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Old 23rd December 2010, 05:12 PM   #21
90999 is offline 90999  China
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Quote:
Originally Posted by 90999 View Post
His mind is : " It's not product , only him in the world, And the sound is the difference between the VMOS and the VFET in NFB AMP. "
His mean is ,not "his mind"
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Old 23rd December 2010, 05:13 PM   #22
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Quote:
Originally Posted by lgqliu View Post
my english si very poor
Because no negative feedback loop circuit, using a different MOS tube out of the sound is different. In addition, this circuit is my own DIY, not manufacturers.
Quote:
Originally Posted by 90999 View Post
His mind is : " It's not product , only him in the world, And the sound is the difference between the VMOS and the VFET in NFB AMP. "
Thank you for your replies and clarifying in this matter
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Old 28th December 2010, 07:09 PM   #23
mos57 is offline mos57  Italy
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Originally Posted by tiefbassuebertr View Post
for me it would be interesting to know more about the differences in sound character by using of the good known IFFP 9240 or an other enhanced P-CH MOSFET. Are there really advantages in such a single ended power stage by use of this rare and expensive SONY V-FET instead enhanced MOSFET's?
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The Vfets advantages can be summarized in less distortion which is a strong advantage when the output stage is also configured with voltage gain, as normally happens in a single ended.

The choice is even more appropriate if you choose to make an amp with no negative feedback
With regard to the sound character of Vfets I can say that moving from Vertical mos to the Lateral mos and from this last to Vfet the sound became less harsh with medium and high more refined and extended.

Following the same path (vertical, lateral, Vfets), I can say that with regard to the bass freq. the sound tends to become a little bit slower and a little less authoritative.

But considering the advantages and disadvantages, for me there is no doubt that except in the case of multiamplified systems, vfets are the best components to achieve full-range amplifiers.

Happy New Year Francesco
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Old 28th December 2010, 08:41 PM   #24
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Quote:
Originally Posted by mos57 View Post
The Vfets advantages can be summarized in less distortion which is a strong advantage when the output stage is also configured with voltage gain, as normally happens in a single ended.

The choice is even more appropriate if you choose to make an amp with no negative feedback

With regard to the sound character of Vfets I can say that moving from Vertical mos to the Lateral mos and from this last to Vfet the sound became less harsh with medium and high more refined and extended.
I have the Sony parts and also some custom high current
SITs which are similar, and I think your observations are
pretty correct.

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Old 29th December 2010, 05:35 AM   #25
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Quote:
Originally Posted by mos57 View Post
With regard to the sound character of Vfets I can say that moving from Vertical mos to the Lateral mos and from this last to Vfet the sound became less harsh with medium and high more refined and extended.
Following the same path (vertical, lateral, Vfets), I can say that with regard to the bass freq. the sound tends to become a little bit slower and a little less authoritative.
But considering the advantages and disadvantages, for me there is no doubt that except in the case of multiamplified systems, vfets are the best components to achieve full-range amplifiers. Francesco
Interesting observations, but what this is related with? I expected it is simply a matter of different transcondactance and, hence, different output impedances. In this relation, I doubt that vfets are good for No NFB full-range amps. They would fit schematics with output transformer, like proposed here by topicstarter, or schematics with reasonable NFB (Yamaha B2), or in preamps (I use power vfets in cascoded SRPP in my preamp, +100V shunt power supply, 160 mA bias, sounds really good).

Last edited by VladimirK; 29th December 2010 at 05:39 AM.
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Old 29th December 2010, 11:48 AM   #26
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Quote:
Originally Posted by mos57 View Post
The Vfets advantages can be summarized in less distortion which is a strong advantage when the output stage is also configured with voltage gain, as normally happens in a single ended.

The choice is even more appropriate if you choose to make an amp with no negative feedback
With regard to the sound character of Vfets I can say that moving from Vertical mos to the Lateral mos and from this last to Vfet the sound became less harsh with medium and high more refined and extended.

Following the same path (vertical, lateral, Vfets), I can say that with regard to the bass freq. the sound tends to become a little bit slower and a little less authoritative.

But considering the advantages and disadvantages, for me there is no doubt that except in the case of multiamplified systems, vfets are the best components to achieve full-range amplifiers.

Happy New Year Francesco
Quote:
Originally Posted by Nelson Pass View Post
I have the Sony parts and also some custom high current
SITs which are similar, and I think your observations are
pretty correct.
Thank you for yor impressions. Because both V-FETs from SONY and Yamaha and SIT's from TOKIN are very hard to find devices for most of us, the actually question for me is follow:
Which circuit topology reach the same (or at least similar) sonic results with currently available Power HEX-FETs like IRF series than vintage V-FETs. I guess only current buffer stages (instead stages with current and voltage gain) allow similar sound quality, no matter whether single-ended or CSPP/PPP resp. Circlomos (totem pole topology). Absolutely to avoid must be the good known "true complementary" PP stages (i. e. P-CH and N-CH), especially if the output stages don't run in pure class A, because this therm is a lie in real life and shall vote only on the schematic drawing for the eyes.
The vast majority of currently professional designers for audio power amps understand that fact unfortunately never.

Last edited by tiefbassuebertr; 29th December 2010 at 11:59 AM.
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Old 29th December 2010, 01:10 PM   #27
AndrewT is offline AndrewT  Scotland
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Default Power mosFETs

What is the difference between
Vertical mosFET and VFET?
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regards Andrew T.
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Old 29th December 2010, 03:05 PM   #28
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Quote:
Originally Posted by AndrewT View Post
What is the difference between
Vertical mosFET and VFET?
there are variable and vertikale mosfet's:
3 VFET Acronym/Abbreviation Meanings - What Does VFET Stand For?
the abbrevation is for both VFET or V-FET, but only the term "Vertikal" stands for the internal structure.
Sony V-FETs similar to
static induction transistor types - go to
http://www.patents.com/semiconductor...e-7417284.html
http://books.google.de/books?id=hMQO...%20SIT&f=false
http://audiokarma.org/forums/showthread.php?p=564413

Last edited by tiefbassuebertr; 29th December 2010 at 03:13 PM.
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Old 29th December 2010, 03:53 PM   #29
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Quote:
Originally Posted by AndrewT View Post
What is the difference between
Vertical mosFET and VFET?
VFET or SIT stands for a class of transistors, which's output (drain current vs ds-voltage at various gate voltages) curves amasingly resemble those of tube triodes. Even their gate design resembles tube's grid.

What is good for me from such an output curves? One is, that low output impedance is due to internal conductivity of a transistor, instead of being totally emulated by NFB in case of MOSFET.
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Old 29th December 2010, 04:39 PM   #30
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<<What is the difference between Vertical mosFET and VFET?>>
Both are vertical (by internal structure design) FETs. The V-FETs (if attributed to
the proper devices) are related to the vertical JFETs (versus vertical MOSFETs),
and came into use in the early '70s, when there were no power MOSFETs (vertical
or lateral) developed yet. So, "they" didn't see the need to include letter J in the abbreviation.
Nowadays, we need to make sure, that we use proper abbreviations for each class to avoid any confusion.
So, V-JFET=SIT (IF the latter are made by the same design:-)).
V-MOS are your garden variety typical switching MOSFETs (from practically all major semis manufacturer) and 2SK1529-30 audio types.
Then there are L-MOS (from a few), which, actually, were developed before V-MOS.
All the typical small signal JFETs out there (like Toshiba's and the rest) are lateral (horizontal) JFETs.
This confusion with "V-FETs" have found it's place in a few books on audio design (in the "historical chapters"), so a "critical" reading will be necessary.
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