Ardent Speaker Camp

[CraigJ]

There is another project which has been occupying my time and effort, which may also be completed for the RMAF meeting. No more on that until there are fruits of the endeavor to discuss.

O.K. then, we'll get Jon to spill the beans.

[Curly Woods]

John,

I think that I would spend more on MDF than drivers using the Dayton/Seas combo :rofl: Well maybe not that cheap, but a bargain in any event. The cost to performance ratio is incredible with these drivers!

[Curly Woods]

John,

Did you laminate 3/8" MDF on either side of the 3/4" MDF? The material just behind the front skin looks like it is a vertical lamination of some kind. What is that material?

[Bear]

I had to drive to a Lowe's 20 miles away- that's where I got them! The three nearby were all out.

Mine was only about 5 miles away. Of course, I made a swing through Rockler while I was out... Thanks for the tip -- this was just what I was looking to add to the shop for these types of projects.

[JonMarsh]

John,

Did you laminate 3/8" MDF on either side of the 3/4" MDF? The material just behind the front skin looks like it is a vertical lamination of some kind. What is that material?

Getting the specific thicknesses I wanted was a bit of a pain, given my limited storage and purchasing resources, and that I can't manhandle 4' X 8' sheets by myself. This project was built with starting from pre-cut 2' X 4' stock, from HD. You have to be careful buying from HD; there's variability in quality; fortunately I had a lot of the 1/4" bought previously, and their current 3/4" at my local stores is OK.

The side panels are made from 3/4 + 1/4 laminated on both sides- you must do that to prevent warping, just as with veneering. That gives the desired 1-1/4" thick sides and back. The top front panel layer is 1/4" MDF + 3/4" LBL + 1/4" MDF, for 1-1/4" total; the second and third layers are 1-1/2" by combining two 3/4" layers. Top is also 1-1/4", three layer lay-up. Titebond III was used for the panel lay up.

[Curly Woods]

I have access to 1 1/4" MDF (I used to own a figured hardwood lumber business, hence my moniker "Curly Woods"). Heavy as hell, but save some steps and much higher quality than the Borgs sell.

If you are having issues with MDF warping, you need to stop buying at the borgs! It should be incredibly stable as it has such a high content of glue in it. You might try spraying or brushing a coat of shellac on the interior of your cabinets in the future. That will seal it and not allow any moisture changes. A woodworker should always finish all surfaces, whether they will be seen or not for this very reason :-)

[---k---]

I have access to 1 1/4" MDF (I used to own a figured hardwood lumber business, hence my moniker "Curly Woods"). Heavy as hell, but save some steps and much higher quality than the Borgs sell.

I'm guessing you carry the high quality baltic birch ply also. You should start advertising here.

It's too bad you can't ship, or I would be more serious about that. I can't tell you how many times people are asking where they can get the birch ply and thicker MDF. I'm constantly recommending hardwood lumber stores, because that where I get mine from. I've never heard of people taking my advice. I think people are just aren't comfortable going to places that don't advertise during every commercial break.

Is there any resource that lists all the hardwood lumber stores nationwide? Is there an association or something? I used to be able to google it and find them for people. But now, it seems like get flooring stores only.

[JonMarsh]

MDF by itself doesn't warp, but if you veneer or layup panels to just one side, trust me, it will! :W That's why panel veneering is usually done to both sides- but with your background, I don't have to tell you about that!

I expect that if I shopped the pro lumber places around here I could get 1-1/4" MDF, but only in full sheets- I used to lug that sort of stuff around in my 20's, but I know better now- a 6'2 guy isn't meant to be carrying 150 lb on his own! :W

[Curly Woods]

John,

The veneering both faces is more of an issue with plywoods. Modern MDF really does not need this treatment, but as a rule it is still done. It still goes back to the fact that as a rule all faces should be finished the same to "seal" the substrate completely. Once this is done, moisture can not either enter or exit the material (in theory).

MDF is so stable that it should not move unless it is seeing some serious moisture though. I always spray all surfaces with shellac as a sanding sealer and or prep, unless they will be veneered. It is just an ounce of prevention to me.

Oh forgot the ask. Did you get you LBL at Home Depot too?

