Postby KevinOConnor » 19 Jan 2011, 12:08
Hi Guys
Yes, I came up with Power Scaling and the term is my trademark - now part of the music biz lexicon, just like our "detuned" cabinets.
Power Scaling can be applied to any tube amp. Our books show hundreds of ways to implement Power Scaling, as Power Scaling is both a methodology and the goal - not just a single circuit approach. When implemented correctly, the amp's tone will not change from full output down to milliwatts. We only claim what the circuit will actually do. The plethora of builders using Power Scaling is a testament to the fact it does work.
All of Marshall's 50W and 100W amps are fixed-biased, just like everyone else's. In some cases, a beefier bias supply add-on is required to add Power Scaling, as not all bias supplies are equal. There is free info on our site about that.
Some of the copies of Power Scaling - which usually are not full Power Scaling - work as well sonically; the YJM and AFD circuits are examples of this. Hall's circuit tried to economize in areas that made it only suitable for low-powered amps. The current London Power kits accommodate any amp up to 900V B+ and up to 5-600W. Past kits were designed for the bulk of amps and did not accommodate the high-voltage Marshalls or Hiwatts. The VM operates close to 500V so is easily accommodated by our kits. No doubt Marshall will add this feature to the VM either as a new version, an addition to the family or as a replacement.
Part of Marshall's former engineering team ran off with the Rolodex and started up Blackstar. They also had our books and have an undefendable* patent for their variation of Power Scaling. As a one-knob solution, it lacks versatility.
On the good side, all the people copying Power Scaling are helping musicians save their hearing. And... if it didn't work people wouldn't copy it.
*won't stand up in court
I am not here to promote my products - most people know about me, the TUT books, Power Scaling, etc. - and have tried to limit any reference to my own site and writings here. I do want musicians to know what choices they have, and that they can lobby their favourite manufacturer to build products to suit the player's actual needs. It is a win-win situation. Customer feedback lets the manufacturer know what will sell, so they can stay in business. The boutique amp biz basically tests and satisfies these waters, then the big companies see what is successful and can make offerings with less risk.
Have fun
Kevin O'Connor