@wwwtttwww and yours is DEFiSIT?
How can I recognize this?
Is in your draft the Mosfets contribution 20% or still the SIT?
How can I recognize this?
Is in your draft the Mosfets contribution 20% or still the SIT?
I don't think there are fundamental differences in the circuit topology, like bush-pull AB and A-class amps.
The difference might just be in the level current it drives load. If Mosfet's current keeps consistent during working, it could be SE follower. If SIT and Mosfet provide same current, it could be bush-pull amp with unsymmetrical structure.
If the mosfet does the heavy lift like SIT5(pure guess), it becomes SE again. The SIT is working as CCS, and the mosfet is doing the job.
All are my guesses.
In the past, I tried to put a large resistor on the Mosfet side and zero on SIT side to get SIT contributing more current.
The difference might just be in the level current it drives load. If Mosfet's current keeps consistent during working, it could be SE follower. If SIT and Mosfet provide same current, it could be bush-pull amp with unsymmetrical structure.
If the mosfet does the heavy lift like SIT5(pure guess), it becomes SE again. The SIT is working as CCS, and the mosfet is doing the job.
All are my guesses.
In the past, I tried to put a large resistor on the Mosfet side and zero on SIT side to get SIT contributing more current.
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Thank you!
I spiced my variant and yours (at least the OS at the SJ/SK pre) and in all cases the Mosfet gives more juice and the SIT less. distortion values are similar at 1 and 10 and 40W in Spice.
So wouldn't it be funny when the SIT would work as CCS only?
Moreover in the circuit Nelson showed at BAF 2022 that is similar to my draft only GRD is at the bottom and rail is +60V, I changed the polarity as he recommended and the SIT is dominant in both cases!
Green SIT and blue the Mosfet
I spiced my variant and yours (at least the OS at the SJ/SK pre) and in all cases the Mosfet gives more juice and the SIT less. distortion values are similar at 1 and 10 and 40W in Spice.
So wouldn't it be funny when the SIT would work as CCS only?
Moreover in the circuit Nelson showed at BAF 2022 that is similar to my draft only GRD is at the bottom and rail is +60V, I changed the polarity as he recommended and the SIT is dominant in both cases!
Green SIT and blue the Mosfet
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In your sim, the Mosfet get its input signal from S of SIT. The voltage at its G is synchronized with with the output.
In SIT 5, both SIT and Mosfet get input signal at same location.
In SIT 5, both SIT and Mosfet get input signal at same location.
So I would always prefer to hear more SIT (more expensive part... :--)) ) and choose this combination from BAF2022.
No matter if DEF or MUFF....
:--))
Currents SIT green and mosfet blue.
ZM just gave me an explanation of the difference DEFiSIT versus MUFF, I have to read 5 times to get it in my mind....!
Thanks ZM!
No matter if DEF or MUFF....
:--))
Currents SIT green and mosfet blue.
ZM just gave me an explanation of the difference DEFiSIT versus MUFF, I have to read 5 times to get it in my mind....!
Thanks ZM!
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Doing more simulations with the BAF2022 and the simplified version SIT.5 both gates driven from common point I see differences in H2 behavior.
The SIT-5 version seems to keep better the H2 dominance with higher loads than the BAF 2022 variant.
May you can have a look too wwwtttwww....
:--))
The SIT-5 version seems to keep better the H2 dominance with higher loads than the BAF 2022 variant.
May you can have a look too wwwtttwww....
:--))
We are getting closer, i smell the good idea burning 😉
Gerd did you tried adjusting both trimmers to see if you can change the H2 distribution and polarity?
The trimmers are not there for the output DC offset since the output is cap coupled.
SB
Gerd did you tried adjusting both trimmers to see if you can change the H2 distribution and polarity?
The trimmers are not there for the output DC offset since the output is cap coupled.
SB
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Another thing to look at is the 4 Ohm speaker load. The SIT-5 specifications show 35W at 8 Ohm and 60W at 4 Ohm and that is unusual for single ended amplifiers. But the SIT-5 MuFF is a bit different from the BAF2022 MuFF in that the speaker output is taken directly from both the SIT drain and the Mosfet drain. Usually the 8 Ohm output is higher than the 4 Ohm output.
The trick in the SIT 5 is the value of the output networks. You can vary the contributions of the SIT and the P channel Mosfet.
As mentionned in the document ‘Burning Amp 2022 – Simple DIY SIT Power Amplifiers’ from Nelson, page 11, varying the ratio of R1, R2 changes the distortion profile and H2 phase. R1, R2 are the ‘output network’ 😉
SB
SB
yess and it is not the same with a 8ohm load and a 4ohm load you must play with the ouptut tap to get the same distorsion profile and level 😉
to add more oil to the fire ......... remember it's also possible to Schade mosfet in negative rail
just one of ways to decrease its xconductance in controlled manner
just one of ways to decrease its xconductance in controlled manner
again with 2R in the source of the Mosfet, better!
green is SIT, blue the Mosfet. Is this about 20%? How can I calculate this exactly? Must I add the green swing and the blue one and then add the sum in ratio to the blue one?
green is SIT, blue the Mosfet. Is this about 20%? How can I calculate this exactly? Must I add the green swing and the blue one and then add the sum in ratio to the blue one?
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