tube ratings?

[samgomez141]

hi, i'm new to these forums and have some tube questions. any help would,, help.

i have a 65 deluxe reverb reissue that i bought late 2006. It's my first tube amp and i have a few questions. it died about a week ago because a bad power tube blew the fuse. and i guess it's about time i learned about the tubes, fuses, ect.

- can you use a slow-blow fuse instead of a fastblow in the amp?
- i'm looking for new 6v6 tubes and found these 6v6-R tubes

they have a few options for these because they have ratings:
low 1-3 gt rating, medium 4-7 gt rating, high 8-10 gt rating.


what do these ratings mean and what does that "R" in 6v6-R mean? the power tube i took out of the amp just says 6v6, no R. on some websites i've also seen 6v6-S, 6v6-C. they all have rating options too.

also, people talk about biasing after putting a new power tube in, but my question is, since they're sold in pairs, does that mean that they come pre-biased? or would you have to bias even if you replace both your tubes with the new pair? am i even sure what biasing is? i'd like to do the work myself and not have to take it into a shop; i'm always eager to learn how to do these things myself so i don't need to take my amp in whenever something goes wrong.

hopefully none of this is too complicated for anybody to read. my ADD is acting up and i'm not gonna bother to proof-read.

[Enzo]

Hi
First, 6V6 is a standard tube type, though you might also see 6V6G or 6V6GT. The extra letters on the end that you are seeing are marketing, nothing more. WIthout looking it up, I suspect the 6V6-R means Russia, -S might mean Svetlanas, and -C might mean CHinese or from the Czech republic. This just refers to who made them and the brand. Russian tubes usually means SOvtek, though other tubes are also Russian. Svetlana tubes are also Russian, but it is a more complex story that just that. Czech tubes are JJ brand.

Most of us have brand preferences, but ANY brand 6V6 will work in your amp.

Groove Tube is a marketer of tubes, and for the most part they don't make them. You can look in a Fender amp and see Groove Tube power tubes with their big colorful labels, but look closer and it still has Sovtek printed on the glass under the Groove label. This is not a secret, Groove doesn't pretend these are not SOvtek tubes. Groove sells the fact they test the tubes and "rate" them. For this, they charge higher prices than other brands. I can buy tested and matched tubes for a lot less elsewhere, so I do.

Tubes have a natural variation in performance. Like some apples are a little larger than others, are maybe a little sweeter than others, maybe a little firmer than others, but they all taste like apples, some tubes run a little hotter than others, have a trifle more gain than others, etc, but they still are the type they are. Tube sellers take certain measurements on each tube, and can then match them up with other tubes having similar characteristics. SOme sellers, like Groove Tube, go further than just matching the tubes, they market the various sets as to whether they are naturally a little hotter or less hotter - a little more curent or less current.

This may or may not mean much to you, depending upon how you play your amp and what you are seeking. Hotter tubes are a little easier to break up into distortion. A cat playing laid back jazz is probably not concerned with breaking up his power tubes anyway, and it won't much matter. At the other extreme, someone trying to be Eddie Van Halen will want to break up his tubes. SO purely for help in selling tubes, they made up this ten level grading system. If it matters to you, then look at the descriptions for each grade performance in the marketing literature. That tries to explain which rating would be best for whuch use. To me, the variations in the tube "ratings" comes to the surface the most when the amp is cranked hard, and less so when played more politely. But that is an opinion. Tonal differences between brands will be pretty subtle, about like tonal differences in brands of strings.

ALWAYS use the proper fuse type and rating. SLow and fast blow fuses exist for a reason. When fuses blow, they are not the problem, something else is causing it. Putting slow fuses wheree fast ones belong is defeating the safety the fuse represents.

Bias is something that gets more attention than it needs. It is like tire pressure in your car. There is always some standard for tire pressure, but if the actual pressure is just reasonable close, the car works fine. Matching tubes is like making sure all four tires have the same pressure, whatever that might be. Matched tubes means that when you set the bias current on one of them, the other one should be about the same. With random tubes, unmatched tubes, then the setting for one would not necessarily result in the same current through the other.

Fender recommends 24ma per tube in this amp. That means about 9.5 watts at idle. DOn't worry too much about the numbers yet. SOme guys might like hotter or cooler settings, but you won't go wrong with factory settings. There is no test point on this amp, so you either need a bias probe or know how to read and set bias current.

The tubes will match each other in a set, but one set may not remotely match another. Now here is where Groove marketing kicks in. If you buy some Groove Tubes with a rating of, for example, 6, then at replacement time, another set of rating 6 SHOULD work at the same bias setting. That assumes nothing has drifted in the amp. You SHOULD check bias every time you change tubes. You SHOULD check tire pressure every time you gas up the car. I know, I don't either.

Bias is not really all that critical. There is too cool, and there is too hot. But there is a wide range of perfectly acceptable bias. SOme guys would disagree and tellyou bias has to be EXACTLY this or that. More power to them, I hope their tire pressure is exactly 37.4 pounds. Pretty much if the amp sounds OK, and the innards of the power tubes are not getting red hot, the bias is close enough. I bet if I changed the current a couple milliamps in most guys' amps, they would not notice.

[samgomez141]

thanks a billion. i'm new to these forums and its really cool to know people actually like to help out