V-FET (SIT) amplifier production

[kiven chen]

A few days ago, I made a post in Solid State sector.
http://www.diyaudio.com/forums/solid-state/255084-v-fet-sit-amplifier-production.html#post3900348
Some say, Pass Labs busy a lot. So I will post here.
V-FET (SIT) amplifier production
I heard a long time ago SIT has characteristics similar to the tube, L-CAO from Zhongshan, China now has developed a low-power V-FET (SIT), I was fortunate to get L-CAO free V-FET.Recommended by site friends-Niu Gur (? - ??? - Powered by phpwind).
Today I buy a pair of 7.5K:300 from the Taobao's tube headphone amplifier output transformers,(LopentÀÖÅË, StandardϵÁе¥¶Ë¶ú·ÅÊä³ö±äѹÆ÷S-E101£¬Õýʽ·¢ÊÛ(188Ôª/¶Ô£© - ÀÖÅ˵ç×Ó - Æ·ÅÆרÂôÇø - µ¨ÒÕÐùÒôÏì²ÄÁÏÍø ÒôÏì|½»Ò×|µç×Ó¹Ü|µ¨»ú|µ¨»úÍøÕ¾|µ¨»úÂÛ̳|µ¨»ú²ÄÁÏ|Êä³öÅ£|±äѹÆ÷|µçÔ´Å£|µç×è|µçÈÝ)For the V-FET preamp amplifier
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[kiven chen]

Temporary design a circuit diagram, please give me your hand to improve the circuit.

VGS=-0.9V,ID=7.5mA.

 

[DIYspaceW]

Looks interesting...

 

[kiven chen]

new idea,

 

[kiven chen]

DIY 2 channel testing power supply
A:0~22V,
B:1.2~23V.

 

[kiven chen]

Use existing components, DIY a SIT tone control circuitry.
I've never heard such a sound, I don't know how to describe it, is called a novel sound.
Have a sound spring is enough feeling, this voice is not annoying.

 

[kiven chen]

Q2UD=16V

 

[aoc]

Very interesting, would be interesting if can be use as pre-amp.

 

[kiven chen]

Adjust some parameters.
Remove the voltage regulator,
Q1 bias resistors,
51 ohms in parallel in the Q2 source.

 

[Nelson Pass]

Looks offhand like the part can dissipate about 2.5W, so you can consider
biasing it at higher current and/or voltage to improve the performance.

 

[kiven chen]

I will try, but needs cooling device. I'm thinking about how to fixed it. Now it's temperature is about 50 degrees c.

 

[kiven chen]

1000Hz gain is 8.5
Yellow for the input blue output.
Bass 100Hz, high 10KHz,
Adjustment to the maximum 2V/,
Adjust to the smallest 0.2V.

 

[kiven chen]

Adjustment

 

[woody]

Are they for sale yet and how expensive are they?

 

[kiven chen]

Are they for sale yet and how expensive are they?

I heard that in July to sell, I don't know how expensive it is. And I get is a giveaway for testing.

 

[mos57]

Kiven , there are people here on the forum that for decades has tried the V- FET and only in recent years , they have been available ( at least for the DIY ).

They are typically power Vfet or even the SIC power JFETs , but no signal vfets are obtainable with the exclusion of some 2SK79.

Now you have launched the stone in the pond or the best bait to lure us minnows . But not so easily we fall in.

The device that you presented could be very interesting to best complement some circuits. Especially with a mu and a gm about 3 times the 2sk79 it looks excellent .

But we are aware of a few things :

1. the signal vfet proved much more difficult to obtain than those in power (the various 2sj19 , 2sj24 , 2sk69 , 2sk78 , 2sk63 ).
2. Nowday are present study and development for SIT but only for high power and certainly not to meet the demands of the audio.
3. In order to achieve vfet takes high-tech and investment and LAO CAO seems to be currently producing up to now only speakers that is quite another matter.

So we'll see in the coming months if it is all true and if we can get some sample to test it.
Please therefore notify us when you have some information about it and where we can buy it.

Sincerely, Francesco

 

[kiven chen]

Hey, Francesco
I was fortunate to get a few samples
I asked Lao Cao, he says the VFET are hand packaged, very few in number, only for testing.
Around July, should be able to buy it on EBAY.

 

[kiven chen]

Kiven , there are people here on the forum that for decades has tried the V- FET and only in recent years , they have been available ( at least for the DIY ).

They are typically power Vfet or even the SIC power JFETs , but no signal vfets are obtainable with the exclusion of some 2SK79.

Now you have launched the stone in the pond or the best bait to lure us minnows . But not so easily we fall in.

The device that you presented could be very interesting to best complement some circuits. Especially with a mu and a gm about 3 times the 2sk79 it looks excellent .

But we are aware of a few things :

1. the signal vfet proved much more difficult to obtain than those in power (the various 2sj19 , 2sj24 , 2sk69 , 2sk78 , 2sk63 ).
2. Nowday are present study and development for SIT but only for high power and certainly not to meet the demands of the audio.
3. In order to achieve vfet takes high-tech and investment and LAO CAO seems to be currently producing up to now only speakers that is quite another matter.

So we'll see in the coming months if it is all true and if we can get some sample to test it.
Please therefore notify us when you have some information about it and where we can buy it.

Sincerely, Francesco

Looks offhand like the part can dissipate about 2.5W, so you can consider
biasing it at higher current and/or voltage to improve the performance.

With radiator. There is no higher power supply voltage. Change output headphone amplifier output transformers.
But the gain was much smaller, I have to change the circuit later.

 

[kiven chen]

The use of power transformer (115v + 115v:12v + 12v) to do the audio output transformer. No big negative feedback loop.
Sounds good.

 

[kiven chen]

Yellow input,
Blue output.
Audio software audio signal generator,
8 ohm resistive load.