Arvo Pärt MkIII "Heavy Metal" Testing...

[AJINFLA]

The Force is strong with felt
It may be even stronger within Bondo. ;)
Liberal doses on the back of the Pyle/MCM guide you must.

Cheers,

AJ

p.s. They are ribbed for pleasure (and I would imagine strength) also. Non too resonant to begin with.

[Evil Twin]

That might be a faster and less expensive solution than using chop glass and resin to reinforce it- but for the latter there would be no question about the adhesion, and the weight wouldn't go up as much.

Of course, the correct answer is try both and compare.

[Rudolf]

Well, that IS a drawback to this and BDS, is that neither seem to handle interaction with the floor. Particularly that has an impact for the woofers (say, dual 12's near the floor); there's going to be something like a mirror image reflection, depending on the material.
Mirror image is what the author of EDGE is recommending. Looks like Diag. 26/27 in Chapter 5 (http://www.dipolplus.de). Red is without floor, green with floor.

Did you know that Martin King today has published an OB simulation worksheet including floor-, back- and side wall interaction? Have a look at http://www.quarter-wave.com/Models/MathCad_Models.html :T

Rudolf

[JonMarsh]

Thanks for the links! I did something like that years ago for box systems- it will be interesting to take a look at Martins' OB simulation!

~Jon

[CraigJ]

Did this sticky become unstuck?

Yesterday, I brought the Arvos out of the basement and into the "family room". My wife's only comments were, "when are you going to put a back on those speakers?" :jawdrop:

No back, no way.

Craig

[cjd]

Get creative with acoustically transparent fabrics on a frame. :)

C

[ThomasW]

Did this sticky become unstuck?Jon 'unstuck' it because he's working on a new baffle design. The idea is to start a new sticky with all the newest information, as opposed to force people to wade through 15 pages of posts......

I'll restick this then Jon can cut it loose when he's ready to go with the latest and greatest design...

[CraigJ]

So my Type 2 and Type 3 Arvos are already obsolete? :thud:
Glad it's fun building and just mdf....

Craig

[JonMarsh]

No, it's that the Type 3 is really a fairly significant change from the original U baffle Arvo. I've done a substantial number of panel simulations now with "The Edge" for baffle size, shape, and driver location- though I tried many other things, the Type3 is still "wining" for the moment, though I may make another pass at the Type 2 for "traditionalists". The Type 3 as it stand now very much should work well for a 200-250 Hz crossover, with acoustical properties supporting that with a passive crossover.

What was a little harder was getting the midrange location so that with a single midrange it's a smooth as a dual midwoofer Arvo (one of the reasons I used that approach earlier), and I think I have one that will work well for a single C90 (can you imagine the cost of MTM C90s!?!?!?!), as well as a single 830-883.

A set of first test baffles have been laminated up (true 3/4" BB ply, plus 1/4" HDF on each side), and more would have been done last weekend if some other issues non-audio related hadn't intruded. (maybe this coming weekend, but then there's a bunch of work stuff going on right now, so no promises).

I've also figured out some ideas for how to handle the spars and bracing and make it more "buildable" for those without access to a large format plotter, so I'll have to test that out, too.

The initial "proof" of the pudding will be finishing the first test baffe and seeing if stuff measures as I expect from the simulations, and if the mechanical baffle design is stiff enough. I think it will be... but the proof is in the pudding. Have all the hardwood bits selected. Oh, and there's that waveguide stuff to work out- got to get the router table going this weekend.

Will probably build two pair ultimately- one pair with the Aurasound and Accuton drivers, and Bolivian Rosewood, and another pair with RS315HF, 830883, RS28a, and white oak or maple hardwood. The second pair might have a waveguide, too, depending on how well that controls the tweeter flare near cutoff. Depends on the baffle strength- the RS315HF are a lot heavier, of course! Maybe need to beef up the baffle a little more for them.

