Aluminum cabinet? (FE206En) Need Advice

[Kraemerkid]

Hello everyone

This is my first thread. I have been searching this forum for a long time and joined recently. All i can say is i have learned so much and want to try everything

I have a tube amp kit coming to me tomorrow from Tubedepot.com (8LS) and want to make a set of full range monitors to pair with. The drivers i will use are the Fostex FE206En (from Commonsenseaudio.com). They look really nice and from what i have read, they preform very well. Bass is not a issue for me. I have subs for that

So onto my questions. I want to make a cabinet out of aluminum, i mean the entire thing. All the sides, bracing and ports etc.... Is this a bad idea? I don't see many speaker cabinets made out of aluminum. The cost is high and can be time consuming but i have the funds and time.

Would the resonance of the metal be an issue? Would i still put insulation inside the cabinet (i think it's called damping material)?

I am no expert when it comes to speaker design, crossovers or anything like that but a full range speaker doesn't seem to hard.

Over the years i have made many things at my shop. Customized this and customized that. Made enclosures for Class D amps, Gainclones and some tube amps. Also made tons of thing for my Emotiva gear. I can pretty much make anything. Some things take longer than others.

Here are some projects i've done in the past:

Any suggestions or insights on my idea of making an aluminum cabinet would be wonderful

 

[Richard Ellis]

Have you ever heard of the 'Minimus 7' ???? It was a metal (Aluminium?) enclosure loudspeaker of miniscule dimensions. It had a 4" driver and a dome tweeter. Perhaps it was one of the first metal "mini-speakers" on the market. Others of that era were the ADS brand metal speakers..among others. My guess is the metal used was Zinc rather than Aluminum, as they did not "want" to "ring" at all! The Minimus 7 did bring so-called mini-speakers onto the forefront of consumers......sold at Radio Shack stores, they were everywhere.
As you seem to have easy access to CNC machines, the world is your oyster for designs.......far beyond what has already been made.
Give us your thoughts............& we'll brainstorm on this.




_______________________________________________________Rick.........

 

[picowallspeaker]

Hi , great jobs you've done !
The 'grooves' (sorry for the translation )onto the metal panel are very nice.
They can also take an active part in speaker construction , on the baffle to limit diffraction from the speaker to the panel , or at the (rounded) corners .
The depth and distance between them , and their width would determine which
frequency to cut..or delay
But the primary function of a cabinet is to isolate the front wave and the back wave produced from the speaker , and also to let only the membrane vibrate ;
so , with a little cabinet it's easy to do that , much more thinking is implied in making a larger ,for powerful speakers ,cabinet . A parallelepiped is easy also ,but the flat panels are likely to resonate , anytime .

 

[Kraemerkid]

Hi Rick,

I looked those speakers up online and believe they are casted out of aluminum (from what i read). Really small speakers. Good for a computer setup or surround speakers in a HT setup.

The dimensions of the cabinet (mine) will be around 15H" x 12W" x 12D". Thinking of using 1/2'' aluminum plate. Any smaller i think the ring effect would be prominent. But i have never done this before and there is not much online about this, so i could be wrong. Maybe 3/8" or 1/4" would be okay??

I would use plenty of damping material to help with resonance. Plus use stainless steel hardware. Don't know if steel hardware would effect the magnet on the driver but i will just use SS hardware.

The baffles would be easy to make and could be secured and located with pins and screws. The port could be square and exit the front of the cabinet on the bottom.

To top it off it could be anodized in black or any color i want.

 

[planet10]

For the kind of setup you are envisioning, a sealed box will likely work best. You'll also, at a guess, need to XO the subs up around 120 Hz of so.

These drivers (FExx6En) are not designed to be used in reflex or sealed enclosure but can be used in a small (usually sealed) enclosure XOed to a sub each. It has been done with FE126En, and FE166En, haven't seen sims for the FE206En but when i go downstairs i'll model it up. My guess is that your suggested enclosure could well be twice as big as needed.

Al is a good enclosure material, you want it strategically braced to get the ringing up high enuff that it won't get excited. 1/2" is way overkill, 1/4" is likely fine, especially if you bend it.

dave

 

[picowallspeaker]

The dimensions of the cabinet (mine) will be around 15H" x 12W" x 12D". Thinking of using 1/2'' aluminum plate.

