Lateral CFA 120W - BSA

[Lazy Cat]

it is not OITPC anymore

It is, -28 dB by level, but still is.

 

[thimios]

I will try to lower the VAS current a little as stll is a bit high(5.4mA).
I will try smaller value caps in the same time.

 

[thimios]

C8, C11=330nf.... Unstable again.

 

[dadod]

C8, C11=330nf.... Unstable again.

OK leave it without caps, performance does not change much without it.

 

[thimios]

Tested even with 120nf.... Unstable.
I hope to come back in stability after removing. 😱

 

[thimios]

Ok. stable again... no caps!
R14, R18=510R.
VAS current =3.8mA VR23=352mV.

 

[thimios]

Lets see how this will perform affter vas current fine tuning. 😉

 

[thimios]

New test.
Power supply linear +/-50v
Bias=136mA
Offset=0mV.
VAS current= 3.8mA

 

[thimios]

The rest.

 

[thimios]

Damir CFA lateral 120W

STEPS TEST.

 

[maty tinman]

For now, H3 > H2 distortion 😱

Thimios, you are a tireless machine. Surely they must be the Mousakás that you eat.

 

[LKA]

STEPS TEST.

this amp should have better performance
look at to mine, very similar topology but use vertical mosfets and more stable compensation scheme

 

[dadod]

Thinios, tank you, you don't gave up easily.😀

 

[thimios]

this amp should have better performance
look at to mine, very similar topology but use vertical mosfets and more stable compensation scheme

What is the common point if we speak for a different amplifier and a different test gear? 🙂

 

[dadod]

this amp should have better performance
look at to mine, very similar topology but use vertical mosfets and more stable compensation scheme

What is point in this, who said that lateral mosfet will generate less distortion then verticals? Laterals have other advantage.
You can open your thread and show your amp.

 

[thimios]

Thinios, tank you, you don't gave up easily.😀

I don't gave up never! 😎

 

[thimios]

What is point in this, who said that lateral mosfet will generate less distortion then verticals? Laterals have other advantage.
You can open your thread and show your amp.

Yes, and if you want an independent test, you can send me an unassembled pcb and i wii take care😉

 

[thimios]

For now, H3 > H2 distortion 😱

Thimios, you are a tireless machine. Surely they must be the Mousakás that you eat.

Please see post #251,the sound card loop test.
Testing using a sound card isn't highly accurate, this depends from the sound card's characteristics.
Commercial gear for THD measuring or audio band frequency analyzer is out of mine buget.
We keep some money for Mousakas

 

[thimios]

Damir CFA lateral 120W

Driving 4 R LOAD.

Please take into account that power supply is 300VA.

 

[schillg11]

actual state

hi Damir, hi thimios,

after 2 days of rest from from discussions and and measuring of the prototype build from thimios, i am interested in the actual state of the Lateral CFA 120 BSA ( my name is Black Superb Amplifier; since the pcb has a black mate soldermask).

My planned DC supply is about +/- 52 V. What are the actual pcb modifications, changes in values, additonal equipped parts, parts not to equip? i followed the discussions in the thread, but i am not sure, which is the actual parts list for thimios working prototype.

Damir, BOM of the class A type misses R0= 10R. Is it possible to reduce the LP R1C2 to a smaller frequency, since the 3db-pint is about 1,5 MHz (C2new at 1nF or 2,2nF?)

BR
Günni