Power Amps.

[DummyLoad]

I just pissed-off someone on another forum, bad. This isn't my month. Sorry.

that's hard to believe.

> ...NOT the place to go for innovators. Most people here are stuck in the past... Arrogance abounds

lol! that's a good laugh right there. OK, mr. edison, show us what you've got.

--pete

[Bluemeany]

I can think of many audiences who have applauded a clever amplifier detail or admired the sound a guitarist gets.

My opinion is certainly that it hasn't all been done before - the topologies maybe but the sounds no - the fact that the guitarists of today don't sound like the guitarists of the 1950s are proof of this.

[VMS]

I can think of many audiences who have applauded a clever amplifier detail or admired the sound a guitarist gets.

My opinion is certainly that it hasn't all been done before - the topologies maybe but the sounds no - the fact that the guitarists of today don't sound like the guitarists of the 1950s are proof of this.

Yes, but this topic is about power amps. How many ways can you really design a power amp section of a guitar amp.

What is the latest trend in power amp design amongst the great new amp designers?

[Bluemeany]

Power reduction and distortion control. The larger amplifier companies have produced some really interesting power control systems in the last few years and they continue to develop new ones every year. Blackstar's DPR is one example. The bias monitoring and power reduction on the slash signature amp by Marshall is another. I know others are working on dynamically controlling the amounts of negative feedback to adjust damping and clipping transition points as the controls of the amplifier and levels of input change.

It's easy to say that "it's all been done before" and, to some extents, the use of valves in an audio amplification system has been done to death. But - it's usually from a hi-fi point of view. How much research into a full overdriven guitar power amp has really been done? Kuehnel has done some in his 2 books which address power amps but that's not a lot in the grand scheme of things.

Yes, there may be a set number of topologies that work but coaxing out all the new sounds and interesting ways in which they can be used will continue.

[jojokeo]

Power reduction and distortion control. The larger amplifier companies have produced some really interesting power control systems in the last few years and they continue to develop new ones every year. Blackstar's DPR is one example. The bias monitoring and power reduction on the slash signature amp by Marshall is another. I know others are working on dynamically controlling the amounts of negative feedback to adjust damping and clipping transition points as the controls of the amplifier and levels of input change.

It's easy to say that "it's all been done before" and, to some extents, the use of valves in an audio amplification system has been done to death. But - it's usually from a hi-fi point of view. How much research into a full overdriven guitar power amp has really been done? Kuehnel has done some in his 2 books which address power amps but that's not a lot in the grand scheme of things.

Yes, there may be a set number of topologies that work but coaxing out all the new sounds and interesting ways in which they can be used will continue.

You're talking about voltage and/or negative feedback control right? How does this make for the power amp section to be completely re-designed or a breakthrough in power amp section design the way we know it from long long ago?

Please also answer the first fundamental question by VMS which is the main point here?

[VMS]

It's easy to say that "it's all been done before" and, to some extents, the use of valves in an audio amplification system has been done to death. But - it's usually from a hi-fi point of view. How much research into a full overdriven guitar power amp has really been done? Kuehnel has done some in his 2 books which address power amps but that's not a lot in the grand scheme of things.

Yes, there may be a set number of topologies that work but coaxing out all the new sounds and interesting ways in which they can be used will continue.

I kinda agree with you on that one and I'm not trying to start anything here but on the subject of power reduction it looks like large companies are now doing what Kevin O'Connor did about 15-years ago.

AFD100 amp reduces volume by reducing screen voltage, here is a patent from 1942 with the same idea.

Another important object of my invention is to provide an audio amplifier whose output energy level is regulated by varying the screen voltage thereof thereby to provide distortionless and efficient volume control.

http://www.google.com/patents/US2367357

[TIMBO]

I got to believe that here in OZ the amp builders tried just about every trick in the book when designing their amps only because they used components that were available to them and most were used in televisions.
This is a good example of what they had to save on expensive parts.
http://el34world.com/Forum/index.php?topic=18639.0
The competition between builders was huge and they resorted to tactics to slow down their rivals, mystery box and painted components.

When looking at Aussie built amps they are pretty much the same circuit and to get them to sound different to a Marshall or fender, change the tone.

SO, I can only think 50 odd years ago they tried the reinvent the wheel but found that ROUND is the only way to go.

BUT stick with it.

[PRR]

> here is a patent from 1942

Interesting patent.

Wonder if he tried it.

As you reduce Vg2, the maximum power output goes down, but the input level to reach that reduced power goes *down*. "Volume" goes up, and distortion is reached *sooner*.

So as a complete volume control for a radio, I think it is a bust.

In combination with a conventional volume potentiometer (or RF-IF grid bias), it may make sense. If the pot is way down, the radio can't be playing the full 400mW. If on battery (portable) we don't want the current demand of a 400mW amp when playing way-down. So the switch could back-off the power stage to 100mW or 25mW, have half or quarter the battery drain.

Simple Vg2 "power control" has been seen. I think I showed it on a revision of my Third-Watt. I spent some time test-bench experimenting with it on a much bigger SE amp, and it does work. At least for the case where you "usually" want to work near the edge of distortion, are willing to manage pick and knobs to get there, but need "distortion" at 16 Watts for stage or 0.5 Watts for bedroom. While I had not seen the 1945 patent, I bet I saw it "somewhere".

[VMS]

This one was published in 1934:

https://www.google.com/patents/US1978008

[kagliostro]

About the control of G2 voltage we were discussing the TubeTown VVR kit (that the seller indicates for G2 Control and for Power Adjustment)

https://www.tube-town.net/cms/?DIY/Amp-Tools/VoCo_Variable_Voltage_Control

called Variable Voltage Control (VoCo)

here

http://el34world.com/Forum/index.php?topic=14308.msg135099#msg135099

Franco