This thread is a follow-on to my thread last year on getting TDA1521 to play nicely in parallel with lower gain. In short, it wouldn't cooperate so I decided to switch the design over to TDA7294. Yesterday we got the first in-a-box prototype up and running. Here's a pic to whet your appetite :
Probably the most unusual thing about this amp is its power supply, a hybrid of linear (a standard toroid) with a high powered buck regulator. The reason the power supply isn't an off-the-shelf switching brick is because I wanted to avoid common-mode noise which comes as standard with such a choice. I did much of the development work on the buck regulator last year but its still not quite optimized - you may note the buck regulator's output inductor isn't tied down to the PCB because its very much a work in progress. Some of the back story to the PSU is told in last year's thread. I've attached the amp board schematic, there's nothing much out of the ordinary there except perhaps for it being a single rail design and the provision for an external bank of supply rail caps. This prototype has about 85,000uF of rail capacitance per channel by virtue of its two out-board cap banks. Having a buck reg means the soft start is built in so with this amp there can't be such a thing as too much rail capacitance....
(More to come later)
Probably the most unusual thing about this amp is its power supply, a hybrid of linear (a standard toroid) with a high powered buck regulator. The reason the power supply isn't an off-the-shelf switching brick is because I wanted to avoid common-mode noise which comes as standard with such a choice. I did much of the development work on the buck regulator last year but its still not quite optimized - you may note the buck regulator's output inductor isn't tied down to the PCB because its very much a work in progress. Some of the back story to the PSU is told in last year's thread. I've attached the amp board schematic, there's nothing much out of the ordinary there except perhaps for it being a single rail design and the provision for an external bank of supply rail caps. This prototype has about 85,000uF of rail capacitance per channel by virtue of its two out-board cap banks. Having a buck reg means the soft start is built in so with this amp there can't be such a thing as too much rail capacitance....
(More to come later)