Arvo "Classic" Build

[JimS]

New Year - time for a new project.

I'm starting a build on a "classic" Arvo with the RS28A, M8A and RS315HFs. Passive on the upper, CX2310 on the bottom. Form factor similar to Jacob's, although final aesthetics tbd as I go.

I hoped to be further along at this point, but work's been keeping me pretty busy. Most parts in stock & ready to go. I've been having a tough time finding Baltic Birch in the DC area (even the two specialty wood stores I've tried nearby only carry 5 or 8 ply), so I may just go with glued up MDF/HDF.

Thomas - how are your new baffles coming? I did a quick mock-up and it looks like I can lower the tweeters about an inch (final height 52")- is this about what you ended up with or were you able to squeeze them down a bit more?

Off on a work trip for a few days - hopefully some progress to report next weekend.

Jim

[ThomasW]

I build the Arvo's as upper and lower modules. The individual sections have been built for months, but aren't assembled.

One can decrease the distance between the lower M8a and the upper 12" to lower the overall height.

Originally I planned to have them operational for JonW's visit, but the weeks of snow and bitter cold have focused priorities toward survival as opposed to speaker building.

[soho54]

Good luck. :T

I found that visually the most I could remove is one inch between the MTM and woofer sections. This balances the areas between the MTM, woofers, and top trim piece. I decided not to alter anything in the end.

You could also take another .5 inch from the MTM/woofer section if you take it off the top of the main baffle as well, and make the top trim piece .5in taller. Of course you have to compensate on the sides as well by taking .25in from each side ('cause .5in is getting to close to the 12's), and taking a .5in increase in overall width. The extra .5in width shouldn't cause a problem, but it's a lot of work for an extra .5 in lower tweeter.

Also if you look closely at the pic's of mine from the side, the trim is 2in wide and the base is only 1 5/8in high. You can only tell if you are lying on the ground. Every little bit helps.

[JimS]

Not only am I building Jon's speakers, I appear to have taken on his mantra as well . . . "slow work takes time" :B

Between 50 hour work weeks w/ mucho travel, coaching kid's hockey, playing live music again after a few year hiatus, and keeping the house from falling apart, life has conspired against me getting these underway the past few months.

Finally, some progress to report . . .

Found 13 ply birch at the local BORG (8x4 so it's not the great stuff, but it was $23 and had enough non-knotted area to get two nice front panels). Rough cut and glued the birch up to 3/4 MDF. Tomorrow should be final cuts on the front panel and routing for drivers. Hopefully I'll post some pics this weekend.

Current plan is to do a 'negative' of Thomas' and Jacob's look - birch panels on the front stained a bit darker (thinking teak-ish to add some yellow to go with the M8As), edges routed for roundover (some wood putty to fill the edge voids), then truck bed liner for the roundover edges and backside. So overall look would be wood front panel with black sides and trim all around (not really trim, but optical illusion from the roundover) . . . unless anyone tells me this is a really bad idea for some reason.

I also like Darryn's idea of the rounded top, but unsure if I'm willing/able to go to that trouble right now . . . since the tweeter is offset, I don't think a minor rounding would do too much damage diffraction-wise . . .

https://www.htguide.com/forum/showthread.php?t=21550&highlight=arvo

Jacob - it's unclear from your pics how you did the hollow for the base wiring - is it 2x1s glued to the sides of the oak base and rounded over?

[ThomasW]

So overall look would be wood front panel with black sides and trim all around (not really trim, but optical illusion from the roundover) . . . unless anyone tells me this is a really bad idea for some reason.

Framing anything with a black border creates visual 'closure' around whatever is framed. A secondary effect is that it will make the speaker look smaller.

A rounded top baffle is not an approved change.... :naughty:

Glad you finally have time to work on these.... :T :B

[JonMarsh]

Yeah, complicated lives make for slow woodworking or project building. It's looking like the 2nd half of 2007 may turn that around for me, due to the mandatory PTO thing. Hoorah!

Meanwhile, I'm looking out a panoramic window at the SFO international terminal at a very foggy and cloudy SF sky, waiting for my flight to Frankfurt.

Just picked up another variant on my Concepts unlimited 3D, called ViaCAD (Punch Software bought Concepts), and for $99 MSRP (either windows or Mac), it's pretty cool, everything but the surface materials and advanced rendering, and actually has some spiffy new ease of use features, including new preformatted document templates, a new way of switching between 2D and 3D, enhanced libraries, and a large collection of Quicktime movie tutorials (the main reason I bought it, for $84.99.