~Jon

[Marzen]

Jon, could you post or send me your files for the RSS315HF-4? I'm bogged down with laminate flooring at the moment & no me-time in the near future for fiddling with SoundEasy. Thanks.
Ward

[Marzen]

RS314HF 4ohm

Here's the RS315HF- not the same Q and LF corner behavior- this driver has not been run in, so possibly that will make some difference. Pretty flat from 50 Hz to 800 Hz or so- without EQ, it would sound lighter in the bottom end, but I bet the lower midrange definition will be fairly good. Will need to do some cluster tone nonlinear distortion and shaped sine burst linear testing as a follow up shortly.
Never mind on the data files, I finally got my jig back together, now with added voltage dividers for increased power readings. If you should get around to doing the cluster tone & shaped sine burst testing could you please go into some detail as to your settings/setup as you did with this earlier post. Thanks.
Ward

[Hank]

Here's a link to the custom dipole that a local customer had Craig at Selah design: http://audiocircle.com/circles/viewtopic.php?t=27731

[JonP]

It may be even stronger within Bondo.
Liberal doses on the back of the Pyle/MCM guide you must.

p.s. They are ribbed for pleasure (and I would imagine strength) also. Non too resonant to begin with

That might be a faster and less expensive solution than using chop glass and resin to reinforce it- but for the latter there would be no question about the adhesion, and the weight wouldn't go up as much.

Of course, the correct answer is try both and compare.

Getting back to this thread after a while......

I have a thought... there is this fine stuff called "Quake Hold", what is also called a "museum putty", that is used to tack things down on shelves. This stuff is like Silly Putty, but leaves truly next to no residue. Works well for added mass Vas measurments, it's pretty massy.

I'd guess it would be pretty lossy from a vibrational point of view as well, and it will sure stick where you put it. Filling all those nooks and crannies with it should do a pretty good dampening job. Another advantage, it would be reversable... you could pull it out of there if you wanted to. I will use that, when I get there, for a different project that I have those Pyle/MCM horns for.

Jon (another one)

[Hank]

Here are those dipoles that I sliced for a local customer (he assembled and veneered them). Greg of Selah Audio designed them:
http://i60.photobucket.com/albums/h19/Hank12006/Jasonsdipoles1.jpg
My impression: VERY neutral-sounding. They're in an apartment, so I can't listen to them at live performance volume levels. That acid test remains to be done in a couple of months when he moves into a house.

[TacoD]

Wow nice looking.

[Beau]

Jon, in the original Arvo design, where did the rise up to the dipole peak occur for the woofers? Was this one of the reasons that you decided to go for a flat baffle?

Beau.

[seattle_ice]

The current working network design for the Arvo is as shown below, but this could change a little more- might bypass the series attenuation to pick up the 12 kHz + level on the RS28a

(Is this something that would make any serious difference?)

Need to do a final sanity check on the tweeter section- this is with the M8a.

http://www.htguide.com/forum/attachment.php4?attachmentid=2497&stc=1


I'll draw up one sometime soon with the high pass elements on the midwoofer removed, and no EQ in the passband (there's not much here anyway- the asymmetric layout helps with flattening the axial response, as it would for an enclosure style speaker).

I am not sure if I quite understand what the purpose of this would be.

~Jon


I have put together a few crossovers, but nothing this complex. I look at it and can't even tell which driver is which. Nothing like getting out of your comfort zone to make a person feel ignorant.

[Eric S]

Thomas,

Some time ago, you had indicated that you and Jon had replaced several of the caps in the tweeter network with Theta Audio Caps and noticed a large improvement in the sound. Looking at the D5 network, there are a number of caps there. Did you replace all of them with the Thetas? Or did you just replace select caps? (if so, do you happen to remember which ones?)

Thanks,
Eric

[soho54]

I'm not Thomas, but you want to replace the ones in series, C2 and C3. Then if you wanted to, bypass c11, c10, and c9 last.

[ThomasW]

Where 10mdf represented 1/2 or so the value of a cap in the tweeter section, I removed a 10mdf GE and put in a 10mdf Theda Audio cap.

There certainly was an improvement, but "large' is not a word I would use to characterize it. It was significant enough that it justified the cost of the caps, but understand I get them for PE's wholesale price which is $10ea less than retail.

Note that the MTM section of my Arvos is powered by a Ayre V5-xe. So the active electronics aren't the limiting factor for SQ.

In playing around with my Maggie project, I found 2 -1mdf Theda Audio caps in the spare parts box. I tried these as 'bypass' caps in the tweeter section of a pair of MMG's (the stock cap value was 24mdf) in this situation, there was no audible difference at all....

