Remember the Arvo Pärt project?

[ThomasW]

http://home.comcast.net/~audio-worx/loadedArvo.jpg

Well, it's being brought back from a near-death experience. There are some changes with the newest version. :clap:

1)Different tweeter, oh so cool, and oh so expensive, ScanSpeak 9800 alu dome instead of the Vifa XT25 8)

http://www.partsexpress.com/images/276-506m.jpg

2)Different woofers, a pair of Adire DPL 12"s instead of the 10" Titanic MKII's :D

http://www.adireaudio.com/diy_audio/drivers/adire/DPL12.jpg

3)Instead of Jon's one piece design, the new version will utilize a bottom (woofer) module and a separate top (MTM) module. This will allow quick module updates and save my back when moving the speakers around.

I'd like to post some cool CAD graphics of the intended design, but creating those would take me longer than building the actual cabinets. ;)

So stay tuned, next week there will be some pictures of the real thing.... :T




theAudioWorx (http://www.theAudioWorx.com)
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[Pat]

Thomas, you must have finished up all your other projects, since you seem to be starting a few more :) 8)

How's the knee?




Pat's Page (http://pat.home.mchsi.com)

[JonMarsh]

The "orignal" version will be completed also, but with the different tweeters... :banana:

Slow work takes time.... ;)


~Jon




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[ThomasW]

Hi Pat!

Other projects not completed, but yeap knee is better, not longer feel that it's going to collapse when I walk down the basement steps. :D

Jon's going to fly out here for a week the second week of January. My goal is to have some prototypes ready for testing and XO design development while he's here.




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[sfdoddsy]

Looking forward to seeing the new Arvos. I split mine into two parts for similar reasons, although I usually have the MTM panel sitting over the bass module for space and aesthetic reasons.

http://www.doddsy.net/blackbob7.jpg

Steve




Steve's DIY Dipoles (http://www.doddsy.net/steve6_008.htm)

[Pat]

Glad to hear your getting around better :T

3 weeks to get those prototypes ready 8O




Pat's Page (http://pat.home.mchsi.com)

[JonMarsh]

Ola' from Sunny Denver.


http://audioworx.virtualave.net/ArvoEyesOnly.jpg


Slow work takes time.... :coffee:

But the work is proceeding... looks promising. This is the predicted result from measurements, for the current all passive crossover design. These measurements are with Titanic Mk11 10" (really 11"), but DPL 12's are expected to have raw measurements which are essentially similar, due to the influence of the U baffle.

~Jon




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[Hank]

Hmmm...mighty flat line there. :)

[ThomasW]

This is a tease, this is just a tease, please do not adjust your set....... ;)

The interesting thing about that plot Hank, is that unlike all the Linkwitz designs, Jon's design isn't using active EQ and is using all passive crossovers.! 8O

Now on to actually building the thing to see if the LspCAD predictions are correct.. :D




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[JonMarsh]

...must wind more inductors.... :rx


~Jon




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[Hank]

The all passive wasn't lost on me. ;) Might Mr. Cauer be involved?
I wish you Poohbah's had been at C.E.S. I think you boys would have been impressed by Adire's upcoming 6.5" (I'm talking ULTISSIMO line source mid-woof as well as...) and 4", both using xbl^2 technology.
Anyway, go forth and build! Your public wants actual speaker performance graphs and listening notes. :)

[JonMarsh]

Mr. Cauer lent his usual assistance in the midwoofer to tweeter crossover, as with the M8's. We've also dummied up a design for the DPL 12's with active woofer to midwoofer crossover, and passive top, which Thomas will probably use, especially since the DPL12's aren't quite as sensitive, and there's something of a significant back order situation on the 10" MK11's. :cry: This is a problem, as I need another pair!

Finished winding all the inductors for a complete passive crossover set, so Thomas can set his up that way in the future; with a couple of switches, it can be converted between modes. Maybe some pics tomorrow. ;)

~Jon




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[JonMarsh]

ThomasW has kept me locked away in the basement and family room, working my fingers to the nubbin (as John Lennon would say, were he with us, "I've got blisters on my fingers!"). Actually, in this dry Colorado weather, it's just cracks.

http://audioworx.virtualave.net/LeftTW_ProtoSS.jpg

As I write I'm listening to Norah Jones on ThomasW's proto's- we cobbled up a setup with a hybrid crossover (in order to work with Tom's choice of DPL12's, also PE Titanic MkII are back ordered), part of the passive design, with some elements bypassed, and an active Marchand crossover at 175 Hz.

With all levels set to nominal when we first powered it up, the balance was surprisingly good with Jennifer Warnes, "The Hunter" (XRCD version). No time this afternoon for test equipment, just a quick dial in by ear before we went out to dinner.

http://audioworx.virtualave.net/AVTWPairSS.jpg

But this obviously has a lot of potential, and is surprisingly close for not even being the actual LspCAD design (different woofers, seat of the pants crossover mods). Very nice sound from midbass through highs; a real see through characteristics to the backing vocals and lesser instruments layered up on the Jennifer Warnes disk. The system does the usual dipole thing of ignoring much of the room signature, and sounding more like big headphones than a speaker in a room.

The Scanspeak tweeter seems to be a very good choice; very clear and clean, even with the relatively non-high end gear we've got hooked up. (Liteon LVD2001 DVD player, old Sony preamp, Aragon BB's).

Bass and midrange definition are also very good, but it seems to me that with the DPL12's there's even a little less low bass than my sweeps and earlier tests with the Titanic MKII; (different raw driver characteristics) but then, I picked the Titanic's for some specific characteristics.

I suspected that some EQ in line with the LF feed to the DPL 12's (maybe about 6 dB at 40 Hz?) would fill out things on the bottom. I've got a design for a little active class A NFB box with balanced differential inputs and outputs (plus single ended) that I'm going to use for mine; last night we slipped ThomasW's Behringer in the LF amp circuit, and at 6 dB of boost at 40 Hz with 100/60 bandwidth, it did the trick nicely, even for Laurie Anderson. Jacque Loussier "Play Bach" was pretty amazing; some of the best drum, standup bass, and piano reproduction I've heard. Undoubtedly a lot must be credited to the dipole speaker freedom from room signature.

Unfortunately, I'm heading off for another cross country business extravaganza next week, so fine tuning the system is a little ways off. My daughter Elaine and I head back to California late tomorrow morning- have to say the weather has been great out here for this time of day.

One of the surprising things was how good the Liteon sounded; though it's a bit glitchy in operation occasionally, the playback quality may be one of the best under $500 players I've heard.

Best regards,




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[Pat]

Very cool guys!




