Preamp tube replacement - the manual says "don't"!

[Zoner]

Looking back at the MKIIC manual, I came across an interesting line or 2. I lost one of the original STR415's in my IIC+ and when I was digging around "under the hood" it occurred to me that the preamp tubes in this thing might be 20 years old. There are some ancient looking Tungsram's in there and none of the preamp tubes is a Boogie item. The amp sounds great - and I mean the best I have ever heard for my playing style, and the manual says "Do not replace your Boogie preamp tubes except to remedy a specific problem: regular replacement is not required, except for 6L6's." and "If you play several times a week, your 6L6's (but not your 12ax7's) should be replaced at least once a year for best tone" O.K., but what is the downside of using what look to be really old preamp tubes? The amp is dead silent and as I said, sounds amazing - although we'll see what happens when the replacements for the (original?) STR415's are in there. Are 12ax7's really that durable? Am I missing out on some additional magic using these old tubes? Would this amp have shipped with Boogie tubes originally and what is the best replacement for the European 12ax7's? I think I might look into swapping them out to see what is up since the preamp tubes are (relatively) cheap, but I could use a suggestion from experiences MKIIC+ players. Thanks. Z

 

[Murphy Slaw]

"GOOD" 12ax7's will last for decades.

I would never change a good tube.

Best of luck.

Murph.

 

[stokes]

Dont replace those Tungsrams.If they sound good,just leave them.No Mesa preamp tube will sound as good as a good NOS Tungsram.I have 2 Ampegs with preamp tubes that have been in them since the '60's and are still going strong.

 

[psychodave]

Tungsrams are one of my favorite pre-amp tubes. I use them mostly for the PI in amps...since they have a wonderful depth to them. I say leave them alone. 8)

 

[212Mavguy]

Dont replace those Tungsrams.If they sound good,just leave them.No Mesa preamp tube will sound as good as a good NOS Tungsram.

+1

Please believe what the two previous posters said about Tungsrams, whether the really old British or the relatively newer Hungarian ones, they are a really sweet tube. Takes a HUGE amount of hours before a vintage 12ax7 goes south. Have seen time and time again where a well used vintage tube has sweetest tone in circuit compared to the same tube brand new old stock. Keep the faith in what you have as being special!