What is the cause of Mosfet Mist or Veiling?

I use to know the answer to this question ,but had forgotten!Some amps sound Dark while some seem to have a veiling over the voice info.I have heard this from various amps and was wondering what the cause is?
Other Amps display a very forward signature while other's are more layed back and give a wide and deep soundstage which I favor.
Other's can be Tizzy in the Treble while other's lack Bass!

What are people in the know opinion on these signature's?
mist = low bias.

This mosfet thing seems to be a false rumor that just won't go away; I dunno how many times others have claimed that all mosfet's do this. I believe these complaints must be setup-related, which in no way differs from any other improperly-setup system of any topology.
In fact I've favored mosfet's with my speakers ever since I first auditioned a mosfet Luxman Ultimate series amp about 18 years ago. I tried out some other amps, but kept going back to that mosfet. When that amp eventually failed just a few years ago (parts no longer available) I began auditioning lots of equipment all over again, & eventually settled on an Accuphase product which I didn't even KNOW was mosfet for the first few weeks that I had it (I mistakenly believed that it was bipolar).
I did hear a couple of other mosfet products that did not synergize at all well with my rig; two Belles designs & a Conrad Johnson. These amps all received some nice reviews by others, so it wasn't the fault of the products, just did not synergize well with my particular combination of cabling & speakers.
Your issue I believe is not regarding mosfet's per se, but does relate to component & cabling synergy, which is really no different than any other design.
I agree, there is no such thing as Mosfet veiling. If anything this came about because of a great number of low cost Mosfet amps coming onto the market about 10-12 years ago. They were just not so great implementations and this is how that was manifested, imho.

The other issue of "soundstage" is a more complex issue and has to do with all sorts of factors. Most of them, again, have to do with the quality of the underlying circuit, and how it is implemented. Lesser implementations of otherwise good or excellent circuit designs will show various and assorted sonic "deficits."

Likewise better implementations of lesser circuits will do better than the lesser implementations of the same... of course, we're limiting this discussion to the amp itself.
I prefer bipolar amps but have heard some fine sounding MOSFETs. The main thing that I have read about MOSFETs is that they are not linear and need much regulation to make them sound good.
Hi Rwwear, if you remember reading that mosfets are not linear either you remember wrong or the material you read was wrong. Mosfets tend to have greater linearity then most bipolar devices.

The Gamut is a good example of what can be done with them.
My understanding is the same as Ralph's, that MOSFETs are actually more linear than bipolar transistors.

You could be right, I'm no expert.

Kudo's to Ralph. How often do you see a manufacturer pat a competing manufacturer / technology on the back with the highest of praise and do it by name in public ? While i know that the Atma's are tube based and the Gamut is SS / Mosfet, I think that this says a lot about Ralph's honesty and "inner peace" : ) Sean
Thx for the responses!Yes,I do agree about Ralph's comment.It also shows that coming to this BB for the answer's to questions that we audiophiles need answers to are fielded by those who are really in the know!Where else are you going to get that kind of service!

I had an Harmon Kardon Amp at one time that was made of a Bi-Polar design.I switched to a B&K amp because the HK kept blowing the fuses in my Maggies!I wounder if this had to do with the linear factor which is associated with MOSFETs?
I never blew another fuse again!

Thx for the info!I will save this link for reference!
No. Linearity of the output devices has NOTHING to do with an amp blowing fuses.