I admit I started to buy vfet amp years ago influenced by some "internet influencers" they make me to believe they have unique sound, like no other trasistors can compare.
So, I got Yamaha b-2, Yamaha b-1, recently a Sansui ba-1000. Sure they sound similar sweet and smooth and i am satisfied.
I also found that not all vfet amp is so sweet and smooth for example hitachi ha-500f. I haven't heard one but according to kitr's review and listened to some youtube recordings I feel it sounds a little dull maybe on par with sony ta 4650. lacks some airy and live feel of ta-8650 from videos recorded in same environment. So I feel circuit design is more important.
I wonder is that true no other transistor can achieves sound like vfet? what about mosfet, high current mosfet like uhc or lapt, SiC depletion jfet? Anyone know any non-vfet amp with similar sound?
I am also curious about how vintage vfet compare to modern lowest distortiin class ab amp(
topping la90) or a GaN fet class D?
So, I got Yamaha b-2, Yamaha b-1, recently a Sansui ba-1000. Sure they sound similar sweet and smooth and i am satisfied.
I also found that not all vfet amp is so sweet and smooth for example hitachi ha-500f. I haven't heard one but according to kitr's review and listened to some youtube recordings I feel it sounds a little dull maybe on par with sony ta 4650. lacks some airy and live feel of ta-8650 from videos recorded in same environment. So I feel circuit design is more important.
I wonder is that true no other transistor can achieves sound like vfet? what about mosfet, high current mosfet like uhc or lapt, SiC depletion jfet? Anyone know any non-vfet amp with similar sound?
I am also curious about how vintage vfet compare to modern lowest distortiin class ab amp(
topping la90) or a GaN fet class D?
yes , i ever heard this virtual fet in my friend's house . a bit dull compared to mosfet ,, if you dont like mini cymbal , then its no problem
Just like any other device how you use it is important.
The VFET/SIT is the closest SS device yet to the triode so falls into the most linear amplification device.
The Sony and Yamaha VFET amplifiers were kinda complex and likely did not get the best out of them.
Have a look at some of th estuff done here. I am very pleased with Nelson’s SIT-3, an SE VFET amp.
Yes, one has to be careful about internet influencers.
dave
The VFET/SIT is the closest SS device yet to the triode so falls into the most linear amplification device.
The Sony and Yamaha VFET amplifiers were kinda complex and likely did not get the best out of them.
Have a look at some of th estuff done here. I am very pleased with Nelson’s SIT-3, an SE VFET amp.
Yes, one has to be careful about internet influencers.
dave
They are very bad. You can send them to me for proper disposal 😉
Have you seen this:
https://diyaudiostore.com/collections/diy-sony-vfet/products/vfetless-round-3-output-stage
What you have there are treasures.
Have you seen this:
https://diyaudiostore.com/collections/diy-sony-vfet/products/vfetless-round-3-output-stage
What you have there are treasures.
So that we're clear, there are tons of vertical fets, mainly Mosfets but also Jfets. The Vfets from the 70's and 80's were a particular depletion mode breed that had low Drain resistance and were thus similar to Triodes.
Like any other gain device, you can use it poorly or well.
Like any other gain device, you can use it poorly or well.
I think those who do not understand more complicated issues like the various IPS, VAS and driver designs, may want to credit the result to a simple matter of output transistor choice. Almost as bad is the choice of CFA, VFA and NGF. But DIYA and the audio business depends on their support.
Here is what I guessed, the triode like Fet will be shining in the most simple and basic circuit like a tube amp. Where as most solid state amp used many complex compensation circuits to get lower distortion, thus make the characteristic of the output device not that obvious?
So in sophisticated commercial amplifiers, the triode-like devices is not the first choice. But in a DIY project that obeys the philosophy of the tube era when hi-fi is not even a word, these devices are the first choice. That particular design, that particular sound is the heart of "Hi-Fi"
Hi-Fi is just that specific sound coloration. You can hear someone talking to you in person which is purely 0 distortion but that is not Hi-Fi, when you recorded that talk and play through some gear that gives you the smooth and lively sound that is Hi-Fi. These Vfets are your best bet to get that Hi-fi sound in an SS amp.
