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Post by Brian on Apr 15, 2010 7:23:28 GMT -7
This will be my first time to retube the Maz. Should I just do the power or should I do all of them? Doesn't have quite the umph it used to. Could the pre amp tubes still be good and I just need to do the power tubes or could the power tubes still be good and I just need to change the pre amp tubes?
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Post by benttop (Steve) on Apr 15, 2010 7:34:14 GMT -7
Think of your tubes in four different categories. Each has its own considerations. 1. Power tubes - they last about 300 hours or so (YMMV), and when they are worn out your amp sounds sterile and weak. A new set will breath new life into your amp. 2. Rectifier - this tube has the least contribution to tone of all of your tubes, but without it, the amp won't work. It's the core of the power supply that powers the rest of the tubes. Generally it either works or doesn't. If yours is working, the only reason you might decide to change it is for a reliability improvement. If you already have a NOS rectifier, do not replace it if it's working! 3. Preamp tubes - these generally last a very long time - decades are not unreasonable. My dad's old 1949 Gibson amp still has its original preamp tubes. Change these for tonality adjustments, and sometimes they do fail or go microphonic. So you address these differently from power tubes. 4. Phase Inverter - this tube looks like one of the preamp tubes, but is situated closest to the power tubes. I separate it out from the preamp because this tube gets a real workout. It drives the power tubes, so it does wear out faster than the other preamp tubes. I think Myles recommends replacing this with every other set of power tubes. Make sure you get one that is matched - this tube actually has two tube circuits inside. If they aren't matched, each side drives at a different level and you get distortion that you don't want. So when it comes to "my amp sounds like poo lately" I start with a power tube replacement. That will bring everything back 99.9% of the time. If most comes back, but we're still a bit off, go for the PI next. Then make tweaks with preamp tubes if desired.
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