toddlgreene
1768 posts
Sep 14, 2010
5:10 AM
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I recently re-tubed my Epi V Jr with a JJ EL84 and 12ax7. I absolutley loved the sound difference they made over the Sovtek/EH tubes that came stock. But, both of the EL84s crapped out on me. Yes, the dealer(Eutrotubes)is aware, and is offering to replace them, and I will send them back. In the meantime, I got to looking around and read some on the RCA 6QB5 gray plates, and found a very sweet price on a pair. Has anyone tried these particular tubes? I haven't received them yet, and also don't know a date of manufacture. Thanks in advance.
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Crescent City Harmonica Club
Todd L Greene, Co-Founder
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LIP RIPPER
304 posts
Sep 14, 2010
7:15 AM
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They interchange with the EL84? I think I have a 6BQ5 left over from a Gibson project.
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TNFrank
32 posts
Sep 14, 2010
7:20 AM
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Long as we're talking tubes:
I've got two matched sets of Audio Classics Russian 5881/6L6GXT's for sale on Evil-Bay. So far no takers but I'm not going to sweat it too much. They're NIB because I sold the amp before I could install em'. I don't think Audio Classics even imports this tube anymore of if it's even made. Either way if/when they sell ya'll can guess what I'll be putting the money into. LOL
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Hohner Harps:
Golden Melody in C(bought in '76)
Blues Band in C(what else,LOL)
Big River in A
Hot Metal harps in G, A, C, D, and E)
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toddlgreene
1770 posts
Sep 14, 2010
7:37 AM
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I don't know if the 6QB5 is a predecessor name or a military designator or what, but if you search for EL84 tubes, you'll find 6QB5 tubes in the same results. I think LJS has used the 6QB5 tubes as well.
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Crescent City Harmonica Club
Todd L Greene, Co-Founder
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barbequebob
1225 posts
Sep 14, 2010
7:41 AM
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EL84 is the European name for them, as is the equivalent of what GZ34 and 5AR4 rectifier tubes are. NOS RCA's are good, but for a Fender amp, I prefer the NOS GE's, and the JJ tubes are basically modeled after them, tho the components are not as heavy duty as the NOS are.
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Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
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barbequebob
1226 posts
Sep 14, 2010
7:47 AM
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EL84 is the European name for them, as is the equivalent of what GZ34 and 5AR4 rectifier tubes are. NOS RCA's are good, but for a Fender amp, I prefer the NOS GE's, and the JJ tubes are basically modeled after them, tho the components are not as heavy duty as the NOS are.
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Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
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toddlgreene
1771 posts
Sep 14, 2010
7:49 AM
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Ditto that, Bob. I got about 2-3 hours of playing time out of each JJ before they crapped out. I plug my Sovtek EL84 back in-no problems(other than it sounds like @%$#).
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Crescent City Harmonica Club
Todd L Greene, Co-Founder
Last Edited by on Sep 14, 2010 8:04 AM
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barbequebob
1228 posts
Sep 14, 2010
7:57 AM
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I've found that the newer stuff being made doesn't last as long as the NOS stuff because unlike when tubes were still being made in the US and Western Europe, the components of the newer stuff is far from military grade, and military grade means heavy duty EVERYTHING from the filaments, the glass, everything, and the only reason why those companies stopped making tubes by 1985 was because their single biggest customer, the military, especially the US military, had all their computers converted from tube to solid state and they already had at the time, a 300 year supply and no musical instrument amplifier comes remotely close to buying that many tubes even if you combined all of them twice over. Watch for the next base closing because that's when you see the next batch available.
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Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
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ridge
93 posts
Sep 14, 2010
8:46 AM
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Bob,
You just need to write a book!
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markdc70
35 posts
Sep 14, 2010
1:47 PM
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Hey Todd, One other thing to check is the plate voltage and watts of dissipation on your power tube. My valve junior came with values high on both accounts; the JJ's may not be able to handle it.
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toddlgreene
1776 posts
Sep 14, 2010
2:25 PM
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Mark-good point. I need to mention that to the guy at Eurotubes. How would you check this voltage, or is it documented somewhere?
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Crescent City Harmonica Club
Todd L Greene, Co-Founder
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walterharp
451 posts
Sep 14, 2010
2:40 PM
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if you don't know how to check tube bias, best to have someone do it for you... can be dangerous business unless you have some electronics experience
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toddlgreene
1777 posts
Sep 14, 2010
2:45 PM
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Sounds like a trip to Randy Landry's house for me-if this continues. I am suspecting the JJ tubes might be a little more senstive or non-tolerant to whatever the hell the plate voltage is in my amp. The Sovtek works fine, without fault. Too bad it sounds like crap. I'm crossing my fingers that theses RCAs will sound good AND last.
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Crescent City Harmonica Club
Todd L Greene, Co-Founder
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walterharp
452 posts
Sep 14, 2010
2:49 PM
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and sometimes just the re-bias can dial in a tube you thought did not sound so great
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toddlgreene
1778 posts
Sep 14, 2010
3:02 PM
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Hmmm...interesting. But that Sovtek is the stock tube. I've played other Epi V jrs, as well. It's a harhsness in the distortion that seems to be an inherent trait of these tubes.
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Crescent City Harmonica Club
Todd L Greene, Co-Founder
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Joe_L
628 posts
Sep 14, 2010
5:13 PM
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I had a set of JJ EL84's in my Pro Jr for a couple of years. I used that amp quite a bit. I had no problems.
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toddlgreene
1780 posts
Sep 15, 2010
4:30 AM
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And I have read mostly great reviews of JJ tubes. They sounded fantastic in this little amp. I'm careful about not moving the amp when the tubes are still hot, and all the other precautions are always taken. I think it's a fluke with the JJs I had- a hairline crack somewhere(none were visible to my eyes)-perhaps incurred during the thousands of miles they have travelled to reach me, as they had the white cloudy halo below the 'chrome' on the tip, indicative of damage to the pins or a crack in the glass. Both of them...hopefully this was just one heck of a coincidence. Again, the Sovtek works fine. I can't imagine the JJs and the Sovtek or any other make of tube would be that different in what plate voltage they accept.
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Crescent City Harmonica Club
Todd L Greene, Co-Founder
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