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Post by roadrunner on Mar 13, 2006 13:45:55 GMT -7
I just had my Maz 18 Jr 2x12's retubed etc. Now when I turn it on I hear this low end hum. Not a buzz, but more of a hum that is pretty noticable. Any ideas? Could it be a bad tube? I can turn on the settings completely off and I still get the hum.
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Post by myles on Mar 13, 2006 14:23:58 GMT -7
I just had my Maz 18 Jr 2x12's retubed etc. Now when I turn it on I hear this low end hum. Not a buzz, but more of a hum that is pretty noticable. Any ideas? Could it be a bad tube? I can turn on the settings completely off and I still get the hum. If there were no other changes it is probably a tube. Try swapping out the phase inverter first. Then move a fresh tube into each of the preamp tube positions one at a time. If you are lucky it will not be output tubes but this is the most likely. What output tubes are you using?
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Post by roadrunner on Mar 13, 2006 14:28:26 GMT -7
Unfortunatly for me, you are speaking over my head! What do you mean by output tubes, and phase inverter? I can tell you that the new tubes are JJ ECC 83S's, and one ECC 81 preamp tubes and JJ EL 84 Power tubes, and JJ GZ 34 rectifier. thanks!
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Post by bluzsteel on Mar 13, 2006 15:54:35 GMT -7
all my Z's have a low em hum , part of the beast I guess. cant hear it when Im playing
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Post by Phil (aka Phil) on Mar 13, 2006 18:12:07 GMT -7
Every time I get this it's due to slightly mismatched power tubes. Sometimes I'm amazed when I use my Weber bias meter on a set of "new" matched EL84's; I've seen some 5ma apart. Some amps like to have 'em *really* closely matched, too.
PDW
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Post by roadrunner on Mar 24, 2006 19:22:10 GMT -7
the low end hum was cause due to a bad power tube. Does anybody else's amp make a somewhat loud hum when turning it on and off of stand by? Mine has done this as long as I can remember, just wondering if this is normal?
thanks
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Post by foxx on Mar 24, 2006 19:45:30 GMT -7
My Mazerati does not make any noise, well sometimes at louder volumes it pops when switched from on to standby, but no hum. Did you change all the power tubes? I believe that you should, unless you can test them to see if they match. I seem to think that I have read about that issue here on the forum. I could be wrong, so you should ask Myles.
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Post by foxx on Mar 24, 2006 19:47:33 GMT -7
P.S. Roadrunner Power tubes and output tubes are the same, just different names. Phase inverter is the pre-amp tube closest to the output tubes.
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Post by roadrunner on Mar 24, 2006 20:47:07 GMT -7
the hum is pretty much gone now that the power tubes have been replaced. I did not do it myself, I took it to a place I trust. They also improved the reverb quite a bit. I'm sure they are matched tubes, they always do good work. I'll have to ask Myles about the hum when turning it on, thanks
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