Tuesday, September 4, 2007

Time for another post on....MY AMP!

LOL... Righto so this is yet another post on my amp. Well after my amp has been completed and weeks of running in, i decided that something is missing in the sound. Compared to the previous amp that i DIYed, it lacked that musicality i would say. I don't get moved when i listen to this amp although the soundstage and details are alot more better. I thought that it could be my opamp that is different cause i used the AD826 i my previous amp and now im using OPA2134. They are in the different league in terms of pricing. The AD826 costs 9 bucks a piece and the OPA2134 costs 4 bucks a piece. Thats more than 2 times the price. I decided to go for OPA2134 this time around because of design constraints. I wanted my amp to have a high input impedance and by doing calculations, i had to use a opamp that had low input current which lead me to use the OPA2134. Okay so anw, i tried swapping the opamps but cannot la, my DC offset jump to over 20mV which i don't feel all right with. So decided to change back and instead do some biasing for the opamp. Yan recommended me to use LM317L to do the biasing as it "takes out the guess work and works much better than using discrete transistors and gates". So went to get the components from SLS and off i started soldering. Solder solder solder solder... and TADA!
Standing up on my circuit board. Point to point wiring. Art work.

So test was up next and boy was it disappointing. It distorted. Crap. Think think think, then suspect is my power supply to my opamp cause i had this circuit to limit the initial surge to the filter caps for the opamp. It actually also limit the maximum current. Removed it and YAY! good sound. Installed it for both sides and done. Did not listen to it but will do so tomorrow.

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