Sony VFET Amplifier Part 2

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Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
MASantos said:
A few questions regarding active devices:

is there any Idss we should aim when choosing the input jfets?

Do the input stage mosfets (2sk2013/2sj213) need matching?

What about the cascade output mosfets?
Click to expand...

You will note at the end of the article the adjustments for different
Mosfets and different Idss for input Jfets. Matching is not required,
but it is desirable to get the Jfet Idss within 1 mA of each other.

:cool:
 
Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
noelectrix said:
Does anybody know what to expect from the
specs/sound if I use my ordinary +-24 VDC First Watt standard PSU? (with
adapted resistors on the amp PCB like advised in the draft). Is it "just" less
output swing or more the overall perfomance of the amp?
Click to expand...

Mostly less output. With 28 volts we get 15 watts. With 24 V rails you
can expect less than 10 watts, but you can also run more bias current.

:cool:
 
M

MASantos

Member
Joined 2005
Nelson Pass said:
Mostly less output. With 28 volts we get 15 watts. With 24 V rails you
can expect less than 10 watts, but you can also run more bias current.

:cool:
Click to expand...

Should we aim for 28V unloaded or maybe 30V unloaded so that it sags a bit under load?

My crippled F4 has an unloaded PSU voltage of +-32 that drops down to 30.1 when biased up!
Should I follow the same principle here and aim for 2 volts over desired PSU voltage?
 
P

plasnu

Member
Joined 2011
MASantos said:
Should we aim for 28V unloaded or maybe 30V unloaded so that it sags a bit under load?

My crippled F4 has an unloaded PSU voltage of +-32 that drops down to 30.1 when biased up!
Should I follow the same principle here and aim for 2 volts over desired PSU voltage?
Click to expand...

What I understand is the rail voltage means the voltage without load, but I'm not 100% sure.
 
T

tadek

Member
Joined 2006
so far I am on the list #1 for this Essentials Kit
I do subscribe messages "Sony VFET Kit Interest Group"
but I did not received any message related to purchase/payment
DiyAudioStore doesn't contain any entry related to this "specific" Kit
It looks that Jason is busy these days.
May be somebody can advice how to pay for Kit
Thanks
tadek
 
D

Dennis Hui

Member
Joined 2002
Paid Member

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Jason

Jason

Founder
Joined 2000
diyaudio.com
Paid Member
Dennis Hui said:
Hi Jason,

In your post here:

http://www.diyaudio.com/forums/pass-labs/276711-sony-vfet-amplifier-part-2-a-142.html#post4790857

you showed USPS Priority International shipping rates. However,
when I tried ordering, I can only see USPS Priority Mail Express International
rate, which is somewhat more expensive.

Is the express option the only one now available? If not, can this be corrected?

Thanks,
Dennis
Click to expand...

Interesting and a little odd! Perhaps something to do with your location? I'm not sure. UPS should be fine, but I am not sure about the insurance situation on UPS. Please email contact@diyaudiostore.com with your delivery address ASAP and we will be able to review this for you. We can often see more shipping options than what is offered via the store interface, which tends to offer "the cheapest slow", "the cheapest priority", "the cheapest express". It might be that UPS price is "hiding" a slightly more expensive USPS Priority option if the system classes them as the same "level" of service. Anyway, let us know your address and we'll see what we can do!
 
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