Now where are those drawings for these cabinets :-)

[JonMarsh]

No, the LBL came from my local (well, 30 miles!) Rockler store. And they carry it as a store special- it's not from corporate, they order it from a local specialty place because of the demand.

As to the MDF, you might be surprised- as a test, and to make something for my weird home made veneering process, I glued up some 3/4" MDF with 1/4" on just one side- I wanted to see if could make some slightly bowed pieces that could be used as veneer clamps for the sides and put more pressure on the center- worked like a charm.

Of course, I've set to see if my unorthodox veneer clamp for the sides will work, but I may know by this weekend.

[Curly Woods]

John, I always try to learn from others experiences rather than from what I am told from manufacturers. All that I can say is that I have never had any issue with MDF moving, unless it has been stored in an unsupported or odd manner.

Don't tell anyone, but I really prefer to have MDF laid up with a killer figured veneer for furniture, as it is way cheaper than using solid highly figured woods, plus the killer figured woods are almost always sold to veneer plants as they pay dearly for the best logs. Plus it will never move as real wood will expand/contract with the seasons.

[JoshK]

My attempt at given Jon a run for his clamp money.

[JonMarsh]

Looking good, Josh! :T

You're obviously a man after my own heart! :B

[augerpro]

Can't wait to hear these in October Jon!! Ever since your NeoD inspired me to build my Delphis I've had a thing for small mids with low order slopes. If I were to pick a cost no object mid these Accuton would be at the top of the list. They really make incredible drivers and the only ones really doing hardcones right.

[bigg]

Hey everyone. What is LBL? :stupid2:

[JonMarsh]

Hey everyone. What is LBL? :stupid2:

LBL = Laminated Bamboo Lumber


It's a manmade wood product created with strips of Bamboo about 1/4" thick by 3/4" wide; the stuff I'm using is glued together on the longer face to make panels. LBL is very stiff compared with MDF, resisting bending forces quite well, but it's not as heavy as dense hardwoods, and because it comes from growth that can be replenished/replaced in 3-4 years, it's considered "eco".


Has an interesting grain pattern on the face.



I'm using it embedded in the first front panel layer of the Ardent; it's what the drivers actually bolt down into. It's expensive, but not as expensive as phenolic or aluminum sheet.

After I already found this and bought it for the Ardents, I read about Jim Salk introducing a high end speaker at AK Fest using trans laminated bamboo sheets. I shudder to think what just the BOM for the cabinet is!!

[Jed]

I shudder to think what just the BOM for the cabinet is!!

I think he said just the wood before machining costs was around $1600 IIRC.

[Txgrizzly]

wow, that its some wild looking speakers, Jed, did you get to hear Jim Salks speakers at that meet? is that anothe driver on the side or is it a radiator?

[JonMarsh]

The HT4 has dual passive radiators. Knowing the driver lineup, I wonder what the system sensitivity is... hmmm, probably not much more than 82 dB after BSC considerations, if that. 80 may be more likely. This model isn't listed on the Salk site yet.

[Jed]

wow, that its some wild looking speakers, Jed, did you get to hear Jim Salks speakers at that meet? is that anothe driver on the side or is it a radiator?

Nope, but I have heard his HT3s, which I thought were great at RMAF a couple years ago. I'm sure the "HT4", or whatever they end up calling it, will be excellent as well. Dennis M is a talented crossover designer.

[JonMarsh]

Estimated price I heard quoted was $10K per pair. They're using that FAL planar wideband driver as a midrange, and a smaller RAAL tweeter. I wonder how the distortion is on that FAL...

[Jed]

Estimated price I heard quoted was $10K per pair. They're using that FAL planar wideband driver as a midrange, and a smaller RAAL tweeter. I wonder how the distortion is on that FAL...

I heard $15K (what's another $5K ), and they are using the OEM version of the RAAL (it can cross much lower than the smaller RAAL), along with a custom FAL driver.

[JonMarsh]

Yeah, once you get up to that turf, what's another $5 grand? I was just quoting what was in an article about AK Fest about the HT4, but if the raw wood cost is $1600, even with his direct to customer model, $10K would be too cheap.

