Legal stuff about producing an amp

[EETStudent]

To have your own line of amps, how much different does it have to be than that of a standard Fender or Marshall?

[tubeswell]

how much different does it have to be than that of a standard Fender or Marshall?

"But, but your honor, who said it wasn't different? (and why do they want to know?)"

Seriously I don't think anyone at Fender or Marshall would be bothered. Heaps of boutique amp makers base their amps on tried and true time-tested Fender circuits. Even Fender based his first circuits on someone else's ideas. So why not hop on back of the conga line?

[Enzo]

Change a resistor a couple ohms and it is your design. The circuits are pretty much all the same. look at an old Marshall schematic and an old Fender Bassman schematic. Ignore the part values, just look at the circuit. Do you really see much difference? I could sit down right now and draw you a complete schematic for a working amp. I am not bragging, many of us here could do that. You would look at it and say how much it resembled a MArshall, or a Fender, or whatever. You'd be right. All of them resemble all the others.

Input stage: 100k plate resistor, 1.5k cathode resistor, bypass cap (pick a value), 1 meg grid resistor, a couple 68k resistors to the input to make a 6db pad, 0.022 coupling cap to next stage. Hell, that could be half the amps on the planet.

Look in the back of the RCA book. There are sample circuits - you are free to use them, Leo Fender did. There are also charts of recommended component values in a typical circuit with individual charts for common tube types. Those are a great place to start. All that data is free for anyone to use.

What you can't copy is the drawings, the pc board layout (the copper art), the panel graphics, the model name.

ANd no one is concerned that a student is making an amp of two in his basement and selling them to his friends. There are commercial amp makers here on this board every day. You have a long way to go before you are the tiniest blip on Fender's radar.

[black_labb]

not picking on bruce, but mission amps (along with that many other manufacturers) base their whole designs of replicating vintage amps. bruce does a great 5e3, which is what he is known for. these guys put huge amounts of work getting their amps to sound like the amp they are copying.

[EETStudent]

cool stuff. I dont necessarily plan on popping out a line of my amps anytime soon. I was just interested in how that stuff works

[Marty]

The patents on the old circuit designs have run out so the design is in the public domain for anyone to use. Where you will run into trouble is when the amp you are selling starts looking very much design-wise like someone else's in the market. A company like Marshall with a very distinct styling would come after you for trademark or trade dress infringement because these rights live as long as you use and activly protect them from infringement.

[teemuk]

I’d be more worried about getting appropriate certificates that prove your amplifier is safe enough to be sold to other people.

[Enzo]

Yes, I wonder how many of the various boutique amp builders out there have UL approvals.

[bluefoxicy]

Look in the back of the RCA book. There are sample circuits - you are free to use them, Leo Fender did. There are also charts of recommended component values in a typical circuit with individual charts for common tube types. Those are a great place to start. All that data is free for anyone to use.

What you can't copy is the drawings, the pc board layout (the copper art), the panel graphics, the model name.

ding ding ding. There's pretty much one way to make a 12AX7 work, or an EL84 or EL34 or 6V6. There's one way to make pizza too. It's almost the same thing, just a little extra stuff here and there in between.

Try creating a very original power supply stage.

[Steve Conner]

Many years ago, when I was young and naive, I set out to make a guitar amp that was, in fact, totally different to everything else, including the power supply.

http://scopeboy.com/toastpix.html

I think I succeeded: it looks different and sounds different too. But generally speaking, musicians don't seem to want different. If you look at the builder forums on here, the most popular project is probably the Mission 5E3 clone.

I can understand this mindset, after all, if you're going to plunk down a few hundred dollars on something without hearing it first, well, you want to know what you're going to get. But still, musicians are a conservative bunch. Look at the sales of Strats, Teles and Les Pauls compared to the Parker Fly. So, yes, be different, but don't expect it to sell...

[MWJB]

"Yes, I wonder how many of the various boutique amp builders out there have UL approvals." from my experience it's somewhere between very, very few indeed and none?

At least one builder here in the UK makes an effort to make sure wires are relevant colours for purpose, but I'd expect most who were "vintage inspired" would want to be as close to tradition as possible.

"I’d be more worried about getting appropriate certificates that prove your amplifier is safe enough to be sold to other people."

A friend of mine recently bought a "serviced" amp...not one internal voltage or current had been checked adjusted, sounded absolutley dreadful, power tubes were on the verge of meltdown, but the AC cord had been PAC tested & had a nice little sticker! Nationally applied, mass market standards are typically minimum standards & very minimum at that - your well known bespoke, boutique builder will typically build to a standard way beyond a national commercial QA standard. Noise floor and longevity (not to mention tone - an advantage of going to a small scale builder is a product can be tailored to your needs) are probably better bench marks. There's any number of QA approved, budget Asian amps that hum like hell from the get go, some can't finish a set before power fade sets in.

My father called out the PAC test man to come and check a domestic appliance for legal reasons, £600 call out! How much is a fuse?

Costs for "irrelevant" standards would usually be prohibitive for small scale builders who are not benefitting from "economies of scale" like mass market builders.

