GT rated 6's & Mesa grays sound better than 4's & greens

[talltxguy]

I've got a Mesa 295 and was wondering about having adjustable bias put on it. Thought I'd go through a few more tubes before I do.

I had some GT 6L6's rated at 4 & Mesa EL34's rated at green; and the amp sounded good. Guitar Center had some GT 6L6's rated at 6, so I went ahead and threw them into my 295 along with some Mesa EL34's rated at gray. The amp sounded really good.

I haven't even tried Eurotubes' matched set for the 295 but am curious to see how their power tubes compare to my new GT tubes and the gray Mesas. I asked one of the guys at Eurotubes how their Mesa-biased power tubes might compare to a GT power tube rated at 6, and I didn't get a straight answer. Maybe he just didn't know, or maybe he did know and didn't want to admit it? Surely the Eurotubes power tubes, if they were rated like the GT tubes, wouldn't be much more than 6 anyway...right? Maybe 6.2 or 6.3 if that existed?

I'm thinking the 295 was biased a bit more on the warm side compared to some of Mesa's amps? I just can't imagine this amp sounding much better than it does now. :lol: Anyway, I see no need to have adjustable bias put on the amp. Matching higher current tubes to the 295 seems to work well.

 

[dodger916]

There's little difference between the current draw of a Mesa Green versus Mesa Grey. Changing from a GT 4 to a GT 6 should provide a earlier power tube break-up. This is the opposite of what the GT website mentions because they are referring to adjustable bias amps.

 

[stephen sawall]

Mesa vs Groove Tubes scale
Red
4
Yellow
4
Green
5
Gray
5
Blue
6
White
6


There is no such thing as 6.1, 6.2, 6.3 ..... Mesa and GT do not match very accurately. There are vendors that match them a lot closer. A lot of vendors do not even measure as accurate as Mesa and GT. Notice Mesa is fine with a 4~6 range.

There is a range all amps work best in and it is a pretty large range. Where you like it is only a matter of taste. It is a lot bigger than 4,5,6.

A lot of people like a rating of 8 in their Mesa .... it would depend on the model. I would not know what is recommended for your amp.

I have know Bob (the owner) from Eurotubes for years, been to his home several times. He recommends tubes often that are very outside of the range of what Mesa recommends.

He likes amps running a very hot bias and sets up amps that way. I would guess he well recommend something that would be on the GT scale 8 or more. I do not like most amps running as hot as Bob does. It is only taste.

The reason Mesa recommends colder bias is it makes tubes last longer and well cause less problems with amps. Like just about anything else when run hotter it has more problems.

The other thing is as tubes are used the measurement drifts. Even if they are matched perfect in a few months they are often way off. If they are not burned in correct before measuring it means about nothing. Most do not burn in long enough .... in fact most do not burn in at all.

I have a THD Flexi 50 .... it is very easy to adjust the bias on it. Hotter does not always mean a better sound. If too cold it well just be harsh. It effects the sound in many ways and as said above it is only a matter of taste.

There are a lot of different tubes and the bias range is only one variable in the way they sound.

 

[talltxguy]

Appreciate the feedback guys. Eurotubes has always given me great service and great products, which was why I was a bit puzzled by the no-answer thing the last time I called. The guy was friendly but did dodge my question.

Nonetheless, I still plan on trying out some of their JJ's in my 295 when the funds are available.