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Post by Ridgeback on Jun 13, 2019 14:14:17 GMT -7
I was just playing my Z-28 head when a loud crackling showed up. I went over to turn the amp volume down and it had no impact on the volume of the crackling. I'm assuming that it's a tube. I have a spare ef-86, 12AX7, and spare 6V6s, not sure if I have a spare rectifier on hand. Does the fact that the volume knob had no impact on the crackling narrow down which tubes I should swap out first? Thanks.
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Post by "Z" Steve on Jun 13, 2019 15:51:11 GMT -7
I would start with the EF86, then move on to the 12ax7. I would use the pencil or pen to tap the 6V6's to see if one of them is microphonic - that could save you from having to re-bias with the new 6V6's.
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Post by Ridgeback on Jun 14, 2019 6:18:26 GMT -7
Thanks. I plan to put it on the bench today. I'll report results for future reference. It's probably due for a bias check anyway. I don't remember doing that when I bought it a couple of years ago from Mark (Basement Enthusiast) as it sounded fine out of the box.
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Post by Joey Beverages on Jun 14, 2019 8:19:56 GMT -7
Had a similar situation a couple of years ago ..... 6V6 tubes were the culprit.
Hope your '28 is better soon
cheers always
Joel
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Post by Ridgeback on Jun 14, 2019 8:50:33 GMT -7
Mine turned out to be one of the 6V6s also. Fortunately, I've had a lot of 6V6 amps in the past and have a bunch of really nice pairs in the tube stash. Not sure if I'm going to bother removing the chassis to re-bias right away or just play it and see how it sounds first. It's easy to be lazy.
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