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dantheman 3rd January 2010 05:51 AM

Smooth break-up
 
What features of a cone make it break up smoother? I know guitarists think a ribbed cone. Is this correct? Anything else?

Thanks,

Dan

Geek 3rd January 2010 06:28 AM

Hi,

I find the smooth cone breaks up a lot smoother, while the ribbed cones are brighter/crunchier.

A motor that fades smoothly as the linear excursions are reached. Almost exclusively the domain of AlNiCo, but neo magnets have similar properties.

Cheers!

thadman 3rd January 2010 06:36 AM

Quote:

Originally Posted by dantheman (Post 2033008)
What features of a cone make it break up smoother? I know guitarists think a ribbed cone. Is this correct? Anything else?

Thanks,

Dan

A material which inherently possesses significant damping will yield a *smoother* breakup.

Cone geometry is a VERY complex phenomenon with regards to modal behavior. However, a shorter cone angle should yield a *smother* breakup.

rcw 3rd January 2010 08:37 AM

Work done at the bbc and by Raymond Cooke at k.e.f. found that a cone with a hyperbolic shape would operate as a aperiodic transmission line for a band extending a certain amount above its piston frequency.
This gave rise to the k.e.f.B200 style driver used in the various b.b.c. monitors.

The Jordan full range drivers is an extension of this work.

If you push up the piston range by using something like Aluminium, and keep the cone diameter to no more than around 100mm.then you have a driver that can theoretically cover the entire audio range, (except for low bass), with no resonances in the audible band.
rcw.

Don Hills 3rd January 2010 09:43 AM

Quote:

Originally Posted by Geek (Post 2033024)
Hi,
A motor that fades smoothly as the linear excursions are reached. Almost exclusively the domain of AlNiCo, but neo magnets have similar properties.

What particular qualities of an AlNiCo magnet (compared with a ferrite magnet) allow the motor to "fade smoothly as the linear excursions are reached"? I can believe that the two magnet types will generally perform differently, amongst other reasons being that AlNiCo magnets can allow eddy currents to flow where ferrites won't, but I have always understood that performance at the excursion extremes is determined almost exclusively by gap and pole geometry rather than magnet material.

Geek 3rd January 2010 09:53 AM

Hi Don,

The structures between the two tend to be quite different. Modern AlNiCo guitar speakers tend to follow traditional designs (magnet held in the middle of a U-shaped metal piece) that don't have as near tight tolerance or structure as their modern ceramic counterparts.

That's how it was explained to me on guitar forums.

Cheers!

Don Hills 4th January 2010 10:03 AM

In a traditional AlNiCo speaker, the inner pole piece is fastened to one end of the cylindrical AlNiCo magnet. The other end of the magnet is fastened to the U shaped piece, which curves around and is fastened to the outer pole piece / top plate. I disassembled many such speakers in my younger days, to acquire the magnets for experimentation.
I haven't pulled apart any modern AlNiCo speakers, so I can't speak for any changes that have happened in the last 40 years or so.

Don Hills 4th January 2010 11:48 AM

... what I left out from my previous post is that there's nothing about the construction of an AlNiCo magnet driver that makes it any less precise than a ferrite magnet driver. So if they sound different, then they are designed that way on purpose.

dantheman 5th January 2010 02:35 AM

Quote:

Originally Posted by thadman (Post 2033029)
A material which inherently possesses significant damping will yield a *smoother* breakup.

Cone geometry is a VERY complex phenomenon with regards to modal behavior. However, a shorter cone angle should yield a *smother* breakup.

Quote:

Work done at the bbc and by Raymond Cooke at k.e.f. found that a cone with a hyperbolic shape would operate as a aperiodic transmission line for a band extending a certain amount above its piston frequency.
This gave rise to the k.e.f.B200 style driver used in the various b.b.c. monitors.

The Jordan full range drivers is an extension of this work.

If you push up the piston range by using something like Aluminium, and keep the cone diameter to no more than around 100mm.then you have a driver that can theoretically cover the entire audio range, (except for low bass), with no resonances in the audible band.
rcw.

Thanks Thadman and RCW! This is more like what I'm looking for. So I'm sort of looking for a flattish cone made our of a soft material in order to have an extended and smooth HF response? I don't want to see those high peaks that metal drivers often have even if their pistonic range is better. Anyone know of a 15" or 12"er that has these characteristics? What about doping a paper cone? Would a ribbed paper cone then be better than a straight paper cone?

Thanks again,

Dan

thadman 5th January 2010 04:24 AM

Quote:

Originally Posted by dantheman (Post 2035412)
Thanks Thadman and RCW! This is more like what I'm looking for. So I'm sort of looking for a flattish cone made our of a soft material in order to have an extended and smooth HF response? I don't want to see those high peaks that metal drivers often have even if their pistonic range is better. Anyone know of a 15" or 12"er that has these characteristics? What about doping a paper cone? Would a ribbed paper cone then be better than a straight paper cone?

Thanks again,

Dan

Acoustic Elegance produces several drivers which are characterized by a smooth, extended response. The AE TD12M and AE TD15M are prime examples.

If it helps, I believe Augerpro has taken measurements of the TD12M.


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