Fostex and TINY! xmax

[doggy]

So i have been reading old postings-on page 200 now, surprising how much interesting stuff in those old posts when not much going on in the current postings...anyways if a driver seems useless if it has .28-.25 mm x-max, why manufacture it??? Some believe that a ample x-max is absolutely necessary for a BLH or RLH? I guess i should not believe my own ears?

[planet10]

The purpose of BLHs is to take advantages of what comes from a driver with low xMax.

dave

[doggy]

The purpose of BLHs is to take advantages of what comes from a driver with low xMax.

dave

yes, totally agree! so the Japanese engineers were thinking about the diy community building BLH or perhaps being augmented with a sub-bass. Seems like all these light cone large magnet drivers are for horns. My own personal preference is to get the most detail out, revealing all; so i guess the ff85wk is good at that?

[planet10]

The FF85 is really good at that, it just has limited bass capability.

Just before we swirched Emken in (what i'm listening to now) had uFonkenSET sitting on top of woof-wT each with 2 x EL166. Really quite a stunner.

dave

[Scottmoose]

Limited linear excursion is usually part of the price of relatively high efficiency for a given driver size.

A point to consider which isn't widely appreciated is that there is no industry standard definition for what Xmax actually is. There are several that can be, and are, used. Some take it as 10% THD under LF loads for e.g. Others establish it as being the absolute value of the height of the VC winding minus the magnetic gap height /2. And there are a few more. This isn't to say that excursion doesn't matter, obviously it is preferable to keep it as low as possible, but it does illustrate that Xmax is a somewhat nebulous concept and however you wish to define it, it isn't necessarily a point beyond which the overall behaviour / sound will fall apart. It depends on the driver design.

[chrisb]

Originally Posted by Scottmoose

Limited linear excursion is usually part of the price of relatively high efficiency for a given driver size.

A point to consider which isn't widely appreciated is that there is no industry standard definition for what Xmax actually is. There are several that can be, and are, used. Some take it as 10% THD under LF loads for e.g. Others establish it as being the absolute value of the height of the VC winding minus the magnetic gap height /2. And there are a few more. This isn't to say that excursion doesn't matter, obviously it is preferable to keep it as low as possible, but it does illustrate that Xmax is a somewhat nebulous concept and however you wish to define it, it isn't necessarily a point beyond which the overall behaviour / sound will fall apart. It depends on the driver design.

"Ooh, ooh, mr Kotter, the dog ate my homework - would it be OK if I borrowed Mark's (Fenlon) notes and hand my essay in tomorrow?"

"I'm sorry Arnold, I'm afraid I can't let you do that"

[Scottmoose]

I believe Mark has made this point (or similar), but it's easy enough to find other sources too, Wikipedia included. I don't have them to hand, but if memory serves, Eargle & Dickason for e.g. use different calculation methods too.

As for Fostex, the data sheets for their Japan-only special editions probably give the best indication of their priorities, and those of their core home-market customers. Generally you'll find a nominal impedance value, 1m/w sensitivity, rated input power, cone radius, Fo, Mo (equivalent mass) & Qo (roughly analogous to Qt -see Beranek). And that's about it. The large / small signal parameters & T/S filter theory popular in the west hasn't historically had much traction over there. Nagaoka for e.g. never used them.

[secanbj]

Regarding Scott´s earlier post

A scan from the book series "Nagaoka Tetsuo´s special technique to design the orginal speakers", long title I just whish i could read them

[tuxedocivic]

For those who have the experience with Fostex, how much abuse can they take? I mean, a lot of drivers have a rated xmax that can be pushed pass without much problem. Are the Fostex like this. Particularly the FE83

[ra7]

They can take a bit of abuse, but they'll let you know that they're unhappy. Result is not pretty.