fabricated steel enclosure bad for driver performance?

[mrkahn]

I am a newbie messing around with the idea of a steel enclosure. I have alot of experience with metalwork but almost no experience with speaker development. I have done some cool stuff with aluminum and stainless steel but now I am curious about steel. I know it is magnetic so I am concerned that it will have some sort of negative effect on the magnetic field of a driver.
Am I heading into a problem? someone save me from myself.....

 

[camaudio]

the thicknesses and structuring needed to keep it from flexing would prolly make it rather heavy/expensive

you would def need to know what you are doing to mill thing properly aswell, and ya cant have any air leaks

other than resonant freqs getting in the way, i cant see why not

 

[critofur]

Definitely no negative affect magnetically ~ possibly a positive one in that it may reduce stray magnetic fields (shielding).

If you were to combine Aluminum and Steel with one layer of each your cabinet will be more "dead", particularly if there is something viscous coupling the two layers.

I would consider something with curved sides to obtain a high degree of stiffness without having to make it excessively thick.

 

[Svante]

The magnetics is not a problem. Anyway, stainless steel is not magnetic, right?

The bigger problem is the resonant properties of steel. It has very little losses, which probably will result in very narrow/loud resonances, possibly at rather high frequencies (depending on wall thickness).

It is a cool idea, but I would be careful to attach some sticky material to the inside of the box walls to increase the losses in the wall and thereby attenuating the resonances.

 

[Andersonix]

Go with aluminum. I can think of two commercial enclosures made from aluminum, although their names escape me this minute. One is KEF...

 

[marchel]

One of the problems I could think of in a metal box, Is the behavior of the inductors on the XO. It might cause the values of inductors to shift.

 

[legris00]

Working on a Steel (3mm thick) based near-field active monitor loudspeaker. Pretty heavy!
Absolute nightmare to get the radius on the corners without causing any distortion. Could not find the gear to do this properly at uni, so got it sent to a specialised company.

It's my uni final year project and because of time issues: I am doing only one side at the moment. Waiting to hear how it sounds likes...
Will try to post some pictures soon and probably do a post on the whole project when I get some testing done in the anechoic chamber (scheduled for next week)

 

[dublin78]

Sounds like a cool project.

There is no reason why the XO has to be inside the cabinet. You could have it outside, or even near the amplifier and then bi-wire.

This would also give you the option of using an active crossover, which would mean that you would not have to follow an existing design - You would need an active XO and an extra amp tho.

 

[legris00]

Hi dublin78,

This is what I am doing indeed. Have the amplifier section in a rack next to it with:
2*power amp
2*power supplies (2 transformers)
one crossover board with input differentiator and phase shift network.

Can't wait to test it. Will make a post when done

 

[mrkahn]

Sounds like a cool project.

There is no reason why the XO has to be inside the cabinet. You could have it outside, or even near the amplifier and then bi-wire.

This would also give you the option of using an active crossover, which would mean that you would not have to follow an existing design - You would need an active XO and an extra amp tho.

Thanks for all the replys.
If I put the crossover inside the cabinet, would it have to be somehow isolated from the enclosure? Perhaps in a non conductive box of its own?Will this isolate inductance problems?
I am trying to avoid another amplifier for this design...

 

[mrkahn]

The magnetics is not a problem. Anyway, stainless steel is not magnetic, right?

The bigger problem is the resonant properties of steel. It has very little losses, which probably will result in very narrow/loud resonances, possibly at rather high frequencies (depending on wall thickness).

It is a cool idea, but I would be careful to attach some sticky material to the inside of the box walls to increase the losses in the wall and thereby attenuating the resonances.

Hey Svante,
The wall thickness I plan to use is 1/2" steel (13mm) Very thick and heavy. I have a lot of this material left from a job and I can cut it on my waterjet. I plan on seam welding it into a closed chamber so no losses will occur.
That being said, I dont know what type of resonance I will be dealing with or at what frequencies? any thoughts on how to calculate or anticipate what I will end up with?
with that thickness of metal would an inner layer of damping compound be necesarry? I am scared of building a Bell that at a specific frequency it rings like crazy... Aluminum does not seem to do this in my previous experiments but steel has interesting audible characteristics when excited.