Protected by patent
This design is protected by the US patent 5097223 but Analog Devices gives permission to build this amp for personal use. Those of you who want to read the patent, send me a message. I have a pdf file of it.
I have negotiated with Analog Devices about a permit of manufacturing pcb's in a small scale and this is now solved. This means that pcb's bought from me can't be used in a commercial product. If this is the case license must be obtained from Analog Devices.