Callin Doctor Vood

[sumitomo]

Hey Vood could you explain Mosfot,I was listin' to a Blackstone mosfot OD pedal and I know BYOC has a OD2 pedal with a mosfot upgrade.But I just dont know what the heck Mosfot ?Thanks Sumi You da Man

[tunghaichuan***]

Sumi,

Hey Vood could you explain Mosfot,I was listin' to a Blackstone mosfot OD pedal and I know BYOC has a OD2 pedal with a mosfot upgrade.But I just dont know what the heck Mosfot ?Thanks Sumi You da Man

I'm not Dr. Vood, but it is MosFet. It stands for "metal oxide semiconductor field effect transistor." It describes what the tranistor is and what it does.

This Wikipedia article has more than you probably want to know.

tung

[duhvoodooman***]

It's just a kind of transistor; MOSFET stands for metal oxide semiconductor field efffects transistor. Over the years, they've become the most commonly used type of transistor, surpassing bipolar junction transistors (BJT's). They require very little current to operate and have large input impedances, which is a desirable property for use in effects pedals. They also have an internal diode structure, called a "body diode" which allows them to be used for signal clipping. This is the property that is being used in MOSFET overdrives, like the Blackstone pedal you mentioned. Other popular MOSFET OD's include the Hermida MOSferatu and the Fultone Fulldrive 2 MOSFET. The tonal effect, from what I've heard, is a somewhat warmer, fuller & smoother character than silicon diode clipping gives. "More tube like" is what they always say, and I guess that's a pretty reasonable description.

The OD2 MOSFET conversion kit allows you to install MOSFET's not only for the clipping, but also for the input and output buffers, the clean boost part of the pedal, and even includes a MOSFET-based opamp. I didn't like the MOSFET opamp as well as the other two provided with the kit (sounded a little duller to me), and I didn't see much point to the MOSFET output buffer and used a BJT there, based upon a recommendation I read from effects guru Jack Orman. He commented that the higher impedance MOSFET input buffer helped preserve the higher frequencies, but BJT's gave better drive performance at the output buffer.

[tunghaichuan***]

Thanks for the detailed explanation, good stuff. :

It's just a kind of transistor; MOSFET stands for metal oxide semiconductor field efffects transistor. Over the years, they've become the most commonly used type of transistor, surpassing bipolar junction transistors (BJT's). They require very little current to operate and have large input impedances, which is a desirable property for use in effects pedals. They also have an internal diode structure, called a "body diode" which allows them to be used for signal clipping. This is the property that is being used in MOSFET overdrives, like the Blackstone pedal you mentioned. Other popular MOSFET OD's include the Hermida MOSferatu and the Fultone Fulldrive 2 MOSFET. The tonal effect, from what I've heard, is a somewhat warmer, fuller & smoother character than silicon diode clipping gives. "More tube like" is what they always say, and I guess that's a pretty reasonable description.

The OD2 MOSFET conversion kit allows you to install MOSFET's not only for the clipping, but also for the input and output buffers, the clean boost part of the pedal, and even includes a MOSFET-based opamp. I didn't like the MOSFET opamp as well as the other two provided with the kit (sounded a little duller to me), and I didn't see much point to the MOSFET output buffer and used a BJT there, based upon a recommendation I read from effects guru Jack Orman. He commented that the higher impedance MOSFET input buffer helped preserve the higher frequencies, but BJT's gave better drive performance at the output buffer.

[markb]

There is a school of thought that says that most MOSFETs used in the clipping stage of OD pedals are only using the internal diodes anyway. So maybe we should just think of them as another variety of clipping diode and lose a little less sleep.
In the Fulldrive II, switching to MOSFET clipping gives a less compressed OD that cleans up a bit better from the guitar. This is my only experience of MOSFETS in the clipping stage but the difference is quite apparent.

[duhvoodooman***]

There is a school of thought that says that most MOSFETs used in the clipping stage of OD pedals are only using the internal diodes anyway. So maybe we should just think of them as another variety of clipping diode and lose a little less sleep.

In clipping stages, I think that's exactly right. And I sleep like a baby.