High Power Hi-End Hybrid Amplifier End 2023
started on November 20 ^st , 2022

• no global feedback design
• passive components without any compromise on any section
• only few parts on the signal path, only 3/4 active components
• very short signal path
• very low output impedance (near to 0.1ohm) for high damping factor (near to 80)
• very high output current, output devices able to manage 60A
• high output power to drive any loudspeakers including ESL, 140W on 8ohm and 250W on 4ohm
• very good slew-rate
• large frequency band, near to 1.5MHz for the IRF820 configuration
• high separation from power supply for all the sections
• power supply separated for each channel
• zero noise
• ultra low distortion in the current amplifier
• zero dc offset, dc servo loop
• no fuse on the signal path
• no relay on the output signal
• only a single vacuum tube for the voltage amplifier
• only one interstage capacitor on the signal path
• high input impedance 110Kohm
• high voltage gain able to be driven directly by any source
• voltage stage and driver stage working in pure class A operation
• high efficiency near to class AB
• compact chassie

Here the link to buy the complete pcb set

I don't get money from this Ebay shop.

The output stage pcbs has been design to optimize the signal path with large wire for the high current signal.

You should increase the thickness of the high current pcb tracks with tin (see photos).

If possible add your comment on this amplifier or post photos of your Hybrid Amplifier End 2023 on:
diyaudio.com / Hybrid Amplifier End 2023




VOLTAGE AMPLIFIER + CURRENT AMPLIFIER





The old configuration

   where 

• the capacitors near the output transistors are charged slowly so the fuse inserted before does not blow
• after switch-on the output stage should start without dc offset and it will wait the vacuum tube warm up

R1,R25                            47Kohm   1/4W  1%   Vishay Dale RN55
R2,R14                            10ohm      2W  1%   Vishay PR02
R3,R36                            280ohm   1/4W  1%   
R26,R27                           2700ohm    2W  5%   Vishay PR02
R34,R35                           15ohm      2W  5%   Vishay PR02
R23,R33                           270ohm     1W  1%
R24,R28                           5600ohm    2W  5%   Vishay PR02
R5,R6,R7,R8,R17,R18,R19,R20       0.47ohm    5W  5%   Vishay AC03
R15,R16                           220K     1/4W  1%
R55,R56                          2200ohm  1/4W  1%   Vishay Dale RN55
R51,R52,R53,R54                    220ohm  1/4W  1%   Vishay Dale RN55  
R4,R13                            6800ohm    2W  5%   Vishay PR02
R29,R30,R21,R22                   10Kohm  1/4W  1%
R9,R11,R10,R12                 0ohm            (jump)


C6,C8,C9,C14                      0,47uF  63V  Wima MKS
C1,C2,C10,C11                     100uF   25V   UFW
C3                                empty
C5                                0.1uF   100V   Vishay MKP1837
C7,C17,C4,C24,C18,C20            2700uF 63V Nichicon KG  type 30x35mm 
C15,C16                           1000uF 63V Nichicon

D1,D2                             Zener 15V  1W
D3,D4                             UF4007
D5,D14                            1N4007
D8,D12,D11,D10,D6,D7              1N4148

F1,F2                             FUSE 5A FAST (with fuse holder)

U$1                                 2N5550 o 2N5551
U$3                                 2N5401

Q1,Q3,Q16,Q18                     MJE15033 (PNP)
Q2,Q4,Q14,Q17                     MJE15032 (NPN)
Q9,Q5,Q6,Q7,Q13                   NJW0281G (NPN)
Q12,Q11,Q8,Q10,Q15                NJW0302G (PNP)

IC1                               OPA134, OPA602 (you can use many others single op-amp like the TL071)

The connections are 63862-1 (CUT STRIP) by TE Connectivity / AMP (cod. Mouser  571-63862-1-CT, cod. RS 718-7987)

SIMULATIONS

Here all the files to simulate this circuit with LTSpice software.

• Power Diamond with LL1667

• Power Diamond with IRF820

• Power Diamond test integrated protection

• 6Z51P-Triode.inc (include IRF820)

• OPAx132.LIB

• OPAx134.LIB

Download triode.asy from Ducan's Amp Pages.

