Trial no.01 voltage feedback amplifier for TH500i

10 Feb. 2012 by Thanaporn, 916 views.

My trial no.01 DIY amplifier circuit for TH500-i.
Because of that, I'm building and design my new power amplifier project called TH500-i. It is actually be an integrated amplifier but I would initially design and build the amplifier part first.
It is a 250w per channel power amplifier. Design approach is to bring together the advantages of a voltage-feedback circuitry, and no global-feedback circuitry together.
Therefore, the feedback will be made ​​only in the Voltage Amplifier Stage(VAS). The driver stage and output stage there is no feedback loop whatsoever. In order to reduce the interference and unwanted distortion cause by feedback voltage from the loud speakers.
Design.
The design can be described as follows.
The input stage is composed of a non-complementary differential circuit with cascode circuit to improve linearity. The second stage is a part of VAS consists of a cascode circuit as well. The third and fourth stages are the current driver stages. The fifth is the output stage using a pair of high-speed power transistors from Sanken.

diy amplifier th500i

Construction.
Because of the desire to make it for testing purpose and let see how good it works. I'm hurry up to make it done, so all electronics device pins be directly soldered together. Although it will look cluttered because of
not installed on the PCB. But it works well without any oscillation.
This is what I would like to share now. In fact, I have already created another test circuit, it was really interesting. So, I'll post it later. Thanks for reading.