is not what it once was, and for this reason the Chancellor ordered a detailed cost benefit analysis of the proposed and possible enclosure materials.

Based on this, the use of Panzerholz was ruled out, due to the expense in the necessary quantity. However, the investigation of piano pin block suppliers who carried this product also revealed the wide spread usage of a similar but substantially less expensive alternative, hard rock maple ply. This is available in the same widths, lengths, and thicknesses as the Panzerholz delignit, but at a nearly 50% cost savings. Obviously that does not put it in the pricing realm of B2 or C3 fir plywood...

After some scheduling issues with the freight company, delivery has finally been completed. It is most impressive if somewhat unnerving for the neighbors to see a Correlian YT-1300 freighter hover and land on the lane in front of one's residence. After that, the actual delivery was anti-climatical.




It does not look like 500 lb of wood, does it? Appearances are deceiving...



Inspection of the cargo and transfer to short term storage left no doubts about the specifics of the material delivered. Keep in mind, this is a 1-1/4" thick piece, and the actual material is hard rock maple, by spectrographic analysis.





Panels 22" wide and 59" long, 5 of 1-1/4" and 4 of 1-1/2" thickness were ordered to fulfill the construction plan for the sides, front and rear baffles, and top and bottom pieces. Inner baffles and extra braces are to be fabricated from LBL board, not LBL ply.

[DS-21]

http://www.homedepot.com/p/UltraTouc...6482/202710055

The BL stuff works well for killing the 2kHz cavity resonance in an Aura Whisper. Better than polyfil. Given that the acoustical problem is similar, I bet it would work well on a less high-tech driver such as the Accuton, too.

As an FYI aside, last year we tried a bunch of those delivery companies that provide you a recipe and all of the ingredients to cook it. Hellofresh and the like. (None of them stood out as usefully better than just figuring out what to cook, for us.) Often the ingredients were insulated with Ultratouch enclosed in paper.

[flamethrower1]

And where in this galaxy did you source your piano block material from?
I ordered and recieved a 18 x 14.5 x 2.25 thick piece of the Falconwood from Great Lakes Piano Supply and that was just shy of 3 bills to my door.
Stuff is dense and heavy, I can see 500lbs of material on that pallet, hence the pallet.
Anyway, I had some test pieces to see how it was boring holes in th 1 to 2 inch range, went better than expected.
The bits were good forstner bits recently purchased, they do heat up a lot, just have to take it easy I guess.

[TacoD]

Bad news, good news...

Materials logistics are continuing to move forward, but not without some compromises in efforts. The imperial treasury is not what it once was, and for this reason the Chancellor ordered a detailed cost benefit analysis of the proposed and possible enclosure materials.

Based on this, the use of Panzerholz was ruled out, due to the expense in the necessary quantity. However, the investigation of piano pin block suppliers who carried this product also revealed the wide spread usage of a similar but substantially less expensive alternative, hard rock maple ply. This is available in the same widths, lengths, and thicknesses as the Panzerholz delignit, but at a nearly 50% cost savings. Obviously that does not put it in the pricing realm of B2 or C3 fir plywood...

After some scheduling issues with the freight company, delivery has finally been completed. It is most impressive if somewhat unnerving for the neighbors to see a Correlian YT-1300 freighter hover and land on the lane in front of one's residence. After that, the actual delivery was anti-climatical.




It does not look like 500 lb of wood, does it? Appearances are deceiving...



Inspection of the cargo and transfer to short term storage left no doubts about the specifics of the material delivered. Keep in mind, this is a 1-1/4" thick piece, and the actual material is hard rock maple, by spectrographic analysis.





Panels 22" wide and 59" long, 5 of 1-1/4" and 4 of 1-1/2" thickness were ordered to fulfill the construction plan for the sides, front and rear baffles, and top and bottom pieces. Inner baffles and extra braces are to be fabricated from LBL board, not LBL ply.

Very nice quality material!

[sdl2112]

Very nice indeed...no worries of voids here I'm sure. :T

How does the external ply look for finishing...good for a nice clear coat?