Pat's Page (http://pat.home.mchsi.com)

[Andrew Pratt]

Jon I'll probably kick myself for asking but given I own four M8a's, two XT25's and four tempests and a BFD what would it take for me to build a pair of these part's? XO mod's? Also how would you classify their sound in comparison to the M8a's...keeping in mind I'd be using tempest woofs and the XT tweeter?

Also why did you face both DLP12's forward and not reverse one to cancel movement forces?




http://www.htguide.com/CFBoards/images/signatures/andrew_sig.jpg (http://www.mts.net/~glendap)

[JonMarsh]

Hello Andrew,

The driver configuration I selected, with the specific baffle, was designed to work together as well as possible in matching efficiency and frequency response before the use of any crossover; so that a passive crossover was feasible. The DPL12's are not quite the right efficiency and FR for my original design, and Tempests or Shiva's would be even less close, though with an electronic crossover and multiple power amps as we're using for Thomas, plus some external EQ, could probably be made to work.

Note that when you mount the drivers with one set facing forward and the other backwards, the voice coils are wired out of phase, and the cones move in phase- there is NO cancellation of movement forces in this configuration, only cancellation of even order distortion, which is not really that large in proportion to 3rd and 5th order distortion in the selected drivers.

Only the W frame cabinets with LF drivers facing each other has any cancellation of cone movement forces, and this cabinet configuration introduces other problems with the response above 125 Hz (resonances due to cavity) which are unacceptable for this design; note that Linkwitz himself does NOT use that configuration in the Orion design, only in dipole subwoofer cabinets intended to be used only below 100 Hz.

Thomas should probably comment on the differences in the sound; I only had an evening and part of the next day to listen. However, the biggest difference is that the dipole rejects most of the room sound, and is actually a bit more forgiving of placement than a box or tower type speaker, and it has a more coherent sound due to the lowered comb filtering from side wall, floor, and ceiling reflections. This allows you to hear more into the recording, including better imaging, than with a box speaker in most rooms, unless the room is carefully treated and setup.

Plus, the bass/midbasds region has the sort of openness and ease that you get in the very low end with a good IB sub.

We selected the SS9800 because it's quite compatible electrically with the Vifa XT25 (Vifa and SS are both part of DST) with regards to impedance curve and basic frequency response (to below 1 kHz) and efficiency, but also because it's one of the lowest distortion tweeters on the market, being quite comparable to the SS2905 and Seas Excel tweeters. It's one of the most neutral tweeters I've heard, and though not as efficient as the Td120dx2 Focal, it is happier playing lower.

Best regards from Seattle,

Jon




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[ThomasW]

Andrew,

You would need to make totally new XO's. You can't simply modify your existing ones. Note that the Arvo XO is MUCH MUCH more complex, complicated, and expensive as compared to the M8aMKIV. I'll upload some XO pics over the weekend.

The Arvo images somewhat like a planar, but has slightly better overall focus. The bass as Jon said, is detailed/defined like that from an IB.

Since we've yet to actually dial in the performance with test gear; I'll just say that the overall performance is quite good. but not yet world class. When we are able to do the final tweaking and adjustments, I expect exceptional performance ...




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[JonMarsh]

Thomas is right, in my late night fatigue I didn't notice, Andrew, that you seemed to be interested in modifying/rebuilding your M8's into this configuration. The tweeter crossover is close to the same, but the midwoofers are wired in series, as are the LF woofers, and with the network response required the midwoofer crossover is MUCH different (as in totally) from the M8. Also, the LF crossover has got a couple of real honking inductors if you do it passive. Active, you have to do some adjustments with an equalizer to pull it all together.

Regards,

Jon




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[Andrew Pratt]

what is the XO point for the sub part? I have quite a lot of flexibility with the Rotel 1098 pre amp on the LFE XO so i could always use that for the lower base bin if need be. I'm very happy with my M8a's so this is more out of boredom/curiosity then any real desire to upgrade...still I love projects:)




http://www.htguide.com/CFBoards/images/signatures/andrew_sig.jpg (http://www.mts.net/~glendap)

[ThomasW]

what is the XO point for the sub part?

Andrew,

It's not a sub, the Arvos are a fullrange speaker. So the bottom pair of drivers are being used as woofers, not subwoofers. Also the Rotel XO won't work, since the Arvo XO is a special design to compensate for the effects of the dipole mounting of the drivers. Our use of the Marchand is just a 'bandaid' to get the project up and running.

I realize that this is a departure from our normal 2-way (with sub) designs. The goal with the Avro was to have a fullrange speaker (passive XO) that would run off a single amp. The reason my prototypes are running with an active XO on the woofers is that PE is out of stock on the 10" Titanic MKII's. That meant the only woofers we had readily available were from the stash of DPL12"s I bought during the Adire preproduction offer. When PE gets 10" Titanics back in stock I will build a 'finished' version of Arvo using those woofers.




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[JonMarsh]

As Thomas implies, the crossover is very specific to the Arvo as a full range speaker due to the acoustical effects from dipole mounting. These are several, dependent on the driver and baffle design, and go beyond a simple 6 dB/octave roll off due to bass cancellation.

The LF drivers were chosen for it's voice coil inductance, efficiency, and response profile, which is further modified by the short U frame baffle it's used in. In combination, this results in fairly flat response on the low woofer from 100 Hz to 225 Hz, with a strong acoustical roll off above 250 Hz. The LF crossover is not a simple "X dB/octave, but incorporates some staggered poles and zeros to minize the LF output out of band, while managing the transistion band response. As you can see from the summed frequency response plot, the main LF crossover is at ~ 225 Hz in the full passive design with the Titanic MkII.



http://audioworx.virtualave.net/ArvoEyesOnly.jpg


The M8a woofers are wired in series, with an elliptic filter on the top as previously, but have a somewhat complex high pass crossover so that in combination with the panel/driver acoustic response, the net result is a 4th order LF HP filter. This includes compensation for the rear basket to front interaction that results in the classic lower mid peak, which has to be compensated with a notch filter in the active implmentations such as SL has developed.

The raw characteristics can be seen in this plot, which is the combined output of the LF driver and mid woofers WITHOUT any crossover, and with very long sampling time and hence, some room reflections causing ripples in the measured frequency response.

http://audioworx.virtualave.net/AP%20M+L%20MLS.jpg

The midwoofer has a response bump between roughly 250 Hz and 600 Hz which has to be accounted for; this is a "best case" scenario, because the baffle, panel, driver, and crossover have been chosen so that this response bump is located where it can be compensated out by shaping the HP network portion of the M8a crossover. Obviously, nothing comparable exists in the two way box system. ;)

Again, contrast that "raw" measurement with the results with drivers and passive crossover shown above it. Though the network is pretty "beefy" by two way box standards, it's really not that bad to build (compared even with the 8" MTM three way "Modula" system I did in the early nineties using MB dome mids and tweeters, with Scanspeak woofers).