It's weird, they have two SKU's listed for the Mac version, one saying "no operating system", for $84.99, and the other version listed "for Mac operating system" for $99.95. I just got the former, installed it on my MacBook Pro last night, and did a test load of some CU files (no problem). It has a slightly more refined user interface, and the owners manual is the size of a conventional paperback, which is really quite convenient (comes with double sided reference cards the same size).

I have installed the older Concepts Unlimited 3D on windows just to see how it works, and it's just fine, almost all of the features of the Mac version.

ViaCAD specs



Certainly worth checking out for anyone looking for easy to use (Logicursor is what was originally the smart snap in Ashlar Vellum), fairly powerful (excellent 3D solids tools and import/export).

We now return you to your regularly scheduled programming. ;W

~Jon

[tyler]

Certainly worth checking out for anyone looking for easy to use (Logicursor is what was originally the smart snap in Ashlar Vellum), fairly powerful (excellent 3D solids tools and import/export).

Jon,

Have you compared this to Alibre Design? It doesn't look like you can beat the price on ViaCad though.....

[JimS]

Framing anything with a black border creates visual 'closure' around whatever is framed. A secondary effect is that it will make the speaker look smaller.

That's the idea . . . higher WAF if they appear to be mini-towers as I sneak them downstairs!!

Unfortunately just lost one other good illusion as well . . . my mitsubishi 55805 (calibrated, duvetyned, etc.) blew the convergence ICs last week (apparently a pretty common occurrence on these models after 5 years due to bad solder joints), so I needed a quick replacement for the rest of the Stanley Cup until I can figure out how to fix it. Went to the dark side (sony lcd) and it is waaay thinner and nowhere near as tall, so I lose the TV towering over the speakers look as well. (PS - new lcd's still leave quite a bit to be desired compared to a well-calibrated crt - sxrd might be a different story but didn't have the $$ to try that out.)

[soho54]

Jacob - it's unclear from your pics how you did the hollow for the base wiring - is it 2x1s glued to the sides of the oak base and rounded over?

That is the idea. I wanted a thick, but lite base. I also didn't want any end grain showing. It was a perfect fit.
Here is a better pic, before sanding.



The edging is 1x2" with a 3/4 chamfer. The main base is 3/4" oak, so there is a little over 1" for wires under there. :T

Not shown is that I also screwed some 1x1" strips along the base/trim joint for needed extra strength. It doesn't touch the ground, but it doesn't need to. (On the underside, 1x1 cheap pine stock... don't tell.)

Good luck.

[JonMarsh]

Jon,

Have you compared this to Alibre Design? It doesn't look like you can beat the price on ViaCad though.....

It would be hard to beat the Alibre Design Xpress price!

They look similar in some important features, like assoicative modeling with parametric based history. Concepts/ViaCAD do support aerospace conventions for conics and other constructs.

What I DON'T see for Alibre is a Mac version, which is my primary computing platform the last few years. Concepts (CSI) and ViaCAD are available for Windows or OSX 10.3.9 and higher. Missing part booleans would be a significant drawback to me- (the Xpress version), but who knows? the price is right! Concepts/ViaCAD really excels at 3D solids, you can get some idea of the capbilities on the CSI site.

[Eric S]

Looks like a great start, Jacob. I've got my drivers and the wood working starts next. Well, next as in after my front sidewalk, rock retaining wall, 2 trees, and 30+ bushes get planted in the front yard...

Slow work does take time :B

[JonMarsh]

30!!?!?!!!

Oh yeah, now I remember what I didn't like about being a house owner..... :W

~Jon

[Eric S]

OK, 30 was a rough guess. Looking at the plan again, it shows 37 bushes/shrubs in total. I figure I won't be able to put a saw to some wood (either financially or time-wise) until September...

So keep going, Jacob! If you don't mind, I'll steal your very nice ideas when I get around to working on mine!

Eric

[soho54]

Looks like a great start, Jacob.

That's old news. I finished them a year ago now, remember? I was wondering if you ever got around to slapping yours together yet. It's funny how life can sometimes put things on hold for so long.

Whatever happened with that coil winder?

[Eric S]

Finished already, my, my, how forgetful I am :B

The coil winder is actually a project I can complete in a reasonable timeframe. I bought a cheap electronic counter that will run off of a 9v battery. Next I need to cut the cores for winding the coils on. The bobbin will be a 3-piece device: a circle core and two end-plates. I need to play with my saws for a little while to cut my circles to the appropriate thickness and diameter.

The trick is that I haven't yet come up with the best way to "lock" the circle core to a handle for winding it. I suppose just using a threaded rod with locking nuts will work if they are made tight enough. I was thinking that perhaps purchasing the copper magnet wire would be my best move since metal prices seem to keep going up. I'll buy the caps later...