[Evil Twin]

By plywood standards this might be AAA material, if such a category existed, because we did not see any cut outs or patches in the surface material. On the other hand, the grain is rather bland, basic quarter sawn maple, nothing distinguishing in a cosmetic sense. A natural finish is one option I have considered, but given all known proclivities, it should come as a surprise to no one if they wind up being done with either a gloss piano black finish or satin black finish, with some natural wood highlights under consideration where the tweeter and midrange are mounted.

Yes, TacoD and others, it seems to be very nice material and striking a reasonable compromise between the all out expense of delignit and more common lesser materials. In this case, LBL board will be the hidden "inexpensive" material used for baffles and braces.

[Evil Twin]

And where in this galaxy did you source your piano block material from?
I ordered and recieved a 18 x 14.5 x 2.25 thick piece of the Falconwood from Great Lakes Piano Supply and that was just shy of 3 bills to my door.
Stuff is dense and heavy, I can see 500lbs of material on that pallet, hence the pallet.
Anyway, I had some test pieces to see how it was boring holes in th 1 to 2 inch range, went better than expected.
The bits were good forstner bits recently purchased, they do heat up a lot, just have to take it easy I guess.

As previously mentioned, they were sourced from the same location being considered for delignit, Vanda King's Piano Showcase.

[Evil Twin]

For those who enjoy gazing at unusual wood products, a more close up picture is provided...



I believe this material shall prove to be fully satisfactory. New premium blades are in route, and the tooling platform assembly has been completed this weekend. Lighter and more maneuverable than some other cutting systems discussed on the forum recently, it is more a tie fighter than a Super Star Destroyer...

[Steve Manning]

For those who enjoy gazing at unusual wood products, a more close up picture is provided...



I believe this material shall prove to be fully satisfactory. New premium blades are in route, and the tooling platform assembly has been completed this weekend. Lighter and more maneuverable than some other cutting systems discussed on the forum recently, it is more a tie fighter than a Super Star Destroyer...

Now that's what I call void free, much better than the Minerva material, for not much more in cost.

[flamethrower1]

For comparison purposes here is a pic of the Falconwood I received.
Tim from Great Lakes Piano Supply mentioned that he has 4x6 sheets of this in 1 inch

[Evil Twin]

Is the base wood material Beech for the Falconwood, as in the case of delignit? Falcon wood is well favored on many of the piano forums.

The piece above which I posted is 1-1/4". As is often the case for maple ply for pin blocks, it uses much thicker layers than the relatively thin veneer like layers for beech ply.

[augerpro]

I suspected there might be an issue with cavity resonance in that Accuton. Not chamfering the backside of a baffle can cause issues and that driver looked like a worst case. That said, if it can be damped it might still live up to its promise. I think the denim insulation is a good suggestion - it's pretty much all I use to line boxes now. Cheap, thick, easily applied, and the measurements I've seen (IIRC) suggest very broadband absorption, not far behind Corning 703 and well ahead of polyfill or commercial "acoustic" foam. Might be an opportunity to test all of the above and add the data pool Jon.

[flamethrower1]

Is the base wood material Beech for the Falconwood, as in the case of delignit? Falcon wood is well favored on many of the piano forums.

The piece above which I posted is 1-1/4". As is often the case for maple ply for pin blocks, it uses much thicker layers than the relatively thin veneer like layers for beech ply.

Yeah, the Falconwood is beech, the plys were actually thicker than what I have seen on the net for Delignit.
They look pretty close to the same thickness as what you have.
I know the 1 1/4 is normally used, maybe a good deal could be had with the 1"

[sdl2112]

Surely the force is strong with this one. The vehicle of delivery must be comprised of only the finest pin board materials. I believe the emperor would be pleased with the second scene.

[Evil Twin]

Surely the force is strong with this one. The vehicle of delivery must be comprised of only the finest pin board materials. I believe the emperor would be pleased with the second scene.

Now THAT is entertainment... with appropriate cultural values and technique! It would seem to have been filmed in 4K originally, as resolution up to 1440P is claimed to be available for playback, but download who's only 1080P. Still a useful option for those with the necessary tools... it is now safely stored in my video repository.