The only active equalization needed on the complete design is a shelving or broad band boost at ~ 40 Hz, of around 6 dB. Then I'd recommend crossing in a monopole sub such as an IB below 40 -50 Hz.

I'm debating whether to make this another AudioXpress project or not; when we get a little more done, I'll probably contact Ed Dell and see if he's interested. The wood working in it's present form is pretty simple;
we just may do some additional studies to see if there's any significant benefit from a more complex baffle design.

Best regards,

Jon




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[Al Garay]

Have you seen that Acoustic Visions has the Titanic MKII's in stock:
http://www.acoustic-visions.com/~acoustic/products/subwoofer_drivers/parts_titanic_10_mkii/

What about using the 12" MKII's instead?

Al

[JonMarsh]

Interesting; I didn't realize they carried these drivers, too!

Howver, the pricing isn't quite as attractive, as we have a wholesale account at PE.

The 10" (which is actually an 11") was selected becuase it enabled a somewhat narrower baffle width and smaller overall baffle( note the difference in size between the DPL prototypes and my original, and I was going for "small footprint"); and because of it's inductance/FR response (~ 6 dB/octave roll off above 75 Hz). The ten also has a cleaner top end, and a higher first breakup mode. Hence, reasonable performance to 200 Hz, with allowance for the crossover roll off above that; it could be a bit of a struggle with the 12, requiring a lower crossover. With some effort, I'm sure it could be doable, but probably requiring an active approach (the coils grow quite a bit between a 225 Hz crossover and a 150 Hz crossover, for example! :LOL: )




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[JonMarsh]

There have been some inquiries about just how complicated the passive crossovers are, considering the design of Linkwitz's crossovers for the Orion- which in active format require quite a few OpAmps...

Here's a pic of the parts required to build a stereo pair....


http://audioworx.virtualave.net/Parts_Is_PartsSS.jpg

and from the other side of the table...


http://home.comcast.net/~audio-worx/XOcomponents.jpg

Not really all that bad; and no worries about digititus in a DSP based crossover, or dynamic range limitations in D/A converters with 25 dB or more boost/cut on come outputs...

Now, it's an open question as to wheter there are more side effects from multiple OpAmps in the signal path, or from a big passive network. I'm sure you'll get pro's and cons both ways. But this way is a lot simpler to integrate into a conventional system. Even Charles Hansen doesn't think a commercial bi or tri-amplified diople speaker is feasible, and is trying to develope a passive crossover version- or at least wants to. He wants a single woofer driver, and hasn't found anything suitable so far, with the efficiency, Xmax, and midrange to cut the mustard.

Best regards,

Jon




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[PMazz]

Damn Jon!!!!

I hope you don't attempt to get on a plane with all those. I can see you now....."But officer, I swear.....they're for my speakers!" :)

You weren't kidding about some xover work to do it passively. WOW!

Pete

[ThomasW]

Pete,

The big cluster caps are my way of saving money, and creating a high quality cap at the same time.

One can buy 10mfd GE caps at Madisound for $.90ea in 100pc lots. Creating high value caps using clusters of the GE caps, results in a cost savings of some 50% over buying large value Solen caps. The drawbacks are having to assemble the clusters, then dealing with the size of the resulting XO boards.

I'll shoot some pics of the assembled XO boards and upload them later today.......




theAudioWorx (http://www.theAudioWorx.com)
Klone-Audio (http://www.klone-audio.com)

[JonMarsh]

Those were just for Tom's crossovers... ;)

Didn't try to smuggle Arvo crossovers out of Colorado! :D


I've got some of the parts for mine, but have to get some more together- I'm debating the GE route (I've got a few of those, too), or the Solen route (also a few, mostly purchased for the M8t&a. :banana:

Probably going to order the big inductors from North Creek...

Now I'm pondering how I'm going to put the final version of the base together, so I can get a little more height on the speaker overall, but match it esthetically to the original design. I gotta feeling it's gonna involve solid oak in some form. :righton:

~Jon




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[sfdoddsy]

Yikes!

Now I know why I plumped for an active crossover.

:)




Steve's DIY Dipoles (http://www.doddsy.net/steve6_008.htm)

[JonMarsh]

Yeah, I suppose the passive route looks a little intimidating when you lay out the parts like that, but then I really wanted something I could hook up to a single power amp and have fun with. I've done systems with three and four way active, and they're a little cumbersome in their own way.

This will have a signal processing box in line between preamp and power amp, to provide the LF EQ below 75-80 Hz (only down to 40 Hz or so with this one), and probably a balance tilt control. The latter will be included because of the discrepency between many good jazz and classical recordings, verus close miked rock and roll. The latter, on a flat system, are usually too bright, and could benefit (and in fact are mastered) assuming a slight system down tilt above about 2 kHz, so that will probably be enabled via passive Eq in the OTA stage also. Details to be worked out.

So, some might say this isn't "pure passive", but then no filter dividing networks will be active, and it will play OK with pretty flat balance to 75 Hz without any EQ at all. That's close enough in my book.

Gotta have something to do with my Palladiums, even if I have enough of them now to do a biamp stereo setup. I think I'd rather build another set of Arvo's and use one pair for the "rears".

Best regards,

Jon




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[ThomasW]

One thing Linkwitz doesn't address is panel resonances. This is something Jon and I noticed with my prototypes. They vibrate, and they vibrate much more than I expected.

A while back I stumbled on Steve Houlihan's dipole speaker website (http://www.surfnetusa.com/sho/home3.htm) Steve has a webpage (http://www.surfnetusa.com/sho/BBContent/Vibration.html) dedicated to trial and error testing of damping methods to control the vibrations of his baffles.

As Jon and I progress with our Arvo projects, we'll work on this resonance issue.




theAudioWorx (http://www.theAudioWorx.com)
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[JonMarsh]

The resonance shows up as blips/glitches in the LF driver impedance curves. We didn't measure Tom's working proto's, but my personal Arvo's are pretty low, compared with some of the curves Steve shows. But my personal Arvo's are laminated up panels with 1/4" HDF, solid oak side bars, and U frames also made with 1" thick laminated 1/4" HDF. Maybe that makes a difference; plus, the panels are a little shorter overall. My Arvo proto feels stiffer than Tom's made with 3/4" MDF.

Of course, there's always the exotic materials department which we could let loose on this problem....

Thomas has found some aircraft aluminum in 1" thick sheets; of course, I'm the fanboy for phenolic sheet... but I guess we'll probably have to see how well we can do with more mundane materials.... ;)




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[ThomasW]

My Arvo proto feels stiffer than Tom's made with 3/4" MDF.

