Bias Readings in Mesa Roadster w/ 3 sets of 6L6's

[jenksdrummer]

Mesa STR-440 "10 AC GRY". These are the stock tubes that came with this amp...(readings gathered from Weber Bias Probe and my cheapie radioshack DMM, amp settings of course identical for each test...)

1: 39.6

2: 47.7

3: 33.8

4: 36.2

 

As you can see, not very matched at all...I'm a bit surprised by this as Mesa denies warranty claims if you use anything but Mesa tubes with this level of mis-match (wonder if they've heard of the Magnuson-Moss Act? (http://en.wikipedia.org/wiki/Magnuson%E2%80%93Moss_Warranty_Act - specifically under Requirements, last paragraph of the wiki article)

 

 

Next: Ruby 6L6GCMSTR. Purchased from Lord Valve, with special request that they be more geared towards Mesa product line. Of note, these are identical tubes to the stock tubes...just with a Ruby label rather than a Mesa one. I was disappointed when I bought these because they were identical, and I put the stocks back in after checking the bias...

 

1: 28.6

2: 29.4

3: 28.1

4: 29.4

 

Better matched, but pretty cold with an average of 28.9. Given the baseline for the stock tubes is an average of 39.3, these are significantly colder.

 

 

Next up, GT 6L6-GE "7"

 

1: 32.6

2: 35.3

3: 34.8

4: 32.7

 

Given GT's horrible reputation for mismatched tubes, these aren't that bad. 33.8 average, still colder than the stock tubes, but at least they're better matched.

 

In a few days, another set of Ruby 6L6GCMSTR's will be coming in from Musician's Friend...so they'll be "Ruby Matched"...I'm curious how they'll stack up compared to a known tube vendors matching (and higher pricing), as well as see if they trend towards a warmer bias...closer to stock.