goes to SGK!
Toni, by the way, have you ever put the 200W CFA in a box and compare the sound with your amps?
BR, Damir
Nice performance, very respectable THD numbers, although the bias current seems a tad on the high side in terms of no signal dissipation, how does the bias track over the operating temp range ? It would be an interesting exercise to use a peltier device to "exercise" various manufacturers Mosfet's from say -50 to 150 C. Use a constant current source to force a drain current of say 50 mA and plot the Vgs versus temp characteristic. Years ago I ran some tests of the common "linear audio grade" IRF devices in 200 - 50 V range and they seemed to hover around ~ -4.4 mV/C at 50 mA and behave fairly linearly.
I dont think so,
We dont talking about speed of current.
Shorter NFB that will decrease induction of track.
SA2015: using vertical mosfets IXTH80N20L and IXTH48P20P
just sent this to fab. Hopefully no routing errors.
This time a have placed the ground planes on top. The SK76 heatsink can be mounted without isolation washers.
BR, Toni
just sent this to fab. Hopefully no routing errors.
This time a have placed the ground planes on top. The SK76 heatsink can be mounted without isolation washers.
BR, Toni
Attachments
Thx! To which BIAS value /post are you referring? 100 - 150mA for the V-MOSFETs are needed to get good THD results at crossover region. Higher BIAS up to 500mA is possible if you want to get more watts in Class A region. The bias is constant in between 5% from room temperature to > 60-70 degree heatsink temperature.
BR, Toni
I was mainly referencing/thinking of consumer applications like home theatre where 6 channels of fairly high idle dissipation (assumed at least 100 mA) can really add up to high temps within a chassis/enclosure. Perhaps with Cordell style local output stage error correction one could lower the idle current to say 30 - 50 mA and obtain similar THD numbers ?
#2171
astx is offline astx Austria
diyAudio Member
Join Date: Jan 2011
Location: Tyrol / Austria
Default SA2015: using vertical mosfets IXTH80N20L and IXTH48P20P
Test sample using 1 pair of IXTH80N20L and IXTH48P20P up und running!
Quick THD+N tests (80k bw) with SOA circuit in situ:
THD+N 20k@100W@8R: 0.0035%
THD+N 20k@200W@4R: 0.0042%
#2171
astx is offline astx Austria
diyAudio Member
Join Date: Jan 2011
Location: Tyrol / Austria
Default SA2015: using vertical mosfets IXTH80N20L and IXTH48P20P
Test sample using 1 pair of IXTH80N20L and IXTH48P20P up und running!
Quick THD+N tests (80k bw) with SOA circuit in situ:
THD+N 20k@100W@8R: 0.0035%
THD+N 20k@200W@4R: 0.0042%
You can go for lower bias but THD will increase especially at crossover region. For the SA2016 using L-MOSFETS I have done some test with very low bias. See table at post#1765
For V-MOSFETs you will need always higher bias to get respectable values. Maybe I have some sparetime to repeat measurements also for SA2015/V-MOSFET variants at low bias currents.
BR, Toni
For V-MOSFETs you will need always higher bias to get respectable values. Maybe I have some sparetime to repeat measurements also for SA2015/V-MOSFET variants at low bias currents.
BR, Toni