[soho54]

Found JonM's old post about it. From the "New MTM's in the Worx..." thread.ThomasW has not been a believer in "botique" caps or crossover components, but when we modified his Arvo Parts this last November with AudioCap Theta 10 uF caps in both of the tweeter caps (paralleled with the necessary GE or Solen caps to get the balance of the value) he became a believer. My Arvo's have been that way since day one. At $40 a piece per 10uF cap, it's not something everyone will go with, but I'd do that before I'd buy high buck interconnects or speaker wires. Thomas was pretty amazed at how much denser and heavier these caps are. Available through PE. Obviously, that would raise the cost quite a bit. Mine will be that way, as are my M8ta crossovers being built.
Man, was it really in late '04 when Thomas' Arvos were converted? 8O Time flies by sometimes. I've been lurking for years now. :B

[ThomasW]

Man, was it really in late '04 when Thomas' Arvos were converted? 8O Time flies by sometimes. I've been lurking for years now. :BYep....

[Eric S]

Thanks for the insights, Thomas! Much appreciated!

Eric

[CraigJ]

Hi Jon,

If you are still around, is it O.K. if I add three inches to the Arvo Type 3 baffle for tapering (1.5" 15 degree taper each side)? I am hoping to make the final version now that the snow has fallen. 1.5" Baltic Birch + 1/4 Hard board each side.

Welcome back....for now.

Craig

[JoshK]

I am making slow progress on mine finally as well. I've cut all the pieces and currently veneering them before doing the driver cut out. The iron-on method works a treat!

I am laminating solid 2x2" mahogany trim around the sides to accomodate a 1.25" roundover. The Veneer is ribbon mahogany.

[CraigJ]

Hi Josh,

Congratulations on your progress. I bet your speakers will look fantastic. I've decided to add an inch and a half to my baffle instead of adding trim. The trim will be a solid color to blend with a veneered baffle (tbd).

Yes, the iron on method is easy and accurate and your Ribbon Mahogany will look beautiful! Do you have construction photos?

Craig

[JoshK]

I was planning on taking some construction photos, but so far they would be boring as they are all flat pieces but a few of the veneering process would be nice.

[JonMarsh]

OK, this is an update promised to a few folks who want to run the Arvo Part "Classic" bi-amped between woofers and midrange and passive otherwise- sometimes known as the TW Special Edition, though his weren't ever implmented as shown below (being first isn't always being best). ;)


Here's the LspCAD Diagram. I'll explain what this means in practical terms....

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

This looks a little different from a pure passive crossover in LspCAD. The TF1 block on the left in the woofer network represents the active crossover low pass- it's two 2nd order filters with Q of 0.707 cascaded, which gives a Linkwitz Riley 4th order Low Pass, such as you might get from a Behringer CX2310. That's followed by a buffer G2 with gain of unity.

Next is the secret sauce- the outboard inline passive LF equalizer, such as might be inserted between your active electronic crossover and power amp. Here, it's been developed for a nominal load of 22 kOhm, which happens to be the input impedance of Aragon power amps. (that's R14; in practice, R14 is omitted, or if you have an amp with higher impedance, a resistor is used in parallel so that the resistor plus your amplifier's input resistance equals 22 kOhm). This can be built in mono or stereo into any kind of small chasis with input and output connectors such as RCA; to do balanced, just build a circuit for the hot and low XLR pins. Resistor should be 1% for EQ tracking precision; caps 5%, preferablly film and foil or metalized polypropylene film, at least. Total insertion loss is about 10dB, so you'll have to have your LF crossover output cranked up, and your HP output turned down to balance.

That's followed by another buffer, becuase the passive filter can't drive a driver; that represents your power amp. Gain is unity again; in practice in the real world, each power amp stage might have a gain of 26 - 30 dB; we don't need to represent that here.

The corner frequency to the LP is set to 150 Hz. How come? Well, to get things to work nicely with those fixed inflexible active crossovers, given the transfer function of the drivers, we have to play some games a bit to get a nice crossover behavior. Due to the peaking of the woofer in the U-baffle, and the 8" open mid bass starting to give out, we can achieve a good acoustical transfer function crossover at around 200 Hz by having the electrical set to 150 Hz; in combination with the driver performance, we get more or less what we want acoustically, though I have to run inverted phase on the midrange for it to sum in the crossover region. Can't fix that in the active fixed crossover, whereas with a passive I stagger poles and zeros to get the ideal acoustic transfer function, or pretty close. (see plots further down, SPL and transfer function.

In the middle section, we take out the series cap and parallel inductor, and have to adjust impedance compensation and other network values to get the desired midrange bandpass. As much as possible I optimized for standard sized components and smaller caps or impedance compensation networks. The high pass is a LR-4 also set to 150 Hz, since we have to keep the frequencies the same with a standard analog electronic crossover.

