In article ,
Trevor Wilson wrote:
*Depends on implementation. The MOSFETs, of course, will always sound
like MOSFETs - dull, boring, undynamic and compressed.

I've got a pair of 150w MOSFET amps in the workshop - so listen to them
quite a lot. Actually Maplin kits, but with a rather better power supply.
And they sound as sweet as a nut. Home made speakers too sort of thrown
together out of Audax units left over from a job. But one of those happy
coincidences that just work well.

--
*Don't use no double negatives *

Dave Plowman London SW
To e-mail, change noise into sound.

"Pete"

I am looking to build an amp for home theatre/hifi use.
currently have an amp using Hitachi's default design for mos fets from the
'80's ( 2sk49 2sj50 I think ).

** Those are Hitachi's famous TO3 pack " lateral " mosfets as used in many
famous hi-fi and professional power amps.

They are extremely easy to use, exceptionally rugged and have NO issues
with biasing or bias stability. Plus they will share current automatically
when used in parallel.


I plan using LM4702 but have three options for the output stage.

bipolar
SAP15P and SAP15N
2SA1943 and 2SC5200

mosfet
2SK1530 and 2SJ201


** Those Toshiba numbers are NOT lateral mosfets at all - but switching
types with a low gate voltage threshold.

Such devices do not have any of the desirable characteristics of the Hitachi
laterals.

Biasing is a pig, thermal runaway is just itching to happen.


..... Phil

Phil is probably right that I'll not gain much or ven anything from the
Hitachi design I have now.
But it will always niggle at me that there maybe a better design nowadays.
MOS appeals from the robustness angle but I'm not convinced it's best for
audio, relatively few manufacturers seem to go that route apart from in car
audio..........
So this is my current target

http://www.tech-diy.com/Amplifiers/L...702_Sanken.htm

I take on board that the SAP15's may go out of exisitence in the future but
I could always change the output stage to something else should the worst
happen.
I even have 2 pair of SAP01M fets but looking around they don't appear to be
stocked so they must have been a non-starter ( I got them as samples when
they came out )

thanks for all your comments.

Pete

"Pete"

Phil is probably right that I'll not gain much or ven anything from the
Hitachi design I have now.

** Huh ???

Are there posts from me here in invisible ink now ??

Cos I cannot see what the OP is replying to.



.... Phil

"Phil Allison" wrote in message
...

"Pete"

Phil is probably right that I'll not gain much or ven anything from the
Hitachi design I have now.

** Huh ???

Are there posts from me here in invisible ink now ??

Cos I cannot see what the OP is replying to.



.... Phil







Phil,

Sorry, I was flicking through all the replies and took your reply a little
out of context. There was a lot to digest ( is my excuse.....)

"** Those are Hitachi's famous TO3 pack " lateral " mosfets as used in many
famous hi-fi and professional power amps.

They are extremely easy to use, exceptionally rugged and have NO issues
with biasing or bias stability. Plus they will share current automatically
when used in parallel."


Pete

"Pete"
"Phil Allison"
"Pete"

Phil is probably right that I'll not gain much or ven anything from the
Hitachi design I have now.

** Huh ???

Are there posts from me here in invisible ink now ??

Cos I cannot see what the OP is replying to.


Sorry, I was flicking through all the replies and took your reply a little
out of context. There was a lot to digest ( is my excuse.....)

"** Those are Hitachi's famous TO3 pack " lateral " mosfets as used in
many
famous hi-fi and professional power amps.

They are extremely easy to use, exceptionally rugged and have NO issues
with biasing or bias stability. Plus they will share current automatically
when used in parallel."


** Where is there any connection between my post and your comment at the top
???

Must be in invisible ink - right ?



...... Phil