I have an Engl Ironball with EL-84s in the power section. I also have a leftover set of spare power tubes, and I'm curious as to if they would change the amp tone. I don't have the experience nor the tools to adjust the bias, but would it be safe to swap the tubes, fire it up to check quickly and the swap back or do I run a significant risk of damaging the amp?
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Testing EL84 tubes
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Testing EL84 tubes
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1973 Aria 551
1984 Larrivee RS-4 w/ EMG SA/SA/89
1989 Charvel 750 XL w/ DMZ Tone Zone & Air Norton
1990's noname crap-o-caster plywood P/J Bass
1991 Heartfield Elan III w/ DMZ mystery pups
1995 Aria Pro II TA-65
2001 Gibson Les Paul Gothic w/ PG-1 & SH-8Tags: None
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I don't think the risk of ruining the amp is big unless the tubes are bad or really off-spec.
Don't expect them to bias right off the bat, though.
There is a small risk. But at the same time, there is also a risk of the current tubes blowing and taking out a transformer with them if you're really unlucky and something goes catastrophically wrong. Not that it will. It more than like will not. But the risk is always there.
I'd go ahead and pop them, give them a quick try, and then go back to the others.
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Thanks for the input. Did a quick swap - no change in tone, but it seems to have removed some unwanted background whooshing.
It's not self-biasing, at least not according to the user manual. I found the bias pot, but nothing about where to connect the multimeter. Guess I'll take it to a tech.--------------------------------------------------------
1973 Aria 551
1984 Larrivee RS-4 w/ EMG SA/SA/89
1989 Charvel 750 XL w/ DMZ Tone Zone & Air Norton
1990's noname crap-o-caster plywood P/J Bass
1991 Heartfield Elan III w/ DMZ mystery pups
1995 Aria Pro II TA-65
2001 Gibson Les Paul Gothic w/ PG-1 & SH-8
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Originally posted by beaubrummels View PostWouldn't a 20W 2xEL84 amp be cathode biased? There's little to no risk in changing like for like tubes. Don't know if you'll hear a difference in sound.
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Originally posted by Coma View PostI found the bias pot, but nothing about where to connect the multimeter. Guess I'll take it to a tech.
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So after a short chat with someone who actually builds hi-fi tube amps, I decided to put the spare (matched) set in and yeah, seem to be working fine so far.--------------------------------------------------------
1973 Aria 551
1984 Larrivee RS-4 w/ EMG SA/SA/89
1989 Charvel 750 XL w/ DMZ Tone Zone & Air Norton
1990's noname crap-o-caster plywood P/J Bass
1991 Heartfield Elan III w/ DMZ mystery pups
1995 Aria Pro II TA-65
2001 Gibson Les Paul Gothic w/ PG-1 & SH-8
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Originally posted by beaubrummels View PostWouldn't a 20W 2xEL84 amp be cathode biased? There's little to no risk in changing like for like tubes. Don't know if you'll hear a difference in sound.Guitars
Kiesel DC 135, Carvin AE 185, DC 400, DC 127 KOA, DC 127 Quilt Purple, X220C, PRS Custom 24, Washburn USA MG 122 proto , MG 102, MG 120.
Amps PRS Archon 50 head, MT 15, Mesa Subway Rocket, DC-5, Carvin X50B Hot Rod Mod head, Zinky 25watt Blue Velvet combo.
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Originally posted by Rex_Rocker View PostYeah, no. I would not think almost any Metal amp would be cathode biased. There are exceptions, of course, like the Krank Rev Jr. But for the most part, cathode biased and Metal amps are kind of antonyms, LOL.Guitars
Kiesel DC 135, Carvin AE 185, DC 400, DC 127 KOA, DC 127 Quilt Purple, X220C, PRS Custom 24, Washburn USA MG 122 proto , MG 102, MG 120.
Amps PRS Archon 50 head, MT 15, Mesa Subway Rocket, DC-5, Carvin X50B Hot Rod Mod head, Zinky 25watt Blue Velvet combo.
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Originally posted by Ascension View Post
With big bottle amps that is true but not EL84 amps for the most part. Every EL84 powered amp I have owned has been cathode biased. That includes several Vintage series Carvins, a few Boogies,Orange Tiny Terror, my Zinky Blue Velvet and several Jet City amps. Almost all my EL84 amps have been gain monsters, so--.
All of the current generation of Mesa mini heads are non-adjustable fixed bias. The EVH stuff is adjustable fixed bias. The Ironball is too. The Peavey MH's. 95% of the primarily-Metal-focused EL84's kind of are, dare I say.
FWIW, my EVH LBX was louder and held together better than my Krank Rev Jr. (big bottle 5881-powered but cathode-biased). I bet there was more to that than just being cathode vs. fixed bias, but it also did so compared to my Dark Terror (also cathode-biased). That's not to say the EVH held together in a full-band Metal scenario... but it almost did. At least better than the Krank and the Orange.
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