I bought a Chinese imitation KSA5 headphone amplifier. The static current of the final power transistor of this amplifier is 100mA each. The radiator is small, and the heat is serious. The temperature is very unstable. It cannot be used normally. The structure of the original machine can no longer add a radiator. I decided to design a new KSA5 PCB with the layout of the traditional power amplifier. A new radiator is large enough, and the temperature is stable, The static current of the final power transistor is enough to reach the ideal Class A amplifier. I only use the all-aluminum chassis. The power transistors, regulated power supply power transistors and temperature feedback current transistors used are all installed on the same large heat sink. This heat sink is directly installed on the aluminum base plate of the chassis, which can maximize the heat dissipation of the all-aluminum chassis. The chassis and heat sink have arrived, and PCB design has begun.
The following photo is the original KSA5 headphone amplifier I bought. My newly designed headphone amplifier also uses the same chassis.
Try my mods to KSA-5 - maybe you don't need a new PCB and that big heatsink. Modded KSA-5 runs much cooler yet performs better.
Or look here - someone already made a PCB with all output transistors lined up along its edge. Have not tried that one, though, so no promises.
Or look here - someone already made a PCB with all output transistors lined up along its edge. Have not tried that one, though, so no promises.
Hi alexcp,Your KSA5 is very good. I designed the new KSA5 PCB to be produced in small quantities for my friends who like listening to earphones. So I still want to design the KSA5 according to my own idea. The heatsink has arrived, and the volume is a little large. I am worried that the regulated power supply cannot be placed on the amplification PCB, so the regulated power supply part decided to be placed in the power supply cell, so I found a small heatsink
for the regulated power supply.
I first designed the power circuit. I separated the power PCB from the amplifier PCB, so the power PCB was also designed as a PCB independently. I can't find the original circuit diagram of the Krell KSA5 for the time being. When debugging the China clone KSA5 two years ago, I used SIGMA22 power supply, which had poor results. China clone power supply is a traditional and simple regulated power supply, and now it works well, So I still use the power supply to design the circuit diagram. The data available from the original version of krell KSA5 power supply is ± 21V. Many forum articles say that it is better to reduce the sound quality to ± 19V. I still consider using the original version of KSA5 power supply to design first, and then compare it with ± 19V. The circuit diagram has been designed, and parts have been purchased to design and manufacture PCB.
The main components are placed in the power grid space of the chassis. It seems that the space is very compact. The regulated power supply board needs to be stacked two pieces to be placed in the chassis
