25-02-2015, 08:24 PM
Hi Gents, as mentioned earlier, for audio use linearity is important.
A lot of line output valves have more than adequate power but poor linearity. as they are designed for fast switching (pulse) operation where this is not important.
This problem has been overcome by driving them on G2, with G1 being used at a fixed bias to set operating point.
The drawback to this is that the driving voltage needs to be in excess of 100v and be direct coupled, this does have the advantage that there is no coupling cap with its phase shift.
This has been tried and there are circuits on the web. A close search will even reveal characteristic curves for some power valves when using G2 drive.
Ed
A lot of line output valves have more than adequate power but poor linearity. as they are designed for fast switching (pulse) operation where this is not important.
This problem has been overcome by driving them on G2, with G1 being used at a fixed bias to set operating point.
The drawback to this is that the driving voltage needs to be in excess of 100v and be direct coupled, this does have the advantage that there is no coupling cap with its phase shift.
This has been tried and there are circuits on the web. A close search will even reveal characteristic curves for some power valves when using G2 drive.
Ed