Hey! I think we're getting just a little TOO personal here.......... :B




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[JonMarsh]

Hey! Are you admonishing me?!?

admonish:

VERB: 1. To criticize for a fault or an offense: call down, castigate, chastise, chide, dress down, rap1, rebuke, reprimand, reproach, reprove, scold, tax, upbraid. Informal : bawl out, lambaste. Slang : chew out. Idioms: bring (or call) (or take) to task, call on the carpet, haul (or rake) over the coals, let someone have it.


We'll just rename your implementation of the Arvo Part the "Flexible Flyer" :D




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[ThomasW]

Hey write you own material don't plagerize others :a>'>




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[Dennis H]

Actually, SL does address panel resonances. Lots of double thickness areas in the bass bin. Deep side rails to stiffen where the mid panel meets the bass bin - 4-6" at the joint tapering to 2" at the top. A sorta constrained layer construction of the mid panel - 3/4" + 1/4" with flexible glue between and glue block stiffeners on the back side.

That said, I haven't seen an Orion up close and personal so I can't say how well it all works.

[ThomasW]

Dennis,

Oops, I didn't properly phrase my statement. :cry:

I expected SL to be as exacting in his examination of potential panel/cab resonances, as he is with other aspects of the design. Now perhaps he has done this, it wasn't an issue, so he chose not to discuss it. Or perhaps he discusses it in the plans, I don't have access to them. I only have the website info. I saw the front panel reference in his text and the bracing in the photo's.

For the Arvo design we'll measure, diagnose, and cure, any issues with panel/cab resonances. That info will be detailed in this thread and on our website.




theAudioWorx (http://www.theAudioWorx.com)
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[ThomasW]

Just finished my first extended solo audition of the prototypes.

It's interesting; in any design where we've used the M8a woofers, I've heard details that were new to my ears, in recordings I thought I had memorized. The Arvos are no exception.

So ................

I LOVE THESE SPEAKERS!

No, they aren't in the same league as my big hybrid planar array. But they are delightful. Detailed, but relaxed. No slam, not for metal heads. Just beautifully clear, articulate, airy, and musical.

Since the system is currently powered by my lowest performing electronics, I can't wait until it's time to fire up the high end gear.......Hey is that the sound of rapture????????

Suppose it's the new tweeter? ;)

Next step; build a 4 driver dipole sub to augment the bottom end..... Then buckle your seat belts, put your tray tables in their upright and locked position. Prepare for lift-off cause we're gonna .......
:party:




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[JonMarsh]

I think they're growing on Thomas.... 8)

Which is a good sign. I think the tweeter plays a signficant role, but also probably the dipole behavior up to 1.25 kHz. And reasonably low distortion, too, not just from the tweeter, but also the midwoofer array, which running down to only about 200Hz is pretty "relaxed", and the moderately long throw woofer array.

I'm looking forward to Thomas getting the parts sent out to me, and getting my own crossovers built. Maybe/hopefully I'll start the tweeter networks this weekend with parts I have on hand.

ThomasW should be receiving a rather heavy box today, via UPS.... something to hook up to the Arvo Part's! Let's see if the party quotient goes up any!

;b>'> :party: :clap:

Thomas, can you toss a couple of the LPADs for testing into the box, too?


Time to go get some breakfast! :eating: :coffee:


~Jon




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[ThomasW]

Arvos + Ayre Power = Bliss.........!

Many thanks Jon, :T




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[JonMarsh]

Cool!


:amen:


Not too surprising. Are you running a V5 on top and an Argon on the bottom? That combination should work quite well.... :-y

~Jon :yeah:




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[Davey]

SL mentions panel vibration/resonances concerns a few times on his website so I'm confident he's investigated this. I believe he feels these are not of major concern because as a result of the layout the radiation from the panels themselves is also dipolar in nature. Kind of a self-cancelling-radiation....SCR. I just made up an acronym. :)

Anyway, I haven't tried this but I suppose if you taped an accelerometer mid-panel you'd see some activity, but if you then attached one on the opposite side of the panel and summed their outputs you wouldn't see much.

As SL is inclined to mention all the time...."Dipoles are a whole different ball game."

Jon/Thomas. The Arvo project is very cool!

Cheers,

Davey.

[ThomasW]

Kind of a self-cancelling-radiation....SCR. I just made up an acronym.
Were that the case it would be great. Unfortunately when the panels themselves are acting as 'transducers', the front and rear waves radiating from the panels, are interferring with the sound coming from the drivers. This is true regardless of whether or not the speaker is a dipole.

Now my quick and dirty prototypes define the term 'flexible flyers'. When Jon gets his properly built baffles operational, we'll take some measurements and see what's really going on.
Jon/Thomas. The Arvo project is very cool!
Thanks. We're have a couple more surprises up our sleeves for these speakers, so stay tuned. ;)




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[Davey]

Thomas,

I understand, but relatively speaking how big a problem is this? I mean how much panel damping is enough?

Cheers,

Davey.

[ThomasW]

Davey

We'll know the answer to that after we've measured the resonances of Jon's baffles. His have much more robust construction as compared to my 'flexible flier prototypes' :D




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[JonMarsh]

Other's who have "fought" panel resonance find that it's observable on the impedance curve, and that it makes some notes or ranges of the bass thicker or more forward than it should be.

Compared with ThomasW's baffles, mine are slightly smaller, laminated up and are thicker, and use solid oak as both "decorative" end pieces but also part of the panel bracing.

The "observed" glitches on the impedance curve in the range between 50 Hz and 200Hz are quite low. We didn't characterize Tom's panels that way, but it would be the logical thing to do.

Thanks. We're have a couple more surprises up our sleeves for these speakers, so stay tuned.

Gosh darn, Thomas, you aren't trying to give hints about the "Arvo Ultra" already, are you? :gossip: :naughty:

That's a problem when we haven't fully completed the orignal design and we're already thinking about upgrades- better not leak any more!

:smackbutt:

~Jon




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[JonMarsh]

Some preliminary testing on an alternative woofer was done today. The Sonic Craft SCC 300 is a cousin of sorts to the DPL12, having the same basket, though not quite as extreme a venting on the pole piece. It has just slightly lower Xmax, but markedly higher nominal sensitivity, especially considering the 2.83 VRMS is driving a nominal 8 ohm driver, not four ohms.


