Thanks very much about your support!
Thanhs Sir! Before I smell smoke...
I share my update corrected PCB here after, with two option: original and alternative (2SA970 -2SC2240 replace 2N5401 - 2N5551) for anyone like it.Attachments
No you have done a mistake somewhere recheck it again
offset is ok but that should be constant enough whether there is input signal or not
This leads to distortion in LF and slightly may be in HF
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pre-drivers have virtually no effect on output offset. Except if you blow up one of the pre-drivers. That would affect the output offset.
Yeah. Thanks Vitor too! I checked datasheet of TO-92, most BCxxx and 2Nxxxx is C-B-E, or E-B-C (simple reverser side). And most 2S Japanese transistors is E-C-B. So, I try first to build with 2S and BC transistor. If I have more time, I'll repair my mistaken PCB posted. Today, I check carefully one by one component and hope it no more errors. Sorry because my limited English, hard to describe my thinking to be write understandability (I only read is better).viktor also said that you should pay attention to a TO92 transistor pin-outs too. Man,viktor said soo much...
I add variable input capacitor, a couple 0.1uF bypass in parrapell with decoupler el-cap pair, multiturn trimmer for higher quality option. And resistor 2.2k // with bias adjusment trimmer set for safer.
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my opinion is negative of C6 - negative feedback dc isolation connect with ground (better is same input audio ground) in all of shematic I saw. In my PCB, I make that too. However, waiting for an answer' author is best.
