VSSA Circlotron

[UltimateX86]

hi,

yes if i invert the supply it work too, but I can not say if it's good or not on this schema because it only has 30db gain in open loop and even less with the cascode

I will try R6 / R14 to the ground

 

[UltimateX86]

R6 / R14 to the ground = 0 gain 🙂

 

[N101N]

I said R19 and R25, a small technicality.

 

[UltimateX86]

In fact i use a 10V dc supply on cascode base to simplify...

 

[N101N]

OK, I would replace J3, J4 with a resistor, run the drain-source at about 2 V, and refer R19, R25 to ground.

 

[banat]

R6 / R14 to the ground = 0 gain 🙂

strange 🙂

 

[UltimateX86]

strange 🙂

and very difficult to set the bias

 

[UltimateX86]

Jfet + css + cascode + differential feedback

http://circlotron.audio/data/simulation/img/circlotron1.6A.png
http://circlotron.audio/data/simulation/img/circlotron_fft_1.6A.png
http://circlotron.audio/data/simulation/asc/circlotron1.6A.asc

 

[UltimateX86]

Hello,

I reproduced this graph with a simulation

exicon poshpull :
http://circlotron.audio/data/simulation/img/wingspreadMosfet.png
http://circlotron.audio/data/simulation/asc/WingspreadMosfet.asc

exion circlotron :
http://circlotron.audio/data/simulation/img/wingspreadMosfetCirclotron.png
http://circlotron.audio/data/simulation/asc/WingspreadMosfetCirclotron.asc

can someone check my simulation?

[http://circlotron.audio/data/simulation/img/wingspread.png

thanks

 

[UltimateX86]

I used my application to realize 16 187 040 simulations 🙂

Results:

1) increase the 100ohm R to ground increases the distortion, I vary from 100 to 1000 in steps of 100
2) decrease the quiescent current of the input stage decreases the distortion, I vary from 2 to 2.6 in steps of 0.2
3) the distortion is lower when the VAS has a very low current OR very high (2ma vs 15mA)
4) Generally distortion decreases with the increase of mosfet current, at 1w as at 100W, except at mid power ...

0.03% THD 10khz 100W 4ohm
0.0005% THD 10Khz 1w 8ohm

 

[N101N]

Distortion highly depends on loading. You cannot simulate dynamic loading, but it needs to be taken into account in determining currents. You can, however, calculate valid voltage, current and resistor values for the whole circuit. Would you do that, please?

 

[UltimateX86]

all viable values and measure + thd @28V 4ohm output :

72000 combination :
http://circlotron.audio/data/simulation/brute/DISTO_20180905.csv
http://circlotron.audio/data/simulation/brute/DISTO_20180905.ods

bias op simulation : (I read binary raw file)
http://circlotron.audio/data/simulation/brute/BIAS.asc
http://circlotron.audio/data/simulation/brute/BIAS.net
http://circlotron.audio/data/simulation/brute/BIAS.png

thd simulation : I read log
http://circlotron.audio/data/simulation/brute/THD.asc
http://circlotron.audio/data/simulation/brute/THD.net
http://circlotron.audio/data/simulation/brute/THD.png

 

[N101N]

How to upload a local image file?

 

[UltimateX86]

Send me by mail or on photobucket.com, I upload it on the forum or on my web site

 

[UltimateX86]

I used the output like yamaha :

http://circlotron.audio/data/simulation/img/bjt_circlotron_1.4A.png

http://circlotron.audio/data/simulation/asc/bjt_circlotron_1.4A.asc

 

[alnikst]

http://forum.vegalab.ru/attachment.php?attachmentid=270620&d=1468348851

 

[N101N]

Not too bad.
R17 and R19 should go to output.
I would drastically reduce the value of R24 and R25

 

[UltimateX86]

Hello,

anyone know TINA ?

I would like to simulate a circlotron with LME49830 but I can not get a current on mosfets

https://www.diyaudio.com/forums/att...779d1551451705-lme49830-tina-lme49830-tsc-txt

https://www.diyaudio.com/forums/att...4d1551694070-lme49830-tina-circlotron-tsc-txt

thanks

 

[UltimateX86]

schematic in png

 

[UltimateX86]

four CFA version