[dlneubec]

Jim told me that the bamboo was so hard that it took one of his guys two days just to finish sand it. He was talking about coming up with a lower cost version that uses a smaller dia. subwoofer (a 10", IIRC) so that the woofer box could match the mid box in width. I believe the subwoofer is custom made for them by John J. over at Acoustic Elegance. With a smaller subwoofer, he could simplify the box design and construction and perhaps have an MDF version available to bring the costs down. BTW, I believe he said that the subwoofer crosses to the FAL at up around 400hz. I know Dennis and Jim checked out a lot of heavy hitters for midrange drivers and felt that the FAL driver was a clear winner, as was the RAAL tweeter.

Jeff Bagby did the bass bin design and he indicated is was pretty much flat to 20hz.

[Carl V]

it is & was an interesting speaker at AK fest.

Last I heard the smaller bass driver was performing
at nearly the levels of the bigger unit. And the OEM
Ribbon is quite nice. Oh & all is not perfect in the world
of FAL drivers....there has been some QC issues.

The Beast likes plenty of power.

And like curly woods I too cover the interior MDFor BB with
Shellac sanding sealer. I also brace like hell (BB)
...so no warping has been noticed over the years.

Looking forward to hearing your designs again Jon
are ya going to go out to that 'swanky noodle'
palace again....good food. I beleive it's one of Thomas'
haunts.

[JonMarsh]

it is & was an interesting speaker at AK fest.

Last I heard the smaller bass driver was performing
at nearly the levels of the bigger unit. And the OEM
Ribbon is quite nice. Oh & all is not perfect in the world
of FAL drivers....there has been some QC issues.

The Beast likes plenty of power.

And like curly woods I too cover the interior MDFor BB with
Shellac sanding sealer. I also brace like hell (BB)
...so no warping has been noticed over the years.

Looking forward to hearing your designs again Jon
are ya going to go out to that 'swanky noodle'
palace again....good food. I beleive it's one of Thomas'
haunts.

I'd be surprised if we didn't! But so far I'm not thinking that far ahead- right now, It's managing my "critical path" for all the things that need to be done between now and the end of the 3rd week in September, including new business travel!!

[PhilDSP]

Jon recommends hardwood also (see his AudioXpress article).

I'm just curious if anyone has any sound logic of why it sounds better? The braces are just taking axial tension and compression. The panel deflections are so small, the stress on the braces would be very small. I have wouldn't expect their to be huge demand on them, and as such probably anything could work. The difference between the E value for the very best hardwood and an engineered product is at best 26%. While that is significant, I just keep thinking that the stresses in the braces are going to be so small.

According to the charts I've seen Baltic Birch has a higher maximum modulus (rigidity) than oak and both are at least 3 times greater than MDF. That means MDF would need to be 3 times as thick in one dimension for the same resonance damping.

The likely reason that solid oak is superior is that there's a significant variation in the modulus for Birch (and other plywoods) depending on the orientation of the grain. Probably solid oak has much less variation.

[JonMarsh]

Good comments, Phil.

Let's think about this also.... I'm a former electric guitarist. Les Paul was a pretty smart fellow, and tried a lot of different configurations before coming up with using a very dense hardwood top panel (hard rock maple) backed by a softer wood for the rest of the body shape (mahagony).

Now, ideally, we want the driver mounting to be very stiff, resonant free, and not taking energy out of the drivers... so that all the energy goes into the room. Now, can you imagine what a guitar with an MDF body might sound like? I don't think it would have the sustain of my old Les Pauls, and for the same reasons, I'm moving away from MDF for the front panel baffle. In the past I've settled for just reinforcing it with hard woods, now I think it's time to try something different. Maybe not aluminum baffles yet, ala Magico and YG Acoustics, but something better than MDF.

[Dave Bullet]

All things being equal... can one rigidly clamp a driver, measure distortion and do the same on an MDF baffle (nearfield or allowing for bafflestep farfield) - show distortion as a delta between the two to quantify?

[JonMarsh]

The problem is not only the baffle, but resonances in the structure of the driver- this I've demonstrated to my own satisfaction, but then Sigfriend Linkwitz identified the problem and one solution much earlier with the Orion.

This is also addressed even for drivers with rather stiff frames like the Accuton C79 by Avalon Acoustics, and in the construction of the Eidolon and other speakers.

