My hybtrid tube preamp + class D power stage prototype amplifier.
First step: volume potentiometer with switch, switch power by relay, DIP switch to configure oscillator frequency of power stage.
Major changes in next version: no DIP switches, oscillator set to 1.2MHz, dealy muting and no power switch because capacitors with low ESR can stick the contacts together.
Minor changes: increased load on the anode voltage converter to reduce the noise level.
The appearance of the first (prototype) version:
![[Image: Widok-Przod.jpg]](https://i.ibb.co/CnBq4fY/Widok-Przod.jpg)
Final schematic (for the next versions):
![[Image: schemat.png]](https://i.ibb.co/Gx5tghs/schemat.png)
Inductors:
MSS1210 - 10uH: L1-L4, 1.5mH: L5
MSS1278 - 330uH: L6
MSS7348 - 680uH: L7, 1mH: L8
All inductors manufactured by Coilcraft
Capacitors types:
MKS2: C3, C4, C9-C12
0805 size, X7R: C31, C32, C41-C43, C44, C46, C48, C49, C54, C55
1206 size, X7R: C13-C16, C52, C57, C58
1812 size, X7R: C21-C24
0805 size, C0G: C1, C2, C5, C6, C17, C29, C30, C39, C40
1206 size, C0G: C17-C20, C25-C28
hybrid (OSCON): C7, C8, C45, C47, C51, C53
standard aluminium: C33-C38, C50, C56, C59
Capacitors voltages:
C5, C6, C56, C57, C58: 100V
C7, C8, C9, C10, C51: 63V
C3, C4, C11, C12, C20-C32, C39-C43, C46, C48-C50, C54-C56: 50V
C33, C34, C35, C36, C37, C38, C59: 35V
C47: 25V
C44: 16V
C45: 10V
Resistors:
Mini-MELF 0204: R1-R16
MELF 0207: R17-R20
1206 0.5W: R30
0805 0.125W - all others
Resistors tollerance:
1% all Mini-MELF, MELF and R31, R32, R34, R35
5% all others
Electron tubes:
V1, V2, metal-ceramic (nuvistor) triodes, mu=32, gm=11.5mA/V - 6S51N or 6S51N-V (russian products).
V3, subminiature magic eye DM70
Layout of PCB
top side:
![[Image: Hybryda-TPA3116-bottom.png]](https://i.ibb.co/vZ37j0R/Hybryda-TPA3116-bottom.png)
bottom side:
![[Image: Hybryda-TPA3116-top.png]](https://i.ibb.co/MPFGnxz/Hybryda-TPA3116-top.png)
PCB dimensions: 147mm * 98mm
Preamplifier stages, typical voltage stages on triodes. Cathode resistors unblocked. The achieved gain of the degree is approximately 14 times.
Magic eye controlled by two voltage doublers with a common output condenser. Both rectifiers are supplied directly from the positive output terminals. No regulation, for full control of the 22.5 - 24 V voltage generator, the "exclamation mark" is completely extinguished.
IC2 - a buck converter that powers lamp glow. Set the VR1 potentiometer to 6.3V at TP1 point.
IC3 - a boost converter for 47V anode voltage for tube preamplifiers and 70V voltage supplying the magic eye. The R33 resistor adds an additional load to the converter, reducing the noise level.
T1 - automatic mute after failure detected by TPA3116 system.
T2, RL1 - mute after turning on the power, eliminating two crackles in the loudspeakers, the first after switching on the voltage and the second when the preamplifier tubes are already emission.
First step: volume potentiometer with switch, switch power by relay, DIP switch to configure oscillator frequency of power stage.
Major changes in next version: no DIP switches, oscillator set to 1.2MHz, dealy muting and no power switch because capacitors with low ESR can stick the contacts together.
Minor changes: increased load on the anode voltage converter to reduce the noise level.
The appearance of the first (prototype) version:
Final schematic (for the next versions):
Inductors:
MSS1210 - 10uH: L1-L4, 1.5mH: L5
MSS1278 - 330uH: L6
MSS7348 - 680uH: L7, 1mH: L8
All inductors manufactured by Coilcraft
Capacitors types:
MKS2: C3, C4, C9-C12
0805 size, X7R: C31, C32, C41-C43, C44, C46, C48, C49, C54, C55
1206 size, X7R: C13-C16, C52, C57, C58
1812 size, X7R: C21-C24
0805 size, C0G: C1, C2, C5, C6, C17, C29, C30, C39, C40
1206 size, C0G: C17-C20, C25-C28
hybrid (OSCON): C7, C8, C45, C47, C51, C53
standard aluminium: C33-C38, C50, C56, C59
Capacitors voltages:
C5, C6, C56, C57, C58: 100V
C7, C8, C9, C10, C51: 63V
C3, C4, C11, C12, C20-C32, C39-C43, C46, C48-C50, C54-C56: 50V
C33, C34, C35, C36, C37, C38, C59: 35V
C47: 25V
C44: 16V
C45: 10V
Resistors:
Mini-MELF 0204: R1-R16
MELF 0207: R17-R20
1206 0.5W: R30
0805 0.125W - all others
Resistors tollerance:
1% all Mini-MELF, MELF and R31, R32, R34, R35
5% all others
Electron tubes:
V1, V2, metal-ceramic (nuvistor) triodes, mu=32, gm=11.5mA/V - 6S51N or 6S51N-V (russian products).
V3, subminiature magic eye DM70
Layout of PCB
top side:
bottom side:
PCB dimensions: 147mm * 98mm
Preamplifier stages, typical voltage stages on triodes. Cathode resistors unblocked. The achieved gain of the degree is approximately 14 times.
Magic eye controlled by two voltage doublers with a common output condenser. Both rectifiers are supplied directly from the positive output terminals. No regulation, for full control of the 22.5 - 24 V voltage generator, the "exclamation mark" is completely extinguished.
IC2 - a buck converter that powers lamp glow. Set the VR1 potentiometer to 6.3V at TP1 point.
IC3 - a boost converter for 47V anode voltage for tube preamplifiers and 70V voltage supplying the magic eye. The R33 resistor adds an additional load to the converter, reducing the noise level.
T1 - automatic mute after failure detected by TPA3116 system.
T2, RL1 - mute after turning on the power, eliminating two crackles in the loudspeakers, the first after switching on the voltage and the second when the preamplifier tubes are already emission.