So in sophisticated commercial amplifiers, the triode-like devices is not the first choice. But in a DIY project that obeys the philosophy of the tube era when hi-fi is not even a word, these devices are the first choice. That particular design, that particular sound is the heart of "Hi-Fi"
Hi-Fi is just that specific sound coloration. You can hear someone talking to you in person which is purely 0 distortion but that is not Hi-Fi, when you recorded that talk and play through some gear that gives you the smooth and lively sound that is Hi-Fi. These Vfets are your best bet to get that Hi-fi sound in an SS amp.
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Perhaps instead of amplifiers, you could invest in speakers?
These are not rubbish at all, they are Victor Sx-500 dolce II. Internal alnico for both tweeter and woofer, real wood panel, real wool damping filling. the paper cone's sound I like the most. I have not heard any bookshelf I love more.
I am planning using 3 or 4 harman kardon fullrange planar and a 18 inch woofer each side to make a 2-way speaker but I am in doubt It would sound any better, but the distortion of mid to high should be lower and could bring more tiny details.
https://www.diyaudio.com/community/...-planar-full-range-from-harman-kardon.395838/
I am planning using 3 or 4 harman kardon fullrange planar and a 18 inch woofer each side to make a 2-way speaker but I am in doubt It would sound any better, but the distortion of mid to high should be lower and could bring more tiny details.
https://www.diyaudio.com/community/...-planar-full-range-from-harman-kardon.395838/
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That is pretty accurate.
Tube amplifier designers were counting every tube, whereas transistor amplifier designers can use more transistors to get better performance without making the cost prohibitive. IC designers have the luxury of nearly free transistors.
Ed
All the amplifiers you mentioned are catastrophic circuits and catastrophic setups. Their sound has nothing to do with the Fets. You could use the best sounding transistors and it would always sound like crap.
Just saying...i love my speakers, have quite a few, but in main system, i circle about 3 pairs. We have often with friends listening sessions, comparing amps or speakers and offcourse drinking brewski.
My speakers are based on two 15" woofers per side in open baffle dipole, 8" midbass open baffle dipole, and planar tweeter slim grs, with foster planar supertweeter. One arrangement for example. Biamplified, with classAB plate amps for woofers, classA amps for rest.
Now when i am moving, i packed most of the stuff. But in the mean time, i hooked bookshelfs, just to have some sound. Same sources, same amps. Boy, am i dissaponted. Bookshelfs are good ones, 6.5" aurum cantus with ribbon tweeter. Measure good, flat, bsc, bassreflex tuning to 40hz...not bad for bookshelf, but not even close to my 4way main speakers.
I can hear the bassreflex, voices are boomy, resonating. I hear small box reflections, nothing is so clear as open baffle free of reflections. Dynamics is not there, all seems compressed. Scale of orchestra is missing.
I would not be able to live with small 2way bookshelf.
Youtube recordings!? You must be joking... 🤢
Please just donate your parts (or the whole amps) to the Sony VFET group buy so that someone can make good use of them.
There are only two amplifiers where the j-V-fets are connected drain-to-drain to the output: Sony TA-4650 (singels) and Sony TA-5650 (twofolds). All other j-V-fet amplifiers have a classic topology with the sources (or emitters - bjt) to the output. SIT's and the like from N. Pass are the current exceptions (hats off!).
There is no other topology that can manage an stable output as all other drains from whatever fet and collectors from bjt's have an high output impedance making it impossible. With tubes, triodes especially, only an output transformer is needed. So we're stuck with available V-fet's and SIT's until stocks depletes.
