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Peter Wieck Peter Wieck is offline
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Default Grounded Grid?? Really?

On Thursday, November 6, 2014 2:54:05 AM UTC-5, Donut wrote:
Hello!
My friend is working on his preamp and he shows me the circuit lately. The preamp named Grounded Grid and claimed that the circuit is GG as well.

However, some people called it a mu follower.....SO what is this?? GG or mu follower?

http://i2.photobucket.com/albums/y48...e/ggpreamp.jpg

I'm really curious!!



I think you are getting hung up on nomenclature, as pretty much any amp/pre-amp is a "mu-follower" at some level, and the schematic you linked is often called many other things than "Grounded Grid" as well. Note that the grid grounds are either via the volume control (shorting to ground on the input side when at lowest volume) and via high-ohm resistors on the output side. Not directly as with (some) power-amp designs. So, the meaning of "ground" is shaded. Note also that one way to test pre-amp noise is to measure with shorted inputs - to ground.

http://analogmetric.com/ebay/GG%20or...0schematic.png

Remarkably similar, isn't it? Another design described as 'grounded grid'.

So, as a general statement, (very nearly) all grounded-grid systems are also mu-followers, whereas not every mu-follower system is a grounded grid.

I am not an EE, I am rendering an amateur's informal interpretation based on limited formal knowledge but a long history of tinkering and experimentation with tube-based equipment.

Peter Wieck
Melrose Park, PA