Few square waves and rise time measurements of the First One amplifier module.
1. 50 kHz
2. 200 kHz
3. mid signal level rise time
4. high signal level rise time
Calculation from picture 4, 60 V (90% Vpp) in 250 ns results in:
Slew Rate of 240 V/us
1. 50 kHz
2. 200 kHz
3. mid signal level rise time
4. high signal level rise time
Calculation from picture 4, 60 V (90% Vpp) in 250 ns results in:
Slew Rate of 240 V/us
Attachments
Last edited:
Measurement showing the First One's behaviour at 2,77 MHz sine signal.
We can see 0,9 Vpp input sine signal present on CH2 and 14,3 Vpp output signal on CH1
Calculations from the plot:
1. Voltage gain is x15,89 or +24 dB at 2,77 MHz
2. Linear voltage gain of the First One is +27 dB, meaning that 2,77 MHz is exactly -3 dB gain point
3. Phase shift at 2,77 MHz is 76°
4. 10 Ohm zobel load (Zr+Zc) dissipates 2,4 Wrms at 2,77 MHz
We can see 0,9 Vpp input sine signal present on CH2 and 14,3 Vpp output signal on CH1
Calculations from the plot:
1. Voltage gain is x15,89 or +24 dB at 2,77 MHz
2. Linear voltage gain of the First One is +27 dB, meaning that 2,77 MHz is exactly -3 dB gain point
3. Phase shift at 2,77 MHz is 76°
4. 10 Ohm zobel load (Zr+Zc) dissipates 2,4 Wrms at 2,77 MHz
Attachments
The task was to find a proper output inductor and test the amp to all possible values of capacitance as a load, to be sure there are no chances for the amp to oscillate, no matter what kind of speaker cable is connected to its output terminals.
Lowest possible output serial inductance to fulfill upper demands is 0,2 uH, very practical small size still to be located on PCB.
Few pictures attached as follows:
1. Plot of 10 kHz/20 Vpp square waves on 6 Ohm +1 uF load. Upper trace amp's output in front of inductor, lower trace behind the 0,2 uH inductor.
2. 32 ppm THD10k spectrum 20 Vrms on 6 Ohm load (60 Wrms/6 Ohm)
3. 24 ppm THD10k spectrum 20 Vrms on 6 Ohm + 1 uF (90 Wrms/4,3 Ohm impedance). We can see that 1 uF loading capacitor completely filtered out third harmonic and elevated the second for 5 dB. The whole THD droped for 8 ppm but since third harmonic is also present in the input signal, this THD reduction is actually bad, not preserving the input signal integrity.
4. 0,2 uH output inductor and 1 uF loading capacitor in series with on/off switch
5. Complete measuring assembly
Lowest possible output serial inductance to fulfill upper demands is 0,2 uH, very practical small size still to be located on PCB.
Few pictures attached as follows:
1. Plot of 10 kHz/20 Vpp square waves on 6 Ohm +1 uF load. Upper trace amp's output in front of inductor, lower trace behind the 0,2 uH inductor.
2. 32 ppm THD10k spectrum 20 Vrms on 6 Ohm load (60 Wrms/6 Ohm)
3. 24 ppm THD10k spectrum 20 Vrms on 6 Ohm + 1 uF (90 Wrms/4,3 Ohm impedance). We can see that 1 uF loading capacitor completely filtered out third harmonic and elevated the second for 5 dB. The whole THD droped for 8 ppm but since third harmonic is also present in the input signal, this THD reduction is actually bad, not preserving the input signal integrity.
4. 0,2 uH output inductor and 1 uF loading capacitor in series with on/off switch
5. Complete measuring assembly
Attachments
Looks great!
Nice measurements, very good components, will probably sound very good 🙂
Count me in for a pair (stereo).
Regards,
Danny
Nice measurements, very good components, will probably sound very good 🙂
Count me in for a pair (stereo).
Regards,
Danny
Hi Milan
Yes I still prefer SMPS over classic PSU, because of some major advantages:
- direct and brutal charge of the main energy reservoir capacitors provides power on demand
- fast no delayed transfer over galvanic isolation by means of 100 kHz square waves
- smaller overall size, smaller footprint, smaller secondary capacitors
- lower weight, lower price, no mechanical hum
- integrated soft start, short current protection, protection shutdown, etc.
Nice if you liked the amp from the Belgrade exhibition presentation, well, present version V1.2 of the First One amplifier is its tuned-up version in all respects, how can I say, pure audiophile version with the best parts available.
Yes I still prefer SMPS over classic PSU, because of some major advantages:
- direct and brutal charge of the main energy reservoir capacitors provides power on demand
- fast no delayed transfer over galvanic isolation by means of 100 kHz square waves
- smaller overall size, smaller footprint, smaller secondary capacitors
- lower weight, lower price, no mechanical hum
- integrated soft start, short current protection, protection shutdown, etc.
Nice if you liked the amp from the Belgrade exhibition presentation, well, present version V1.2 of the First One amplifier is its tuned-up version in all respects, how can I say, pure audiophile version with the best parts available.
Class AB, double die mosfet pair 250 W-16 A continous, each.
THD10k 100 Wrms/4 Ohm only 0.004 %, IMD19+20k 80 Vpp/4 Ohm only 0.003 %, 200 kHz square waves on 4 Ohm, is that looks like PWM to you?
Maximal power is normally presented just before clipping with 0,1 % level. Every amp comes to clipp eventually, it is its natural limit. 🙂
Had NC400, NC1200 and they don't come no where near close soundwise, the First One is a very different kind of beast. 😉
THD10k 100 Wrms/4 Ohm only 0.004 %, IMD19+20k 80 Vpp/4 Ohm only 0.003 %, 200 kHz square waves on 4 Ohm, is that looks like PWM to you?
Maximal power is normally presented just before clipping with 0,1 % level. Every amp comes to clipp eventually, it is its natural limit. 🙂
Had NC400, NC1200 and they don't come no where near close soundwise, the First One is a very different kind of beast. 😉