Intellectual Property

[drz400]

I didn't take into the consideration that fact that people get patents on other peopels designs, to do so is just disgraceful.

What I meant is that it is ironic that a company who likes to patent things like "channel Switching" would resort to rippining the SLO off down to every resistor. I think the only thing different is a brighter treble cap and a presence control after the EQ

[rfgordon]

According to US Patent law, one can obtain a patent not just for original ideas, but for improving on the "prior art" or for combining two or more items (which may have already been patented by others) in a novel way.

It is very easy to get a patent, though the process is somewhat cumbersome and expensive. However, that may be changing. There is a case before the Supreme Court (forgive me, the case name escapes me at the moment) which addresses just such an issue. The case involves software, if I recall correctly, but the decision will have significant implications for any and all future patent-seekers.

If you want to look at lots of amp patents, check out Google's patent database. You'll notice that most filings omit component values--this offers some measure of protection for the idea, since patents are public knowledge.

[ampdan]

There is nothing new under the sun. All of these amps are based on circuits that became public domain decades ago.

[steve-o]

Hey all,
I'd have to say, as a newcomer to this forum, that everyone I've worked with here has been awesome, (for a funny take on this word, check out this comedian:
http://www.youtube.com/watch?v=0rYT0YvQ3hs ), and that has made this 1st project all the better to work on.
I also think that it's important to respect that people are trying to make an honest living from amp making. Builders like Soldano or Mike Z. don't exist to provide us with schematics. We benefit indirectly from their gainful self-employment.
I like the idea of sharing schematics through PM-ing. It protects the designer's work from being picked up by unscrupulous characters and allows us to get inspiration from their hard work.
Not that my opinion was in demand, but there ya' go...

[lastwinj]

there are very few manufacturers who can truly design up a marketable tube circuit. just about eberything with tubes has been done. drop it. lets make some money.

germ

[ampdoc1]

I just want to post an addendum to one of the remarks above. I'm not sure what legal problems Kittyhawk had in the US, but in the end a quality problem with their American products did them in here. I liked Kittyhawk, and in fact, wrote the first review on their amps for Guitar Player. But a couple of years later, their distributor (Latin Percussion, if memory serves me correctly) sold all their stock to an independent seller. I helped a friend purchase one, and it was only a matter of a week or two before the power transformer failed. In the end, it turned out that this was a common problem with their products in America. I know my Quattro preamp which I purchased years later, has a replacement PT. Too bad, they made some very good sounding amps!

ampdoc

[FUCHSAUDIO]

According to US Patent law, one can obtain a patent not just for original ideas, but for improving on the "prior art" or for combining two or more items (which may have already been patented by others) in a novel way.

There have been some really good points made in this thread.

The sad reality in all of this is that many prior art ideas have been patented by people like Mesa, as "new ideas".

Mesa's managed to protect things that go back to the 20's ! Simul-class is a fine example. Just the concept of channel switching, having a solo volume control, etc. are nothing new under the sun, but if you have deep pockets you can pull a patent on it.

Sal Trentino has patents on switching from fixed to cathode bias in a tube output stage. It's nothing new, but he realized it hadn't been patented before.

Dennis Kager holds an expired patent on his "RMS control". A wirewound pot in the cathode circuit of an output stage to vary wattage. Clever, cute, didn't sound all that great, but it did work. I'd bet if you looked long enough, you could find it may have been done before.

Soldano (from what I understand) did actually sue Peavey when it was determined that the 5150 was a little too "inspired" by the SLO-100.

The problem with any patent is that you as the inventor will need to defend it, if and when someone decides to take it for themselves. The guy who invented the delayed windshield wiper on cars, and the guy who invented the rachet wrench, are prime examples of people who spent much of their lives chasing large conglomerates over patents that were stolen, infringed on, or sold for too small an amount. Both were near death before the auto industry and Sears finally paid them what they were entitled-to. They spent much of their lives chasing the money.

Another interesting point is the statement that "there is nothing new under the sun". This is not entirely true (there's lots of cool circuit topologys you might love to use or try, but not necessarily like how they sound or feel to you as a player).

I believe the reason many of the designs like wrecks, and Dumbles are embraced is because of how they sound and feel. They grew out of Fenders. If you look back you'll find Fender abandoned pentode preamps in the early days. Did people not like them ? Were they not reiable, who knows ?

I've played with pentodes, hybrid fet/tubes cascodes, power supply regulation, tube diff-amps, tube/op-amp circuits etc. (in both tube audio and guitar amps) and there's lots of ways to make things quieter, measure better, or have more gain, less noise, etc. Problem is "better" is not always really better.

[drz400]

Soldano (from what I understand) did actually sue Peavey when it was determined that the 5150 was a little too "inspired" by the SLO-100.

I guess nothing became of that.

But have you looked at the preamp lead channel of a Boogie Rectafrying? It is almost EXACT SLO100, just a different treble EQ cap and a high cut after the EQ if I remember correctly. I would have thought Soldano would have gone after them before the 5150, at least 5150 made an attempt at being different. I also heard that VHT makes claims they are the first to use a "depth" control for guitar power amps, but I see the same circuit in the Radiotron Designers handbook

[summitcity]

I Think the DIY crowd is just trying to build amps with good tone. Tube circuits are Science and Math. The Math dosen't change how can you patten 2+2? Sure I know there is alot more to it than that but how many guys have a favorite amp with only a Volume and Tone Control. Does changing the slope realy make a new Circuit? I guess one should error on the side of integrity but I like to take a peak at what is in those amps. Funny how simular they can be.

[drz400]

I Think the DIY crowd is just trying to build amps with good tone. Tube circuits are Science and Math. The Math dosen't change how can you patten 2+2? Sure I know there is alot more to it than that but how many guys have a favorite amp with only a Volume and Tone Control. Does changing the slope realy make a new Circuit? I guess one should error on the side of integrity but I like to take a peak at what is in those amps. Funny how simular they can be.

Absolutely but the SLO 39K is on a cathode, not a slope
That is pretty damm unique and the COMPLETE rectum frying amp is a copy, not just the cathode resistor. This seems pretty low for a company who prides themselves on being patent happy with patents on dual rectufriers and channel switching, voltage control etc.