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Sony Vfet Illustrated build guide
Sony Vfet Illustrated build guide
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Old 12th July 2018, 05:10 AM   #631
Seegs108 is offline Seegs108  United States
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Quote:
Originally Posted by Zen Mod View Post
I was joking ..... do your own - in your way , of course

I never measured , but I can estimate Babysitter is decreasing temp somewhere between 5 and 10C

difference between me being concerned and totally indifferent
Good to know. Before adding the fans I was reading 57C at the base of the heatsink, now I'm reading 37C. Ambient room temperature is 24C. Even though it's an ugly mod, I feel much more comfortable leaving the amp on for extended listening sessions now.
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Old 23rd July 2018, 12:49 AM   #632
dcbingaman is offline dcbingaman  United States
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Well, fellow solder soldiers, I finished my Pass / Sony VFET amplifier and it sounds divine driving my ancient pair of Spendor SP-1's. It can get loud enough to annoy my wife, too. I know its related at 15 watts Class A into 8 ohms. Not sure I've seen rating where it clips, but I haven't found it in practice at any reasonable listening level.

Bias - my tech friend and I did this together and it really wasn't hard at all. We check all the resistances and then voltages set the driver bias and then set P1 and P2 at the VGS voltages written on the VFET's +1 volt. When we soldered the VFETs in and powered her up there were no pyrotechnics at all. Quiet as a church mouse with symmetric DC offsets of -0.4 Volts on both sides. We let her run for an hour and the bias drifted up a little, but not much. Judicious work with P1 and P2 got the DC offset below 10mV on both sides. (It is hard to to better than this with these 1-turn pots.)

it is a really sweeeeet sounding amplifier !!
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Last edited by dcbingaman; 23rd July 2018 at 12:52 AM.
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Old 23rd July 2018, 01:03 AM   #633
Zen Mod is offline Zen Mod  Serbia
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Sony Vfet Illustrated build guide
you can go back later and change these input signal wires to even thicker ones

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Old 23rd July 2018, 01:04 AM   #634
Zen Mod is offline Zen Mod  Serbia
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and while you're changing these , to be fatter than speaker ones , route them separately (input vs. speaker)

move speaker lines bellow pcbs , leave input ones where they are , above pcbs
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Old 23rd July 2018, 01:06 AM   #635
dcbingaman is offline dcbingaman  United States
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One other note - I am driving the VFET with a Broskie Aikido line stage with 6922's - gain of about 15. This is WAY more than the VFET needs. I can't get the volume past about 8:30 ! I would guess input sensitivity is less than 2V. Fortunately I'm using ALPS Black Beauties and I have a Black Beauty balance pot, so level tracking is not an issue. In any event, if you are using digital sources with a standard output of 2V, a Pass B-1 buffer stage should work just dandy with this amp.
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Old 23rd July 2018, 01:24 AM   #636
dcbingaman is offline dcbingaman  United States
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Originally Posted by Zen Mod View Post
and while you're changing these , to be fatter than speaker ones , route them separately (input vs. speaker)

move speaker lines bellow pcbs , leave input ones where they are , above pcbs
Zen - I'm using Kimber PBJ for the inputs - works fine. Outputs are 16 ga stranded wire with "bright colors". I routed high to avoid the power supply circuitry. Like I said the thing is quiet as Lenin's Tomb. Not sure I want anything to go under the PCB's.

I am also using a pair of IXYS Hexfred bridges - these are supposed to be exceptional quiet RF/EMI wise. They cost a little more (about $17 USD), but they have been excellent in every Pass project I have done, (Pearl 1, Pearl 2, FW F3, FW F5T, Sony VFET).
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Old 23rd July 2018, 01:50 AM   #637
Zen Mod is offline Zen Mod  Serbia
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Sony Vfet Illustrated build guide
just for fun , if you ever in mood for that , try replacing input wires for some solid core , no thicker than 0.15mm

twist it semi-tight

maybe you'll hear difference , maybe not

in case of later , you can always write here that ZM is a Dodo

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Old 23rd July 2018, 02:09 AM   #638
dcbingaman is offline dcbingaman  United States
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Zen, I have read too many of your posts ! I would NEVER call you a Do-Do !

I routinely use 20 ga solid wire in my low voltage applications.....I just had this Kimber stuff laying around, so i used it here. It sounds pretty good as an interconnect. I can tell you there is no noise with this stuff. Now there may be more Divine Angels to be discovered in the signal, but the VFETs are pretty heavenly all on their own !
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Old 14th August 2018, 10:58 AM   #639
wdecho is offline wdecho  United States
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Sony Vfet Illustrated build guide
Does anyone remember where to find the schematic on how to test the V-fets?
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Old 14th August 2018, 11:04 AM   #640
Dennis Hui is offline Dennis Hui  Canada
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Sony Vfet Illustrated build guide
Quote:
Originally Posted by wdecho View Post
Does anyone remember where to find the schematic on how to test the V-fets?
Try here:

Sony VFET Amplifier Part 2
Sony VFET Amplifier Part 2

Cheers,
Dennis
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