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Post by bigben55 on Dec 15, 2018 10:05:36 GMT -7
How long SHOULD new production 6V6s last in the Z28? Mines a 1x12 combo. I play loud, usually at band levels, either full tilt or edge of breakup, generally with the Brake Lite on 2, and often use a boost/OD, so I know I'm working them hard. I also know the amp was biased by a pro tech this spring, to Dr Z specs. Right now I'm using JJ 6V6S tubes with damper rings. What's the groups experience?
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Post by Christopher on Dec 15, 2018 11:16:30 GMT -7
I give mine a year's tour of service and then retire as backups when playing as often as you mentioned. Unless you hear mush coming out of your amp they're working as intended. You'll notice when they start to go bc the tone gets dull and doesn't have the zip a fresh set does.
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Post by bigben55 on Dec 15, 2018 12:50:51 GMT -7
I'm starting to notice some rattling/vibration that I didnt before. I know JJs "used" to rattle in combos, but was told they changed something in the manufacturing/have the double mica option(mine) to help fix that. Guess this is the start of the need for new ones. I'm sure it's the power tubes(replaced the preamp tubes). The 6V6s have 8 months on them.
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Post by Christopher on Dec 15, 2018 16:15:47 GMT -7
I'm not a fan of JJs from some bad experiences with every tube type they make. Rattle is something all tubes are capable of but if you're finding the 6V6s rattling you can get tube dampers or move on to another pair of matched tubes. I like TADs the best of modern production tubes but to each his own. Make sure they're biased by a tech so you get the best tone. Most preamp tubes will outlive us but EF86s can go microphonic and rattle, too so check that.
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Post by bigben55 on Dec 15, 2018 16:52:55 GMT -7
I just bought 2 NOS EF86s. Both labeled Westinghouse(rebrands for sure). One is Russian, looks like a Winged C, the other says Made in the USA but I cant ID it. Put that in there, nice sounding tube.
With my 1st Z28, I remember going from JJs to Tung Sol Ri 6V6s because the JJs rattled. Great sounding tubes, lasted about 6 months, which sucks. Went thru 3 pairs in 2 years. I scored some RCAs and sold them with that amp.i have emailed Dr Z and he said he designed the Z28 AROUND jj 6V6s! I dont want to tube roll. I buy quads and so I do have two fresh JJs.
They still sound right. They didnt used to rattle, now they do. And I have damper rings on them. Does this mean they're on their way out?
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Post by Christopher on Dec 16, 2018 5:39:49 GMT -7
The rattle may be indicative of the tube internals being loosened up from use. To see if the plates are going bad put amp in a dark room and power it up. Watch the plates for a cherry glow when you take it off standby. That would tell you they're on the way out. Rattle happens even on new tubes as the tolerances for today's tubes aren't as stringent as they used to be. My experience has been if you're going through glass as quickly as you are your amp may be biased too hot. If you love the tone then expect to replace them frequently. I like a little squish on my 6V6s and have used NOS tubes to great effect bc amp gets dirtier faster than with the 6L6-esque JJs. Those bottles tend to make the amp larger and bigger sounding than a 6V6 amp to me. I've had EL84s go bad and it's very noticeable bc the output is junk and the top end goes to crap. I'd do what makes you feel best about your '28. Grab a quad of matched JJs and get your tech to bias your amp with a pair and keep on rocking. Doc knows his circuits and tubes and if he prescribed it there's a great chance it's going to sound spectacular.
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