Add these following ines in the file C:\Program Files\LTC\lib\cmp\standard.bjt or in C:\Users\[Windows user]\Documents\LTspiceXVII\lib\cmp\standard.bjt to have the transistors models:

.MODEL Qnjw0302g pnp IS=5.16751e-16 BF=114.657 NF=0.895716 VAF=50.2189 IKF=6.409 ISE=3.9641e-15 NE=4 BR=1.47167 NR=0.923324 VAR=255.567 IKR=6.34299 ISC=3.96408e-15 NC=2.82194 RB=2.66347 IRB=0.1 RBM=2.0828 RE=0.0001 RC=0.0652395 XTB=1.45322 XTI=1.08126 EG=1.05 CJE=2.14504e-09 VJE=0.4 MJE=0.376227 TF=2.16864e-09 XTF=1000 VTF=843.737 ITF=501.348 CJC=5e-10 VJC=0.95 MJC=0.251547 XCJC=1 FC=0.8 CJS=0 VJS=0.75 MJS=0.5 TR=1e-07 PTF=0 KF=0 AF=1

.MODEL Qnjw0281g npn IS=4.36849e-12 BF=98.1488 NF=1.01332 VAF=37.9046 IKF=9.71849 ISE=1e-16 NE=1.8326 BR=0.79921 NR=1.09994 VAR=339.743 IKR=5.77305 ISC=1e-16 NC=2.71592 RB=2.74892 IRB=0.33289 RBM=2.74892 RE=0.000344671 RC=0.03203 XTB=1.7742 XTI=1.12262 EG=1.20598 CJE=3.66793e-09 VJE=0.74806 MJE=0.85 TF=2.27115e-09 XTF=1000 VTF=912.955 ITF=296.602 CJC=5e-10 VJC=0.95 MJC=0.270858 XCJC=0.98254 FC=0.8 CJS=0 VJS=0.75 MJS=0.5 TR=1e-07 PTF=0 KF=0 AF=1

.MODEL Qmje15032 npn IS=3.7344e-10 BF=86.8313 NF=1.23974 VAF=31.5491 IKF=9.1678 ISE=9.2499e-12 NE=3.28127 BR=5.59346 NR=1.33161 VAR=2.1791 IKR=5.15023 ISC=4e-13 NC=4 RB=9.54492 IRB=0.1 RBM=0.1 RE=0.000568481 RC=0.0931741 XTB=0.737036 XTI=1.04983 EG=1.206 CJE=3.05969e-09 VJE=0.648491 MJE=0.352663 TF=4.94819e-09 XTF=1.50001 VTF=1.0001 ITF=0.999982 CJC=3.00108e-10 VJC=0.600021 MJC=0.40991 XCJC=0.8 FC=0.534651 CJS=0 VJS=0.75 MJS=0.5 TR=1e-07 PTF=0 KF=0 AF=1

.MODEL Qmje15033 pnp IS=7.51228e-10 BF=134.35 NF=1.25737 VAF=12.5778 IKF=1.88497 ISE=7.74267e-12 NE=3.34528 BR=5.14173 NR=1.47488 VAR=1.4505 IKR=7.47186 ISC=3.25e-13 NC=4 RB=4.37743 IRB=0.1 RBM=0.1 RE=0.000332989 RC=0.381218 XTB=0.223027 XTI=1 EG=1.05 CJE=3.06005e-09 VJE=0.64838 MJE=0.352991 TF=4.78203e-09 XTF=1.50001 VTF=1.00006 ITF=0.999988 CJC=3.00101e-10 VJC=0.600019 MJC=0.409916 XCJC=0.8 FC=0.534975 CJS=0 VJS=0.75 MJS=0.5 TR=1e-07 PTF=0 KF=0 AF=1
 

POWER SUPPLY FOR THE CURRENT AMPLIFIER

The following is an example of normal power supply, there are 2 toroidal transformers with about 300VA.

You can use min 4 x10000uF and max 4 x 22000uF.

It is possible use switching power supply modules, one per channel to to avoid ground loops.

There is a little difference in sound by hot switching between conventional power supply made of transformer, diode bridge, capacitors and these switching power supplies.

These modules are availbale at low cost on Alixpress shop.

Input voltage: AC200-240V
Output: ;
     Main voltage +-55V/6.5A;
     Independent 12V/0.5A;
     Auxiliary +-12V/0.5A (with the main voltage for ground)
Voltage regulation accuracy: main no-load ±3%, with load ±3%; (when AC220V input)
Continuous power: 350W (can work continuously for long-term 350W work at 25°C ambient temperature, fan cooling is required)
Rated power: 700W (can work continuously for about 5 minutes at 25°C ambient temperature)
Instantaneous power: 900W (power generated during dynamic signal impact, less than 100 milliseconds)
Conversion efficiency: Max 98%
Dimensions: length, width and height = 96*96*38mm
Weight: 310g

It is possible use also a pair of MEAN WELL LRS-150-36 connected in series to obtain a dual voltage.

It is a 150W Single Output Switching Power Supply with a variable DC output in the range 32.4 ~ 39.6V.

There are integrated protections for short circuit, overload, over volatge, over temperature.

