I would like to share with you the result of my new hybrid amplifier.
The my first version of this my amplifier was made in 2010 then i made some improvements.
The new version uses a very simple and cheap tube driver with 6Z51P or D3a that can deliver 40Vrms with a single tube.
The distortion is about 1.5% at 33Vrms so about 150W on 8ohm.
This project collects all the experiences made in these years then it born with all these characteristics:
The my first version of this my amplifier was made in 2010 then i made some improvements.
The new version uses a very simple and cheap tube driver with 6Z51P or D3a that can deliver 40Vrms with a single tube.
The distortion is about 1.5% at 33Vrms so about 150W on 8ohm.
This project collects all the experiences made in these years then it born with all these characteristics:
- 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 ?W 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
Attachments
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The current amplifier is a perfect Diamond Buffer used in some chip like the LH0002 and the BUF634.
This configuration has been analyzed very well in the article Bulding better buffer on Electronics World november 1992.
The same design as been used in many Audio Research amplifiers like the Audio Reasearch D100 and the D400.
Also the Pioneer A-09 and the M-6 use a Diamond Buffer on output stage but these implement dynamic current generators with some stability problems.
Advantages of this type of configuration compared to a conventional:
● compensation of Vbe non-linearities between driver and final so very low distortion without feedback
● high slew-rate and large frequency band
● temperature run-away compensation without sensors if driver and final transistors share the same heatsink
● high input impedance if driver stage use current generator (I1 & I2) auto protected by short circuit on output
Disadvantages of this type of configuration compared to a conventional:
● the bias current in the driver limits the current supplied to the load
It is evident that there are many benefits, but to overcome the problem of the current supplied to the load you need to study well the working points of the driver and final.
This configuration has been analyzed very well in the article Bulding better buffer on Electronics World november 1992.
The same design as been used in many Audio Research amplifiers like the Audio Reasearch D100 and the D400.
Also the Pioneer A-09 and the M-6 use a Diamond Buffer on output stage but these implement dynamic current generators with some stability problems.
Advantages of this type of configuration compared to a conventional:
● compensation of Vbe non-linearities between driver and final so very low distortion without feedback
● high slew-rate and large frequency band
● temperature run-away compensation without sensors if driver and final transistors share the same heatsink
● high input impedance if driver stage use current generator (I1 & I2) auto protected by short circuit on output
Disadvantages of this type of configuration compared to a conventional:
● the bias current in the driver limits the current supplied to the load
It is evident that there are many benefits, but to overcome the problem of the current supplied to the load you need to study well the working points of the driver and final.
All the pcb will be available at low cost on Ebay shop or you can download the Eagle files to produce these in your local area
I don't get money from this Ebay shop.
I don't get money from this Ebay shop.
