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ahhh, pro life or choice eh? so its religion, politics and mosfets......don't forget about divx and beta!

a lot of this is going to boil down to the quality and operational specs of whichever component you're using, be it a bipolar or mosfet transistor.
I do know how they function however. I think that was covered in the first two semesters of college. Anyway, the bipolar vs mosfet argument is almost as heated though not quite as old as the vacuum tube versus solid state amplifier arguments.
everyone has their preferences.

to each his own my brotha

Bipolar Junction Transistors, BJT, replaced tubes in the early days of solid state. BJT are current controlled devices, this mind that collector is function of base current.
The high alinearity, specially at high current, introduce great amount of harmonic distortion. The fact that hfe decrease when collector current increase determinate the harmonic distortion composition, distortion has big components beyond the thirds, this components aren't ear masked.

Bipolar Transistors are less linear than Mosfets. The following is from Mb Quart's website:

MB Quart uses MOSFET devices in both the power supply and output stages of amplifiers. This means better: thermal stability, switching speed, ultra low output impedance and wider bandwidth linearity. MOSFETs operate very similarly to vacuum tubes in that they are more linear than bi-polar transistors. However, MOSFETs can deliver the midrange clarity without the limitations of transient response and high frequency phase shifting normally associated with tube operation. Bottom line, we use the best components so you will too!

actualy mosfets are about all you could use for the output stage really, but in regards to the power supply and input stage, as I've stated before;
We've seen both MOSFET (Metal Oxide Silicon Field Effect Transistor) and Bipolar transistors used in audio amplifiers. Claims have been made that each is superior. I have seen claims that MOSFETs have a tube ("Valve" to the British) sound. This is more folklore. The musicians and their instruments are supposed to have "the sound", not audio equipment! MOSFETs are tougher than Bipolars, and can pull closer to the supply rail. It takes more Bipolar transistors to achieve the same power as a MOSFET, therefore Bipolar amps tend to be more expensive. But, MOSFETs are very non-linear, compared to Bipolars and require much more feedback to achieve reasonable distortion numbers. They are a great choice for bass amps, as low frequency audio is not difficult for a MOSFET. The most expensive car and home amplifiers almost always use Bipolar transistors. Note you'll only ever see MOSFETs used in class D amplifiers, as this is the only type that can be used in such a topology.

I'd rather pay more and use more bipolar transistors to achieve better linearity and lower distortion though, than use MOSFETs to save cost or space.

I am not saying bi-polar sucks, it is widely used in home audio. Mosfets however are a better choice in car audio as they are more stable in the harsh car environment.

Oh boy, here goes the neighbor hood.

Let me get my lawn chair, umbrella and a lemon aide!



Sit back and watch the show people

Mosfets have better thermal properties, faster switching, and just plain sound better than bi-polar transistors, when in the car environment. there is simply too much voltage fluctuations which the Bi-polar transistors are more sensitive to. thats why very few car audio manufacturers use Bi-polar, they aren't as reliable in the 12v world, when you can have the best of both worlds (tube vs. Bipolar) with a mosfet.

are you serious? bipolar? Mosfets are a million times better for your output stage. you are kidding right? lord in heaven, please tell me he is joking.

sounds like the zapco competition series amps with their symbilink processing for remote amplifier status monitoring and adjustments.
nice amps. I hope they used bi-polar transistors and not mosfets in the power supplies and amplification stages.