- Item: 4-Channel Class AB Power Amp
- Type: SA 2012
- Posted: 17 September 2013
- Builder: martin
- Country: Austria
- Comments: 2
SA 2012
The circuit schematic and the circuit boards for this amp were designed by a friend. He then was so kind to present a whole set of boards as well as several parts and the programmed microcontroller to me! Thanks again astx, very generous! So I had to build this amp. It will be used with an active crossover-preamp combo.
The amp is based on the Texas Instruments LME49830 input stage chip. The output stage is formed by six MOSFETS per channel. Two big 550 VA transformers, MBR40250G 250V/40A Schottky rectifier diodes and two capacitor banks of 80.000µF each form the substantial +72V -72V power supply. The finished amp weighs 35,9kg which is a bit more than 79 pounds.
There is a microcontroller board with a PIC processor for the all the housekeeping functions of the amp. Power-up and stand-by is operated via a relay board. Additionally the microcontroller constantly checks the outputs for DC. There are three thermal sensors located in different positions within the chassis. In case of a fault, the unit would be shut down immediately. The controller board further has connections for the indicator LED`s, provides the muting signal voltage and even offers an RS232 interface for connecting a personal computer.
The amp is build around a central U-channel steel backbone. The transformers and the whole power supply are shielded with soft steel sheet metal components. The steel components are powder coated and have a glossy finish. The power relay board, microcontroller board, ground lift boards and mains filter are located in the lower compartment. There are additional shielded channels at the sides under the capacitor banks. In these channels the input cables and some low voltage cable are routed. This layout made wiring very easy and AC, DC and signal carrying cables are very well separated. This prevents unwanted EMI induction.
When I had finished the parts of the case the anodizing was carried out masterfully by Wulti and astx. Thanks a lot for the hard work, my friends! For the exterior I used inoxidable steel parts in combination with anodized aluminum. The transformer covers may give an optical hint on this fine amp´s sheer power.
The amp is based on the Texas Instruments LME49830 input stage chip. The output stage is formed by six MOSFETS per channel. Two big 550 VA transformers, MBR40250G 250V/40A Schottky rectifier diodes and two capacitor banks of 80.000µF each form the substantial +72V -72V power supply. The finished amp weighs 35,9kg which is a bit more than 79 pounds.
There is a microcontroller board with a PIC processor for the all the housekeeping functions of the amp. Power-up and stand-by is operated via a relay board. Additionally the microcontroller constantly checks the outputs for DC. There are three thermal sensors located in different positions within the chassis. In case of a fault, the unit would be shut down immediately. The controller board further has connections for the indicator LED`s, provides the muting signal voltage and even offers an RS232 interface for connecting a personal computer.
The amp is build around a central U-channel steel backbone. The transformers and the whole power supply are shielded with soft steel sheet metal components. The steel components are powder coated and have a glossy finish. The power relay board, microcontroller board, ground lift boards and mains filter are located in the lower compartment. There are additional shielded channels at the sides under the capacitor banks. In these channels the input cables and some low voltage cable are routed. This layout made wiring very easy and AC, DC and signal carrying cables are very well separated. This prevents unwanted EMI induction.
When I had finished the parts of the case the anodizing was carried out masterfully by Wulti and astx. Thanks a lot for the hard work, my friends! For the exterior I used inoxidable steel parts in combination with anodized aluminum. The transformer covers may give an optical hint on this fine amp´s sheer power.
Comments
- miglio80
- 18 September 2013 at 06:43AM
- Very nice work!
- Alex Tech
- 6 September 2015 at 01:21AM
- I like the design of the amplifier very much. Well put together, eveything I is top quality. How does is sound? And how much ?
Leave a Comment
