There's a new Randall Smith in town

[Gaz]

This really irritates me:

https://www.google.com/patents/US20130028447

[Smokebreak]

So its a dual ganged 50K. One being a master before the PI, the other being kinda like the Mohave "Power dampening" on the PI cathode, but there's a 3K3 across it to limit.

[RockinRocket]

Well is it unique/original? I don't have a problem with that. But Smith that's another story.

[Phil_S]

WTF, a pot on the cathodes of a LTP? I guess it can be patented. Defending a patent is a whole other thing, a whole other thing that takes deep pockets. Meh.

[Smokebreak]

Well the only thing that maybe possibly be considered unique would be that it does the volume cutting in 2 places at the same time, by different means.

So with patents in general, taking this one or example, if you changed it to 100k pots, and a 3K9 resistor, does that satisfy not breaching any patent laws, or whatever ?

[Gaz]

What I find most absurd is that the amp is otherwise a dead clone of a Marshall, (with some whatever EF86 wannabe Vox channel), and they have the gall to patent something, let alone two common MV's shoved together in a dual gang pot. I think they should be working on their lam-o FX loop instead.

Maybe we can summon them here will the power of Google alerts...

3rd Power, third power, hybrid-master TM

[RockinRocket]

Not to derail but is this a good sounding MV? How does is rank to other MVs? Badcats K master is patented or pending makes me wonder

[Gaz]

Not to derail but is this a good sounding MV? How does is rank to other MVs? Badcats K master is patented or pending makes me wonder

http://www.londonpower.com/tube-amps-faq

Scroll down to where Mr. O'Connor tells it like it is. I hate this marketing crap.

[RockinRocket]

http://www.londonpower.com/tube-amps-faq

Scroll down to where Mr. O'Connor tells it like it is. I hate this marketing crap.

Cool read thanks. It talked about the Kmaster and Id still like to see a schematic. Did that article talk about the Hybridmaster?

[Ken Moon]

I built several variations of this amp, and I still have one with this MV, which is very similar to the Carlsboro and Mojave MVs:

[img698]http://i514.photobucket.com/albums/t346 ... atic_1.png[/img]

I have mixed feelings about how it sounds - sometimes I like it, but usually I leave it all the way up.

It never crossed my mind to patent it, though!

I have used a Mesa-patented circuit that I like a lot, which is a Cut control that goes between a Marshall-style post-tone stack MV and the PI (series line-up of a 22k resistor, .003uF cap, and 25K pot, connected from the input of the PI to ground).

Since I first saw the Mesa patent, I've seen several commercial amps with this exact circuit. Who knows if Mesa really "invented" it?

[Smokebreak]

That's the one I've used a couple times, Ken, and I agree nothing to really write home about. Cut volume by 1/2 or so IIRC and affected the tone. I have an amp that has this one, a normal pre-PI and a PPIMV, and the only one I use is the good ol normal master.

[RockinRocket]

Well the only thing that maybe possibly be considered unique would be that it does the volume cutting in 2 places at the same time, by different means.

By cutting the volume in two places happen to have a reaction to one another that works better this way perhaps?

[Gaz]

Well, I'm guessing that's what made them feel so clever, they up and patented it.

Normally, a pre-PI master reduces drive to the phase inverter, meaning less PI and power tube overdrive. Starving the PI like that lowers the headroom, and kind of counteracts the effect by making the PI easier to drive. Normally if you just have it like in Ken's Talon amp you will get more perceived distortion as you turn it down, which may or may not be desired. As Ken pointed out (and I remember him saying years ago he was on the fence about the master), it's not really that great or transparent sounding. I doubt the addition of the pre-PI master really makes it that much better.

While I am sometimes impressed by clever uses of regular potentiameters, I just find this kind of marketing pathetic. Think about the real engineers and innovators putting power scaling and elaborate attenuators inside their amps. To me this reeks of wannabe boutique cloners posing as engineers. It takes one to know one!

[Smokebreak]

Only 1 way o find out
I would imagine that was the design goal. But if you look at the PI cathode, it's a 1K5 + 50K//3K3 = 4K6 , Turned all the way down. Turned up or "out of circuit" it's only down to 1K5. My point is that that's not a terribly large range to affect volume that much , so perhaps the designer feels it produces some pleasing affect while the other gang actually affects the volume. Who knows . I'm totally speculating .

[teemuk]

I think this is a pretty clever scheme. They combine a generic attenuator-type master volume control to another control that adjusts LTP tail current and therefore headroom of the PI stage.

But is it patent worthy? Being combined from several decades old prior art it probably isn't a big deal to build a solid case against patent infringement claims, but it's probably at least on some level a legal process not something to argue at Internet forums so...

Anyway, Id' like to see what happens when they try to defend their patent that consists of a generic volume control arrangement that has been used for nearly a century and an adjustable tail current source, which is likewise several decades old prior art and has been used throughout the years for the same patented purpose by at least a dozen of different guitar amp manufacturers.

Think about the real engineers and innovators putting power scaling and elaborate attenuators inside their amps.

Well, that, IMO, is a piss poor example of cutting edge engineering given that regulated power supplies are probably a century old invention as well and that adjustable regulated power supplies have been used to knock down amplifier output power since what...? Well, at least the very first PATENT concerning using adjustable regulated power supplies to reduce guitar amp's output power dates way back to early 1970's. First patents for amp attenuators are probably even older. That's about 50 years worth of prior art as well. Things invented about half a century ago are hardly innovative in my book even if they are given fancy new trademark names like "power scaling".