i found a pair of fender groove tubes glg-c gold series on craigslist for 20 bucks so i had to get them. I have a mesa boogie nomad 55 i was wondering if the tubes in it went out (or just began to sound bad) would i be able to replace the mesa ones in the amp with these? Also the amp itself is self biasing.

thanks,

sosa

Do you mean 6L6 valves? I suspect so.

If I were you, I wouldn't bother paying for Mesa valves which are often poorly matched despite the prices.
Just get a matched pair or quad of 6L6's from somewhere like

http://www.eurotubes.com/

Theres a lot of hype about valves and the supposed benefits of some brands over others. What people like Mesa and GT don't tell you is that they buy exactly the same chinese and eastern european valves everybody else buys, but charges you 200% more for putting their name on them. They don't actually make the valve.

Theres also a lot of nonsense written about certain manufacturers. I've had good and bad valves out of most of them. I think Svetlana are the only ones that have never let me down, but I only bought 4, El34's off them. JJ I've had a couple of bad valves from, but have bought loads of their valves. 12ax7s mostly. So with that in mind, a good reputable seller is well advised. If the valve is bad, they will likely replace it.
2nd hand valves are never a good idea unless you have a tester. I use a couple of old Mullards and a Brimar preamp valves but thats a very different thing to poweramp valves. They either sound right or they don't.

Also get your amp checked anyway. Despite it being self biasing components wear causing problems. It may not be the valves at all.

_________________
No no and no

Hi jsguitar93,

Groove Tubes and Mesa Boogie are the most thoroughly tested tubes on the planet. Most resellers of tubes all use the same make of tubes, but GT and Mesa test their tubes to much higher standards than others, before they label them. You got a good deal on the tubes that you bought, just call Mesa and tell them which tubes and which amp model that you have, and they can tell you whether they are a good match or not. As long as the new tubes are working, and are the same type as the original tubes (ie, both sets are 6L6s), it is OK to put them in and try them, no harm in that, and if they sound good it's fine. I actually use groove tubes in all my amps, and I recently repaired a Mesa amp that had a pair of Winged C 6L6 for the inside pair, and a pair of GT 6L6 for the outside pair, and it sounded fantastic.

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.

Really?

Far more common than Mesa would have you realize.
http://www.amp-fix.com/biasing%5B1%5D.htm

_________________
No no and no

Thanks everyone so much for the help i really appreciate it. i do plenty of amp repair on my own and have gone through my fair share of fine feeling electric shocks if you know what i mean. So i was just wondering if i was just deciding to change the tubes for just the reason of trying them out and turn out liking them and want to leave them in, would the auto bias not be enough? and if its not sufficient would i be able to manuel bias by bypassing the auto bias. Not to sure how this auto bias system works I personally was a huge love of the manuel bias pot and biasing solder joint check on the fender deville lol so simple just a turn and you can get it just right lol.

thanks alot.

jsguitar93, do you have the schematics for your Mesa amp? In order to modify the bias circuit, it would be much easier if you have the correct schematics. You wouldn't bypass anything, but you would change the circuit components depending on how your amp is biased (ie, grid biased or Cathode biased). The Mesa amps are usually very accepting of the GTs in the 4-7 rating range (white label), they are a close match to the Mesa tubes. Even if the GTs are a different number rating, like the red (8-10) or blue (1-3) they should still work fine in your amp. A quick call to Mesa will verify which tubes are a good match, they have nothing against GTs in their amps. If you try the GTs and like the sound, that's good enough, no problem leaving them in there. As long as your new tubes don't red-plate (Plates glowing red), they should be fine. Don't mistake the orange filament glow for red-plating.

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.

alright i will try them thanks for the help i really appreciate it. They are in fact level 8 rating so we shall see what happens do you have any other advice? ill watch the plates and catch em before they explode hopefully lol.

I seriously doubt if the tubes will red-plate, but visually checking newly installed tubes is a good habit to get into. The "8" is a red label, late breakup tube and should be fine in your amp.

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.