IEC, plug in & grounded power cords & some sort of protection/cage around hot components should keep the "health and safety" man from your door - and wind up folks who have to undo a dozen nuts just to change a tube!

As Steve notes, if building amps for sale, even if you depart from "the path most trodden in some respects", potential buyers will often want some point of reference/sense of familiarity...difficult to get away from billing stuff as a "50's/60's so & so, but with more drive/more W/better compression/sweeter tone" etc.

Also be aware that even building amps that are perceived as "simple" can take years of honing to end up with a world class product.

[Steve Conner]

Hi MWJB

As I work in the UK electronics industry, I have my own opinions about this stuff, most of them too foul to be printable.

The relevant certification for selling in Europe is the CE mark, that covers safety and electromagnetic compatibility. It costs in the tens of thousands of pounds to have your product actually tested, but CE stickers are pretty cheap on eBay, so many small companies just don't bother. (Don't ask how I know this )

The risk of getting your ass sued is fairly small, provided your product doesn't actually:

Blow out and hurt someone litigious.

Cause major damage that is covered by somebody's insurance policy, like setting your local House O' Blues on fire. The loss adjusters will come sniffing around for any possible way that the insurance company can squirm out of paying. If the fire was started by a non-approved amp, they could sue the amp builder for the damage instead of ponying up themselves. I guess theoretically, if you burnt your house down with your own homebuilt amp, your home insurance wouldn't be obliged to pay out, but it would take a very clever loss adjuster with a heart of pure granite to do this.

Sell enough units that your competitors will start looking for ways to put you out of business. If you don't have the right approvals, all they need to do is shop you in.

If you want to export, you need to meet the standards in the country you're exporting to, too. If you ever wondered why some components, like switches and transformers, are covered in dozens of weird looking logos, those are the approval marks for various countries. To ponder: Does importing a Mercury Magnetics PT to the UK and fitting it to a recent UK-made Marshall void the CE approval?

Also be aware that even building amps that are perceived as "simple" can take years of honing to end up with a world class product.

This is very true, and I totally respect what builders like you and Bruce of Mission Amps do. But I'm more of a "Woohoo, let's try plugging some stuff together and see what it sounds like" guy. The honing mindset can only ever make incremental improvements inside a fixed frame of reference. If you want to bust the frame of reference altogether, and invent a completely new tone, you have to start messing around at random.

I guess at least I have the common sense not to try selling the results

[MWJB]

"But I'm more of a "Woohoo, let's try plugging some stuff together and see what it sounds like" guy. The honing mindset can only ever make incremental improvements inside a fixed frame of reference. If you want to bust the frame of reference altogether, and invent a completely new tone, you have to start messing around at random."

Don't get me wrong, I'm all for empirical development...& got a few "leftfield" mutants sitting about (though admittedly, probably more "edge of the box" than right outside of it), given up trying to sell them though...conversation usually goes like this..

Prospective punter: Wow, that sounds good, what's it based on?
Me: Er, not really based on anything particular, just an idea I had/tripped over/stole.
PP: How much?
Me: One off price, lifetime warranty, how does £??? sound?
PP: Very reasonable, it does sound great...can you build me a Fender (insert favourite, most revered model here)?
Me: Yes, but it won't be any cheaper than the other boutique models...it WILL be tailored to exactly what you want though.
PP: I really just want a stock Fender so & so.
Me: But there's a dozen different known circuits for that model, I can give you the one that sounds closest to what you want?
PP: Hmmm, I'll tell you what, I DO need a couple of fuses, lamps & 12AX7s...

...and back to the day job! :-)

[Steve Conner]

This is all too true! :-[

My "day job" is industrial R&D: I get hired by corporations to build them new gizmos that they need but that don't exist. I'm currently designing test equipment for the electric power industry.

It's a lot easier than trying to improve on an established concept like a guitar amp. Kind of like building an experimental Bigfoot trap instead of a better mousetrap. By the time the client finds a Bigfoot to try his new trap on, the project is done and you're off working for someone else...

[jrfrond]

Yes, I wonder how many of the various boutique amp builders out there have UL approvals.

THIS is the point here! THIS is the real legal stuff that can destroy you! Forget about plagarism of time-tested circuits whose copyrights have expired. If you market a piece of electronic gear that is AC powered and do not get UL and CE approval, you run the risk of becoming VERY broke, IF by some chance any personal and/or property damage is caused by a faulty design in your amp. Approval costs big $$$, takes time and is fraught with bureaucracy, which is why many small-timers don't do it.

Ditto for liability insurance BTW.

Good point Enzo.

As far as circuit plagarism is concerned: there are finite ways to design a tube guitar amp, with near-infinite tweaks that can be performed. Along the way, there have been some creative innovations, but when it comes down to it, most of the desirable amps are either blatant ripoffs built with superior quality, and/or an amalgam of features culled from other designs, building-block style, and subsequently tweaked to work. Nothing wrong with it though. Fender licensed the Western Electric designs, and the rest is history.