Power Tube Colour Coding

[bucketbot]

As a new UK Mark V owner I thought it would be a good plan to get a complete set of spare tubes in case of any future probs.
I went online to the main UK distributor who offers new tubes for sale & was surprised to find no reference to the colour coding that I have seen frequently mentioned on this site. :?

So I e mailed him & asked why & got this reply:

" The reason there is no colour choice is because all the valves are tested to work within the bias requirements of all Mesa Amps.
The colour coding separates the valves but doesn’t really affect the amp."

Is that right? :?

If so why the colour coding in the first place? :?:

 

[58boogie]

Color codes are just to match tubes within specific ranges (e.g. how many MA they draw), so if you only need to replace one or two power tubes you can match them up.

Some guys swear the different colors make a difference in tone. But the factory and the "experts" say that it has no impact on tone and are just used so the customer can switch out power tubes easily.

Search on color codes, there are other threads on this forum where this is debated back and forth.

 

[bucketbot]

OK, Cool. Prob all I need to know.
So may as well get a full set.
I have a TAD Bias probe for biasing my Carvin amps so can easily measure the exact current myself after swapping them out to check for any large variance.

 

[talltxguy]

Taking your own bias measurements and form your own conclusions is a great idea!

In fact, I would encourage you to not only check out different Mesa output tubes but also try other manufacturers' output tubes - provided you keep that bias probe handy.

Some guys will tell you that running your tubes at 70% of max plate dissipation is the way to go. Others will quote 60% or 50%. I think it is up to you and your ear. The bias probe is good to be careful, but I still think the ears work best.

 

[talltxguy]

Taking your own bias measurements and form your own conclusions is a great idea!

In fact, I would encourage you to not only check out different Mesa output tubes but also try other manufacturers' output tubes - provided you keep that bias probe handy.

Some guys will tell you that running your tubes at 70% of max plate dissipation is the way to go. Others will quote 60% or 50%. I think it is up to you and your ear. The bias probe is good to be careful, but I still think the ears work best.

 

[bucketbot]

Taking your own bias measurements and form your own conclusions is a great idea!

In fact, I would encourage you to not only check out different Mesa output tubes but also try other manufacturers' output tubes - provided you keep that bias probe handy.

Some guys will tell you that running your tubes at 70% of max plate dissipation is the way to go. Others will quote 60% or 50%. I think it is up to you and your ear. The bias probe is good to be careful, but I still think the ears work best.

yeah I may well do some experimenting after a while. I also have 2 Carvin X100B heads, one with JJ6L6GC & one with Winged C EL34, both heads are based to around 70% (Current being around 42 & 36 ma respectively with a variance of less then 2 ma between each tube).
Sounds great! :mrgreen:

 

[dodger916]

Based on current draws, the Reds and Yellows give more headroom while the Whites and Blues have earlier breakup. Following is a link to one of the forum threads. JoeyB's comment at the end of page 1 sums it up: http://forum.grailtone.com/viewtopic.php?f=33&t=39067

 

[bucketbot]

Just out of interest what kinda stock bias current per tube are Mesa fixed Bias amps generally set at?
EL34 & 6L6??

Also what's the average Mark V PLate voltage?

 

[lesterpaul]

this thread has some useful info
http://forum.grailtone.com/viewtopic.php?f=33&t=38013&start=30

 

[bucketbot]

OK, Cool. Prob all I need to know.
So may as well get a full set.
I have a TAD Bias probe for biasing my Carvin amps so can easily measure the exact current myself after swapping them out to check for any large variance.

OK, well I finally got around to doing this & this is what I got:
Values are going from R to L viewed from chassis rear after the Rectifier tube.
Measurements taken with all 3 channels set to 90W mode. Clean channel engaged. All Masters & Output turned down to zero.

V10 26.2 ma Outer
V8 33.6 ma Inner
V9 58.1 ma Inner
V11 35.2 ma Outer

Quite a variance!! Should I be worried? The amp is new & only a month old. :?
Powertubes are 6L6 with Grey bands on bases with writing saying 10AC YEL.

One thing I noticed was if I swapped the tubes around I always got a similarly high reading for v9? :?
Also similar readings for the other 3 slots regardless of which of the 4 tubes I put in?
This type of amp is all new to me so is this normal? :? :?:

 

[dodger916]

OK, Cool. Prob all I need to know.
So may as well get a full set.
I have a TAD Bias probe for biasing my Carvin amps so can easily measure the exact current myself after swapping them out to check for any large variance.

OK, well I finally got around to doing this & this is what I got:
Values are going from R to L viewed from chassis rear after the Rectifier tube.
Measurements taken with all 3 channels set to 90W mode. Clean channel engaged. All Masters & Output turned down to zero.

V10 26.2 ma Outer
V8 33.6 ma Inner
V9 58.1 ma Inner
V11 35.2 ma Outer

Quite a variance!! Should I be worried? The amp is new & only a month old. :?
Powertubes are 6L6 with Grey bands on bases with writing saying 10AC YEL.

One thing I noticed was if I swapped the tubes around I always got a similarly high reading for v9? :?
Also similar readings for the other 3 slots regardless of which of the 4 tubes I put in?
This type of amp is all new to me so is this normal? :? :?:

I doubt that's normal; in fact it seems pretty messed up! As pairs, I would think the outer and inner sockets should be very close.

 

[bucketbot]

OK, Cool. Prob all I need to know.
So may as well get a full set.
I have a TAD Bias probe for biasing my Carvin amps so can easily measure the exact current myself after swapping them out to check for any large variance.

OK, well I finally got around to doing this & this is what I got:
Values are going from R to L viewed from chassis rear after the Rectifier tube.
Measurements taken with all 3 channels set to 90W mode. Clean channel engaged. All Masters & Output turned down to zero.

V10 26.2 ma Outer
V8 33.6 ma Inner
V9 58.1 ma Inner
V11 35.2 ma Outer

Quite a variance!! Should I be worried? The amp is new & only a month old. :?
Powertubes are 6L6 with Grey bands on bases with writing saying 10AC YEL.

One thing I noticed was if I swapped the tubes around I always got a similarly high reading for v9? :?
Also similar readings for the other 3 slots regardless of which of the 4 tubes I put in?
This type of amp is all new to me so is this normal? :? :?:

I doubt that's normal; in fact it seems pretty messed up! As pairs, I would think the outer and inner sockets should be very close.

Of course not normal, this was an old post that was resolved elsewhere. :wink:

http://forum.grailtone.com/viewtopic.php?f=33&t=56312