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Post by skydog958 on Nov 9, 2006 15:13:52 GMT -7
I was wondering what are the signs of a preamp tube going microphonic. Sometimes I feel my amp feeds back way too easily and often. I was told you check it by tapping the preamp tubes with the amp on to see if it causes ringing and feedback. Is this true? Are there any other signs of microphony?
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Post by texblooz on Nov 9, 2006 16:14:19 GMT -7
Microphonic tubes do feed back easier. Tapping each preamp tube with a pencil will let you know right away which ones are microphonic.
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Post by John on Nov 9, 2006 17:51:22 GMT -7
It can be as bad as what I call tube whistle. You're not playing, the volume on your guitar is off, but your amp is making a sound. Usually a high pitched 'whistle' sound.
And I just tap the preamp tubes with the back of my fingernail. very lightly. If you hear a rattling, perhaps it's time to change it.
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Post by mudskipper on Nov 9, 2006 20:31:57 GMT -7
I was wondering what are the signs of a preamp tube going microphonic. Sometimes I feel my amp feeds back way too easily and often. I was told you check it by tapping the preamp tubes with the amp on to see if it causes ringing and feedback. Is this true? Are there any other signs of microphony? the amp might start to squeal uncontrollably. tapping on the suspected preamp tube is a good test. the first tube in the preamp stage tend to be more microphonic than others anyway, though. some of the microphony is good, IMO. the amp sounds more, um..., "airy" and feels more sensitive to the touch, too. you might also get some scratchy sound as if someone was scratching your speaker cone with a chipstick. hope this helps,
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Post by guitarboy02451 on Nov 15, 2006 18:39:04 GMT -7
Ditto to what Mudskipper and gtrman3 said. Sometimes it can sound as if there is an battle going on inside your amp. I had loud high pitched noises that roll off to a rumble at the tail end.
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Post by Strato on Nov 22, 2006 10:14:51 GMT -7
you might also get some scratchy sound as if someone was scratching your speaker cone with a chipstick. hope this helps, Whoa now... Ive been getting that alot recently. Ussually, i just get a real quiet static sound... like the sound you hear when you arent on a real channel on the TV. But sometimes, I hear the choptick sound. Ussually i hear it right when i turn the amp on from standby. Thats the best ay I have ever hear it explained. Does this indicate a possible microphonic tube? If so, will the pencil test work?
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Post by johnnyl on Nov 22, 2006 12:30:04 GMT -7
That's funny... I hear the chopstick on the speaker thing occasionally too w/ my Ghia. It's mostly after just a few minutes of being on. I can get it to stop by 99% of the time by just wiggling my PI tube.
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