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Re: Thanks, Stu.

Sorry I have all my 8417's packed away and I haven't the time to dig them out and examine them (I'm to attend CES this weekend). I would suspect the Philips/ Sylvania tubes have the fewer pins, however. The tube functions are identical, with the exception of the the grid leakage of the GE models. You can tell GE manufactured tubes because they have an acid etched/sand blasted nomenclature on the tube and below that is a braille type dot code.

If you have the the GE modified 8417 from QS the model number decal will state 8417G. The Philips models have no G after the 9417.

Noise from a tube amp is almost impossible to diagnose long distance. If you suspect a tube, simply swap the tubes from one channel to the other, being careful to readjust the bias. You can also remove the input tubes one by one (amp off, starting from the input) and then turn the errant amp on. If it is that tube, then the noise will disappear. Don't bother with the output tubes, but try the swap technique instead.

Check the pins of the output tubes. The tubes have wire leads inserted into the nickel plated octal socket. If the socket shows signs of corrosion ( black corroded patches) take a piece if fine sandpaper, or those green Scotch Brite pads and clean of the black or corroded patches. That can cause noises.

Most if not all of this has been covered in previous posts by various contributors, BTW.

Stu

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