I adjust my HCA-750A's bias like you said. I did not have a volt meter at hand, But I did have a indoor/outdoor thermometer from radio shack. Here is what I did. Please tell me if this was sufficient. I let the amp sit for an hour idle. I popped the cover, and put the thermo sensor in between the same center fins in the heat sink. waited for 45 min for the most correct reading I think I would get (by this i waited until the thermometer readout would stay steady within .2 degrees of the same temp for at least 10 minutes. here is what I got. The amp's idle current was produceing each heatsink to idle at about 29 degrees C. give or take .3 offset. I raised the bias and repeated the same steps as above until both heat sinks idled at around 47.1 +/- .2 degrees offset. I put the cover back on. I put the amp back into the system, but it was so late at night that I could not power it up to hear if there was any difference in sound. What d you think- Is this sufficient? What is the class that the amp is running at this point? Thanks for your patience and time!
Sounds ok, so far. You are still operating class A-B 2, but you should now have little or no significant Xover distortion.
So how significant is the improvement in sound that I should hear when i fire it up and do some serious listening tonight and was the initial 29 degrees C too actually degrading my sound all this time? Oh and by the way, I know you said that you receive no royalties for the 750, but your name is printed on the curciut board oddly enough. At any route, the amp has served me well as my first real amp. I have it partnered with the 850 pre. is there anything else that I could do to imrove upon its performance? The other night I was curious to see if my panamax line condition (max 1000+) really had an effect on the sound, so i plugged the 750 right into the wall socket. Well, to my surprise, it sounded so much smoother, on the pc, it sounded much brighter. I had a midrange bloom i thought was not possible from my 6.5's. I was amazed. Needless to say my amp will not be going back onto the max. Is the amp safe being plugged directly into the wall? Sorry for the long post. Thanks again, and if the 750A is simmilar to the design of the 1000A, then kudos to you Mr. Curl!
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