[kirknelson]

Maybe not aluminum baffles yet, ala Magico and YG Acoustics, but something better than MDF.

Concrete? It would be heavy but extremely rigid. I don't think creating a baffle cast would be too difficult and material cost is low. Am I correct in thinking that it would be fairly inert as well? It is mostly sand afterall.

I'm not sure how well it would take veneer though.

[JonMarsh]

I'm not sure how well it would take veneer though.

:rofl: :rofl: :rofl: :rofl: :rofl: :rofl: :rofl: :rofl: :rofl:

[ThomasW]

Concrete box:

[Hdale85]

....Aren't those lovely looking.

[JonMarsh]

Ya know, I think I'll stick to my LBL for a while...

[theSven]

Is this the start of your addiction to LBL???

[Hdale85]

If only LBL wasn't so expensive

[kirknelson]

....Aren't those lovely looking.

Haha, yeah those look kinda painful.

How about these:

Image not available

Full build here...in German.

Oh and those baffles are beautiful Jon. :T

[---k---]

Thomas, Are those yours? I would be interested in seeing more photos, just pure curiosity.

[ThomasW]

Thomas, Are those yours? I would be interested in seeing more photos, just pure curiosity.

No they're from a thread on DIYaudio

http://www.diyaudio.com/forums/showthread.php?t=51449&highlight=concrete+speaker+cabinets&page=3

[Hdale85]

Hmm...was that thread an April fools joke or something? Honestly....Did you see the driver mounted in it? I'm sure it functions...but it sure don't look pretty at all.

[AlanH]

Ya know, I think I'll stick to my LBL for a while...

Wow those are nice looking baffles...Given the relative newness of LBL, should we assume that they're for another new project that's sharing time with the Ardent's?!?!?

[JonP]

I'm not sure how well it would take veneer though.

Lots of sandable primer. Lots. Gallons and gallons... Did I say lots?

That, of course after the case of diamond 40 grit orbital sander disks to get things smoothed out a bit... 8O

[PhilDSP]

Let's think about this also.... I'm a former electric guitarist. Les Paul was a pretty smart fellow, and tried a lot of different configurations before coming up with using a very dense hardwood top panel (hard rock maple) backed by a softer wood for the rest of the body shape (mahagony).

Now, ideally, we want the driver mounting to be very stiff, resonant free, and not taking energy out of the drivers... so that all the energy goes into the room. Now, can you imagine what a guitar with an MDF body might sound like? I don't think it would have the sustain of my old Les Pauls, and for the same reasons, I'm moving away from MDF for the front panel baffle. In the past I've settled for just reinforcing it with hard woods, now I think it's time to try something different. Maybe not aluminum baffles yet, ala Magico and YG Acoustics, but something better than MDF.

I'm thinking that an ideal baffle or bracing panel would have highly rigid outer surfaces with one or more inner layers of a material with high damping properties, especially for low frequencies. I guess that's basically a constrained layer approach. High grade hardwood plywood should fit the bill as the outer surface.

[dlneubec]

I did the bass bin baffles for my BaSSlines out of 3/4" wide by 1-1/4" thick laminated hardwood, makore and hickory, backed by 1/4" HDF. They are very solid and pretty vibration free. The driver is also press supported along the back of the magnet with the bracing structure (see filler brace) which ties it to the rest of the box. BTW, hickory is extremely hard!

In fact, the ribbed box construction with cross bracing is probably the deadest box I've built as well. A couple more side to side to back and ties from between the braces vertically were added after the photo below was taken. Other than the MDF cross brace across the front behind the baffle (I ran out of oak) all the rest of the bracing is oak. Besides reinforcing the stiffness of the 3/4" MDF sides, the oak ribs give considerably more surface for the side to side bracing to be glued to, rather than just the end of the brace to the all. This bracing structure uses less volume of space, I believe I calculated around 25%, than the typical window bracing and should weigh less as well. These boxes (without the hardwood baffles!) are surprisingly light.

Bass Bin Baffle construction
Ribbed box construction

[JoshK]

Wow those are nice looking baffles...Given the relative newness of LBL, should we assume that they're for another new project that's sharing time with the Ardent's?!?!?

Yes, enquiring minds want to know.