Fostex FW168HR

[MisterTwister]

http://www.madisound.com/catalog/pro...oducts_id=8642
has anyone tried it?
based on provided specs, this must be an excellent full range driver.

[steviedon]

Sorry to say this driver is far from full range. I wouldn't expect it to perform very well past 10k from the response graph. Stick to the FE series drivers for full range duty.

[chrisb]

Originally posted by MisterTwister
http://www.madisound.com/catalog/pro...oducts_id=8642
has anyone tried it?
based on provided specs, this must be an excellent full range driver.

Fostex's "provided" specs should be taken with a healthy dash of kosher salt.

Originally posted by steviedon
Sorry to say this driver is far from full range. I wouldn't expect it to perform very well past 10k from the response graph. Stick to the FE series drivers for full range duty.

OTOH, if the HF roll off is as benign as the other Sigma series Full range drivers with which it shares a lot of physical features, it could make for a very decent sounding 2-way with a reasonable dome and a simple cap hi-pass filter.

However, the sensitivity, and moreover price of this model should give one serious pause to consider steviedon's suggestion. For at least $40 less per driver, the FE168EZ would be an obvious choice.

Before you proceed with selecting any driver(s), the first of several questions you should ask yourself is: what type/size enclosure can I accommodate?

[MisterTwister]

it plays slightlty over 10k which is good enough.
and there is no need for baffle step circuit due to tilted response.
apparently there is no cone breakup in that woofer..
since we can't trust fostex data, I'll wait till someone buys and measures this driver. based on fostex graph it is the best 6.5in full ranger
has anyone measured FE168EZ ?

[planet10]

This driver is very similar to the midbass used in the NF-1 monitor, Cap XOed tweeter at 12k. Very good.

dave

I'd love to have the cash to play with these.

dave

[Scottmoose]

I suspect it's a nice driver for what it is -I'd be inclined to treat it as you would, say, the FE208ESigma, as a wide-band driver supported by a tweeter rather than a full-range (OK, OK, so all 'FR' units are really either just wideband mids or very large tweeters, but you know what I mean ). I don't believe for one second though that there is no cone breakup. If that's the case, it'd be a scientific miracle.

[BudP]

The cone appears to be permanently broken up. Perhaps this allows the energy to sneak off intact? Seems to be enough of a twisted sort of logic to work. Would be interesting to do a tap test on the cone to find out if they have side stepped the resonance node issues.

Bud

[InclinedPlane]

That brings me back to something that's been rolling around in my head for ages. The problem is that any smooth-profile cone cannot act like a true piston unless its material is unreasonably thick or heavy, which ruins it in other ways. To make it light enough yet stiff enough is the heart of loudspeaker cone engineering. This Fostex crumpled cone seems to be an advance, no?
But what I was thinking of was a cone with an up/down radial shape, like the sides of the Resse's Peanut Butter Cup candy inside wrapper. Make it like that, but corrugated all the way to the middle - radially. Wouldn't this offer far more stiffness without much more weight? Wouldn't all areas of the cone be far more in step with the VC?
I've seen this design on one vintage set of drivers, but nowhere else. There must be some other problem with it that I don't know about.

[BudP]

InclinedPlane

I think the real problem arises due to there being another form of energy that is expressing, at the nodal resonance points. We would need to capture and extinguish all of the transverse wave energy, that is ringing within the emitter structure at 3 or 4 times the speed of the "sound" wave of similar structure, that has been emitted first at the voice coil and subsequently travels as a wave motion transformation between deep sprung meshes of molecules in emitter and adjacent air. This should then cause all "breakup" modes to disappear.

A pure piston driver with a time stretch to the piston action across the emitter diaphragm, one that does not move all at once but instead allows the wave of molecules in the emitter, pushing other molecules in the air, to travel up the emitter in coherence with the original wave emitted into the air, should be a perfect driver.

Lincoln Walsh provided some insights into this and some moderately successful attempts to make his ideas real can be found. Walsh did not have an answer to the transverse ringing problem, that plagues the emission profiles of the energy provided by the pistonic ripples, and so even this is not a complete answer.

If you can imagine a way to kill this transverse wave with just a single traverse, or at most one reflection, then I think your idea will have very good success. I can see how a nearly vertical wall, with crenelations and a voice coil the size of the lower edge of that wall, with a gentle dome attached to the voice coil and with a damping suspension at the dome center, might just accomplish this.

Bud

[MisterTwister]

InclinedPlane, I agree with you. Typical cone profile is not ridgid enough. IMO making corrugated cone connected to corrugated spider would be a good solution. Essentially what fostex has made here. One thing bothers me though, they left cone's edge flat, they could've made it ribbed up to its edge.