Imp 8 ohms
Re 5.31 ohms
Qms 13.47
Qes 0.457
Qts 0.442
Vas 145.0 liters
Fs 25 hz
Xmax 15.55 mm
Xmech 25 mm
Spl 90.2 dB @ 2.83 V
Le 2.125 mH
Mms 110.65 grams
Mmd 103.63 grams
Cms 362.52 µM/N
Rms 1.304 kg/s
Sd 530 cm²
Bl 14.14 TM
No 0.478
Pmax 250 watts


Biggest concern was whether it would be "noisy" in the rear output when hitting some significant cone excursions; after connecting it up and driving it at 25 Hz for two hours at 3/4" peak to peak, I can say I don't think that will be a problem; I never noticed it was running, due to the free air dipole cancellation, and the lack of extraneous noise.

First milestone check passed- next will be measuring in the new test panel being constructured, and seeing if sensitivity and other paramters are mostly as specified. The top end reportedly is relatively extended and smooth; all we need is 400 Hz clean for a 225 Hz crossover.

http://www.soniccraft.com/images/scc1.jpg


So far, it's looking good. :banana:

Speaking of new test panels, this morning I laminated up the raw front baffle for the new test system. It's a little different, being laid out to handle the 12.5" frame of the SCC 300. This baffle will be 1-1/2" thick, laminated from 6 layers of 1/4" HDF. It took almost a quart of Titebond II to complete the assembly; tomorrow I'll take it out of the clamp. Finished width will be the same as the first Arvo Proto's, but the height will be 54" instead of 48". The backs will have a bit more counter recessing than the last ones, which were only 1" thick, and will also have an additional brace in the woofer section. And these were drawn up in AutoCAD, instead of on the back of a napkin, like the first ones two years ago. :LOL:

There's more pieces to laminate and cut out, so I don't expect to have this new test platform together for another week or so.

~Jon




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[Al Garay]

RIGHT ON JON!

Glad the SCC300 is working out. Can't wait to find out how it works in the latest Arvo.

Al

[Stevepaul]

Jon,Thomas,

Great to hear things are coming along. I am a new member here at this forum. I have been communicating with Thomas off-site and thought I'd register at this forum considering I am going to be building the Dipole design you folks are working on.

The SS9800 tweeters are here, the M8n's are on order....can't wait to start ripping wood and soldering xovers.

Thanks guys,
Steve

[JonMarsh]

Welcome to the HT Guide Al and Steve!

I'm pretty excited myself to see how this newest version works out- the SCC 300's look pretty good.

The new baffle is quite a bit heavier than the first one I built, but that's partly due to being half an inch thicker, too.

I'm having some of the inductors custom built by North Creek, as the very low DCR values in larger inductors aren't readily available from many sources- about the only other comparable NAFT source is Solen, CA. I got my first batch in last week, too; they look pretty good, and measure dead on spec. These were sourced for the values required for the MkII 10" Titanic; if as expected, I go ahead with the SCC 300', I'll just end up unwinding them a bit to create the new values required, as they'll be somewhat lower for a 4 ohm speaker.

I'll bring my digital camera home from work where I use it in the lab a a lot, and take some better pics of the SCC 300 and North Creek Inductors.

I'll be creating PDF's of the cabinet drawings from AutoCAD; if possible, I'll host them with URL links for download; otherwise, it will have to be email.

Best regards,

Jon




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[sfdoddsy]

If you need hosting, I'd be happy to stick the plans up on my site. I have bandwidth galore and my Bob's would be glad of the company.

Steve




Steve's DIY Dipoles (http://www.doddsy.net/steve6_008.htm)

[JonMarsh]

Thanks, Steve, that's very generous.

I popped for a hosting deal with Virtual Avenue Net the beginning of the year, so for now I'm in good shape, no where near my bandwidth limits.

We're having a lot of fun with these speakers; it's also inspired me to get my butt in gear with the new board design for my Aragons, which whill retrofit the amplifier modules with a Non loop or interstage feedback design. That's coming along quite well in simulation; should start PCB layouts soon.

Best regards,

Jon




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[Stevepaul]

Hey folks,

I had the M8n's on order from Parts Express and they had listed them as out of stock until April 2nd. Lo and behold......the UPS man shows up at my front door on Friday night (3/5) with a large box. :oh:

"What is this?" I ask myself..........out come 4 M8n's with attractive light bronze cones! I showed them to my new wife and she said "those are so pretty". So, I proceeded to tell her my plans for putting the ARVO's in the great room.....and she said, "Don't put those ugly grill cloths over those pretty cones.....They match the color of the walls". !!!!! OH LORDY! I then told her that the speakers would be about 54" tall...almost as tall as her. She says, "Oh....thats fine, it's your hobby, have some fun with it". OK....what the hell is going on here!!!! :bluezoned:

Do I have the best wife....or what!

Anyways, the M8n's are here and the SS9800 tweeters are here.....things are coming together!!

Steve

[Al Garay]

Is Nordstom's having a sale?

You are a lucky man!

Al

hey Jon, I would be very interested in your cabinet instructions. I would like to build the woofer section of the Arvo using my 2 SCC300 drivers as a altenative to my single sealed 4.0cf SCC300 sub.

Why would you prefer multiple layers of HDF as opposed to MDF/BB sandwich?

[JonMarsh]

Short explanation might be I just enjoy being a pain in the @ss. :)

Longer explanation would be for others to use what they prefer, on a construction results versus construction ease.

I haven't been afraid to experiment in the past with some various combinations. I have used true BB ply with HDF lamination with good results. But for the strongest results, the multiple layer HDF has worked best. YMMV.

These cabinets used a combination of those techniques- for the critical front panel, pure HDF laminated up; for the sides, lamination of HDF and BB ply.


http://audioworx.virtualave.net/LivingRoomW_DrvrsSS.jpg


HDF mills and routes better than BB or any kind of ply. For that reason, I prefer to not use any kind of ply for front panel duties. Now, for a dipole speaker, you don't have much else besides front panel! ;)

The FP will be recessed routed for the drivers, and backside a 45 degree chamfer will be used to open up the window area for the midwoofers and woofers.

~Jon




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[ThomasW]

Gees I ordered 4 sheets of BB ply today, $35/sheet. 8O

And I'm bummed, can't find a supplier for the 1/4" Corian wall material. I can get the 1/2" stuff, but hate to pay for that much material, when it's only going be used as a veneer......... :cry:

Can't decide between this "Space Black"

http://www.dupont.com/zodiaq/images/large/CC_SpaceBlack_lg.jpg

And this "Night Sky", for the baffle and sides...

http://www.dupont.com/corian/images/large/CC_NightSky_lg.jpg




theAudioWorx (http://www.theAudioWorx.com)
Klone-Audio (http://www.klone-audio.com)

[Hank]

Jon, I haven't said, but I admire your cabinets, know what a mass you're manhandling there. Lots o' labor in those laminate/angle cut mamas. Of course we know they're not too heavy for a young guy such as yourself ;)

Thomas, you've found a supplier who will sell you small pieces of Corian?? You've done the seemingly impossible! There's always been a problem with that - seems as though Corian limits sales to fabricators of countertops only. Did you find one that will sell you scraps? Don't sweat the 1/4" versus 1/2" thing - you've managed to buy small quantities of Corian! Reality check: is it acoustically "dead" enough to warrant the hassle?

