Why some amps use grid leak as the input stage?

[Chuck H]

All my friends here are young, very smart, very attractive, women, and best/rarest of all, sane. It is as if they are a different species when comparing to the girls I met back in the US

Being in the US myself, I don't even need to know what you do about Russian women to know your telling the truth

[dmartn149]

When it comes to great tone vs. great playing, vs. writing a great song, it's not an either/or proposition. We might be able to find time to work on all of these. Many of us are not making a living in music, so we may play our guitar, or work on our tone or anything else that gives us pleasure without worrying about whether or not it will sell a record or sell out show.

[Gingertube]

Alan,
I know you like to understand the theory,
I wrote a little essay on grid current here;
Grid Current - an essay
I explains grid leak bias.
Cheers,
Ian

[guitician]

New tread...http://music-electronics-forum.com/t35776/#post336110

[Zozobra]

Besides, "tone" is highly overrated and never sold a record or sold out a concert.

Tell that to the doom metal crowd

[km6xz]

A much easier to agree on topic...It renews my faith in the female of the species there are sane, feminine super smart fit, fun loving and emotionally mature specimens in such large numbers. It seems that the US culture trains women to be either mentally sharp or attractive but never both in the same person.

Regarding the tone issue, I am approaching it, not as a hobbyist musician but from the pro side where there is a need to communicate with other people. There are no rules or suggestions for those who play for their own amusement alone. When an additional human[s] is the intended audience, that is what I am talking about. All the talk of tone and seeking it without developing a personal style is just hot air and no one but the solo hobbyist musician will ever hear it. Usually that is a good thing. Even skilled communicators need production assistance in focusing the project on the audience and perception that often is lost in the artistic moment.

[Alan0354]

I would contend a lot of this. I don't think owning an amp that happens to have this sort of bias on the input stage is, in itself, knowledge of the circuit or even what it's doing. It is only one part of a whole amp after all. You suggest that the tube doesn't care if it's grid is negative WRT the cathode or if the cathode is positive WRT the grid. At face value that IS accurate. But in this case it's very misleading. A tube that is biased 1.8V positive at the cathode is a very different thing than a tube that's biased .6V negative at the grid. How different? 1.2V of bias! The cathode biased arrangement typically employed generates about three times the bias voltage of grid leak circuits. So the GL tube is biased hot. That means it's going to saturate a good deal before it cuts off. That's a lot of asymmetry compared to a cathode biased triode. Then there's the fact that the cathode doesn't fluctuate, but stays at a steady 0V. With cathode bias the DC voltage jumps up and down due to the cathodes resistance in the current path. This affects the envelope of attack. and compression characteristics. Then, of course there is the huge input impedance of the GL bias. We've already agreed on that part. Does the GL bias triode sound different than a cathode biased triode? I'm certain of it. I've just never experienced it for myself. I've never swam in the Indian ocean either but I know it's wet.

But in GL, the input cap can be charged up and down just like the cathode cap, thereby changing the bias voltage according to the amplitude of the input signal. I think that's a push.

But your point of GL bias hot is valid as unless you use a super high value grid resistor, you don't have enough voltage develop across the grid resistor. I hate large value resistors as all sort of secondary problem arise.......leakage due to dirt, susceptible to cross talk and whole host of other problems.

[Alan0354]

I think tone is more important to the person that plays the instrument than the audience. I have to PARTIALLY agree that audience don't care as much how your guitar sound, they listen to the totality of the song, the solo and all.

BUT to the guitarist, it's everything. Don't you ever experience that when you get the right sound, you feel a chill down your spine, your body resonates with the sound and you feel you are so much more into the playing that you feel you play better, more soul and you enjoy it a lot more? Isn't that just as important than how it sounds in the recording? To me, I listen to my body whether the sound I created is right or not!!!

So I can see both side and I have no intention to get into this!!!!