Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Robbiez on May 22, 2012, 07:41:53 am
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I have spent a while browsing through the forum. I have to say that there is an immense amount of information to disseminate. I know what I will be doing in my leisure time the next few days. :w2: In the meantime, I have a few questions. Maybe I just need to add before I ask my questions; I do have an electronic background. I started out my career, many moons ago, as an electronic technician.
My questions:
I have heard a lot of people speaking of a “clean” channel and an “overdrive/dirty” channel. Can a member send me a block diagram of this? I was always under the impression that I have to drive the tubes into 75% of their range to get the overdrive sound. The only way I could do that, and stay friends with my neighbour and my wife :l2:, is to install a Variable Voltage Regulator.
This might sound like a silly question, but if I want to install a VVR, then it might be a valid one. How do I calculate the output of a tube amplifier?
Thanks for your help so far. As soon as I start, I think I might have more questions. :w2:
Have a peaceful day and be blessed.
Robbie
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In a simple rational amplifier, the first stage to overload is the last (most expensive) stage.
If that's a 100 Watt job, and you drive it 50%-200% of 100 Watts, you will make non-friends in the next town over.
Even a 5 Watt Champ or Junior driven to the max will annoy several houses.
There are plans around to build mini-amps using small tubes like 6AU6, 12AU7, 6AK6, which will overload at a part-Watt. That's still pretty loud in any speaker suitable for guitar.
> a "clean" channel and an "overdrive/dirty" channel
The last stage is not the only stage, and music creation is often not "rational engineering". The "channels" are typically small tubes, not the final power section. You can amplify guitar in a couple/three stages to about "100V swing" in a small tube that can only make 50V cleanly, then cut it down to 5V-10V to drive the power stage well below its 20V-30V overload point and well below Full Roar, but distorted. (And of course you can scale small stages so they don't overload first, "clean".)