The tweeter network isn't modified from the last Dayton RS28a design; it has the upper range response EQ tweak (R6, R10 and C12) instead of plain Lpad; this gives the RS28a a little more life in the top octave.


http://audioworx.virtualave.net/ArvoPartBiamp-SPL.jpg


This is the transfer function of the total crossover design- if you want to try this with a DCX2496, this is your target.
http://audioworx.virtualave.net/ArvoPartBiamp-XfrFunctions.jpg

So, in summary, two way electronic at 150 Hz, passive inline LF equalizer for bass lift below 100 Hz (about 9-10 dB max), and a passive midrange to treble crossover.

[300b-luc]

OK guys, this is in response to requests for prelimin detailed info on current baffle design, crossover, and LSPCAD modeled behavior.
3/17/05 Note the links below are broken and can't be fixed, since the hosting server no longer exists. See the end of this thread or the other Avro thread for the latest data.
Front Dimensioned Drawing PDF (http://audioworx.virtualave.net/ArvoPartV2Front.pdf)
Side Dimensioned Drawing (PDF) (http://audioworx.virtualave.net/ArvoPartV2side.pdf)
Prelim Crossover Schematic PDF (http://audioworx.virtualave.net/ArvoRC1Schematic.pdf)
LSPCAD Plot Diagrams (http://audioworx.virtualave.net/ArvoTC2RC1Diagrams.pdf)
The cabinet diagrams don't detail the Oak side panels or other trim features I'm considering. It also doesn't detail the rear relief bevel I'm using for the drivers- like this...
http://audioworx.virtualave.net/ArvoUpperBack.jpg
~JonI wonder if somebody could help me in getting some detailed plans for the speaker system since I cannot find the right links
thank you
Luc

[Dennis H]

This thread is only 3 pages and has the cabinet drawings, the latest crossover and some comments on drivers.

http://www.htguide.com/forum/showthread.php4?t=21550

[JimS]

There's also pictures of the test baffle construction as well as the current "classic" version at the link in Thomas' sig which might be helpful.

http://www.theaudioworx.com/

Jacob also did a great job of photo-documenting his construction.

http://www.htguide.com/forum/showthread.php4?t=19861&highlight=arvo

[Eric S]

Hi Jon & Thomas! I have now accumulated a nice stack of speaker boxes and am beginning to think about constructing the speaker baffles for a set of 5 Avros for my basement theater (crossovers will come a little later...).

The construction of the left and right speakers is easy enough, but how should I build the center channel?

I was planning on taking each of the TC woofers and pushing them out to the sides and sliding the M8a & tweeter panel down until it hits the floor, so that they MTM is sitting between the woofers.

My question is: How do I structure the support pieces on the back side of the center channel's baffle?

In the original design, the pieces on the back of the baffle surround the woofers, but now the woofers are separated by the MTM section. Should I "box" in each woofer individually and leave the MTM section "open"? If I do box the woofers individually, should I keep the approx depth of the rear pieces close to the original design (approx 8 inches deep at the top and keep the same 75% angle as it extends to the floor), or should I do something entirely different?

Thanks for your guidance!
Eric

I'd either box each section individually, or just use a baffle one each side of the 8's, and leave the 12's open on the sides, but increase the size a bit- maybe 18-20" for the baffle size from the "divider" to the edge.

[JonMarsh]

Link to the 8 ohm 12", http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-444


Interesting driver for IB or Dipole applications - Qts of almost 0.5, adequate sensitivity (86 dB/watt); two in parallel might be pretty good for an Arvo Part with 4 ohm net woofer impedance.

[crackyflipside]

I guess since I got to hear the Arvos against the seas WWMT my opinion might count for somebody contemplating on building one.

Without going too far into strange adjectives and words. The Arvos were much clearer in the midrange and especially in the high-end. Cymbal crashes sounded much crisper and realistic. I'll be honest that I didn't notice a difference in the sound of dipole bass vs monopole bass (although the drivers were not mounted completely secure). In terms of the soundstage, the wwmt's did provide a well centered sound, with the arvos the soundstage sounded much wider and enveloping.

The biggest difference to me was the clarity in the midrange and high-end.

Edit: And for that reason, now I will be forever disappointed by speakers that don't perform on par... :cry:

[soho54]

Hit with the Arvo curse huh? ;)