Cloning Class A Classics Continued..

So OK for DIY projects to then flip on Audiogon or ebay, but nothing that really resembles a business?

One of the reasons for my question was that I assumed a lot of the old classic circuits were more or less in the public domain by now.

Doesnt Nelson Pass allow that? Or would that be just for personal use?

Tim Rawson builds certain clones.

Why do you think there is a great market for older M series Yamaha class A amps!

Do you mean "Replica" of old class A amps. That is what they used by criminals to commit a fraud. They sell pricy things like Swiss watches using the fany makers Name and Trademarks and do a pretty convincing job of it.. Almost every Dupont lighter on ebay is guaranteed to be a Replica. They are never sold as replicas just a real emphatic this an 100% Authentic .....
If you are honest I am sure there are several designs that are copied so much they are Icons and have become public domain, such as the Long Tail Mullard scheme for tube amps. The makers of these amps don't say that this is just an old ho hum design but the amp they make under their banner is full of all sorts of new and better technologies.If You sell a Pass like type A amp please get Permissuion and a liscense from him perhaps you can call it Brand Passionite-X based on a true Pass design.
You can always find the Schemata of the old great amps and many I assume have used some of or most of the old design to build their own Brand. I hope they never say this is a Krell KS or KM series no plataue bias amp "replica" . Just call it your amp company model 100-A pure class A etc...And do us all a favor by not making it exactly like the brand you are using for a template. It would be better to do a few things differently and don't make the amp appear to be a Krell or whatever..

There are still patent issues to contend with. Nelson Pass is kind enough to share some product design with the DIY community, but I'm pretty sure he stipulates that any use be non-commercial. I think there was a licensed clone of the Aleph 30 available at one time.

I'm not aware of Krell or others releasing designs, so you are talking about pirated copies.

Hypothetically, if I bought such a Clone I'd want some assurance of support over its lifespan. That would drive up the cost and make the clone far less competitive with the original.