Tube Amp Questions

[DucksEliminated]

I have a question. I have been running a Fender Super Champ XD for about 5 years on the same set of tubes. I have played a few very small live gigs were it got pushed very hard. I have never replaced the tubes on it since i bought it. I havent had one blow on my yet, is there any reason to change them? If so, how often do you guys change your tubes on your amp? If you have this amp, what tubes do you recommend putting in? I hardly ever gig with it unless were doing a very small gig. I use it mainly for jamming at home, so it gets used ALOT.

[telex76]

You really should have a spare set of tubes just in case.
Get a spare set of JJ's, you could change the tubes to see if you hear a difference.
If it sounds better keep the new ones in, save old set for spares.
If you can't tell a difference in sound, leave whichever set in you wish and have the other for spare.

[richey88]

I'm about 5 yrs on mine with the stock tubers too......just gigged it (I use a 2x12 cab w/ mine for gigs, never get past 5 on Ch. 1) last month, sounded awesome! I don't gig so much anymore, but probably should look into a new set.

[6942]

You'll start losing volume and bass response, when your tubes are starting to expire.

[t-luxe]

If you swap the power tubes, you'll need to re-bias. Wouldn't be a bad idea to check the bias anyway if you haven't ever done so. The XD's were famous for being biased too cold from the factory.

http://www.archive.agileguitarforum.....php?tid=11815

[DucksEliminated]

Originally Posted by t-luxe

If you swap the power tubes, you'll need to re-bias. Wouldn't be a bad idea to check the bias anyway if you haven't ever done so. The XD's were famous for being biased too cold from the factory.

http://www.archive.agileguitarforum.....php?tid=11815

How would a guy know if this needs to be done? I have never heard of this before.

[Frodebro]

I have a Peavey Classic 50/50 rackmount power amp that I bought new in 1995 or so, and it still has the original power tubes in it. They have tons of hours on them, including a bit of cranked to the max time, but overall they haven't worked all that hard (that amp gets LOUD), and it still sounds really good. New tubes would probably be a noticeable difference, but since it still sounds good I have no intention of changing them out. Plus, eight EL84s is going to be a bit on the pricey side...

[gndboy]

As a thumb rule, if you play your amp like six hours per day, six days per week, the power tubes should become suspect somewhere between twelve and eighteen months. Thumb rule. Obviously, if you play hard or the amp is in a hot environment, the longevity of tubes will be impacted. This is for power (output) tubes. Generally, non-power tubes will last a lot longer, even longer than you.

If your amp is fixed bias and has an adjustment potentiometer, I suggest a totally dark room. Find the nominal value for the grid bias voltage from a service manual or schematic or wherever, and use a VOM to set it roughly. Adjust the bias potentiometer such that the power tube plates just no longer glow. Do this in a totally lightless room. That will put you pretty close to the sweet spot. If the plates glow it will sound great but the tubes will not last. Just no more plate glow, and you're there.

[t-luxe]

Originally Posted by DucksEliminated

How would a guy know if this needs to be done? I have never heard of this before.

The bias is basically like the idle speed on your car, it sets the "idle speed" of the power tubes.
Fixed-bias amps(like your XD) require re-biasing when you change the power tubes. If you follow the link I posted it will give you the instructrions on how to do it yourself. If you're not knowledgable on tube amp safety, you'll need to take it to a tech. There can be potentially lethal voltages present even with the amp unplugged.
If the amp still sounds lively and responsive, you're probably OK with the old tubes. If you change power tubes, you'll have to figure in the cost of re-biasing the amp unless if you can do it yourself.

[BobbyZ]

I don't know what part of North Dakota your in Ducks but you might want to learn how to to your own biasing.
In a state with only one area code techs are few and far between.

Shoot last Sunday night I drove from Sidney Montana down to Beach ND then over to Fargo. Didn't see one tech the whole way. (well it was kind'a dark)

[Hiker]

No.

Go for a minimum of one spare of each tube type. Some people prefer a matched set (spares) for the power section (6V6). Just don't fall into the trap of paying a premium for a matched set (if you can help it).

[DucksEliminated]

Originally Posted by BobbyZ

I don't know what part of North Dakota your in Ducks but you might want to learn how to to your own biasing.
In a state with only one area code techs are few and far between.

Shoot last Sunday night I drove from Sidney Montana down to Beach ND then over to Fargo. Didn't see one tech the whole way. (well it was kind'a dark)

No joke man, Its 70 mile to the closest city of any significance...I think i can figure it out, T-Luxe posted that link as well.

[klast]

Originally Posted by DucksEliminated

I have a question. I have been running a Fender Super Champ XD for about 5 years on the same set of tubes. I have played a few very small live gigs were it got pushed very hard. I have never replaced the tubes on it since i bought it. I havent had one blow on my yet, is there any reason to change them? If so, how often do you guys change your tubes on your amp? If you have this amp, what tubes do you recommend putting in? I hardly ever gig with it unless were doing a very small gig. I use it mainly for jamming at home, so it gets used ALOT.

I may be wrong, but I think this amp doesn't wear out tubes in the same way as a conventional tube amp since it is hybrid digital/solid state/tube amp. At least that seems to apply to the Vox Valvetronix amps, the tube of which lasts very long.
So, unless you notice that it starts to sound bad, no need to replace the tubes.

Klas