Why called boost not overdrive?

[otsismi]

I've come across a lot of mosfet booster schematics like the sho, and the slambox. They all start clipping the transistor about 1/4 way through the turn of the gain pot. Why then are these circuits not considered overdrives?

[Vallhagen]

Without havin a clear answer i guess its open to speculation... ?

Its all about convention i think. Like placing music in genres.

An OD is an OD
Distortion is Distortion
Fuzz is Fuzz
Boost is Boost...
and maybe HighGain is HighGain

...even if there often is a thin line between them. I myself labeled my Blüe Monster "OD", even if it really is more of a distortion thing. I think...

Cheers

[madbean]

Boosts are a subset of overdrives. They are overdrives without attenuation (master volume). Most of the time they don't have tone controls, either. Of course, there are always exceptions....there's no real rules everyone follows.

[otsismi]

Wow madbean. Honor. Thanks for the response. I just got my chunk chunk board from you.

Secondary question: the thunderpuss claims to be a clean boost but looks very similar to the sho and slam box. What makes this one cleaner than the other two?

[jkokura]

I'm not sure why you don't think the SHO is a clean boost?

Boosts usually simply take the signal fed them and then 'amplify' or raise the volume of the signal. They do so through various means, including the transistor gain types you're using. Clipping occaisionally happens when you overload the gain structure of the boost. For example, by lowering the bias of the transistor or feeding an extremely hot signal, you can overload the device.

An overdrive/distortion usually depends on 'clipping' or purposeful distortion. This is usually cause by either purposely overloading a transistor or IC (similar to the example above), or by inserting diodes into the signal to 'clip' or distort the signal.

All that said, a pedal entitled 'overdrive' can still be used to boost, and a pedal marked as a 'boost' can sound much like an overdrive. Those times usually depend on when and how they're used.

Also, keep in mind that the gain situation AFTER the pedal often matters. For example - if you boost an already distorting device (pedal, amp, etc) it will likely distort MORE.

I can use a SHO turned up past 3 o'clock on the dial and it doesn't overdrive my signal. I can also use it at 9 o'clock on the dial and it will overdrive my signal. Totally depends on the guitar, the amp, and the other pedals I'm using.

Jacob

[otsismi]

In my mind a clean boost will not clip in and of itself. It simply amplifies the signal cleanly. Of course I know that an amplified signal fed into the front end of an amp will overdrive the preamp tubes, but clean infers that the boost does not clip on its own. Maybe I'm building it wrong but, my sho's at full gain produce thick distortion. Not something I would expect from a "clean boost"

[jkokura]

Then I'd say you built it incorrectly, or your guitar and amp are too hot.

Jacob