Some people are interested in more powerful CFA amp, and this is 200W//8ohm and 400W//4ohm.
It uses lateral MOSFET output transistors like Hitachi 2SK134/135 and 2SJ49/50 or similar from Toshiba 2SK1056 2SJ162 or from other producers.
Interestin part of this amp is use of TPC compensation, but unusual one with one capacitance branch connected to the output instead to the VAS collectors.
That brings 20kHz distortion down significantly.
This thread is open to discussion and suggestions as it’s tried in simulation only.
As CFA uses very low feedback resistance there is significant power dissipation on series resistor, and I show two schematic, one with lower FB resistors and other with double values. I case if Rf is 220 ohm at full power dissipation go up to 14 W and in case if Rf is 480 ohm it halved. Still this resistor should be parallel combination resistors to distribute power dissipation. first is low FB resistance, this gives lower distortion and higher slew rate.
Damir
Zener protection diodes moved from drivers emitter to drivers bases on suggestion from JohanB (not good idea) 200W MOSFET CFA amp - Page 87 - diyAudio
Argument about stability: What is important is the outer feedback loop
200W MOSFET CFA amp - Page 67 - diyAudio
Better protection suggested by Wahab: 200W MOSFET CFA amp - Page 88 - diyAudio
First listening 200W CFA, post #740: https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-74.html#post4278243
Index:
1. 200W CFA VMOFET, the last schematic and the BOM is here on post #770 200W MOSFET CFA amp and the .asc zip file is here on page #775 200W MOSFET CFA amp
2. 100 W CFA assembling instruction on post #911 200W MOSFET CFA amp
3. PS regulator BJT version assembling and testing instruction post #912 200W MOSFET CFA amp
PS regulator layout errors post #919 200W MOSFET CFA amp
PS Regulator BOM post #988 200W MOSFET CFA amp
4. Corrected 100 W CFA schematic and BOM post #947 200W MOSFET CFA amp
5. astx real amp 200W measurements. post #851 200W MOSFET CFA amp
6. some RNMarsh real amp 200W measurements. post #787 200W MOSFET CFA amp
7. 200W CFA assembling instruction with schematic, balanced add schematic and corresponding BOMs.post #1230 www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-123.html#post5311565
8. 200W CFA VMOSFET printed board rev. 1.3.2 has some silk screen errors:
200W CFA VMOSFET-dado-1_3_2
Silk scree errors:
D21 rename to D8 and revers
D20 rename to D5 and revers
D23 rename to D20 and revers
D5 rename to D23
D22 rename to D21 and revers
D8 rename to D22
Q9 rename to Q5
Q7 (on the left) rename to Q9 2SC3503
explanation on page #1289 link http://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-129.html#post5539928
9. 200W CFA board rev 1.3.2, corresponding balanced add board and PS regulator MOSFET board with BOMS. page #1405 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-141.html#post5725721
10. 200W CFA some soldering explanation, unbalanced input and balanced inputs, post #1415.
There is silkscreen error on 200W boards rev.1.3.2, input connectors wrongly marked, IN SIG GND should be GND SIG https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-142.html#post5740471
post# 1506 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-151.html#post6031569
11. MOSFET PS regulator testing, post #1416. https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-142.html#post5740493
12. MOSFET PS regulator oscillating in some cases, remedy on post #1456. https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-146.html#post5904223
12. 100W CFA board rev 1.4 and PS regulator (BJT) rev 1.3 post #1491 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-150.html#post6000469
13. BJT PS regulator short connection in rev 1.3, look how to rectify it #post 1535 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-154.html#post6158297
14. Shared gerbers for 100W version #1,588 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-80
It uses lateral MOSFET output transistors like Hitachi 2SK134/135 and 2SJ49/50 or similar from Toshiba 2SK1056 2SJ162 or from other producers.
Interestin part of this amp is use of TPC compensation, but unusual one with one capacitance branch connected to the output instead to the VAS collectors.
That brings 20kHz distortion down significantly.
This thread is open to discussion and suggestions as it’s tried in simulation only.
As CFA uses very low feedback resistance there is significant power dissipation on series resistor, and I show two schematic, one with lower FB resistors and other with double values. I case if Rf is 220 ohm at full power dissipation go up to 14 W and in case if Rf is 480 ohm it halved. Still this resistor should be parallel combination resistors to distribute power dissipation. first is low FB resistance, this gives lower distortion and higher slew rate.
Damir
Zener protection diodes moved from drivers emitter to drivers bases on suggestion from JohanB (not good idea) 200W MOSFET CFA amp - Page 87 - diyAudio
Argument about stability: What is important is the outer feedback loop
200W MOSFET CFA amp - Page 67 - diyAudio
Better protection suggested by Wahab: 200W MOSFET CFA amp - Page 88 - diyAudio
First listening 200W CFA, post #740: https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-74.html#post4278243
Index:
1. 200W CFA VMOFET, the last schematic and the BOM is here on post #770 200W MOSFET CFA amp and the .asc zip file is here on page #775 200W MOSFET CFA amp
2. 100 W CFA assembling instruction on post #911 200W MOSFET CFA amp
3. PS regulator BJT version assembling and testing instruction post #912 200W MOSFET CFA amp
PS regulator layout errors post #919 200W MOSFET CFA amp
PS Regulator BOM post #988 200W MOSFET CFA amp
4. Corrected 100 W CFA schematic and BOM post #947 200W MOSFET CFA amp
5. astx real amp 200W measurements. post #851 200W MOSFET CFA amp
6. some RNMarsh real amp 200W measurements. post #787 200W MOSFET CFA amp
7. 200W CFA assembling instruction with schematic, balanced add schematic and corresponding BOMs.post #1230 www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-123.html#post5311565
8. 200W CFA VMOSFET printed board rev. 1.3.2 has some silk screen errors:
200W CFA VMOSFET-dado-1_3_2
Silk scree errors:
D21 rename to D8 and revers
D20 rename to D5 and revers
D23 rename to D20 and revers
D5 rename to D23
D22 rename to D21 and revers
D8 rename to D22
Q9 rename to Q5
Q7 (on the left) rename to Q9 2SC3503
explanation on page #1289 link http://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-129.html#post5539928
9. 200W CFA board rev 1.3.2, corresponding balanced add board and PS regulator MOSFET board with BOMS. page #1405 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-141.html#post5725721
10. 200W CFA some soldering explanation, unbalanced input and balanced inputs, post #1415.
There is silkscreen error on 200W boards rev.1.3.2, input connectors wrongly marked, IN SIG GND should be GND SIG https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-142.html#post5740471
post# 1506 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-151.html#post6031569
11. MOSFET PS regulator testing, post #1416. https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-142.html#post5740493
12. MOSFET PS regulator oscillating in some cases, remedy on post #1456. https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-146.html#post5904223
12. 100W CFA board rev 1.4 and PS regulator (BJT) rev 1.3 post #1491 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-150.html#post6000469
13. BJT PS regulator short connection in rev 1.3, look how to rectify it #post 1535 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-154.html#post6158297
14. Shared gerbers for 100W version #1,588 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-80
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