[Evil Twin]

Parameterized model in preparation

Substantial progress has been made towards completing a fully parameterized enclosure model, which can be updated and refined by parameter updates, not requiring additional direct modeling modification. The design parameters reflect both the current hardware choices as well as tooling capabilities for the construction and assembly. Top and bottom and internal baffles are not yet implemented, but this render conveys the general design direction and intent.






The front panel is formed from three pieces, including an inner panel which will stabilize the main cabinet during construction and assembly . The raised area between the two upper woofers will incorporate book matched symmetrical thin hardwood trim panel- either Pau Ferro (Bolivian rosewood) or flamed maple.





Thematically the maple might be most appropriate, given the construction material for the cabinet, but the contrast between a piano black or matte black cabinet and the blonde maple could be too much- this is yet to be decided.

These are pictures of the actual pieces on hand. An additional set of pau ferro pieces that is somewhat more figured is on hand, but is not quite as attractive.

The driver arrangement was chosen for several specific reasons-

• To place the midrange at ear height for a normal seated listening position
• To distribute the woofers so that they could work in individual acoustic rear chambers, each with two passive radiators
• To provide a tall midbass sources, as experience shows that this results in more uniform instrument reproduction in that freuqency range with less interaction with the floor and ceiling
• To provide an WMW configuration which also tends to focus the midrange to woofer transition region radiation in a forward direction with reduced interaction with floor and celing boundaries

For those objecting to the uneven spacing of the five 7.5" Accuton Passive Radiators in the Akira, they should be pleased to note that the 6 Wavecor 8-3/4" PR223BD02 (two per woofer, in sealed individual compartments) are quite uniformly spaced, hopefully relieving their OCD cognitive dissonance. As well, these PR's provide a quite optimum loading for the AS190-9-252, actually extending response to below the free air resonance of the Accuton woofers.

Obviously, Wavecor fans should be pleased, too.





Input connectors are Vampire BFBP mounted partially recessed within the rear panel. Including a SpeakOn connector is also under consideration.

[Evil Twin]

Progress continues... along with the climb up the learning curve.




Of course, the logical question which arises from a skeptic, is as the model looks better and more complete, will it actually be possible to build it to realize the esthetic intent and functionality expressed in the model?

This is a very real and practical question, one which only time will answer.

[kravi4ka]

Palpatine Heavy Industries... :heh:

[Steve Manning]

Progress with Fusion 360 I see ......

[Evil Twin]

Grudging progress, but we will take whatever progress we can get... the Force is strong with this program... :storm:

[Evil Twin]

More progress, enough to say that the enclosure fundamentals are complete, enough to prepare a cutting BOM and piece plan. The parameterized geometry and dimensioning came in quite useful several times this evening- saving serious complications if using a conventional direct modeling approach. Fusion 360 is to be highly recommended, for users at any level of experience.










All body parts, sketches, and geometries can and have been unique assigned descriptive names, facilitating discussion of the design as well as preparing piece part diagrams, a BOM cutting list, and work checklist for fabrication.

Impressive...most impressive. The utility of the program cannot be denied.

[Face]

With the materials you're using, it may not be needed, but may I suggest some top to bottom bracing.

[Evil Twin]

Let me share with you my reasoning on that topic.

Generally, I prefer to not have an unsupported span of material exceeding 5:1 for MDF and 6 or 7:1 for stronger materials, such as LBL, BB ply, etc.

For a 3/4" thickness of MDF, this translates to a maximum unsupported braced distance (as between two longer parallel components) of 3-3/4".

For 3/4" LBL or BB ply, this translates to an unsupported span of 5-1/4". you will note an exception to this rule in the design, and the reason for it will be explained shortly.

For 1-1/2" LBL or Maple Ply, the rule then would be 10-1/2". The interior width of the cabinet, which determines the unsupported span, is 9-1/2". So in my judgement, bracing the top and bottom 1-1/2" maple ply panels is not necessary.

