Sony vFET Illustrated build guide

Would a 50V cap last longer compared to a 35V in a 28V circuit?

I have compared lower voltage caps with higher version and 50V have stronger mechanical construction they are biger heavier
and look more resistant to time evenements : humidity, temperature changes, corrosion.
Temperature factor is important as well i like 105 C versions.
My humble opinion :)
Btw snubbering diodes bridge are interesting option to get quiet psu.
 
what do you propose as snubber for the diodes; just caps (10nf ?) parallel to the diodes or something different?

You can modify your bridge with snubbering technique at the end. It's easy modyfication.
Use cap with resistor for each diode.
I can't give response that must be tested individualy for your transformer ringing parameters.
Read in appriopriate snubber thread , find articles :)
 
My F6 power supply is outputting +/- 26v which is at the low end of Nelson's stated operating voltage for the VFET amplifier. Will the VFET amp function ok if supplied with 26v? I note the values of R15 and R16 can be changed, but I don't see the point if 26v is sufficient.
 
Brumjam,

In Papa's words:

"I used an ordinary First Watt type supply design, documented elsewhere, with 22 VAC transformer secondaries to provide +/-28 volts DC. 24 or 25 VAC will work fine, running a little hotter. The minimum recommended for this amplifier is +/-27 volts, but it will run OK with a little lower supply if you adjust the values of R13 through R16 for lower voltage."
 
Jim

Received my kit, and I see that my 2SK82s are marked 97 each, while my 2SJ28s are marked 115 and 116. So I don't have as close a match as I believe was true for your batch.

Would I have to adjust some of my resistors to compensate for it?
Read Papa Diy words :
http://www.diyaudio.com/forums/pass-labs/276711-sony-vfet-amplifier-part-2-a-268.html#post4979955
Your match of 2SJ28 have 0.1 V difference that perfect !
Not easy to find that close transistors.

This DiyVfet amplifier work great without matched transistors
because is only one pair version and use trimmers to adjust anyway.
Hooorayyy :cheerful:
 
Brumjam,

In Papa's words:

"I used an ordinary First Watt type supply design, documented elsewhere, with 22 VAC transformer secondaries to provide +/-28 volts DC. 24 or 25 VAC will work fine, running a little hotter. The minimum recommended for this amplifier is +/-27 volts, but it will run OK with a little lower supply if you adjust the values of R13 through R16 for lower voltage."

This is where I got confused with the documentation. The Firstwatt DIY Sony Vfet addendum mentioned that "This amplifier is designed to operate with voltages between about +/-26V DC and +/-30V DC." and "Other parts of the circuit are not very sensitive to supply values. Practically speaking, you should not try to make this amplifier with rail voltages below 20 volts, and above 32 volts.". 22VAC secondaries are rare in this region, and I can easily get 24VAC secondaries. 24VAC secondaries will give me a bit more than 32V DC (32.5v). Can I use 24VAC secondaries and change R15 and R16 to 56k ohm? Or should I try to have one custom-made with 22V secondaries?

Thanks!
 
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This is where I got confused with the documentation. The Firstwatt DIY Sony Vfet addendum mentioned that "This amplifier is designed to operate with voltages between about +/-26V DC and +/-30V DC." and "Other parts of the circuit are not very sensitive to supply values. Practically speaking, you should not try to make this amplifier with rail voltages below 20 volts, and above 32 volts.". 22VAC secondaries are rare in this region, and I can easily get 24VAC secondaries. 24VAC secondaries will give me a bit more than 32V DC (32.5v). Can I use 24VAC secondaries and change R15 and R16 to 56k ohm? Or should I try to have one custom-made with 22V secondaries?

Thanks!

Exactly Alvin. That's the section of text I was referring to in my post. If it's designed to operate from 26v I should be ok, however the other quote suggests 27v as a minimum. My other transformers will give me about 32v. It sounds like either way it is necessary to change R15 and R16 which is fine.
 
Let's see a practical (and working :) ) example:
My toroid about 650VA, it has four pair secondaries with 24VAC, without load.
Each pair of secondaries has a dedicated diode bridge, and capacitor bank of 4x22000Uf/35VDC.
It gives me +/-29.7VDC at the amp +/- input point, there is some loss on paralleled 4xR0.47Ohm of CCRCC power supply.
I have 102-103mV through R32, so there is almost exactly 1A current flow.
Chosen resistor value is 42.2Kohm for R15/R16.
It gives me almost exactly 20VDC on testpoints T3/T5.
I'm wondering, may I go a little higher, say 22-23VDC?
589472d1483451885-gyuris-pass-sony-vfet2-build-vfet2-beag.jpg
 
this post ist even–steven-rule concerning spamming the tread but also context of building the vfet-amp : ) so hope it´s ok to ask here.

I decided to etch my own PSU–PCB fot the Pass V-Fet since the shipping cost just for the universal PSU is a bit high (and i forgot to add it with the kit). Last not least also a little diy-sweat in recognition to the great convenient kit.

I decided to do it F7-like with the last caps seperate for one railvoltage/channel like in this sketch (postet by nelson, so i hope it´s ok to show it again)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.

Question: can anybody recommend a value for the R´s and how many to use per rail/capacitor?

The "stock" Universal PSU recommends for each rail 4pcs of 0.45R , so 8 for the whole PSU. Should i use 2pcs of the 0.45R per rail (so 4 times 2 pcs) or still 4 times 4pcs per rail?

Maybe easy thing made complicated :D your insight is welcome
 
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