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Sony Vfet Illustrated build guide
Sony Vfet Illustrated build guide
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Old 30th December 2017, 01:16 PM   #411
Rodeodave is offline Rodeodave  Austria
hates ground loops
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Sony Vfet Illustrated build guide
Without the VFETs installed there is also no feedback, since the loop from output to input is not closed. With the VFETs in place the feedback loop is closed and things start to get interesting
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Old 30th December 2017, 02:52 PM   #412
delecoy is offline delecoy  United States
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Originally Posted by 6L6 View Post
Without the Vfet installed the currents in the amp are all pretty low, so small changes in resistance will have a big effect on draw - hence why the pots seems super sensitive. With the circuit running at spec, the sensitivity of the pots will lessen somewhat.
That makes sense. Thank you

I fired it back up this morning to warm up and everything settled back into place where I left it yesterday, with offset bouncing around between +- 75mv for both channels.

To get offset right yesterday I would purposefully slightly overshoot whatever direction I was turning the pot so it could settle back to the value I was aiming for, so tapping the pot to relieve stress also makes sense. I gave them each a small thud this morning just to be sure. Everything stable

Going to pull it back apart and get the vfets in now.

Almost forgot....Thank you guys!

Last edited by delecoy; 30th December 2017 at 03:16 PM. Reason: Manners
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Old 1st January 2018, 07:05 PM   #413
PJN is offline PJN  United States
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I finally had the chance to give my copy of the diyaudio sony vfet a good listen. I burned it in for about 10 hours in my garage fist, and compared to my much loved M2 using single full range backloaded horn speakers. The M2 is a pretty cool running amp for a Pass class A amp, but the VFET is even cooler, barely gets warm. The first impression that I got swapping in the VFET for the M2 and playing the same music was that it seemed more illuminated, maybe lower noise floor or what not, but it seemed easier to hear the subtle details. The overall balance was similar but the VFET has distinctly better control of the base, more of a F6 type grip on the speakers, it has a higher damping factor than the M2 so that might figure into it. So basically sounds great, better base, more detail subjectively than M2. Does it sound better ? I don't know, it is the same dilemma with all Pass amps, they all sound really good, but a little different. That is why you need to build so many of them.
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Old 4th January 2018, 03:43 AM   #414
aspringv is offline aspringv  Australia
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Sony Vfet Illustrated build guide
Hi all, I'm just a bit curious - one of my VFETS is labelled 201 - for a 2sk82 (from the official DIYAUDIO buy) and that seems quite high? If I follow the document properly, that means an initial bias point of 20.1V + 1V = 21.1V?

For comparison, it's matched partner is marked 170, making for a 18V initial bias point.

I just want to sanity check that before I bias up the irreplaceable parts...

Last edited by aspringv; 4th January 2018 at 03:46 AM.
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Old 4th January 2018, 07:30 AM   #415
anilva is offline anilva  India
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Quote:
Originally Posted by aspringv View Post
Hi all, I'm just a bit curious - one of my VFETS is labelled 201 - for a 2sk82 (from the official DIYAUDIO buy) and that seems quite high? If I follow the document properly, that means an initial bias point of 20.1V + 1V = 21.1V?

For comparison, it's matched partner is marked 170, making for a 18V initial bias point.

I just want to sanity check that before I bias up the irreplaceable parts...
Those numbers are not values of measurement, but id number of the VFET. Don't get confused with the two.

Cheers
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Old 4th January 2018, 07:34 AM   #416
aspringv is offline aspringv  Australia
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Sony Vfet Illustrated build guide
Haha! Champion, thank you! The K parts have had the vds rubbed almost completely off...now you say it I can just see an 88 on one.

Woohoo! Thanks
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Old 5th January 2018, 02:48 PM   #417
Arye is offline Arye  Israel
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Default Mains transformer

Hello to all, can someone enlighten me on the minimum power rating of the transformer?
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Old 5th January 2018, 08:09 PM   #418
Rodeodave is offline Rodeodave  Austria
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Sony Vfet Illustrated build guide
Dissipation is P=U*I=2*28V*1A=56W per channel, so about 112W in total for an amp. The transformer should be rated about three times that, so you're looking at 300VA. Better make it 400VA, the difference in price should be negligible. Search the thread, it's been discussed numerous times.
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Old 8th January 2018, 04:47 PM   #419
vanofmonks is offline vanofmonks  United States
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Default Power line filter

I have some of these 6A 120v power line filters 6EQ1 by TE: http://www.mouser.com/ds/2/418/NG_CD_6EQ1_H-1258746.pdf

They are an RFI filter designed for SMPS supplies, but would it be beneficial to the diy vfet amp. Got my boards stuffed and I'm about to start construction.

Thanks
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Old 9th January 2018, 12:25 AM   #420
Eric is offline Eric  United States
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Sony Vfet Illustrated build guide
I don't see how it can hurt. Each of my amp builds gets a one of these (or something similar) built into an EIC power inlet. I kind of view it as standard procedure and judging by the pictures posted, so do lots of other people.

Go ahead and use it!
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