Sony vFET Amplifier Part 2

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#3,972
Soundhappy said:
Papa DIY audio is like good tasting wine, it's taken time in wood barrels to get them at the maturity point.
Two different Single-Ended Vfet's amp's designs hoho :snare: roll apetizer
Burning Amp 2017 - Nelson Pass Informations about DIY Vfet Part 3 start at 1:13: 50
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The V-FETs have been matured since the 70ties. 45 years on Sherry casks!
Jokes aside, so very good the good Mr. Pass does these designs with them.
 
#3,974
My transformer has an annoying buzz so I was going to replace it but the new transformer is giving me +-33V unloaded. Will this drop low enough when the amp boards are connected? Can I load the cap bank with a resistor to simulate the amp load and if so what value and wattage should I use? tia.
 
#3,975
Use a big transformer 500 VA - 1000 VA then idle and loaded voltage is almost the same = very little "copper loss" (and no buzz).
If you know the amp bias current you can simulate that current using a power resistor as load (Use: U = R * I formular). You know U and I then R is easy to calculate: R = U/I. P = U*I …..should be the power rating of resistor. It will get hot! ….for only few seconds you can get away without resistor mounted on heatsink.
Usually the PSU DC voltage for these amps has some margin so I don't think you should be too concerned if voltage is a little higher than expected.
 
#3,976
Marra said:
My transformer has an annoying buzz...
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I had good success with Mark's Quasimodo circuit to damp transformer/diode ringing which dramatically reduced transformer buzz for me.

If you don't have the circuit and want to experiment quickly, all you need are some small film caps and resistors. Check Figure 5 of the PDF linked in the first post. Cx is 0.01uF, Cs is 0.15uF, and R is usually in the range of 20-80R.
 
#3,979
Soundhappy said:
Papa DIY audio is like good tasting wine, it's taken time in wood barrels to get them at the maturity point.
Two different Single-Ended Vfet's amp's designs hoho :snare: roll apetizer
Burning Amp 2017 - Nelson Pass Informations about DIY Vfet Part 3 start at 1:13: 50
Click to expand...

Really nice find Soundhappy. Thank you for that.
So, to my understanding, we can expect 10 W amplifier with no feedback. Frontend will be buffer + transformer. Output semiconductors will be paired as one SIT + one MOSFET, where MOSFET part will act as CCS. There won’t be two very different designs, rather using available N & P SIT’s with corresponding MOSFET’s to get greater number of DIY kits.
If my assumptions are correct, I must ask one question:

What’s wrong with the SissySIT boy? ©ZM
 
#3,980
Nelson Pass said:
Since the P and N parts use a different design, Vince will have to build
two amplifiers.
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tombo56 said:
.. There won’t be two very different designs, rather using available N & P SIT’s with corresponding MOSFET’s to get greater number of DIY kits..
Click to expand...

Simply different or very different design(s) ? Who know ?
The answer is : The One and Only :wiz:
No push-pull but Single Ended , two vfets for full stereo amplifier.
Anyways Vince and Greedy Boyz do build them all :spin:
 
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