Choke on this for a bit...
http://www.diyaudio.com/forums/anal...screte-power-supplies-phono-line-preamps.html
http://www.diyaudio.com/forums/anal...screte-power-supplies-phono-line-preamps.html
Thanks Wrenchone. I'm anxious to see what you come up with, and which Devices you select .
Here is the SPICE model for the C3D0065090D from Cree's official set of models, if anyone is interested.
SPICE suggests it will perform well enough in the F6 circuit used by the DIYAudio boards, yielding dominant second harmonic and virtually no third (.01% THD). Using the alternate 'AC degeneration' version, second harmonic is a little higher but third gets much higher as well. It does not model well in an Aleph circuit - quite a bit of distortion through fifth harmonic or so. Perhaps this indicates in some way the poor sound res07njc experienced using them in his mini Aleph. Seems to perform ok in mu-follower type circuits like the ACA.
SPICE suggests it will perform well enough in the F6 circuit used by the DIYAudio boards, yielding dominant second harmonic and virtually no third (.01% THD). Using the alternate 'AC degeneration' version, second harmonic is a little higher but third gets much higher as well. It does not model well in an Aleph circuit - quite a bit of distortion through fifth harmonic or so. Perhaps this indicates in some way the poor sound res07njc experienced using them in his mini Aleph. Seems to perform ok in mu-follower type circuits like the ACA.
excellent.. I was in the process of modelling the 65090 myself, but have some other stuff competing for my attention, in addition to being a total Spice newbie. It certainly jives with my impression, and it stinks because that part seemed closest in spec to your garden variety IRFP. My next (final) plan was to throw some new resistors at it to play with input current/open loop gain/gate voltage/etc.. I'm not holding my breath.. Good/better news (at least in model) with the F6.
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I have tried it in LTSpice, but get an error message ('Could not load the include file').
What is wrong?
I was looking at some possible devices for some Zen-ish amps + BA1 frontend and saw that IXYS have a new set of SiC Mosfets that are cheap and available...
Looks like they can handle a lot of heat too which is nice
IXFH220N06T3
IXFH270N06T3
Looks like they can handle a lot of heat too which is nice
IXFH220N06T3
IXFH270N06T3
These have tremendously large Ciss:8.5nF and 12.6nF, it can be problem, isn't it?
And how about it:
http://ixapps.ixys.com/DataSheet/IXFN50N120SiC.pdf
And how about it:
http://ixapps.ixys.com/DataSheet/IXFN50N120SiC.pdf
The 1205K runs about 7V Vgs at 2 amps, 30V.
The 1208K is more like 5V Vgs.
That information and the curves suggest that the 1205 would make a
good cascode device, and the 1208 is a candidate for the DEF amp,
both for Vgs and somewhat better bandwidth and linearity.
The 1208's have been out of stock, but I am informed that they are still
making them - apparently they have a large customer who buys them....
The 1208K is more like 5V Vgs.
That information and the curves suggest that the 1205 would make a
good cascode device, and the 1208 is a candidate for the DEF amp,
both for Vgs and somewhat better bandwidth and linearity.
The 1208's have been out of stock, but I am informed that they are still
making them - apparently they have a large customer who buys them....
I ran a comparative series of tests of different devices in Common Source
mode driving 8 ohms without feedback and with low and high signal
source impedance. Distortion vs Ids and Vds and frequency, gain and
frequency response.
As I indicated, most of these parts give reasonably similar curves - most can
be adjusted for distortion below 1% at 1 watt, and a few with lower Drain
impedance can find sweet spots as low as .2%.
The ones with higher Ciss and Cgd need to be driven by lower impedance
if you want 100+ K bandwidth.
mode driving 8 ohms without feedback and with low and high signal
source impedance. Distortion vs Ids and Vds and frequency, gain and
frequency response.
As I indicated, most of these parts give reasonably similar curves - most can
be adjusted for distortion below 1% at 1 watt, and a few with lower Drain
impedance can find sweet spots as low as .2%.
The ones with higher Ciss and Cgd need to be driven by lower impedance
if you want 100+ K bandwidth.
As Nelson has mentioned a preamp able to drive a low impedience
load may come in handy. What about modified the Bride Of Zen to
use a slightly larger mosfet like this one. Perhaps lower the drain resistor
to 250 ohms and run the mosfet at ~ 160ma . I thought this one looks
interesting in that the drain current curve isn't totally flat but does look
like it may curve up just a little,it has almost twice the power handling
of the IRF610 but still has rather low capacitence. And they are rather
cheap.
http://www.mouser.com/ds/2/90/3m0280090d-838555.pdf
load may come in handy. What about modified the Bride Of Zen to
use a slightly larger mosfet like this one. Perhaps lower the drain resistor
to 250 ohms and run the mosfet at ~ 160ma . I thought this one looks
interesting in that the drain current curve isn't totally flat but does look
like it may curve up just a little,it has almost twice the power handling
of the IRF610 but still has rather low capacitence. And they are rather
cheap.
http://www.mouser.com/ds/2/90/3m0280090d-838555.pdf