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Post by big ( Al Z. ) on Nov 1, 2023 13:43:28 GMT -7
Hi Everyone!!
I was getting some static sounds out of the Z 28 when turning the treble and bass above the 2 or 3 o’clock positions. So I decided to clean the tube pins by taking them out and cleaning the pins with Radio Shack spray cleaner. When replacing them, I noticed the sound was worse. When lookin at the tubes, it seems that one of the power tubes is no longer working. The tubes are older and the amp has been sitting so it’s not a surprise.
So I need to purchase a matched set of JJ tubes. Will I have to rebind the tubes if I buy the matched set or should I buy a VHT bias tool, and reset the bias???
And where are you buying tubes from?
Thank you - Al Z.
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Post by bubs42 on Nov 1, 2023 14:03:16 GMT -7
You will need to rebias the tubes or at least check them to make sure they are correct. Sometimes you get lucky.
Eurotubes, Doug’s Tubes, Amplified Parts.
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Post by Chilly Gibbons (Todd T.) on Nov 1, 2023 15:04:57 GMT -7
Recommend ordering a matched set of medium rated 6v6s and biasing to 28mA per the Z website. Also, what made you think one tube is bad? Was the filament not lighting up or other? I have good luck with Tube Depot as well as the previous mentions.
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Post by Ridgeback on Nov 1, 2023 15:32:02 GMT -7
My 2 cents. If the bias was set last when you owned the amp, you can probably get a set of medium rated tubes and be fine. If the last biasing was done before you owned the amp, or if you have changed the rectifier, I'd check\set the bias with the new tubes. I've seen some pretty outrageous bias settings on amps I've bought used.
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Post by big ( Al Z. ) on Nov 1, 2023 18:40:34 GMT -7
No lights on the filament. Kind of obvious. Ridgeback - that’s kind of what I was thinking matched set, medium grade I should be ok without a bias. The VHT bias thing is $99 but I may go over to the local music store to see what they charge to bias it when I get new tubes. Plus I need to see if that solves the initial problem.
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