renx
Well-known member
Hi everybody,
I just wanted to show you all a truly amazing power amp I have been building for the last couple of months, with very good specs...
power.........................225w/4 ohm, 160w/8 ohm
slew rate...................115V/us!!!
freq. response...........10Hz-105kHz (-3dB)
THD............................0.004% 100W RMS/8 ohm
..................................0.008% 180W RMS/8 ohm
..................................0.009% 240W RMS/4 ohm
TIM.............................0.005% 140W RMS/8 ohm (50Hz/7KHz 4:1)
s/n..............................>100dB (100W RMS)
Damping factor............>450 (150W RMS/8 ohm)
It is called "Sigma" and it has been designed by Dr. Borivoje Jagodic from Serbia. Unfortunately, his web site is mainly in serbian http://bas.elitesecurity.org/.
He is a very helpful and understanding person, also an excellent english speaker, you can contact him by mail.
Anyway here is the schematic http://bas.elitesecurity.org/sigmasema.pdf
Its amazing slew rate is almost twice as big as Brystons 4B SST (60V/us) which is twice as powerful as Sigma.
Minimum figures to meet Jung and Pass criterion for audio quality is 65V/us for an amp of 250Watt/4Ohm, 200kHz bandwidth.
As you can see Sigma is fantastic...
Here is the pic of the pcb. I consists of the amplifier, soft start circuit, +-10V PSU, line-in de-balancer and a DC protection circuit for the speaker.
It has been custom designed with copper thickness of 107um (usual pcbs have 17um thick copper).
This is a pic of the +-75V PSU pcb needed for the amp.
The 220V:57V 500VA custom made transformer (more than 4kg in weight) for the 75V PSU and a small one for the 10V PSU.
The heatsink.
The back panel made of plexi, laser cut and engraved.
A simple metal case (also custom made).
The stabilized 75V PSU. 12x4700uF, 35A rectifier...
Populated PCB. The output transistors used are matched Hitachi 2sk1058 and 2sj162 power mosfets.
Both pcbs together, as a mono block.
The two mono blocks finished driving my Dynaudio BM15 speakers.
It can be modified to have a bandwidth of 200kHz and a little nicer phase characteristic by changing the input and output capacitors, but then the stability comes to question.
In this case it makes more sense to use 192kHz converters.
I haven't done any measurements yet, since I have no admittance to the expensive equipment needed. I will post the results as soon as my university starts and the labs open.
Many thanks to Dr. Jagodic for this exceptional design, it truly sounds BEAUTIFUL...
I just wanted to show you all a truly amazing power amp I have been building for the last couple of months, with very good specs...
power.........................225w/4 ohm, 160w/8 ohm
slew rate...................115V/us!!!
freq. response...........10Hz-105kHz (-3dB)
THD............................0.004% 100W RMS/8 ohm
..................................0.008% 180W RMS/8 ohm
..................................0.009% 240W RMS/4 ohm
TIM.............................0.005% 140W RMS/8 ohm (50Hz/7KHz 4:1)
s/n..............................>100dB (100W RMS)
Damping factor............>450 (150W RMS/8 ohm)
It is called "Sigma" and it has been designed by Dr. Borivoje Jagodic from Serbia. Unfortunately, his web site is mainly in serbian http://bas.elitesecurity.org/.
He is a very helpful and understanding person, also an excellent english speaker, you can contact him by mail.
Anyway here is the schematic http://bas.elitesecurity.org/sigmasema.pdf
Its amazing slew rate is almost twice as big as Brystons 4B SST (60V/us) which is twice as powerful as Sigma.
Minimum figures to meet Jung and Pass criterion for audio quality is 65V/us for an amp of 250Watt/4Ohm, 200kHz bandwidth.
As you can see Sigma is fantastic...
Here is the pic of the pcb. I consists of the amplifier, soft start circuit, +-10V PSU, line-in de-balancer and a DC protection circuit for the speaker.
It has been custom designed with copper thickness of 107um (usual pcbs have 17um thick copper).
This is a pic of the +-75V PSU pcb needed for the amp.
The 220V:57V 500VA custom made transformer (more than 4kg in weight) for the 75V PSU and a small one for the 10V PSU.
The heatsink.
The back panel made of plexi, laser cut and engraved.
A simple metal case (also custom made).
The stabilized 75V PSU. 12x4700uF, 35A rectifier...
Populated PCB. The output transistors used are matched Hitachi 2sk1058 and 2sj162 power mosfets.
Both pcbs together, as a mono block.
The two mono blocks finished driving my Dynaudio BM15 speakers.
It can be modified to have a bandwidth of 200kHz and a little nicer phase characteristic by changing the input and output capacitors, but then the stability comes to question.
In this case it makes more sense to use 192kHz converters.
I haven't done any measurements yet, since I have no admittance to the expensive equipment needed. I will post the results as soon as my university starts and the labs open.
Many thanks to Dr. Jagodic for this exceptional design, it truly sounds BEAUTIFUL...