BTW, I vote for "Space Black". Why? More 3-D appearance.

[ThomasW]

Hank

Nope not scrap, full sheets = $$$$$, so the 1/4" vs 1/2" is a HUGE price difference.

Yeap the stuff is pretty dead acoustically.

I like the "Space Black" too and for the same reason, 'depth' .... :D




theAudioWorx (http://www.theAudioWorx.com)
Klone-Audio (http://www.klone-audio.com)

[PMazz]

Shame you're not closer....but shipping Corian would probably be pretty expensive.

Have you called around to countertop fabricators? Sink cut-outs and fall-off can be found dirt cheap....if you can live with whatever's laying around.

Pete

[ThomasW]

Pete,

Thanks for the offer...... ;)

I have a friend that works at a commercial cab shop. Supposedly they'll get me any 1/2" Corian I want. For some reason they don't have access to the 1/4" stuff. Unfortunately their 'drop' wouldn't be big enough for my needs.

I was talking to Jon about this, he made mention that the 1/2" Corian wasn't going to be priced much different from some exotic hardwod veneers. So I may just bite the bullet....

Maybe I'll just go with Hershey's "Special Dark", oh wait that's chocolate :D




theAudioWorx (http://www.theAudioWorx.com)
Klone-Audio (http://www.klone-audio.com)

[JonMarsh]

Yeah, I was going to vote for "Special Dark", too! :LOL:


Not knowing the "scale" of those sample pics, my choice would be "Night Sky", but then I'm not the one going to be living with them!

Of course, that's made me wonder a bit if I should reconsider some of the cosmetics for my own set, but really haven't been able to come up with an idea I like that doesn't sound like even more work than I want to get into! Particularly not with the re-activation of the Argaon Xmod project, and the CPU cycles THAT's soaking up.

I'm thinking I'll stay reall close to my current cosmetic plan, except probably an oak strip divder horizontally between the big woofs and the midwoofer tweeter sections.

Jon, I haven't said, but I admire your cabinets, know what a mass you're manhandling there. Lots o' labor in those laminate/angle cut mamas. Of course we know they're not too heavy for a young guy such as yourself

Hah! I wish I resembled that remark, particularly the bit about the young guy! Well, it's all relative- I'll nver be this young again, will I?

Now see, the way I explained things to Thomas, given what we have in drivers and other components, and given that I estimated the "bargain" price for really good Rosewood for the M8T&A (above) to veneer at about $800, I didn't think he should really sweat the Corian cost- these should be his family room speakers for the next 10 years or so, so just amortize out the cost!

I figure these dipoles are my next to last speaker project for quite a while; the only other one on the drawing boards still is the RD based project. Now, imagine what a stack of JP2 ribbons to complement the RD's above 5 kHz is going to cost- corian or rosewood doesn't look like such a big deal. Let's see, $112 per 5 inches on each side, if I get 8 per side, that's about $1600 of ribbon tweeters. WhooooBoy! But compared to buying something, it's pretty cheap. And like the last ribbon array Thomas and I put togehter, it would probably still be in use 15 years later, with little likelihood of being replaced soon.

I figure I'll pay for it out of the money I save by not getting a new car anytime in the next few years- I'm only putting about 5K miles a year on my Z28, so it's got at least 5-10 years left in it at that rate. The registration this year (it's a '95) is only $79. Sure do like paid for cars. :yeah:

Gotta go laminate up another panel assembly- see youall later!

~Jon




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[Dennis H]

I figure these dipoles are my next to last speaker project for quite a while

Ha! If anyone believes that, I've got a nice bridge to sell them. :rf

[Al Garay]

A good Rosewood veneer finish does not need to cost $800. Unless you are including the cost of labor and finish.

I have seen Dave Ellis and Darren Thomas (http://www.thomaswoodcraft.com) produce beautiful cabinets with veneers from Tape-Ease. You might want to keep an eye on their specials (http://www.tapeease.com/specials.htm).

For example, Tape-Ease currently has a 4'x8' sheet of Teak 2-ply (flat-cut) veneer for about $40. The regular price is closer to $70. And the Teak quarter round sheet is closer to $80.

Rosewood Santos is closer to $205 for 4'x8' sheet of 2ply and $157 for 10mil paper-backed veneer.

The M8ta would look stunning with all different types of finish:
* piano black
* Honduran Mahogany with a stain to match 18th century Mahogany furniture
* matte black baffle with the rest in a lighter veneer like Maple or Beech
* lots of good examples in Jim Salk's gallery (http://www.salksound.com/gallery.html)

Al

[David Meek]

these were drawn up in AutoCAD, instead of on the back of a napkin, like the first ones two years ago

Drawing something up on a napkin isn't a bad thing. The design for this little toy (according to published stories) was originally drawn up on one on a train. . . .

http://webpages.charter.net/djm97/br-p-51_5.jpg

Also, that's some beautiful Corian you are looking at Thomas. I've gotta go for the Night Sky. Subtle, tasteful and perfect for a family room.




David - HTGuide flunky
Our "Theater" (http://www.htguide.com/bilder/index.cfm?fuseaction=arkivbilder&userid=0&selecteduserid=18)
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[ThomasW]

Al

Given that Jon's M8a t&a is designed to be a 'statement' project, he is chosing to go with a very high-end AAA grade rosewood veneer. So yep it's $800 8O

http://www.joewoodworker.com/catalog/images/rosbol305.jpg

David,

I do some of my best work on napkins, old envelopes, or even worse. Frequently even that intermediate step is omitted. I just grab mechanical drafting tools, and do the layout using the raw drivers and the baffle board itself. Doing that really complicates creating a second copy. ;)




theAudioWorx (http://www.theAudioWorx.com)
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[JonMarsh]

A good Rosewood veneer finish does not need to cost $800. Unless you are including the cost of labor and finish.
I have seen Dave Ellis and Darren Thomas (http://www.thomaswoodcraft.com) produce beautiful cabinets with veneers from Tape-Ease. You might want to keep an eye on their specials (http://www.tapeease.com/specials.htm).

For example, Tape-Ease currently has a 4'x8' sheet of Teak 2-ply (flat-cut) veneer for about $40. The regular price is closer to $70. And the Teak quarter round sheet is closer to $80.