Now, about the woofer chamber isolation baffles- these are only of 3/4" LBL, and they are a 9-1/2" span. BUT, and this is quite important, they have essentially common low frequency signals on either side, as the woofers are driven with the same signal in parallel; there is no significant pressure difference or flexing force exerted. Their true main function is to prevent 1/4 wave columnar resonances which would occur if the enclosure were open top to bottom; these would occur around 150-160Hz. So, I deem extensive bracing on these components (the woofer chamber divider baffles) to be unnecessary.

The only other enclosure section of concern is the midrange enclosure, which is to be constructed of schedule 80 PVC Tube, which due to both the material, configuration (schedule 80) and the circular construction, is very, very strong. 5 pieces of 1 foot length are on hand, one will be used just for the midrange damping test article, for evaluating configurations to use and collect additional measurement data for the C90-6-724.

[sdl2112]

Looks like the start of an awesome design. I hope you have plans for moving those around. :E

[Evil Twin]

Looks like the start of an awesome design. I hope you have plans for moving those around. :E

Two words: Appliance dolly

Height: 57"
Width: 12"
Depth: ~25"
Weight: Unknown... less than an equivalent size block of neutronium steel, I expect. Perhaps not much less...

[Navy Guy]

Kurosawa Koncept System

This looks like it might have properties similar to ATS Acoustics Applegate Acoustical Cotton Batts, which have been procured for enclosure lining. The value proposition of the HomeDepot version may be quite high, given the pricing- curious that it is only sold online. One package has been ordered for evaluation. You are to be commended for sharing this information...

The ultra touch is what I use for all my builds now. Very good stuff but it appears Amazon isn't carrying it anymore. I'm not sure why it's so hard to find. Looking great btw.

[Evil Twin]

Home Depot still carries the UltraTouch, and a six roll pack is on it's way since ordered last week.

Many new materials, processes, and design and fabrication tools are being evaluated for this challenging build.

It is planned that an imported Sith apprentice from the state of Texas will aid in completing many of the major raw piece fabrication steps this weekend, in exchange for food and housing and a smattering of instruction in the dark arts. Texas is generally strong in the Dark side, but unfocused and chaotic.

Does one assume correctly that the linked web site is an endeavor of your undertaking? The highly aspirational title includes solid entry level material, but you could go much, much further. Do not neglect the impact of source components; making reasonable recommendations for superior entry level equipment is not a trivial proposition, but there certainly are places to start, such as components like the Cambridge 651W or 851D which could be considered benchmarks at their current price points. It would be wise to at least disclose your own system parameters, when discussing the audibility of driver distortion- not that I disagree with your assertion, far from it. But it carries less weight and audibility if mid grade HT electronics are considered instead of dedicated audio gear.

In my own experience, though many "average" citizens are quite content with the sonics of their home theater system, if one extracts the PCM stream (from HDMI) and routes it to solid midrange equipment (NAD M51, or electronics as mentioned above,) and good speakers for music, the difference in quality is quite startling. Most modern movies have very OCD and careful sound mastering, unlike the compressed streaming music so many today listen to on earbuds.

[Evil Twin]

The European Union comes through, even if the UK is leaving it- HiFiHobbyLaden has shipped AS190s, which should be received next week- reasonable speed, and a good price are to be commended.

Solen is now cleaned out for the time being for Wavecor PR223BD02, and they are all mine- shipped yesterday. So far, matters are unfolding as I have foreseen and planned.

A safe and productive Holiday Weekend is wished for all...

[Evil Twin]

My young apprentice arrived on schedule for his training in the dark arts- matters have proceeded as expected.

A final check was made of blade and fence alignment, even though initial calibration was completed at saw assembly.




This additional check was likely not necessary, but a useful part of the apprentice training- the resulting work quality bore out the superb alignment possible with this dual rack and pinion driven fence system.





In the end, a wholly satisfactory quantity of saw dust was produced.

It should be noted that with the high level of blade and fence alignment, ripping all of the many pieces was accomplished quickly and with no apparent impact on tooling quality or performance. In fact, I had my apprentice check the blade temperature half way through, and as would be expected for a properly aligned fence and superbly sharp blade setup, the blade was barely above the current air temperature. This fact can be born out by the total lack of any burn marks or issues with cut surfaces.

