Harvex, you don't give much to go on but the most likely problem inside the unit in this case is a bad tube. However, if the problem is on both channels, there may be more to this than a simple tube replacement. It would be quite unusual for both tubes in both channels to fail at the same time unless there are problems in front of the tubes. In that case the most likely culprit would be the power supply which feeds both channels. In the case of power supply problems, youare well advised to let a qualified technician diagnose and repair the problem. There are fatally high voltages inside this pre amp and the under-educated, uncareful person can create more problems than a parts replacement can solve.

12AX7's and 12AT7's are dual triode tubes which have the two parts of the tube used as single components whether individually or in tandem. Therefore the tube can appear to be operating correctly when you first do a visual inspection but still have one side of the tube fail. The first thing to do here is look at the tubes in a darkened room to ensure all tubes and tube parts are in agreement with each other. A tube that appears brighter or dimmer than another would indicate the possiblity of a bad tube. A simple tube replacement would be the next step in that situation. If all the tubes appear to be operating properly, I would suggest you take the unit to a repair shop. I don't remember the layout of this pre amp but I don't easily remember a rectifier tube in the C22. If there is one, it would be in the area of the power transformer and that would be the most likely cause of your problems that could affect both channels.

If you have not done a check on all inputs, that would be another step to try. Disconnect and reconnect your sources to various inputs to make certain you have the same problem on all inputs.

And, certainly the most important step, would be to check the tape monitor function. If you have engaged the tape monitor (or someone not familiar with the pre amp has done so without your knowledge) this would cause the problem you describe.

As to tubes, there are quite a few options in tubes. Find you first whether new tubes are required and proceed from that point forward.

You might be a good candidate for a power conditioner. Also- you might want to get your grounding situation checked out by an electrician as that will cause many equipment issues as well. Bad for computers and other appliances too! Getting a dedicated line for your audio system would help out some of the issues you're getting (and make it sound better usually), although if the electricity is not steady when it hits your main house line there is only so much you can do. Again, some large sized conditioners will go a long way towards fixing the problem for your audio system by basically realigning the power to a steady flow.