I certainly appreciate the charm of the little Class A amplifiers. In this case,
when consulted, Sony asked if they could be made to drive the AR-1's
specifically (and provided a pair). This came out to approximately 200 watts
into 4 ohms with a good level of "control".
I don't think the few copies that will be made are much of a threat to anyone,
but with a little luck someone will figure out how to get Class D to do the
job with the same signature.
They draw about 400 watts each.
Always alert to a little tutorial opportunity:
I biased them at 3 amps (per side) which conventionally results in a 6 amp
peak in Class A, and when you do the math you would expect a 288W Class A
peak into 8 ohms, 144W peak into 4 ohms.
This would mean 144W rms Class A into 8 ohms (which it will not deliver due
to voltage limitations). It would also mean 72 watts rms Class A into 4 ohms.
However, there are no Source resistors on the VFETs, not needed as they
share nicely and have a near-zero temperature coefficient. So the curve
of the conduction is basically square law, and when you observe the
cutoff characteristic of the output stage you see that the Class A envelope
is increased by about 75%, so instead you get about 125 W rms Class A into
4 ohms, and that means a 250 W peak, which is probably where that spec
came from in the announcement.
Always alert to a little tutorial opportunity:
I biased them at 3 amps (per side) which conventionally results in a 6 amp
peak in Class A, and when you do the math you would expect a 288W Class A
peak into 8 ohms, 144W peak into 4 ohms.
This would mean 144W rms Class A into 8 ohms (which it will not deliver due
to voltage limitations). It would also mean 72 watts rms Class A into 4 ohms.
However, there are no Source resistors on the VFETs, not needed as they
share nicely and have a near-zero temperature coefficient. So the curve
of the conduction is basically square law, and when you observe the
cutoff characteristic of the output stage you see that the Class A envelope
is increased by about 75%, so instead you get about 125 W rms Class A into
4 ohms, and that means a 250 W peak, which is probably where that spec
came from in the announcement.
Perhaps you want this thread:
http://www.diyaudio.com/forums/pass...e-sit-pp-amp-baf-sit-beast-thousand-psus.html
http://www.diyaudio.com/forums/pass...e-sit-pp-amp-baf-sit-beast-thousand-psus.html
Perhaps you want this thread:
http://www.diyaudio.com/forums/pass...e-sit-pp-amp-baf-sit-beast-thousand-psus.html
Thank you very much. There is so much information available it becomes overwhelming. I will read through the link you sent me.
Thanks again for taking the time and effort to respond.
Ted
However, there are no Source resistors on the VFETs, not needed as they share nicely and have a near-zero temperature coefficient. So the curve of the conduction is basically square law, and when you observe the cutoff characteristic of the output stage you see that the Class A envelope is increased by about 75%, so instead you get about 125 W rms Class A into 4 ohms, and that means a 250 W peak, which is probably where that spec came from in the announcement.
Very nice Nelson! You may be interested to know that Ian Hegglun is busy with cube law class A for a future Linear Audio issue. This will have an even better efficiciency ratio. I think these concepts of square and cube law characteristics are a hidden secret for high-efficiency class A.
Jan
pretty much everything you need to know is in that linked Stereop.... article
under condition that they're adequately informed
however - pretty much believable scenario
No, Acronman still has a few of matched ranks. On my todo list this week is
to verify operation of his remaining N and P ranks together for use by DIYers,
which will open up some more supply before the bitter end.
No, Acronman still has a few of matched ranks. On my todo list this week is
to verify operation of his remaining N and P ranks together for use by DIYers,
which will open up some more supply before the bitter end.
Party on then! Happy 40th vfets!
This is fragment of e-mail i have received from Acronmanelectronics
about 2SK82/2SJ28 in stock:
"Some other customers may have interest to get a few more hundreds pieces for their project.
regards
chee leong
- acronmanelectronics "
ad news for modest diyers...after commands of amplifiers for interested rich audiophiles who read this Stereophile articlewe be without very quickly
Fragment from Stereophile:
" Eventually, he uncovered a stash in Singapore and bought all of them, enough to make the single pair of “Sony VFET Amplifier 40 Year Commemorative Edition” amplifiers at CES. This uses 24 pairs of VFETs as complementary followers and front-end/driver circuitry based on a Pass Labs’ XP topology."
Greedy Papa with SonyVfet'sMonoblock. 32/ch
but economic with his exclusive Pass-sit1's Best regards
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.