Hi,
are lateral mosfets such as 2sk135 / 2sj50 obsolete?
Which power transistors are currently best for audio?
cheers
are lateral mosfets such as 2sk135 / 2sj50 obsolete?
Which power transistors are currently best for audio?
cheers
TO3 packages are hard to find nowadays.
Exicon still manufactures lateral mosfets flatpacks, available from Profusion.
Exicon still manufactures lateral mosfets flatpacks, available from Profusion.
IMHO the topology is more important than the choice of transistors, BJT, lateral or vertical mosfet.
Lateral mosfets have advantages:
• Complete absence of secondary breakdown when compared to BJTs.
• Self limiting current characteristic
Lateral mosfets have advantages:
• Complete absence of secondary breakdown when compared to BJTs.
• Self limiting current characteristic
I did not know that Nelson Pass used lateral mosfets in F7.
The F7 diagram looks almost the same as Jean Hiraga class A.
F7 has no stabilization of the operating point of the power transistors.
What do you think about it?
The F7 diagram looks almost the same as Jean Hiraga class A.
F7 has no stabilization of the operating point of the power transistors.
What do you think about it?
If you look at the F7 manual it states a design goal as "very low thermal distortion and drift".
Lat FETs provide thermal stability to the biasing so that's a reasonable guess I think.
Lat FETs provide thermal stability to the biasing so that's a reasonable guess I think.
Exicon does a whole range
ECF series are TO3 case=source, for replacing Hitachi devices, single or dual die
ECX are TO247, single die
ECW are TO264, dual die
Lateral MOSFETs (Buy Online) | Profusion
Thanks for your explanation. I believe that the F7 has a quiescent current of about 1A in the power stage. Then, about 25W is released on one lateral mosfet. If there is no stabilization of the quiescent current, it may change by about 15% when changing the temperature from 25 degrees to 75 degrees. Do you think it is not much?
Part of the problem is that these things are so stupidly expensive that few commercial manufacturers use them, so the market remains small.
BJTs hold some advantages but not others.
Laterals, for example, are nearly bulletproof and don't require a drive current, while power BJTs typically have a relatively low Hfe.
I've always thought that if they could get the price down, laterals would make fantastic series pass elements for linear power supplies.
But I've seen really great amplifiers built around BJTs, HEXFETs and laterals. It's probably easiest to get the lateral design right, and probably hardest to get the HEXFET design right, but that said I think that the best HEXFET designs are among the best power amplifiers ever built. Obviously that's a subjective statement.
A certain series of HEXFET based amplifiers powered everything from the 1994 Division Bell tour to Lambeau Field. Can anyone guess the manufacturer?
Laterals, for example, are nearly bulletproof and don't require a drive current, while power BJTs typically have a relatively low Hfe.
I've always thought that if they could get the price down, laterals would make fantastic series pass elements for linear power supplies.
But I've seen really great amplifiers built around BJTs, HEXFETs and laterals. It's probably easiest to get the lateral design right, and probably hardest to get the HEXFET design right, but that said I think that the best HEXFET designs are among the best power amplifiers ever built. Obviously that's a subjective statement.
A certain series of HEXFET based amplifiers powered everything from the 1994 Division Bell tour to Lambeau Field. Can anyone guess the manufacturer?