[JimS]

[QUOTE=soho54]
The edging is 1x2" with a 3/4 chamfer. The main base is 3/4" oak, so there is a little over 1" for wires under there. :T QUOTE]

Thanks - that's what it looked like . . . but better to ask twice, cut once . . .

[JimS]

Some progress today

cleaned up edges on main baffles, routed recesses for all drivers, cut the side panels (they still need a bit of edgework, but the angled cuts came out well - I generally had to roughcut pieces close to final size prior to gluing up - now beginning to see the value of a big outfeed table :B )

forgot camera ops:

hopefully more progress soon . . .

[JonMarsh]

Forgot Camera?!? That's the most important tool for HT Guide related projects! :W

Seriously, glad to hear you're finding some time to work on things again. I'm just getting back in that mode myself, and on Tuesday heading out to Denver for some serious DIY. :B

Meanwhile, a little more baffle fabrication then some measurements and design are on today's agenda.

Keep up the good work Jim...

[JimS]

more progress . . .

front baffles done: all driver holes completed (everything fits :T ), backs of mids beveled to 45 degrees, birch edges routed with 1/2" roundover (this was the money cut - no glaring errors :T ), sides cleaned up, tops cut (w/ 70 degree angle on back to match the sides), bottoms rough cut, everything is close enough on the dry fit :T

two questions:

45 degree bevel on backs of M8A is only 1/2" deep bit (1.5" total baffle) - looks like there's still some masking - do I need to buy a deeper chamfer bit or is this enough (thomas' photos look like they're 1/2" - thru 2 layers of HDF - but also looks like that baffle was only 1" thick)

I shortened the design 1" in the middle - the mids are a bit closer to the "top" of the back now - I'm weighing the advantages of just using a single 3/4 piece for the top of the backs - likely slightly less stability but slightly less rear-masking on the mids. thoughts?

4-5 test stain pieces done - leaning towards straight watco danish oil (in walnut) at the moment . . . still planning on a few "combo" tests

digital camera is still with the wife at the beach . . . pics tomorrow

Jim

PS - found a great plastics glue called "surehold: plastic surgery" - don't ask why (set the router down funny and cracked my jasper jig last week & refused to pay yet again for a piece of plastic - next big project I'll go with Pete's homebrew version that rotates around the collet - bet you didn't have fun like this at speaker camp!!)

[ThomasW]

PS - found a great plastics glue called "surehold: plastic surgery" - don't ask why (set the router down funny and cracked my jasper jig last week & refused to pay yet again for a piece of plastic - next big project I'll go with Pete's homebrew version that rotates around the collet - bet you didn't have fun like this at speaker camp!!)

Oh! but we did....

I dropped one router (picked it up by the dust port exit which released the entire weight of the router.) This resulted in a broken jig, I've yet to see if it can be repaired.

Jon had the steel collet collar split on the DW621 he was using. The router started to vibrate madly. He then wrongly accused me failing to adequately tighten the collet when I set it up..... :roll:

[JimS]

I dropped one router (picked it up by the dust port exit which released the entire weight of the router.) This resulted in a broken jig, I've yet to see if it can be repaired.

Oh but it can be :T . . . the "plastic surgery" held it through 4 mid and 4 woofer cutouts - in fact the repair might be stronger than the original piece!!

[kingpin]

more progress . . .

45 degree bevel on backs of M8A is only 1/2" deep bit (1.5" total baffle) - looks like there's still some masking - do I need to buy a deeper chamfer bit or is this enough

Some coarse sandpaper on a palm sander will work perfectly. That's what I used on my 2"mdf baffle to help deepen and open up the back of the driver opening.

Mike

[JimS]

thanks mike - I thought about that & it's what I might end up doing - only issue is that these are open baffle, so someone might peek around back and notice my questionable hand-sanding ability . . .

[chasw98]

Jim:
When do we get to see some pictures?

Chuck

[JonMarsh]

thanks mike - I thought about that & it's what I might end up doing - only issue is that these are open baffle, so someone might peek around back and notice my questionable hand-sanding ability . . .

We promise not to peek...

[JimS]

sorry, no hosting at the moment - attachments should give you some idea

got one fully glued up tonight - pocket hole jig saved a lot of clamps!!

[JimS]

A few more . . .

[JimS]

And a sneak peak at phase II . . . (my build-photo homage to ThomasW's artistic sensibilities)

[chasw98]

Jim:
Thank you for the pictures. It is great to see them in the flesh, so to speak. They look very nice. Can't wait to see more.

