New Fostex range

Dedicated to those large boxes at one end of the room
Post Reply
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#1 New Fostex range

Post by IslandPink »

Not sure when these will be available , but some things of interest.
The frequency response curves look more detailed, more honest -
https://www.fostexinternational.com/doc ... ries.shtml
No Xmax shown, unfortunately.
The 126e-NV looks better than the last one, though not perfect as usual. Pretty good for a FR up to about 5kHz at least.
The 103 looks like a dog - a massive dip at 2kHz which would take all the harmonics out of the female vocals, to my mind.
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Scottmoose
Needs to get out more
Posts: 1802
Joined: Sat Sep 08, 2007 11:03 am
Contact:

#2 Re: New Fostex range

Post by Scottmoose »

Usually assume about 3 months from date of publication as the average, but this depends on individual dealer ordering schedules and stock of existing units.

Re Xmax, if you'll forgive a brief rant -don't forget that in truth it's almost meaningless because there is no fixed definition for what it even is. Small, like Thiele, Novak (and to a point Thuras) before him merely stated 'it is assumed that a peak displacement limit can be established; this limit is designated Xmax', and that '[it is assumed] that diaphragm displacement is linear up to Xmax'. What none of them did was provide specifics beyond this, nor a method of putting a number to it because they knew full-well that it depends on matters outside the large / small signal filter theory they were using. A numerical Xmax figure is usually lumped in with what we now call T/S parameters, but it's actually got nothing directly to do with Small or his predecessors. It's others who came up with methods for putting a figure to it. I stopped counting at about 8 and they all give different figures if you apply them to the same drive unit.

One example: Xmax = 10% THD. Leaving aside the fact that a lumped THD figure iself is pretty much worthless (the individual distortion order figures from 2nd - 5th can tell you something) -well, say we use that definition under which Xmax = 10mm. You have no way of knowing whether THD was at 9.99% for 9 of those 10mm, which isn't likely to sound a whole lot better. Nor does it tell you what the driver's behaviour is like beyond Xmax, assuming there is more mechanical travel in hand, since it may be like a switch beyond which results are instantly terrible (very unlikely) or it may rise in a more or less progressive fashion. No way of telling. And so on. And, of course, different manufacturers use different methods, and they never state which they happen to employ. In some, if they give VC and VC gap dimensions, you should be able to tell whether they used one of the physical methods of assigning a value to it -sometimes as simple as length of VC gap minus the VC length. But that's about it, so unless you measure all drivers consistently with the same methodology, you don't even know if you're comparing like-with-like.

The ideal would be an Xmech value (mechanical limit of travel) and HD2 - HD5 figures provided at different drive levels. Not that we're ever likely to get that, but it would actually be useful.
'"That'll do," comes the cry of the perfectionist down the ages.' (James May The Reassembler)
Website www.wodendesign.com
Community sites www.frugal-horn.com & www.frugal-phile.com
Post Reply