Mark V "Premium Package" tubes from "thetubestore"

Hi All,

Purchased the "premium package" of tubes for my Mark V from thetubestore 2 months ago.

All seemed fine until my amp blew a fuse. Turned out to be a defective JJ rectifier tube (4U5GB). The person a the tubestore told me that she has rarely seen a rectifier tube cause fuses to blow. They are sending me a replacement.

Also noticed that the SED 6L6GC's sent to me had a rating of 28. Not an expert, but when talking the support person at thetubestore, she commented that this seemed to be a high rating compared to what she's seen for Mesa amps. I was a little surprised as the tubes came from them in the package.

So couple questions:

- Anyone tried this "premium package" from thetubestore? If so, what's been the experience?

- Is a rating of 28 too high for my Mesa Mark V?

- Ended up burning 3 fuses due to this issues, can this damage the amp circuitry or transformer?

thx, Norm

I have never purchased the "Premium Package" from the tube store. I usually do my shopping with Tube Depot. Have never had an issue with them. Mix and match myself.

My SED =C= 6L6GC's from the Tube Depot had a rating of 21 and they have worked perfectly, so I think 28 is a bit high for those.

If your amp keeps blowing fuses, you need to have that checked out. Did that start before you installed these tubes or after?

BTW, I have a Mark IV.

The tube rectifiers coming out these days are crap and prone to arcing over when compared to the old ones, so an out-of-box failure, while unlikely, is not unheard of. It has been my experience that if you get a current rectifier tube that continues to operate properly, after the intial burn-in period, that it will last a long time.

I could also see if you got output tubes that were out of Mesa's window on the hot side that you may have some problems. The Tube Store should have had this figured out by now if you specified your amp to them when you purchased your tubes.

Since I don't own a MK V maybe someone else can chime in: Doesn't the two inner output tubes have a different bias setting than the two outer output tubes for the simul-class operation, and, does Mesa ship the MK V with different color tubes because of this? Just wondering.

- Pat.

shytfayse said:

Since I don't own a MK V maybe someone else can chime in: Doesn't the two inner output tubes have a different bias setting than the two outer output tubes for the simul-class operation, and,does Mesa ship the MK V with different color tubes because of this? Just wondering.

- Pat.

Click to expand...

I bought a Mark V just before Christmas. The four 6L6s in it are all "yellow".

My MKV also came with "YEL" STR-440's.

IME if you are going to use non-Mesa powertubes you need to invest in a bias probe. Right now we are guessing that the issue here is only the rectifier tube, and wondering where those "28" powertubes are biased.

I have a quad of "Mesa graded" JJ E34L's that run at about 60% MPD in my Roadster but in the Class A positions of my MKV they are at 85-90%. If I ran those without checking bias I could of had a tube failure, maybe damaging the amp as well.

A $60-100 investment in a good bias probe is less then/equal to 5% of the price paid for the MKV.

Just my $0.02.....

Dom

Dom,
Which bias probe did you get?
TIA.

DangerMoney said:

Dom,
Which bias probe did you get?
TIA.

Click to expand...

I got mine from Weber, but since Ted Weber has passed away they do not carry them anymore.

This is pretty much the same, except mine is a single socket. This probe will give you the needed info (plate voltage & cathode current) to caculate idle plate dissipation:
http://www.amp-head.com/product_info.php?cPath=21&products_id=70

Dom