Fender Patents and Clones

[ojaverde]

How can so many companies be making copies and clones of Fender amps without infringing on the original patents? Are they exact copies ,or do they make small changes to the circuits? How does this work?

[fauxsuper]

Mainly because there weren't any patents. Most of the tweed amps had circuits right out of the Western Electric tube designers manual (Or whatever it was called).

I'm happy there are people out there who make some of these amp designs available at prices working musicians can afford. It's certainly not going to cause the people who currently own the rights to use the Fender name to go out of business.

[iim7v7im7]

Additionally, I might add that patents back then were issued for only 17 years to the assignee (20 years today), so they would have long expired as well.

Bob

[CatfishStudios]

Can one renew a patent after the expiration?

[JohnnyCrash]

Originally Posted by fauxsuper

Mainly because there weren't any patents. Most of the tweed amps had circuits right out of the Western Electric tube designers manual (Or whatever it was called).

Whether from the RCA Receiving Tube Manual, or Western electric, or wherever - most manufacturers borrowed heavily from these books. Not to mention competition prima-facie stole each other's designs.

Looking into an ancient Gibson amp, then comparing it to what some folks did later (even Fender) was like looking at the same circuit.

To consider other practical matters, any given type of tube is manufactured for a certain set of parameters, by the manufacturer. Plate voltage, cathode values, etc there are only so many ways to hit these desired parameters (for instance some amps used 220k plate resistors, others 100k for 12AX7's - but the B+ feed was scaled before the plate resistors anyway to get similar plate voltages).

The idea to bypass cathodes with capacitors of various values was already around BEFORE Leo Fender started using them (though he didn't use them in some of the earliest amps), the concept of Negative feedback Looping had been around before Fender used it. Much of the design/science Leo used over time was already out there in the radio/audio world.

The term "B+" is a carry-over from when batteries were used!

Leo Fender did not invent and think of all of this stuff on his own - it was already established science/technology (not to minimize what he did - he was a genius!).

Originally Posted by fauxsuper

I'm happy there are people out there who make some of these amp designs available at prices working musicians can afford. It's certainly not going to cause the people who currently own the rights to use the Fender name to go out of business.

+1

I'm more glad the copies of these circuits are on the 'net. I've built old Gibson circuits, and tons of Fender circuits. To buy an expensive reissue of a 5E3 would be ridiculous considering the low parts cost.

[teleamp]

The guys with slide rules that designed the tubes, also designed all of those Ionic circuits that amp builders have been using for decades. Western Electric was a biggie, the tube compays gave the circuit designs to mfgers if they bought their tubes.



When someon designs a new tube, we will see a new amp design.

[Dacious]

Leo licenced his reverb straight off Hammond Organ. 'Vibrato' had been around already - I think Magnatones's pitch-shift version awas patented.

[iim7v7im7]

No, patents cannot be renewed. An assignee only maintains rights for the period that the patent is in inforced. This is why there are generic drugs (for example).

:-)

Bob