I always read that is no good having two equal sizes in a cabinet .
There is the Aural proportion which is around 1:1.5
About construction , if you are making a removable baffle , which might be useful for stuffing etc. , you should think also of how to pressurize it , and to make it one piece with the whole enclosure . Foam or neoprene .

BTW I replied to the post 'cos I was thinking of making an aluminum baffle , too . I was thinking only of a rectangle with a hole on it , and secured to a very inert wooden ( Mdf)cabinet .

 

[Kraemerkid]

For the kind of setup you are envisioning, a sealed box will likely work best. You'll also, at a guess, need to XO the subs up around 120 Hz of so.

These drivers (FExx6En) are not designed to be used in reflex or sealed enclosure but can be used in a small (usually sealed) enclosure XOed to a sub each. It has been done with FE126En, and FE166En, haven't seen sims for the FE206En but when i go downstairs i'll model it up. My guess is that your suggested enclosure could well be twice as big as needed.

Al is a good enclosure material, you want it strategically braced to get the ringing up high enuff that it won't get excited. 1/2" is way overkill, 1/4" is likely fine, especially if you bend it.

dave

Dave,
Thanks for your input. I learned a lot from what you just said. Shows how much i know about speaker design Nothing!!!

What would be a good sized speaker? You said mine might be twice as big as it needs to be.

Also it will be so much easier to machine the plates and bracing to size than to bend them.

How important is it for the cab to be 100% air tight?

I have had thoughts on a open baffle design aswell. Wonder if that would be easier or hardier

Thanks guys

 

[Richard Ellis]

Perhaps 1/2" is too thick.........(Can that be possible?). I was thinking a spray-on adhesive rubber compound for the inside in addition to the bracing. A rough finish to adhere to....can't think of a substance right now. There is another Ratio for enclosure dimensions. It is the so-called Acoustic ratio, .7937-1-1.2599 It is suppose to be a mathematically "inert" ratio.......to minimize internal standing waves. It would be best to mount the driver on the 'smallest side' so the baffle-step is easiest to deal with. Run some simulations on baffle-step programs to see where it is best to mount the driver.
Some one inch radius edges I think would work fine.....A material for the front face for absorbing sound...to work the diffractions to the max. Once we get a volume for the enclosure, & you plug in the values for the baffle-step......the driver location often times winds up in the weirdest of places.

______________________________________________________Rick.........

 

[planet10]

Looks like 206En might not be so well suited. A 5.5 litre net box will give you a butterworth rolloff with an F3 (XO point) of ~165 Hz

What kind of amp do you have?

dave

 

[Kraemerkid]

Looks like 206En might not be so well suited. A 5.5 litre net box will give you a butterworth rolloff with an F3 (XO point) of ~165 Hz

What kind of amp do you have?

dave

I'll be using a tube amp that's 8 watts (8LS from Tubedepot.com). But I do have Class D, A/B, a few Lm3886's and few old AVR's.

 

[BillEpstein]

Don't know much about speaker design but I have had the Jumping Cactus Jumping Cactus Loudspeakers speakers at home for extended trial.

They are sealed, 1/2" thick aluminum with relatively inexpensive, very efficient
Eminence drivers paired with active crossovers and amps from Phil Marchand. Sound was far beyond what might be expected from these drivers.

Go for it!

 

[chrisb]

I'll be using a tube amp that's 8 watts (8LS from Tubedepot.com). But I do have Class D, A/B, a few Lm3886's and few old AVR's.

With the sensitivity of the 206 and the fact that small non BLH type enclosures under discussion would require bass supplementation, the 8W tube would be my first choice. Use any of the higher powered SS amps for the woofers - crossed over any higher than 120 or so and you should really consider stereo for that - they needn't necessarily be in the same enclosures.

 

[Greg B]

Would the resonance of the metal be an issue? Would i still put insulation inside the cabinet (i think it's called damping material)?

Yes, but due to the high stiffness most likely at a higher frequency where it can easily be damped out. I'd suggest coating the interior with truck bed lining, plastidip, latex, etc.

