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Balance cathode biased tubes?

2/2/2001 8:44 AM
Brett	Balance cathode biased tubes? I spent the day tracking down the hum in my amp. I removed the ground loops from the input jacks, that helped a bit. I also regrounded the power transformer, poor mechanical connection now soldered, that also helped a bit. Now it only has a mellow hum and the volume control has little effect on it. I checked the bias current, one tube is at 36.5mA and the other is at 40.5mA. It is cathode biased, how do I even them out? They are 7591A tubes and I am broke so replacing them is not an option right now. Any help is much appreciated. Thanks

2/2/2001 8:44 AM

Brett

Balance cathode biased tubes?

I spent the day tracking down the hum in my amp. I removed the ground loops from the input jacks, that helped a bit. I also regrounded the power transformer, poor mechanical connection now soldered, that also helped a bit. Now it only has a mellow hum and the volume control has little effect on it. I checked the bias current, one tube is at 36.5mA and the other is at 40.5mA. It is cathode biased, how do I even them out? They are 7591A tubes and I am broke so replacing them is not an option right now. Any help is much appreciated.

Thanks

Replies:

greg z Usually a 50ohm hum balance pot ins... -- 2/2/2001 12:53 PM
Shea If your speaker output jacks are gr... -- 2/2/2001 10:22 PM