Here we have a number of scrap pieces left over, including 1" on a side side panel bevel cuts...



And here, a tighter close up of some of the remaining scrap pieces.



All told, a very satisfactory performance by both the DeWalt 7491 saw and my new apprentice. The force is strong with this one, though he has much yet to learn.

[TacoD]

That is very impressive, great progress!

[meb46]

Very nice... great to see progress on this!

[Evil Twin]

Steady progress...

Now we are moving into the phase where unforeseen problems and material issues may come to the fore... however, so far, development is going as I have foreseen, with a range of topics addressed in the front end materials design, and some steady progress starting on the wood itself...

[sdl2112]

Nice progress Jon...I see you went with the Maple, that was my choice. I like contrast.

The cuts from your earlier post look very nice...the little Dewalt (and operator) should be commended. :B

I was curious how one would make a precise circle for the Cell drivers...now I see. Good idea using their adapter plate as a guide..(I assume that's what you're doing...or are you going to use the adapter)

Is the maple a cosmetic piece only or are you using it to align acoustic centers better?

[Evil Twin]

Actually the matter of the midrange mounting was a potentially vexing situation, as the suggested/required tolerances for the midrange pass through hole are +0.1/-0mm, which is essentially impossible with wood working equipment, and requires some care with metal working. Additionally, I do not care for the cosmetics of the square adapter, and find that as built, it is relatively flimsy if only supported at the screw mounting holes.

So, the solution is relatively simple... use the adapter mounted to the base cabinet front panel with both screws and epoxy, but with the cylindrical element forwards, not recessed,for a firm mechanical connection to the C90-6-724 driver. The hardwood plate provides the ability to set the mounting depth of the tweeter above the primary front panel plane, and at the same time conceal the midrange mounting adapter, by selective relief routing of the backside of the hardwood plate.

At the appropriate stage of assembly, the hardwood plate will be glued/epoxied to the front panel after attaching the midrange mounting adapter. The rebate depth of the woofers is designed for the hardwood panel to be essentially flush with the upper edge of the woofers when installed.

The overall cabinet tilt back is small, 4 degrees, as there is no need to try to bring the woofer acoustic centers forward as is the case with a conventional Avalon style enclosure- the acoustic origin is essentially flush with the mounting plane. At the frequencies of the midrange to woofer transition band (200 Hz to 1kHz with the planned Duelund network) 1/4" of alignment change has a minimal impact.

From the front, it will appear as if the midrange is seamlessly mounted into the maple panel.

[Evil Twin]

Steady progress... and a front panel milestone

Initial fabrication steps of the outer and middle front panel pieces has been completed...


The last steps for the middle section were milling out the residual material after the center holes were cut out...


This is another of those steps in the process where the right technique results in the desired results without drama- in this case, the key is the router speed setting, relatively slow, and using a low force feed in a CCW direction around the circumference. After milling out all the residual material in both panels, the router bit was barely detectably warm. Of course, an initial cryogenic treatment with carbonite doesn't hurt the process.... :B





Now one can see the set of two forward and two middle front panel sections, ready to be epoxied together prior to the top and bottom cutting operations and the edge bevel cutting.




Completing the inner front panels routing the back panels will be next, followed by trimming the sides and top and bottom panels, and cutting the inner front panel to the correct length and top and bottom bevel.

[sdl2112]

Nice progress Jon...you said you cut in the CCW direction. I've seen this called the climb direction. Are you doing this to reduce tear-out? Do you have a rule of thumb when you use this direction or mix directions depending if it's first or last pass?

http://www.waterfront-woods.com/Articles/Climb-Chip-Cutting.html

[Steve Manning]

I see you caught that to Scott ...... I was wondering the same thing if it were a last pass thing, just to smooth things out?