This model has been choised because it is cooling by free air convection and give until 4.3A.

There are also more expensive models with PFC like the UHP series.

SOFT START -  PROTECTION 

The soft start is necessary only you are using normal power supply with transformer and capacitors.

B1          diode bridge 100V 2A  2KBP01
IC1               4013 or HCF40138
IC2               7805 in TO220 case
IC3               NE555
T1,T3             BC337

C1               100uF  16V
C3               100uF  16V
C4               470uF  16V
C5                 1uF  63V  MKT

R2                22Kohm 1/4W
R1,R3,R6,R8        1Kohm 1/4W
R13              8200OHM 1/4w
R5,R18           4700ohm 1/4W
R4,R7,R9          4.7ohm 5W 

U1,U2          Relay Fider mod. 41.61  12V

The connections are 63862-1 (CUT STRIP) by TE Connectivity / AMP (cod. Mouser  571-63862-1-CT, cod. RS 718-7987)


JP1 led power-on
JP2 led dc detected so fault

and use the following module to add an extra dc protection to switch off th amplifier in case of problems

R17,R14                         empty (not used)
R16,R15                         10Kohm 1/4W
C6,C7,C12,C13                   empty (not used)
C8,C9,C10,C11                   220uF 35V
D8,D9,D11,D12,D13,D14,D15,D16   1N4148
D17,D18,D19,D20,D2,D3,D5,D10    empty (not used)
OK2,OK3                         empty (not used)
OK1,OK4                         SFH610

The connections are 63862-1 (CUT STRIP) by TE Connectivity / AMP (cod. Mouser  571-63862-1-CT, cod. RS 718-7987)

This is the 1NO1NC switch available in 2 configuration Momentary or Latching and you can buy from Alixpress.

The panel cut out  is 22mm, the same of noval socket, so this is the ideal choice for the 10mm front panel.

Use Momentary model if you think to use the Soft start from Alixpress otherwise if you use my Soft start use the Latching type.

CABINET

In order to dissipate all the heat generated by this amplifier in my case I chose this container by HiFi 2000.

I suggest to use the CUSTOMIZATION service by HiFi 2000 for the M3 threading on the heatsinks.

● File dxf to use

If you will use the switching power supply for the current amplifier use this model:

Dissipante 04/300B 4U 10mm SILVER or BLACK
Product Code: 1NPD04300B or 1NPD04300N
temperature coefficient 0,31 C°/W per each side
Internal height 165mm 

If you will use the normal power supply for the current amplifier probably you should use this model:

Dissipante 05/300B 5U 10mm SILVER or BLACK
Product Code: 1NPD04300B or 1NPD04300N
temperature coefficient 0,18 C°/W per each side
Internal height 210mm  

Inner baseplate for Dissipante 300mm
Product Code: 1BASEPD300

Add an internal aluminium panel 3mm size 20 x 29cm

INTERSTAGE CAPACITOR

This is a very hi-end amplifier with a incredible sonic performances but reach this level it is necessary use a very good interstage capacitor.

I suggest these models:

• Jantzen Z-Cap Superior 2.2uF 800V
• Intertechnik Audyn Cap Tri-Reference 2.2uF 630V
• Clarity Cap CMR MKP 2.2uF 400VDC  

See some test results on Humble Homemade Hifi .

MEASUREMENTS

Here a first measurement with 2 x 37VAC r-core transformer.

Here the final measurements with 2 x 55VDC switching power supply.

BIAS

This project does not have a bias adjustment so you have to use the same transistors I used.

In my version with 2 x 36VAC  400VA toroidal transformers I have this bias.

2 x 22000uF 63V on each channel

2 x 46.5VDC on amplifier input

2 x 42VDC after regulators

from 65mV to  69mV on 0.47ohm output resistors so 0.147A for each output transistor

about 800-900mV on the 10ohm resistor so 2 x 90mA on driver stage

4 x 0.147A = 0.59A

2 x 90mA = 0.18A

= 0.76A    =>     2 x 46.5VDC x 0.76A = 71W on each channel

Using a 2 x 55VDC on amplifier input you will arrive to about 95W

PHOTOS & CONSTRUCTION DETAILS

1) set the variac to about + 2v and -2V dc to check that the heatsink is not connected to these tensions
2) control the voltage after the regulators these should rise slowly in a few seconds
3) set the variac to + 15V and -15V to verify that the output voltage goes to zero volts dc
4) set the variac and -20V to + 20c to verify that the voltage across the resistance from 0.47ohm is almost equal among all the transistors (0.05V - 0,06V)
5) set the variac at the final voltage

Here a test environment with a single high power r-core for both channels.