I'm quite familiar with Tape-Ease and many of the other popular sources for veneer, as well as the projects you cite. Thanks for your suggestions, regardless. Note that good figured maple in larger sheet sizes is pretty expensive also- really, it's just a personal, subjective thing; just like some folks like building and restoring old GTO's over a more modern car, I have a real fondness for high grade roswood. To each their own.

But the M8t&a is a rather large cabinet, and as Thomas alludes, for this I prefer to use premium materials- AAA pre-70's cut NOS veneer, which I not so jokingly refer to as "Classic Bang and Olufsen" grade rosewood- mid seventies, not what they and many others shipped later in the 70s and afterwards. It's not easy to find, and it is expensive. But the results, properly applied and finished, are quite striking, but in a mores subtle manner than, say, Zebrawood.

http://audioworx.virtualave.net/LivingRoomW_DrvrsSS.jpg

When you consider the amount of labor and materials and custom tooling I invested in just to get the cabinets to this point, $800 for veneer is not unreasonable. A finished set of Avalon's in the better veneers are ~$15K.

In some regards the whole thing is a bit Quixotic, but it's just my oddball vision for what I wanted in my bedroom system. Something a bit unique, I guess, though obviously not in a completely original way. But since I gave the original founder of Avalon (Charles Hansen) some large, heavily built faceted face speakers around 1980 which lead to his fascination with ultra rigid cabinets and the first Avalon models, I can say that in some sense, things have come full circle. ;)

Regards,

Jon




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[Al Garay]

The picture says it all. Very impressive sheet of veneer. 8)

Al

[Al Garay]

I'm glad the cabinet and finishing work on the Arvo looks less intimidating. What material will you use for the sides and woofer cabinet? 6-layer 1/4" HDF sandwich for the baffle. Will the sides and bottom be a BBHDF sandwich?

Al

[Hank]

I don't understand. Look at the cabinets I just finished, on the third page of my crude. low res website: .http://www.geocities.com/hankbond1/index
That is primo rosewood 10-mil paper backed veneer and looks as good as the pic above, and it was $150 per 4' x 8' sheet. NOWHERE near $800

[JonMarsh]

Well, Hank, on the upside, just think, you'll always be able to underbid me! :LOL:

This veneer isn't paper backed; it's solid, about 0.032" thick. I'll never be the low cost producer, obvously, using stuff like this!

Best regards,

Jon




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[robertwb70]

these were drawn up in AutoCAD, instead of on the back of a napkin, like the first ones two years ago

a little OT here but...

funny you would mention that-I just went to an airshow yesterday and learned that the engineers designed the P-51 after a tour of the Messerschmitt factory before the US entered the war-and looking at early pics shows more than a little similarity-the difference is the mustang evolved and became much better -the BF-109 didn't

Messerschmitt BF-109

http://www.bf109.com/gallery/favourites/gall03favesm.jpg

P-51A

http://www.mustangsmustangs.net/p-51/survivors/images/H41-038.jpg

I've heard the same napkin story about this one too

http://www.wvi.com/~lelandh/b5.jpg




=+=+=+=+=+=+=
"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston

[sfdoddsy]

For Corian, try these guys:

http://stonewood.safeshopper.com/index.htm?993

When I was living in the States they were willing to supply to any size I wanted. Ask for Kenneth.

Cheers

Steve




Steve's DIY Dipoles (http://www.doddsy.net/steve6_008.htm)

[JonMarsh]

Yeah, I've heard about the "conceptual link" between the P51A and the BF109. One of the things which seemed to distinguish US military aircraft development at that time, was the willingness to get an airframe design out the door in a hurry to meet immediate needs, then take feedback and new ideas and steadily upgrade it, addressing shortcomings that were uncovered in the field.

This was a very pragmatic approach; fortunately our "competitors" at the time didn't have the same wisdom, with regards to either personnel, or hardware.

For example, while we rotated pilots who had completed a tour of duty back to home for training new pilots, the Germans just kept them on the frontlines until their luck ran out... and their training program never advanced in quality or effectiveness during the war, unlike ours.

~Jon




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[Hank]

This veneer isn't paper backed; it's solid, about 0.032" thick. I'll never be the low cost producer, obvously, using stuff like this!
Jon, why buy that, when it will be more difficult to work with and won't offer any cosmetic and certainly any sonic benefit?
Okay, don't answer, you saw it, you liked it and you just had to have it ;) We all make impulse buys, despite our male declarations to the contrary.

[JonMarsh]

Yup, that's me, Mr. Impulse Purchase Unlimited! :banana:

My impulses tend to take on an evil life of their own... just ask some of my old girlfriends!


Well, back on topic, slow work takes time, but it's getting there. The basic CAD plans are finished, see the render below. There will probably be some additional oak trim as per the first Arvo Protos. These days the impulses take a while to realize, but fortunately the vision is persistent enough to compensate for the lack of speed in execution!

http://audioworx.virtualave.net/ArvoPartV2Proto2.jpg

If all goes well, later this afternoon I'll be routing front panels. First, gotta do the chores in the back forty and get ready for a hectic two weeks at work- travel to Houston again, the Electronica Power Electronics Conference, and visitation by headquarters technical Marketing person for HV Discretes for some joint project work. The latter will be a little more pleasant than some of those visits, as besides being very smart, she could be a a younger sister to Rebecca DeMornay.

http://us.ent4.yimg.com/movies.yahoo.com/images/hv/photo/movie_pix/twentieth_century_fox/master_and_commander__the_far_side_of_the_world/rebecca_demornay/masterpre2.jpg

Y'all have a good Sunday....


~Jon




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[Hank]

Jon, it might be best for me to join your meeting with the technical marketing person, just to keep you focused. :yeah:
Tough week ahead, huh?

[JonMarsh]

Sometimes the tough part is staying focused on the right or necessary things... ;)

The test panel did get routed Sunday, and the bottom panel laminated up. I like the size (smaller) of the original Arvo a little better, but I have a good feeling about how these are going to sound and work.... cross fingers!

I'm going to be doing some training for her on SMPS topics, and we'll also be doing some evaluations of our new 5th generation CoolMOS, which will be officially announced in May at the PCIM conference in Nuernberg, Germany. If you'd like to help, Hank, then come on out! :party:


The other "ugly" side to my job is the air travel; flying out Sunday, won't be home till about midnight - 1 AM Monday night, then they still expect me to go into work and be ready for the conference in SFO the next day!
:uhoh:


Last weekend I was a zombie because of mechanical flight delay causing me to miss my flight from DC to San Jose, and having to take the last one out of DC to SFO, and finding ground transportation home at 1AM in the morning from SFO. That 1AM was 4AM east coast time, which was where I'd been all week. YUCK! :boohoo:

Have a good week, Hank. ;)


~Jon




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[Hank]

then they still expect me to go into work and be ready for the conference in SFO the next day!
The bastards! :conveyer:

Jon, tell the blue-eyed one that the Texan says "Howdy Ma'am" ;)

[JonMarsh]

Here's a chuckle, Hank. We're actually going to be in Austin for a few hours on Monday; we have to fly up after our HP meetings in Houston, run out to Dell for a quick meeting, then zap back to the airport to beat feet for the left coast.

