Print Page - Orange crush 20L - what is the purpose of the jfet before the power amp

Title: Orange crush 20L - what is the purpose of the jfet before the power amp
Post by: belab on January 01, 2024, 03:15:24 PM

Hi,

what does Q1 jfet do at the input of the power amp?

schematic (https://elektrotanya.com/orange_crush_20l_guitar_amp_sch.pdf/download.html#dl)

Thanks
belab

Title: Re: Orange crush 20L - what is the purpose of the jfet before the power amp
Post by: Tassieviking on January 02, 2024, 02:12:48 AM

I will take a wild guess that it is there as a delay so there is no big pop as the amp is turned on.
The 1uF cap C25 is slowly charged up through the 10M resistor R45 until it turns the Jfet on and allows the signal through. But I could be wrong.

Title: Re: Orange crush 20L - what is the purpose of the jfet before the power amp
Post by: belab on January 02, 2024, 09:07:42 AM

Thanks, my guess was similar.
Happy new year! :)

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Solid State Amplifiers => Schematics and Layouts => Topic started by: belab on January 01, 2024, 03:15:24 PM