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Sony VFET Amplifier Part 2
Sony VFET Amplifier Part 2
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Old 5th October 2019, 06:33 PM   #4031
Sabrosa is offline Sabrosa  United States
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Sony VFET Amplifier Part 2
Quote:
Originally Posted by nashbap View Post
To fully exploit the potential of the Sony Vfet amps you need a preamp that has the spectral harmonics to match, to give you the kind of sound you are looking for.
Mind expanding on this, if you have any additional info?

If I'm remembering correctly, the VFET amps are 3rd harmonic dominant, so are you saying that ideally you would pair it with a 3rd harmonic dominant preamp?
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Old 5th October 2019, 07:12 PM   #4032
cjfrbw is offline cjfrbw  United States
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This VFET version 2 amp sounds great with (or without) the Pass Korg B1 NuTube DIY preamp project (second harmonic generator). I was listening to v.2 last week again on my midrange ribbon and was impressed once again. v.2 VFET is a fantastic and perhaps best of all STAX headphone amp driver with a custom voltage transformer liaison.

My version of VFET v.2 uses single pairs per channel. Not quite as spooky as the First Watt single ended SIT, but not too far and in the family for sure. It sounds cleaner, maybe a little less sweet than the older medieval Sony VFET amps, but more focussed.

I am curious to hear the SIT 3, but I don't know if that will ever happen unless it shows up at an audio exposition.
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Old 6th October 2019, 04:24 PM   #4033
nashbap is offline nashbap  United States
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Quote:
Originally Posted by Sabrosa View Post
Mind expanding on this, if you have any additional info?

If I'm remembering correctly, the VFET amps are 3rd harmonic dominant, so are you saying that ideally you would pair it with a 3rd harmonic dominant preamp?

When I first set up the Vfet amps I used them with my BA3preamp and found the sound a bit edgy. So I figured I needed some H2 and adjusted the Vfet amps to give equal H2 and H3 from the previously dominant H3 setting. This sounded good and I listened for a couple of months this way.

Then I thought what if I increased the H2 at the preamp and again reduced it at the power amp. So I tried that. I experimented with different settings for the preamp and Vfet amps.

Long story short- the 2 pair Vfet amps in my experience, sound best when each channel is set close to the distortion level published by Mr. Pass in his article. This is with feedback.You can then adjust H2(negative and dominant in my case) of your preamp to give the final sound that you like for your music and setup.


nash
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Old 7th October 2019, 04:36 PM   #4034
Nelson Pass is offline Nelson Pass  United States
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Sony VFET Amplifier Part 2
I suppose I could bring a SIT-3 to BAF....
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Old 7th October 2019, 04:52 PM   #4035
vuongan is offline vuongan  United States
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Hi everyone!
Papa has noties: with 24VDC:
22V = 2.5V * (R15+4750 ohms)/4750 ohms 22V *4750 ohms / 2.5V = R15 +4750 ohms 41800 ohms = R15 + 4750 ohms
R15 = 37050 ohms.
You would pick the closest 1% resistor, which would be 36K or 36.5K for R15 and R16.
So with 28 vdc we have R15 or R16 is 44650 ohms. But in the schematic resistors 15 and 16 is 41.2 kohm
Which value is right for 28vdc voltage? 44.6 kohm or 41.2 kohm?
Thanks
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Old 7th October 2019, 05:15 PM   #4036
Sabrosa is offline Sabrosa  United States
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Sony VFET Amplifier Part 2
Quote:
Originally Posted by nashbap View Post
Long story short- the 2 pair Vfet amps in my experience, sound best when each channel is set close to the distortion level published by Mr. Pass in his article. This is with feedback.You can then adjust H2(negative and dominant in my case) of your preamp to give the final sound that you like for your music and setup.
Thanks! That makes sense. Out of curiosity, did you measure the distortion spectrum at the end of the full chain (preamp + amp) once you found the individual settings on each that you preferred?

Quote:
Originally Posted by Nelson Pass View Post
I suppose I could bring a SIT-3 to BAF....
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Old 7th October 2019, 05:43 PM   #4037
cjfrbw is offline cjfrbw  United States
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Quote:
Originally Posted by Nelson Pass View Post
I suppose I could bring a SIT-3 to BAF....
That would be great. I have only seen it in static display, and it probably deserves a live demo showing amongst the gboyz brotherhood.

I could go to for my first BA as a DIY cave man.
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Old 14th October 2019, 08:59 PM   #4038
nashbap is offline nashbap  United States
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Quote:
Originally Posted by Sabrosa View Post
Thanks! That makes sense. Out of curiosity, did you measure the distortion spectrum at the end of the full chain (preamp + amp) once you found the individual settings on each that you preferred?




no but good idea. Nash
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Old Yesterday, 01:16 AM   #4039
rolandong is offline rolandong  Philippines
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Old Yesterday, 01:23 AM   #4040
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Sony VFET Amplifier Part 2
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