As with any BR there still should be a damping material like carpet felt (etc) for the air resonances and reducing midrange reflections through the cone.

I am no expert when it comes to speaker design, crossovers or anything like that but a full range speaker doesn't seem to hard.

You'd be surprised.

The main problem I see with your plan is that the FE206EN is a meant for a horn. It has a rising frequency response inherently, in addition to the baffle step loss. IF you stick in a BR with no compensation, it will rip your ears off. This isn't a matter of bass, but of frequency balance.

Therefore either passive or active EQ will be needed. I also suggest an ML-TL over a standard BR. This will add some output and subjective oomph to the midbass, even if you are using subwoofers.

 

[planet10]

Yes, but due to the high stiffness most likely at a higher frequency where it can easily be damped out. I'd suggest coating the interior with truck bed lining, plastidip, latex, etc.

You should be able to get the resonance signature of an aluminum cab high enuff that they should never get excited. The damping suggested might make you feel better when you strick the cab with your drumsticks, but could well prove detrimental to sonics.

The main problem I see with your plan is that the FE206EN is a meant for a horn. It has a rising frequency response inherently, in addition to the baffle step loss. IF you stick in a BR with no compensation, it will rip your ears off. This isn't a matter of bass, but of frequency balance.

Therefore either passive or active EQ will be needed. I also suggest an ML-TL over a standard BR. This will add some output and subjective oomph to the midbass, even if you are using subwoofers.

I'd suggest going further and consider a more suitable driver for the application.

BTW, as bad as the FE206 may be in such an enclosure it wouldn't hold a candle to the FE138eSR, which takes Fostex shout up to a scream.

dave

 

[newpaton2]

I use aluminum spherical encolsures that are thin so they do resonate if not damped. The best damping I get, and this works very well is a rubbery product used to seal roofs sold here in Argentina, with fibers (it comes in a white color). I mix this with sand and and a few coats to the inner walls. The key here is the addition of the sand, it completely deadens any possible vibrations, works great in my spherical aluminum 1.2mm thick walled enclosures.

 

[boywonder]

How important is it for the cab to be 100% air tight?

Thanks guys

It needs to be as "sealed" as you can make it. Air leaks can change the box tuning.

Caulking, weatherstripping, gaskets, etc.

To get a rough idea of enclosure sizing for a particular driver, download WinISD. It's free, and really easy to use. It's basic but will show you the response for sealed and BR enclosures.

 

[Godzilla]

JUMPING CACTUS LOUDSPEAKERS

Holy Jumping Cactus Batman!

>>> download WinISD. It's free...

Yes, boywonder is correct. But you can also use it online (for Mac users like I am part time by selecting the online version when you visit their website). It's no where near as robust but will allow you to play with the basic curve of the woofer's response and figure the port lenght for you... or tell you what things will look like in sealed boxes... where you can purchase the Eminence parts and build your own, aluminum free, jumping cactus!

 

[asosa]

Aluminum Loudspeakers

Hi,

I am working on a similar project just as you are and been contemplating using some aluminum for my project. I just wanted to know how did it go with your project. Do you have any photos you can post? Can you assist me with my project?

Thanks,

 

[jonnoshore]

I have a pair of metal cabinet speakers, made by a company called RMS audio (Same designer as Avondale Audio - Les W) in the UK. Mine are called "Revelation two", very little information is available on them. They replaced my Naim SBL speakers and sound pretty good tbh. It can be done and I would imagine that Aluminium would be better as the iron cabinets mine are made of makes fitting the drive units through the speaker holes with the magnets "interesting". Just make sure the walls are damped and braced well to avoid "ringing"..

Metal working is something I have access to more than wood working so is something I am 'toying' with regards speaker building... Good luck.

 

[freddi]

aluminum Karlsons - hehe - - FE206EN is an excellent Karlson driver but it takes K12 size (24.5"x16.75"x13.34") to get good "hit" (preferable to my Klipschorns in quality) might be able to go a bit smaller ~ 1 cubic foot rear chamber / 0.5 front - a beautiful wood cabinet with removable 1/2" or thicker polished aluminum wings would be cute.

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