It uses two pairs of MJW3281A/1302A.. They are not super expensive and is available in large
http://www.onsemi.com/pub/Collateral/MJW3281A-D.PDF
50VDC is 120Watt into 8Ohm. It all should give a good low impedance speaker control.
News:
We are starting production of the MIRAND A1 V1.1 as shown on the pictures below.
It is still a reference for what we do of Audio amplifier design.
It uses 1 pair of MJW3281A/1302A. It is rated for no more than 100Watt into 8Ohm and 4Ohm loads. It is stable into 2 ohms load but not for long term uses in 2 Ohms load.
When running as a 50Watt amplifier it can easily drive down to 2 Ohm load.
It is a single ended input Current feedback design. There is only 1 trimmer for BIAS adjustment.
The only thing needed more is to add a power supply and mechanical assembly.
First boards are scheduled to arrive 20.07.18
Amplifier price: 199€/channel + shipping
Pictures below is without the fast on connectors that is mounted on the final version. Second picture is without input capacitor (early version) but for showing how the transistors are assembled. with +/-35VDC in class AB (150mA bias) SK100 150mm is enough cooling.
We are starting production of the MIRAND A1 V1.1 as shown on the pictures below.
It is still a reference for what we do of Audio amplifier design.
It uses 1 pair of MJW3281A/1302A. It is rated for no more than 100Watt into 8Ohm and 4Ohm loads. It is stable into 2 ohms load but not for long term uses in 2 Ohms load.
When running as a 50Watt amplifier it can easily drive down to 2 Ohm load.
It is a single ended input Current feedback design. There is only 1 trimmer for BIAS adjustment.
- Technology: Current feedback with superbuffer output stage.
- Input : SE 10KOhm.
- Output mode: Class A or Class AB depending on bias adjustment, heatsinks and Powersupply voltage.
- Power supply: +/-30VDC to +/-50VDC
- Bandwidth : 1Hz to 800KHz.
- Slewrate : 80V/usec.
- Peak current +/-15APeak
- Protection : Mute circuit and DC protection
- PCB Size: 80x120mm
- Connectors: Faston 6.3mm
- optional input AC coupling capacitor (Mundorf)
The only thing needed more is to add a power supply and mechanical assembly.
First boards are scheduled to arrive 20.07.18
Amplifier price: 199€/channel + shipping
Pictures below is without the fast on connectors that is mounted on the final version. Second picture is without input capacitor (early version) but for showing how the transistors are assembled. with +/-35VDC in class AB (150mA bias) SK100 150mm is enough cooling.
Attachments
Dear DIY Audio Friends.
The Mirand A1 V1.2 is ready.
It is a 4 layer board and this amp is very good sounding and extremely quiet.
What we have done is that we have changed the Size to 120x80mm.
This have made it possible to add the DC and UnderVoltage protection to the amp.
We use Mosfet's with an on resistance of total 7.8mOhm making it possible to use them without heatsinks.
Secondly we have taken the Voltage regulators from the LPS V2.1 to make the +/-15V on the board..
The power supply i would suggest a minimum 300VA 2x24VAC and 2x22000uF
60.000uF and 500 - 600VA 2x32VAC or higher capacitor for an 100Watt amplifier.
It runs from +/-30VDC (1A max idle) to +/-50VDC (max 0.5A idle).. Idle is only suggestions but always take into account the heatsink cooling efficiency.
It can run stable at 100mA if you want to. That is 6 - 10Watt per channel in idle power.
Many options here.
I have attached a screenshot.
So key data:
The Mirand A1 V1.2 is ready.
It is a 4 layer board and this amp is very good sounding and extremely quiet.
What we have done is that we have changed the Size to 120x80mm.
This have made it possible to add the DC and UnderVoltage protection to the amp.
We use Mosfet's with an on resistance of total 7.8mOhm making it possible to use them without heatsinks.
Secondly we have taken the Voltage regulators from the LPS V2.1 to make the +/-15V on the board..
The power supply i would suggest a minimum 300VA 2x24VAC and 2x22000uF
60.000uF and 500 - 600VA 2x32VAC or higher capacitor for an 100Watt amplifier.
It runs from +/-30VDC (1A max idle) to +/-50VDC (max 0.5A idle).. Idle is only suggestions but always take into account the heatsink cooling efficiency.
It can run stable at 100mA if you want to. That is 6 - 10Watt per channel in idle power.
Many options here.
I have attached a screenshot.
So key data:
- Size : 120x80x40mm (LxWxH)
- +/-30 to 50VDC
- 50 - 100Watt @ 8 Ohm.
- 2 Ohm Stable
- Bandwidth : 800KHz
- Only adjustment is bias current, DC servo integrated
- DC and UV protection
- Current feedback
- SE input : 10KOhm
Attachments
Hi updates regarding the usb dac v1.2:
We are today going to send a new revision of the board to production.
We have used a Xilinx cpld to replace LVC logic gates in the version 1.2 and we have seen some artifacts that was not present with the LVC gates. So we have changed the board to use LVC gates and in the same process we have updated the dac to AK4493.
We are still missing to send out dac’s And they have been delayed because of that. They will all recieve the new board.
We are also working on a 99€ dac that is powered by a usb wall plug. The delayed usb dac v1.2 will receive one as gift.
We are today going to send a new revision of the board to production.
We have used a Xilinx cpld to replace LVC logic gates in the version 1.2 and we have seen some artifacts that was not present with the LVC gates. So we have changed the board to use LVC gates and in the same process we have updated the dac to AK4493.
We are still missing to send out dac’s And they have been delayed because of that. They will all recieve the new board.
We are also working on a 99€ dac that is powered by a usb wall plug. The delayed usb dac v1.2 will receive one as gift.
MIRAND A1 V12 specs.
I have attached scope shots.
Measured slew rate is 200V/uSec.
Bandwidth 800KHz.
Distortion at +/-31V and 40Watt into 8 Ohm. <0.01%
Distortion at +/-31V and 80Watt into 4 Ohm. <0.01%
Bias during test : 35mA
total current consumption :100mA
Power disipation : 6,2Watt at +/-31VDC.
DC protection is tested and starts to kick in below 5 Hz. Above it does not limit.
Undervoltage lockout is below +/-21VDC
I have attached scope shots.
Measured slew rate is 200V/uSec.
Bandwidth 800KHz.
Distortion at +/-31V and 40Watt into 8 Ohm. <0.01%
Distortion at +/-31V and 80Watt into 4 Ohm. <0.01%
Bias during test : 35mA
total current consumption :100mA
Power disipation : 6,2Watt at +/-31VDC.
DC protection is tested and starts to kick in below 5 Hz. Above it does not limit.
Undervoltage lockout is below +/-21VDC
Attachments