But there is more! What distinguish that very specific drain-to-drain topology to make it sound so well? I'm a regular visitor of live classical music performances and an owner of a (serviced) 4650 for over a year now. It does indeed sounds very good, close to the original. However, It is not the same as live, but pr-claims like detail, placing and accuracy are in place here, with distance. But why?
One has to analyse and decode the inner working of a triode /V-fet / SIT to understand what's happening in the device. There are only three nodes involved that interacts with eachother, and more intense (!) than with all other semi's or multi-plate tubes. Consider the pentode, which has extra 'layers' (the screen and the surpressor) to protect the grid from being 'influenced' by the up and down swinging anode. Connecting the screen to the anode yields a triode again.
This works well with tubes (N-channel only!), but not with solid state devices, except the V-fet's and SIT's. They're actually conducting devices which must put to a close state by the controlling gate. Normal values (Rds, gate nc) for the 2SJ18 / 2SK60 V-fet's are some 2 ohms.
Is it possible to cook a solid state device with V-fet characteristics? Yes: the V-fet's (obsolete) and the SIT's (very rare). Commercially a no go.
But is it possible to mimic a V-fet? To create with ordinary components, current available solid state devices together with (non-frequency-dependent) simple components like resistors (20% grade) only, comparable with other well known and understood compounds like the differential and current mirror, Darlington and Sziklay, and the lone cascode (all with only two active devices!), a sixth compound, both N- and P-channel, or likewise NPN / PNP variations, that will do exactly tha same as V-fets (& SIT's) can do? Drain-to-drain, collector to collector and 'midpoint-stable'?
YES.
And it is earth-flattening simple. Staring in your blindsight face.
What's involved? Ohm's law, and if bjt's are used, you've only got to estimate the square root of beta for proper biasing. It is even possible to re-create an ordinary tube replacement out of it, say a EC83 or a EL519, using the heater voltage to power some orange (or blue!) leds.
How? That will be disclosed as soon as I get my patent awarded. Two semi's, three resistors, that's all. All (accurate) calculations fit on one single letter.
But currently servicing another 4650 and a 5650 as references, and a curve tracer to build to prove all things for the lawyers. (They are s... l... o... w...)
Cheerio.
If you submitted the patent, your intellectual property is now protected and there should be nothing stopping you from disclosing your invention to us. It may take veeeeery long until a submitted patent gets granted and becomes public. Why wait?
My lawyer takes his time before submitting, hence no disclosure possible.
I try to sell it then, AD, TI, name it.
Ahhh... I love these discussions where listening to music is like a 'discipline', like some kind of strenuous exercise where if you don't feel sufficient pain you know you're doing it wrong. Hence, a 'sweet' sound must by default be less accurate than the grit of reality.
Mouser, Digikey and co have a range of SIC MOSFETs and JFETs that seem promising for linear output stages, even though they're all obviously vying for the electric car market.
Nelson Pass' range of F1, F2, F2J.. etc amplifiers all seem promising for great quality sound. As mentioned somewhere above, open drain outputs are very rare. A unity gain output stage does have certain advantages, but this would probably favour electrostatic or planar magnet speakers, which don't really benefit from a high output impedance. We were just discussing this in a thread on current source amplifiers.
It's becoming clearer in my mind that, for a conventional dynamic woofer, a mixed output impedance could be the way to go. Voltage control in the bass, and a current source in the treble.
Mouser, Digikey and co have a range of SIC MOSFETs and JFETs that seem promising for linear output stages, even though they're all obviously vying for the electric car market.
Nelson Pass' range of F1, F2, F2J.. etc amplifiers all seem promising for great quality sound. As mentioned somewhere above, open drain outputs are very rare. A unity gain output stage does have certain advantages, but this would probably favour electrostatic or planar magnet speakers, which don't really benefit from a high output impedance. We were just discussing this in a thread on current source amplifiers.
It's becoming clearer in my mind that, for a conventional dynamic woofer, a mixed output impedance could be the way to go. Voltage control in the bass, and a current source in the treble.
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