[Evil Twin]

If the router is is cutting with a CCW pass round the inside of the circle, the bit is "fighting" the direction of travel and will generally not have any tendency to try to accelerate the motion in the direction of the cutting pass- this makes control easier, and generally results in a smooth cut. In this case, we are talking about an operation with a pattern bit to remove the remains of about 1/4" at the bottom where the center plug was cut out using a saber jig saw.

On the other hand, I find the same technique advantages when doing deep bevel cuts on the back side of a woofer cut out, and with good bits and this technique can complete a 3/4" bevel cut out in one pass, as done for the outer pieces of the front panel.

[Evil Twin]

Progress continues, albeit at a maddeningly slow pace...

The inner front panels (3rd section of three) have completed most initial machine operations...




And the forward front panel shells are being glued up from the middle and front panels:







As components are combined, and their mass evaluated, the final weight of this technological terror becomes most apparent...

[5th element]

Wow those are coming along really nicely and are going to weigh a ton when finished! I hope your back is holding up!

[sdl2112]

Looking nice...It looks like that hard maple machines well. Would you say it's less likely to splinter then Baltic birch?

Anyway with all this progress going here I better get cracking...

[Evil Twin]

The hard maple is quite different to machine than any other wood product I have tried, including LBL and Baltic birch ply- it produces less dust and machines into fine curled grains and leavings which are not at all abrasive. Apart from the cost, I would say maple ply might be a nearly ideal cabinet material. It does not produce sharp splinters as both LBL and BB can.

Progress continues- more work, less photography, and both rear panels have the PR rebates routed and the through holes routed though not cut out yet. As this task was only on the schedule for incidental time during the coming week, this means we are ahead of plan, and further motivational inducements won't be necessary to stay on schedule.

Additionally, checking and further analysis of proposed crossover configurations has resulted in placing orders with selected US and UK vendors. One minor but welcome cost savings with this configuration is that all the drivers are running flat out- there are no expensive Mundorf or Duelund resistors in series with drivers or driver networks. On the other hand, optimum balance requires minimizing insertion losses, which raises the overall expense, what with AWG12 foil inductors and other premium parts.

Furthermore, finishing process chemicals were ordered today- of course, in the only desirable color, black.

[Evil Twin]

Imperial Lambda Shuttle or FedEx International Economy Courier?

If this is a typical example, the UK has nothing to fear from Brexit.

Now, a question I have to pose to you, for an order placed Sunday evening, and received today Tuesday morning from the UK, which do you think was the more plausible delivery method to achieve this alacrity in delivery?

Custom carry via chartered Imperial Lambda Shuttle, or...

FedEx International Economy Courier? (at under $30 USD)

To clarify, the order was entered and shipped on Monday, and received on Tuesday morning- overnight service.




And as you might surmise, this is the capacitor order for the first stereo crossover build... including Jantzen, Duelund, and Obligatto capacitors.

[Evil Twin]

Correcting the midrange driver design issues

As has been noted previously in this post and by others, the design of the C90-6-724 has one issue which must not be left as is, in order to achieve high quality results. The vaunted cylindrical large voice coil motor also acts as a resonant tube for the rear wave of the drive- though as Accuton claims, it does't "mask" the rear wave, it certainly modifies it substantially in an undesirable way nonetheless in the service of getting a more forward acoustic center and larger driving area for extending the range of the top end breakup.

What better way to gauge the effect of the tube structure of the motor assembly than to measure the rear wave?




Here the resonant effects are clearly seen in the peaks and valleys of the rear wave behavior.

A damper assembly has been fabricated, not unlike the fuel flow injection damper module in a standard Tie Fighter, and attached to one of the sample C90-6-724 for testing...





Now we can see the perturbations in the rear wave as a function of frequency are greatly reduced... keep in mind this is in decibels, which is a log based scale for level.

This should be far more satisfactory...


A quick check of the near field on axis response shows this to be the case- the roll off above 2500 Hz is due to the ratio of the measurement distance to the cone diameter, which when very close will attenuate higher frequencies.

[5th element]

Hmm I wonder if the rear wave dampener has much, if any, effect on the front wave?

From your other measurements the driver shows impressively flat and pistonic behaviour + no anomalies in the distortion either.