Chuck

[JonMarsh]

looking good Jim!

Parts is parts, as Thomas would say.

-Jon

[Jed]

looking good Jim!

Parts is parts, as Thomas would say.

-Jon

Jon,

When taking measurments for a dipole with a passive crossover in mind, what steps must one take to assure accurate results given I know how to take measurements for a monopole?

Thanks
Jed

[JonMarsh]

If you're considering tonal balance just on the design axis, there's really no difference. That's usually the point used for crossover design.

In evaluating a potential dipole design, I think it's important to measure over several angles from on axis, to get an idea of the "pattern" control so to speak- to get the best in room power performance from a dipole, it's my experience, and I believe the recommendation of Linkwitz, that the off axis response should be as smooth and similar in balance to the on axis response. This requirement is why I've moved away from U-baffle designs, though they will give an output capability in on axis bass response over some part of the frequency range. And I never was aligned with the deeper, more "extreme" U baffle designs (cardiode dipole) that JohnK prefers and advocates.

I generally spend a lot of time simulating the baffle design and driver placement to come up with the "best" possible response (or desired response) for the drivers on the design axis. That's why my baffle shapes have changed a bit, and why they have never been symmetrical - there's good reasons for not having symmetry for the baffle design and layout, even for monopoles, though for esthetic reasons we often ignore that. That's why the tweeter is offset to the location it is in for the NatlieP and ModulaMT, for example, as well as for the Arvo Part which Jim is building here.

[JimS]

Parts is parts, as Thomas would say.

-Jon

And in case anyone is interested in the "parts" . . . large caps will be made up of paralleled Aerovox 20 & 28 uF and tweeter will be paralleled 8 uF Ultracaps from apex jr closeouts. The Ultracaps are listed as +/- 10% and all came in low by about 3-6%. Interestingly enough, the Aerovox's didn't have any tolerence listed and all were within +/- 1%, mostly on the high side :E . . . should be much better matched than my ears . . .

Slightly more progress . . . 2nd speaker assembled, bases cut and assembled (same hollow plan as Jacob & Paul for clean wire routing), sanded & wood putty'd (lots) for the BB voids on the edges (now I see why most folks use trim), front baffle finish is beginning to look nice - decided on watco danish oil (after many stain tests), started with one coat of natural and I'm up to 3 coats of light walnut on the first baffle - tomorrow will be back to natural for last few coats.

Tested paint technique on a piece of scrap (for the roundover edges of the baffle) and ran into one potential issue - even after masking there are a few spots where the paint seems to bleed slightly down the woodgrain - it's not too bad, but I'd like to try to keep the lines as crisp as possible - any ideas how to avoid this?

Jim

[soho54]

What type of paint are you going to be using?

Is it the primer or paint that is running the grain?

[bratislav]

Arvos parting ...

Unfortunately, despite Aussie $ having a hike on US counterpart (making all those goodies you guys take for granted available for plebs Down Under like me), it is the UPS decision to stick only to air mail that killed the Arvo for me. As RS speakers aren't available anywhere in the world aprat from Parts Express, I'd have to buy them from that source. Well, for a kit of 4 RS 315, 4 M8a's, for the postage alone I was quoted almost EIGHT HUNDRED BUCKS !!!
That effectively killed the project for me :M :M :M

[augerpro]

I think these guys just started carrying Dayton down under: http://darcheraudio.com.au/

[Dennis H]

Woah, $800 for shipping? Doesn't seem right but it sucks bigtime if true.

[bratislav]

I think these guys just started carrying Dayton down under: http://darcheraudio.com.au/

I know. Still no M8a (but let's say they will do it at some point). The real killer are 315HFs, as they are bulk of the size/weight. And they are only available from PE.
:cry:

[JimS]

What type of paint are you going to be using?

Is it the primer or paint that is running the grain?

I tried both truck bed liner & rust-oleum texured black on the test piece - both bled a bit, but the textured black to a much greater extent - I've used both in previous projects so for once skipped the primer step on the trial piece - I'll retry a test piece with primer and see if there are the same issues or if the white primer seals off the grain a bit better - leaning towards textured black at the moment since it looks a bit classier.

Bratislav - sorry to hear about the AU shipping - I caught the RS315HFs on sale at PE for $100 each with a free shipping coupon, so made the project much more affordable on this side of the pond . . . if you order a few times from PE, they'll occasionally send a free shipping coupon with your order (don't know if there's a $$ limit, but it worked for me within the US) . . . I've been hoping to get this entire project in for under $1,000 but it took a lot of patience with parts orders and I still haven't added up the totals . . .

