VSSA Circlotron

[UltimateX86]

No more peak, no more overshoot

the j113 is the best compromise between distortion and stability

 

[woofertester]

No more peak, no more overshoot

the j113 is the best compromise between distortion and stability

Thank you for satisfying my curiosity. I would call the step response characteristic something like on the verge of oscillation. Critically damped if you will.

During the rise, before the damped ring-down on the flat top, there are two distinct different slopes. I am curious why the rise has two different slopes.

 

[UltimateX86]

HI

As I use bipolar VAS and IRFP150N output, the IRF9520 is always the best suited for temp compensattion or there is better ?

thanks

 

[UltimateX86]

Bonjour,

Last try with with J113, dual compensation proposed by Elvee. (Thank you)

square wave with 10uF and 1uF

89° phase margin with 1uF

spice file : Simple CFA Circlotron J113 version | Circlotron Audio

I will do the same with the 2SK170

 

[Lazy Cat]

Nice damped ringing insured by output inclusive compensation.

Try to be completely GND independent (high Z to GND), meaning true balanced input (XLR: pin2, pin 3 only), so connect mid 100 k input node (now GND) to mid 100 R (2 x 50 R) feedback node and sim if it is problem free.

 

[UltimateX86]

HI,

Thank you for your interest, I tried to remove the GND


I have trouble choosing a reasonable current, 20X feedback and have a sinus output

With 50ohm on RA I have a good sinus but 8mA on Jfet

 

[UltimateX86]

damping factor 100hz = 1khz : 8/((20.705*8)/20.656-8)=421

 

[UltimateX86]

Nice damped ringing insured by output inclusive compensation.

Try to be completely GND independent (high Z to GND), meaning true balanced input (XLR: pin2, pin 3 only), so connect mid 100 k input node (now GND) to mid 100 R (2 x 50 R) feedback node and sim if it is problem free.

In your opinion the BC560 are enough to dissipate 200mW idle and 285mw Max?

The KSA1381 are no longer available

 

[UltimateX86]

with R5 and R6 at 845ohm we could have 24V supply, so 166mW idle and 258mW peak with 28V peak out

 

[alexberg]

KSA1381ESTU are on order with mouser. Delivery around 11.19

 

[UltimateX86]

OK thanks, I did not see it was on order.

here is a solution

just look at Q1 and Q3

 

[banat]

Alternative closer to ground connection of neutralization elements C6/R24 and C7/R25

 

[UltimateX86]

HI banat,

yes I will try this compensation solution. thanks

Do you remember ?

For shure that it is possible to acomodate that VAS on your VSSA Circlotron project , it is look nice with that CCS on VAS collector side , any way try to simulate this schematic to .

https://www.diyaudio.com/forums/att...1410021153-vssa-circlotron-drive-modified-jpg

 

[UltimateX86]

A small test during the lunch break

It works, but it would take a VDS> 40V
(do not watch compensation)

Alternative closer to ground connection of neutralization elements C6/R24 and C7/R25

I tried, it does not work, Do you want asc?

for the moment the only one that gives a good result is the one that Elvee had proposed, but it must be adapted

 

[banat]