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Post by Christopher on Apr 22, 2018 8:50:27 GMT -7
I learned the hard way Friday night that your phase inverter tube matters. My Z-28 was sounding anemic at home and after powering down and back up the volume seemed normal. I decided to gig it Friday and to my surprise when I fired it up it was so quiet wide open you could talk over it. We're talking way past 3-3-3 settings. Knowing this isn't how the amp normally sounds I placed a call to my oldest daughter to bring me a back up before the show started and she carried the dead amp home. This morning I powered it up and no light inside the PI tube. I swapped it out and shazam- the lively response and volume that was absent Friday was there in all it's glorious Z splendor. Hope this helps anyone whose '28 may have intermittent volume issues to check this out first. Lesson learned. And no, I don't carry spare tubes to gigs. They're too fragile for daily transport. I could've used my EH22 caliber w the '28 speaker but this was a five piece band and I wasn't mic'd up but other guitarist was DI into board via his PV30 line out. Needless to say I wanted to hear myself and be heard. The only good news is the new 290DC kicked @$$. I hardly used my pedals bc the guitar sounded so good without them.
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Post by bigben55 on Apr 22, 2018 15:13:23 GMT -7
I always bring a full set of tubes, fuses, and a cheap Joyo American Sound pedal to gigs. That pedal has a cab simulator and can go straight into the pa as an emergency backup. Too much boy scout in me I guess.
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Post by simpleton on Apr 22, 2018 18:00:35 GMT -7
I’ve always carried tubes around too...they fit nice in the Gibson LP case compartment. But at a gig sometimes “trouble shooting” time isn’t available or to chaotic to focus with lights, crowd and stage hands saying hurry up.
tubes are sure impractical with their timing of failure.
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Lesson
Apr 23, 2018 2:22:25 GMT -7
Post by j4gitr (John) on Apr 23, 2018 2:22:25 GMT -7
I’ve always carried tubes around too...they fit nice in the Gibson LP case compartment. But at a gig sometimes “trouble shooting” time isn’t available or to chaotic to focus with lights, crowd and stage hands saying hurry up. tubes are sure impractical with their timing of failure. And dang inconsiderate too. I carry a set set of tubes in a small case with the foam cutouts I purchased just for this purpose, but I also carry a backup amp head.
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Post by bigben55 on Apr 23, 2018 4:40:28 GMT -7
On a gig, I won't troubleshoot. I'll replace all 5 tubes and the fuse and set up the American Sound at a break, ready to plug into the PA. I always buy power tubes in matched quads so I have 2 ready to plug and play. A small flashlight is in there too, with spare cables(gtr and patch), guitar strings and picks, and 2 9v batteries. If all new tubes don't get me back running, that pedal will let me finish the gig. I can swap the tubes and fuses in minutes, no troubleshooting....til I get home. I’ve always carried tubes around too...they fit nice in the Gibson LP case compartment. But at a gig sometimes “trouble shooting” time isn’t available or to chaotic to focus with lights, crowd and stage hands saying hurry up. tubes are sure impractical with their timing of failure.
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Lesson
Apr 23, 2018 4:54:39 GMT -7
Post by TelePrankster on Apr 23, 2018 4:54:39 GMT -7
I don't gig usually, but when I do... I don't like the idea of taking a backup (phisical) amp with me and/or a set of tubes. Most of the times I carry an Atomic Ampli-Firebox with many amp models + cabs loaded into it, in case something fails. It's an amp in a box in a classic pedal format.
I'm not expert when it comes to tubes and I have a question: how do you manage bias settings when changing tubes on the fly with your Z-28? I have a Carmen Ghia which has fixed bias, so I never did anything more than just replacing the tubes. My z-28 was never retubed but I know it's not a fixed bias amp.
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Post by bigben55 on Apr 23, 2018 5:45:30 GMT -7
The Z28 is fixed bias, meaning you have to pull the chassis to adjust the bias pot, impossible to do on the fly. It takes 2 power tubes. I buy 4 matched tubes, use 2, have 2 spares.
I'm not a tech, but what I know is: failed rectifier tube usually blows the fuse. Failed or failing power tubes can too. I've wore out 5 sets of new 6V6s with a Z28 so I kinda know when their about spent. The volume will lessen some, the sparkle will lessen, it'll get mushy, etc. My amp would yield a grating sound as the F#(I think) note degrades. The PI tube can cut volume big time when it's failing, and the EF86 will give you microphonic squeal when it does. It takes longer for the old tubes to cool to the touch than it does to put new ones in. I'd rather play my amp than an amp in a box pedal, so I'll take the time to retube at a set break.
The Joyo pedal is basically a BF Fender amp in a box too. A good $30 insurance plan.
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Post by Christopher on Apr 23, 2018 6:17:14 GMT -7
In ten years of Z usage I've had my share of tube failures but this was my first ever gig failure. No biggie but I don't carry two amps out most days bc my amps are reliable due to great construction, quality components and attention to detail. That said, I'm glad it wasn't anything too big that warranted more time or money.
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