Slightly more progress . . . got both bases sanded and routed with roundovers . . . one more coat of oil on both baffles . . . crossovers layed out and paralleled caps soldered . . . beach trip with the family later this week so likely no more progress until August . . .

[dlneubec]

Tested paint technique on a piece of scrap (for the roundover edges of the baffle) and ran into one potential issue - even after masking there are a few spots where the paint seems to bleed slightly down the woodgrain - it's not too bad, but I'd like to try to keep the lines as crisp as possible - any ideas how to avoid this?

Jim

I'm not sure where you are using it, but you might be able to strike a line with an x-acto blade at the edge where you want the paint to stop and get it to stop running. I've never tried it, so test first for sure.

[soho54]

The trick in this case, is to build a raised or lowered boundary.

Tape off the area with blue tape. Take your time, and don't go cheap on the tape. The easy way is to skip primer and go to a non-tacky, quick drying flat black spray paint. Make sure you test a few brands and get one that does not get tacky. It should go on smooth, and be dry to the touch in ~15min. Go with four or more light coats over a two day period.

Give it a day to sit.

Now all you have to do is roll/spray the texture on. The spray paint has sealed the grain, and hardened over the tape. No soaking under the tape. :T

The method dlneubec posted will work as well, but you will be able to see the scribe line.

I found that I preferred the look of the truck bed liner rolled on first, then gone over with the spray can liner. If you roll it the lumps are a little to much, and the slight gloss it will have make them that much worse. A light coat from the spray can on top, makes things 200% better.

My only other advice is to take your time, go slow, and do the best you can. If you are anything like me, all you will see are the mistakes when you are done. :roll:

I forgot, make sure the speakers are perfect before you add the truck bed liner. Flaws show up like crazy though it. You would think it would hide them a little. Nope. They show through after it totally dries in a day or so, as shiny spots. 8O Don't skimp on the prep-work, and don't add the TBL until the black layer is flawless. Not trying to scare you, just save you some re-finishing work.

[soho54]

Sorry, I somehow missed the part where you said you had used the TBL before. I'm not trying to talk down to you. I just blacked out in that part of your last post. :roll:

[JimS]

Sorry, I somehow missed the part where you said you had used the TBL before. I'm not trying to talk down to you. I just blacked out in that part of your last post. :roll:

No worries - always helps to be reminded of how much of a PITA good prep work is . . .

Tried one more trial piece . . . flat black spray as the first two coats and a little more attention to the tape edge did the trick :T

I'm leaning towards the textured black at this point - it is much flatter & smaller texture than the TBL. Only thing I don't like about it is that it is a pretty good dust collector & not that easy to keep clean.

Veeeery hard to stay on track to finish the cabs and not just mount the drivers and fire them up . . . must resist . . .

[bratislav]

Arvo Maybe

... I'm not giving up (yet).
It looks like I'll have to give up on RS315's, there is simply no way to get them in Oz. I was quoted by darcher A$480 each for them (that is almost US$420!) You'll agree that is a bit too much for a driver that sells for ~$100 every now and then.

But !
I've been carefully studying the semi-active crossover discussed at the end of Arvo thread. What I have in mind is trying some other options for woofers as crossover for them seems relatively straightforward. I know I'll have to watch the phase between bass and mids, but I hope things won't be too different if I get drivers that aren't too different from Daytons in that range .
I have just one question for now - compared to Orion's transfer function, Arvo's seem to be missing the ~8dB augmentation (dipole shelving low pass)at the bottom of the midranges. The same shape can be seen on Phoenix mid panel transfer function too.
I know that baffles are wider on Arvos, but not that much wider. So why is there no such (obvious) thing as dipole equalization for M8a's ? Or is this in a way "implemented" by a U baffle peak perhaps in the same range ?
It may sound stupid but I have to understand it before I attempt to hack it.

Bratislav

[Dennis H]

I have just one question for now - compared to Orion's transfer function, Arvo's seem to be missing the ~8dB augmentation (dipole shelving low pass)at the bottom of the midranges. The same shape can be seen on Phoenix mid panel transfer function too.

It's not really 8dB boost unless you measure from the bottom of the 500 notch. More like 4-5dB from the 850 Hz level. Jon's gets by without all that by a combination of a wider baffle, asymmetric mid placement and a higher cross to the woofers. The asymmetric mids avoid the notch at 500. The wider baffle lowers the frequency where the dipole boost starts a bit and the higher XO reduces the total dipole boost needed. Crossing 2/3 octave higher buys you 4dB less boost on the mids so it all works out.