dc offset

For the three and more legged things
Post Reply
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#1 dc offset

Post by ed »

Moving on from the disappointment of the F6’ inability to drive the electrostatics….I’m working on a 3 stage AB with lateral fets and minimum idle current requirement. So I updated spice to xvii to make a start.

I tested spice with a jfet buffer (2sk170/2sj74)and tinkered with the models to get the idss to match. I noticed that the buffer output has a distinct DC offset, varying with the idss match.

Anybody got a feel for the effects of an offset in an early stage. Academic in this project because I'm unlikely to use such a buffer here, just curious.
buff test.jpg
There's nowhere you can be that isn't where you're meant to be
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#2 Re: dc offset

Post by IslandPink »

First I've heard of the F6 problem !
But seriously, interested to know in what way it failed and just thinking about whether you can insert the electrostats as a complex load in Spice and verify where you're going with this new amp ?
No rush ....
"Once you find out ... the Circumstances ; then you can go out"
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#3 Re: dc offset

Post by ed »

see here!, now pay attention I'll be asking the difficult questions shortly.

http://www.audio-talk.co.uk/phpBB3/view ... f=9&t=7086

It hasn't failed..it's back in the studio set-up driving ariels.
and verify where you're going with this new amp ?
I'm happy with the tpa3116 for what it's worth but after playing with a couple of budget SS class AB amps, one of which took 13 watts out of the wall, I'm curious to see if I can come up with something. It will make a change from taking 300 watts out of the wall if I pull it off. I'm looking at it in an 'object oriented' kind of way, treating each amp stage as though it were a class in an OO program development.
There's nowhere you can be that isn't where you're meant to be
User avatar
Nick
Site Admin
Posts: 15694
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#4 Re: dc offset

Post by Nick »

Anybody got a feel for the effects of an offset in an early stage
I would guess it would be entirely dependent on what follows it.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Post Reply