Talk about band on the run! :driving:


~Jon




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[Hank]

Jon, if I weren't going to be in an all-day meeting with the Pooh-ba's of a Japanese projector company Monday, I'd say call my office from the airport or Dell and let me say HI to the blue-eyed one. If she's German, ask her if she knows any Frankenbergs. BTW, you should see the family crest - main character is a fox with feathers stuck to it's mouth ;)

[JonMarsh]

She's Swedish, last name of Dahlquist. In fact, as far as I know, speaks hardly any German; fortunately for me, English is the lingua franca, still.

Sorry you're going to be tied up, too, or I'd give you a call!

~Jon




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[Hank]

Well, at least ask her to mail me a photo... oh, never mind.
Now, where were we?

[JonMarsh]

Uh, I dunno, was it something about speakers? Yeah, that's probably it... it will come to me sooner or later.

Actually, another reason the Arvo's aren't moving along quite as fast as they should is the CPU cycles being devoted to the Aragon Xmod development. But THAT's a whole other story! :coffee:

~Jon




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[Al Garay]

Follow the advice from the wise turtle in Finding Nemo.... FOCUS DUDE!

We're waiting to rock'on with the Arvo.

Later dude.

Al

[JonMarsh]

Ah, true, Al, true. :yesnod:

But in my defense, most of those stolen CPU cycles have been on my commuter train, where the availability of my woodworking tools is slim to none! ;)

Should have some time today to work on the base and finish the first front panel, while doing laundry and packing for my biz trip tomorrow. :tired:

Have a good weekend, guys!

~Jon




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[JonMarsh]

In the vein of slow work takes time, I'm pleased to say that the time I'm taking is resulting in progress....

The Arvo 1.2 evaluation mule is being glued together today; I expect it to be in the "paint shop" tomorrow AM, and Oak finishing tomorrow afternoon.

Next step will be a new fresh set of measurements, probably on Monday, which I also took off.

Standby for further developments.... ;)

~Jon




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[JonMarsh]

The Arvo 1.2 test mule has been built and loaded without painting, and a new concept for hardwood trim has been developed which is removable and will be installed later.

However, final data and conclusions for the driver direction won't be made until these arrive and are tested also; they were shipped the end of last week, should be in sometime this week while I'm on biz travel again.


http://audioworx.virtualave.net/TC2_Front.jpg


http://audioworx.virtualave.net/TC2_Side.jpg


The TC2+ looks from the specs to be in the ballpark I'm looking at with regards to efficiency for an 8 ohm net driver (voice coils in series), so that doubled drivers in parallel should net ~93dB. Re is high enough that the 4 ohm load minima should be reasonable. We'll see. The linearity is reported to be quite good; especially within a more restricted excursion range of +/- 10 mm, the K plot is VERY flat.

And their cone modes are up quite high- might actually be able to take these high enough to use in a dipole line array with the RD50.

Embarrassment of embarrassments- can you spell "Gilmore Audio Klone"? :naughty:

http://www.glacieraudio.com/images/glmrgirl1.jpg

Plus, they have these really cool dark gray/black inverted aluminum cones, which are so in keeping with the theme set by the HiVi 8's. :banana:

Today, unforunatley, is to be spent working on a notebook adapter design for HP, and a server bias supply for Artesyn. Yesterday was a meeting with one of our key R&D people at the SFO airport while he was in transit back to Munich.

Audio work goes really, really slow when I don't get my weekends.

:banghead:


~Jon




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[Hank]

And their cone modes are up quite high- might actually be able to take these high enough to use in a dipole line array with the RD50

Now you've got my attention. Well, maybe I did sorta notice the Gilmore girl and her nice pair of drivers, but nevertheless I remain interested in a dipole line array.

Jon, I looked at the Gilmore driver cones on one of their speakers at the C.E.S. and was not impressed. They looked like aluminum foil laminated over a rigid material with a honeycomb pattern embossed on them. Maybe you saw a different speaker. You do realize that if you clone those, you'll be subjected to unmerciful ridicule here, don't you? However, a lot could be overlooked if you got your own "model" ;)

[ThomasW]

Hank

That's standard construction for the 'flat' cones. It was invented by Panasonic/Technics a LONG time ago.

We're got another set of 12" evalutaion woofers for the Arvo design on order. These are the TC Sounds TC2+ from O Audio. These have a one piece metal cone. It's construction is identical to that of the Hi-Vi M8a so no separate dust cap. We should have these before the weekend.

Since the Arvo design won't have grills we were looking for drivers that we think are really good looking as well as sound good ........

Since we've been unable to obtain the Hi-Vi M12s, Jon is seriously considering a line of 4 of these/side to be used with his B&G RD50s.

http://oaudio.com/images/front.jpg




theAudioWorx (http://www.theAudioWorx.com)
Klone-Audio (http://www.klone-audio.com)

[JonMarsh]

Yeah, the TC2+ are a significant step up from the driver built for Gilmore; bigger magnet, and a nice inverted hemisphere aluminum cone. Closest thing I've seen to an M12, but over twice the Xmax, and 8 ohms, instead of 4. Net voltage sensitivity for two wired in parallel (4 ohms) should be about the same as two M12 wired in series (which are 4 ohm drivers); lower impedeance, but over twice the Xmax. Probably higher Xmax than the Gilmore audio drivers, as their surrounds look kind of puny.

Now if only I could get my PHD friend in a promo shot, something along the idea of the thinking persons' (engineer's) dipole line array.

Hmmmm. I doubt that her boyfriend in Stockholm would like that... :roll:

Could hardly blame him! :LOL:


~Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[JonMarsh]

Some views for ThomasW of the work in progress and status....

No time for comments today...

PICs processed with QImage and custom Sony D770 plugin. Checkout DDI software, they're pretty cool.


http://audioworx.virtualave.net/Arvo12Empty2.jpg

http://audioworx.virtualave.net/ArvoBack1.jpg


http://audioworx.virtualave.net/ArvoUpperBack.jpg

~Jon


http://audioworx.virtualave.net/ArvoBackWoofers.jpg

[JonMarsh]

Well, we've come a little ways from this point; not any prettier, yet, though!

There's a big stack of Pau Ferro (aka Bolivian Rosewood) in the garage which will be used when I get down to the cosmetic finishing. Didn't publish the schematic in this version, either... probably wise, as it's still a work in progress.

~Jon