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Re: Help with Atma-sphere MP3 and DC offset

Posted by Lew (A) on May 23, 2005 at 07:55:26

In Reply to: Help with Atma-sphere MP3 and DC offset posted by Manuel on May 23, 2005 at 03:48:13:

If this is happening when you are listening to music, and if there are no nasty sounds coming from your speakers, then the DC offset problem is probably not "dangerous", but it is probably best to resolve the problem. Assuming that the circuitry in your MP3 is working properly, the DC offset light just indicates that the tubes you inserted are too different from one another electrically for the circuit to compensate, thereby leaving a little excess DC voltage. There is no inherent incompatibility problem between Raytheon tubes and the MP3. You just need tubes that are better matched to each other. For example, you may be using "used" tubes where one of the pair or one of the two sections in each tube is near the end of its lifespan. If you have several Raytheons (i.e., more than 2), then you can try experimenting with different combinations until you find a pair that don't light up the warning LED. (I am assuming that you are using the Raytheons in the circlotron output section of the preamp. The DC offset circuitry is monitoring those tubes.) I had a very similar experience with my MP1 and was able to resolve it with the help of a Hickok tube tester to select matched pairs.

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