Tubes to replace STR-420 and 7025 12AX7s?

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ibanez4life SZ!
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Tubes to replace STR-420 and 7025 12AX7s?

Post by ibanez4life SZ! » Thu Feb 12, 2009 1:52 am

Hey guys!

So, my two channel dual has been running on these since I got it....sounds like everything I've always wanted.

I recently went to retube the amp with current production 12ax7s, and Ruby 6L6s (identical to the STR-440s, and my amp lost ALL its magic. Sounded like my old 3 channel dual...not good at all :(

So, I went ahead and popped the old tubes back in. Haven't had the chance to fire her back up, but I'm assuming all will be back to normal.

My question...what tubes out there can I get to replace the tubes I have in my amp right now? They're still running, but they're going to go eventually, and the current Mesa tubes apparently aren't doing it for me in this amp....a little surprising for me, as I've always been fine with Mesa tubes, but this is what my ears are telling me.

What's the background on these tubes? The STR-420 is a much smaller bottle than the 440. Where are these tubes made? What should I look for to find something similar?

Thanks much!

Eric
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Re: Tubes to replace STR-420 and 7025 12AX7s?

Post by R_ADKINS80 » Thu Feb 12, 2009 8:05 am

As for the 420's, I'm pretty sure those are Sylvania 6L6's so you might be on the lookout for those. $$$$$ I am not sure what the preamp tubes might be.
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Re: Tubes to replace STR-420 and 7025 12AX7s?

Post by mikey383 » Thu Feb 12, 2009 1:31 pm

The old preamp tubes are Chinese. Not sure what the 420s are, but I don't think they're Sylvanias. I could be wrong though.
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Re: Tubes to replace STR-420 and 7025 12AX7s?

Post by DMTransmutation » Sun Feb 15, 2009 12:28 pm

Don't you need to "burn-in" new power tubes for a few days before they sound right?

I'm sure the tube experts can confirm if I am right or not.
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Re: Tubes to replace STR-420 and 7025 12AX7s?

Post by ANIMATED SUSPENSION » Mon Feb 16, 2009 1:49 pm

DMTransmutation wrote:Don't you need to "burn-in" new power tubes for a few days before they sound right?

I'm sure the tube experts can confirm if I am right or not.
No you don't :D
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Re: Tubes to replace STR-420 and 7025 12AX7s?

Post by ANIMATED SUSPENSION » Mon Feb 16, 2009 1:56 pm

The STR420 is a Chinese tube, great tone but short life usually !! What make are the preamp tubes you bought ?? The Ruby tubes are in spec for use in a Boogie I assume ? Cheap tubes are a waste of money, ALWAYS buy preamp tubes that are tested for high gain and low microphonics, and always buy matched power tubes that are in spec for use in a Mesa amp.
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Re: Tubes to replace STR-420 and 7025 12AX7s?

Post by CoG » Mon Feb 16, 2009 3:46 pm

You don't need to replace the preamp tubes, generally they are good for longer than you'll ever play the amp and it's hard to abuse them in normal usage. You're much more likely to hurt a preamp tube by mucking around tube rolling than by playing it. If you like how the amp sounds, leave 'em. If a preamp tube starts to go you'll know.

Guys also change their power tubes way too often. The only times I have *needed* to change power tubes, it was really obvious to the ear and/or they just stopped working.

So if you don't need to change the preamp tubes, if I were you I'd save that money, and buy the Mesa power tubes. People will have suggestions but we tried a couple different brands of 6L6 in a Roadster and the differences were not significant. EL34s were another matter, I think because they get run hotter and tend to break up more.
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