Exceedingly Rigid

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I've made enclosures out of MDF and Baltic Birch but IMO stainless steel is far superior to both. It's not cheap and it's not the easiest thing to work with but it is far more inert than wood. The curved baffle makes it even stronger.
 

Attachments

  • jx92s.jpg
    jx92s.jpg
    38.9 KB · Views: 712
Yep. It's a shame how rarely commercial manufacturers really explore the rich world of materials. Mostly they just settle for good old MDF which is easy to finish and handle but far from the best in acoustical mathers. I guess at least very expensive speakers could have some effort on that issue as well.

Jussi
 
Jussi said:
Yep. It's a shame how rarely commercial manufacturers really explore the rich world of materials. Mostly they just settle for good old MDF which is easy to finish and handle but far from the best in acoustical mathers. I guess at least very expensive speakers could have some effort on that issue as well.

Jussi

No kidding. It boggles my mind that you can spend astronomical amounts of money for a pair of speakers and yet they are made with MDF. For a manufacturer to ask the equivalent of what a car costs for a product made of the most common materials shows a lot of audacity.


Eva said:
Doesn't steel ring like a bell?

If you shape it like a bell and hit it as such, perhaps if it is properly designed.


sdclc126 said:
I second that question - if metal drivers have ringing issues you'd think that metal cabinets would present similar characteristics.

I haven't heard many metal drivers and I don't believe there are that many on the market. But this is the one that I chose...

Jordan JX-92s

Ted Jordan has been very successful making metal drivers for over 30 years. The highly regarded JX92s is by far the best driver I have ever heard second only to the Visaton B200.

As for the metal cabinet, I borrowed inspiration from a few different sources, those being people who have tried many types of wood in search for the most inert material that would exhibit the least amount of interplay with the vibrations coming from the driver. Thus far metal has no equal. Wood colors tone plain and simple. That is why the artists’ craftsmen of musical instruments are very selective in their choice of wood. And isn’t it curious that nobody manufactures a guitar or a violin out of MDF?


phn said:
I think a bigger problem is the sheer weight of steel. Krell uses the compromise material aluminum.

Weight isn't nearly as much as a factor as cost and the difficulty of fabricating metal in comparison to wood. The average speaker made from 10 gauge stainless steel will weigh about double of its counter part in 3/4" MDF. The picture of the mini monitors at the top of the page weigh a little more than double of the Totem Model 1 (about the equivalent in size and volume).
 
diyAudio Member
Joined 2004
Eva said:
Doesn't steel ring like a bell?

ATC use aluminium enclosures that ring like hell without the baffle on but with them on, they are dead.

Maybe it has something to do with one end being open and not bracing the rest of the material and that's why it rings. Fixing the baffle to the enclosure certainly seems to back that argument up, whilst simultaneously killing the audible ringing and producing a fairly inert enclosure.
 
Cal Weldon said:


Not at all. The violin is producing the music. The colouration the wood adds is part of the appeal.

Loudspeakers are asked to reproduce and should add as little colouration as possible.

That is exactly my point. Enclosures made from wood add coloration to the tone. And while MDF arguably isn't wood, it certainly resonates at a much lower frequency than metal and thereby colors the tone.


noah katz said:
"it is far more inert than wood"

It's not inert at all (compare the ringing of a piece of steel vs. a piece of wood), but it is very stiff.

That makes the resonances higher in freq and easier to damp.

Resonance that occurs at the lower frequencies is far more problematic to the overall tone. If the metal cabinets are indeed adding color to the upper frequencies, it's not apparent. But as you said, these are much easier to dampen. IMO, tone isn’t the only thing affected by resonating wood, imaging suffers too.

FWIW, I made speakers with the same drivers in MDF and Baltic Birch. The steel enclosures are superior in every way.
 
JohnnyBoy said:
If the metal cabinets are indeed adding color to the upper frequencies, it's not apparent.
I used to use Vifa D25AG aluminium tweeters many moons ago. It was a good tweeter except that it had a character that sounded just like aluminium sounds. I later discovered it had a resonance way up at 11kHz.

soongsc said:
The higher density makes metal more difficult to excite. Thus the enclosure resonances do not excite the panels.
I typically find that making enclosures out of 1.5" thick MDF does not make the expected improvement over a 0.75" thickness. It does change things a little, possibly seems to reduce the frequencies involved.
 
lndm said:

I used to use Vifa D25AG aluminium tweeters many moons ago. It was a good tweeter except that it had a character that sounded just like aluminium sounds. I later discovered it had a resonance way up at 11kHz.
Two things that are not right with this driver.
1. It has a mask in front of it which alters the phase characteristics and masks some detail. Normally this is used to hide/suppress a higer frequency resonance.
2. If the dome shape is redesigned, there will be significant improvement.

lndm said:

I typically find that making enclosures out of 1.5" thick MDF does not make the expected improvement over a 0.75" thickness. It does change things a little, possibly seems to reduce the frequencies involved.

It depends on what driver you have. If it's the Vifa you mentioned above, then there might not be any improvement.
 
soongsc said:
It depends on what driver you have.
I find that bracing, which adds stiffness but little mass, has a greater effect on the boxes I build. Still though I often find the need to lead line. Maybe (not sure) lead lining would do well on a steel enclosure.

soongsc said:
If it's the Vifa you mentioned above, then there might not be any improvement.
I don't typically find problems with MDF at 11kHz but with steel, I guess you'd need to be careful there.
 
JohnnyBoy said:
Resonance that occurs at the lower frequencies is far more problematic to the overall tone. If the metal cabinets are indeed adding color to the upper frequencies, it's not apparent.

With the caveat' as you said' that the cabinet shape is correct. I made a 24" mini-TL for a TB driver from rectangular section 1/4" welded steel. It was definitely audible. Step 2 was to glue floor tile backed with 1/8" aluminum to the interior walls. Better, but still not there. Using plastic screws to hold the driver in place and isolating it on a rubber gasket finally brought the 'clang' down to the limits of audibility. Female vocals are still more 'exciting' than accurate though.
 
Uhm, whats wrong with weight? Unless speakers need to be moved I don't see that much compromisse in it. After all many world class big speakers weight a lot and they surely aren't meant for daily movements in the apartment.

I guess 1" / 25mm MDF is pretty regular material in speaker cabinets. Both in DIY and commercial models. Lets keep that thickness. I guess certain size and thick metal, for example steel, can ring on a certain frequency. But the case is totally different compared to 5-50g mms drivers cone since system overall weight is in different scale. But as for 25mm material, how about stacking 10mm stainless steel and have 15mm space for proper "internal" damping, bitumen for example or make a 25mm thick sandwich structure with steel-bitumen-steel for example. Difference to normal MDF is just huge.

Another mather is drivers installation. Such steel-bitumen-steel construction could allow driver fastening into the inner steel layer so any driver vibrations have to go through the bitumen before they can shake the whole cabinet. Using just single layer, for example MDF and damp it with bitumen the bitumen just tries to damp the outer layer from vibrating.

Allthought I've heard some intresting rumours about few commercial manufacturers that seem to think speakercabinets shouldn't even be totally dead. Maybe more like superrigid and supported to the floor with spikes. My present knowledge lead this thinking into an sound reproductive instrument, not a speaker that just reproduces what's input.

And the speakerspikes.. Do you even need them if the cabinet is 100% dead and there is absolutely no sound that could transfer into floorboards? Naturally spikes look cool but their original point feels a bit woodleg improvement to me.

Jussi
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.