vSingle - a simple high-quality front-end
Hello All,
A very simple front-end desidn, based on the same principle, as the first VHex front-end. The critical, most non-linear piece is a single-transistor transconductance stage at the input (Q4). All the rest is driven by the current - highly linear current conversions.
Open loop 1KHz THD is less than 0.05%, with 40db NFB it comes down to 0.0005%, showing around 0.001% in combination with VHex+ OPS (2-nd picture is showing the Fourier analysis at 50W @ 8 ohm, +/-50V rails). 2-nd and 3-rd harmonics are dominant, all the rest are significantly lower.
Simple light compensation, good stability margins.
The VAS output stage can be easily adapted to any swing (OPS rails) - just adjust the value of R16 for having around 3mA through it.
PSRR is lower than the one, shown by the balanced designs, so I recommend to use regulated +/-15V supply (or at least having the good cap multipliers).
The layout is going to be rather simple - a good exercise for somebody who'd like to try
Cheers,
Valery
Hello All,
A very simple front-end desidn, based on the same principle, as the first VHex front-end. The critical, most non-linear piece is a single-transistor transconductance stage at the input (Q4). All the rest is driven by the current - highly linear current conversions.
Open loop 1KHz THD is less than 0.05%, with 40db NFB it comes down to 0.0005%, showing around 0.001% in combination with VHex+ OPS (2-nd picture is showing the Fourier analysis at 50W @ 8 ohm, +/-50V rails). 2-nd and 3-rd harmonics are dominant, all the rest are significantly lower.
Simple light compensation, good stability margins.
The VAS output stage can be easily adapted to any swing (OPS rails) - just adjust the value of R16 for having around 3mA through it.
PSRR is lower than the one, shown by the balanced designs, so I recommend to use regulated +/-15V supply (or at least having the good cap multipliers).
The layout is going to be rather simple - a good exercise for somebody who'd like to try
Cheers,
Valery
Attachments
A single side pcb will be usefulHello All,
A very simple front-end desidn, based on the same principle, as the first VHex front-end. The critical, most non-linear piece is a single-transistor transconductance stage at the input (Q4). All the rest is driven by the current - highly linear current conversions.
Open loop 1KHz THD is less than 0.05%, with 40db NFB it comes down to 0.0005%, showing around 0.001% in combination with VHex+ OPS (2-nd picture is showing the Fourier analysis at 50W @ 8 ohm, +/-50V rails). 2-nd and 3-rd harmonics are dominant, all the rest are significantly lower.
Simple light compensation, good stability margins.
The VAS output stage can be easily adapted to any swing (OPS rails) - just adjust the value of R16 for having around 3mA through it.
PSRR is lower than the one, shown by the balanced designs, so I recommend to use regulated +/-15V supply (or at least having the good cap multipliers).
The layout is going to be rather simple - a good exercise for somebody who'd like to try
Cheers,
Valery
......
That was quick!
Thanks a lot Didiet!
BTW - can you please make an option with a separate 2-pin plug for +/-15V supply - for those who would like to use a separate regulated supply for the input stage. It may fit somewhere in the middle, close to NFB pin.
Didied,
here is the thread with single ops VHex single sided by Abetir.
http://www.diyaudio.com/forums/soli...-amplifier-simulated-tina-23.html#post4685887
here is the thread with single ops VHex single sided by Abetir.
http://www.diyaudio.com/forums/soli...-amplifier-simulated-tina-23.html#post4685887
Didiet, great job - 100% single-sided, very DIY-friendly.
Thanks for sharing!
Cheers,
Valery
