need help re: groove tube 6L6 please

[boogieslayer]

i had one of my groove tubes out (6L6) ...it has a ceramic center looking pin with a fin on one side that fits inside when the tube is put in...
the arrow in the picture below points to it...the only difference between the picture and mine is mine looks to be alot older...its brown ceramic not black...

the center ceramic cover which just looks to be a guide when inserting the tube has broken off the only thing it looks like its covering is the base of the glass blown tube ( the little tail) i superglued it back on very carefully...will it be ok ?

it doesnt seem like it'd interfere with anything...

is that correct?

And...before i forget lol ive been looking at groove tubes...(6L6
s )
whats the difference between say 6L6 GE and 6L6 chp and 6L6 s
what do the different numbers/letters after the 6L6 mean?
ive been looking on guitar center web site just to get a basic idea and dont get it ..
what would be the best tubes for my mark IIc?...some rock alot of heavy metal...
thanks in advance

 

[stephen sawall]

The center post is only to line up the tube with the right pin spots. You did not need to glue it back in. Just need to make it line up right.

Mesa does very good matching. They have six color codes that all fall within a range of a good spec tube. Mesa needs to keep a tight range as their grid biased amps have a fixed bias and therefore expect a tube plugged into the amp to be a tube that meets design spec as tubes did "in the old days". Their color code is as follows: Red, yellow, green, gray, blue, white. The cross reference to GT stuff is that all the Mesa tubes fall into a GT 4-6 range with red and yellow bing a GT 4, green and gray being at GT 5 and blue and white being a GT 6.

GT would take tubes that had problems such as improper test results from being assembled wrong or whatever, tubes which fell outside design range and put them into their low range (1-3) or high range (8-10) and put something of a marketing twist on things describing that a low tube (weak tube) would break up sooner (of course ... it was a weak tube out of spec) and was best for folks that wanted a strong amp to distort sooner. High number tubes (8-10) were best for clean players, jazz or bass as they stayed clean longer. Unfortunately, these out of spec tubes even when properly biased could and generally would exhibit problems more quickly than a tube that was assembled properly.

On Mesa tubes I prefer the blue and white color codes as they are generally the most close to design spec. of the tube type.

You need to look at this ... Most of the 6l6 stuff is here....

http://www.groovetubes.com/tubes_list.cfm?ObjectGroup_ID=108

 

[boogieslayer]

nice i will check it out

thanks for your help

 

[hectitor]

then, Can I change new tubes between their specs and coloursI I mean, my amp uses mesa red ones, then I can put on it, yellow? green, blue, etc etc? there wont have bias problems??
Sorry Im new in this!!!

 

[MrMarkIII]

[/quote]

then, Can I change new tubes between their specs and coloursI I mean, my amp uses mesa red ones, then I can put on it, yellow? green, blue, etc etc? there wont have bias problems??
Sorry Im new in this!!!

Yes, you may change colours. No bias problems.
The colours are used ONLY to match tubes in pairs. You can use any colour, as long as each pair has the same colour.
If you have an amp with four power tubes, the pairs are separated into an INNER pair and an OUTER pair:
Y - X - X - Y
The outside pair (the Y's) can be a different colour than the inner pair (the X's).

 

[hectitor]

thanks a lot dude!!

 

[gonzo]

steven, that link is broken...


try this one, for the GT rating

http://www.groovetubes.com/gtratingsystem.html

 

[stephen sawall]

steven, that link is broken...


try this one, for the GT rating

http://www.groovetubes.com/gtratingsystem.html

It worked a few months ago when I put it up ..... looks like they have a new web page.

Thanks :mrgreen:

 

[dodger916]

Remember: With fixed-bias Boogies, the LOWER the GT number the LATER the break-up. This is OPPOSITE of what GT posts, as their ratings apply to adjustable bias amps. For further reference, here's a Boogie Board discussion. JOEY B's post at the bottom of Page 1 spells it out. Mesa Red and Yellow tubes have latest break-up (most headroom) and A GT rating of 4, while Mesa Blue and White have the earliest break-up and GT rating of 6. Again, it has to do with the fixed-bias nature of Boogies.

Here's a link to the Groove Tubes Distortion Ratings.

 

[stephen sawall]

Most people like a 8 rating in the Mesa amps, even if a 4/5/6 is in the normal mesa range ..... Mesa's are a bit cold biased.