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VSSA Lateral MosFet Amplifier

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Lazy Cat

Lazy Cat

Member
Joined 2007
Yes, recommendation goes to SMPS400A180 unregulated +/-45 V, 400 W power supply. In short modification encircles all ELCOs in the power path:
- 820 uF to 1500 uF/200 V EE series, 105°C, 5,22 A ripple (Panasonic)
- 100 uF to 220 uF/50 V FR series, 105°C, 1,6 A ripple ( Panasonic)
- 10 uF to 47 uF/50 V FR series, 105°C (Panasonic)
- 12 V Schrack relay to short inrush NTC after 2 s, driven by SMPS's auxilary +23 V

After this mod the output voltage drop and ripple parameters reduced to half. Sound one level higher over classic linear PSU. ;)
 
Lazy Cat

Lazy Cat

Member
Joined 2007
VSSA PCB sets packaging big time. Much more fun doing it by listening VSSA simultaneously :D
 

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P

PMI

Member
Joined 2013
Salas said:
What is the -3dB of the working closed loop amp? You can check that point for a sinewave going from 6 graticules down to 4.25 since you got 4MHZ gen capability. Shaan's 1k 100pF input LPF should kick in for about -3dB @ 1.6MHZ anyway.
Click to expand...
The -3db point is around 1.2~1.3 MHz.

Tested with resistive load only, test leads (no speaker wire), no zobel installed, +/-37V rails.

Measured using cursors with the scope on digital setting, and checked against the input at that frequency to make sure the input did not change. The o-scope readings are fairly accurate, but the manual frequency adjustment on the signal generator is very sensitive in the 1-4MHz range, so adjusting the frequency to match the 3db drop exactly, is pretty much impossible.

A square wave is recognizable to about 600-700KHz. The Cat knows his business... :D

I'll post some pics tomorrow when I have a chance to get them off the camera.
 
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