Blowing Tubes

[OscrDGrch]

About 9 months ago, I had my Groove Tubes Soul-o 75 tuned by a local amp tech. This included replacing the entire tube complement with new types (EI 12AX7EG & GT 6L6-GE #7) and biasing. The amp came back sounding more hi-fi in the clean channel, which was what I wanted.

Since then I have blown through two duets of the 6L6s. Is there anything I can do as a relative non-techie to troubleshoot this problem? Thanks in advance for any assistance you can provide.

Cheers,
McE

[bob-i]

About 9 months ago, I had my Groove Tubes Soul-o 75 tuned by a local amp tech. This included replacing the entire tube complement with new types (EI 12AX7EG & GT 6L6-GE #7) and biasing. The amp came back sounding more hi-fi in the clean channel, which was what I wanted.

Since then I have blown through two duets of the 6L6s. Is there anything I can do as a relative non-techie to troubleshoot this problem? Thanks in advance for any assistance you can provide.

Cheers,
McE

Sounds like they're biased too hot. Get it back to the tech for adjustment.

[OscrDGrch]

Sounds like they're biased too hot. Get it back to the tech for adjustment.

Makes sense. Thanks!

[Grimace]

Are you running in class A or A/B? I have one of those amps, and it goes through cheap tubes like breath mints. I have had luck with NOS 6L6s, they last a long time. But I prefer EL34s in it. I use russian EL34s, like the new Mullards, and they do not last a long time in Class A/gnarly mode.

That amp puts a ton of voltage on the plates, make sure the amp tech took that into account. If he just set it by looking at current flow, they could end up running a bit hot.

Run the amp in Class A/B and have it biased slightly on the cool side to have the tubes last longest.

[slider313]

I would stay away from the Groove Tubes,first as they are higher priced than most and, second they are not any better than the brands that are out there. Marketing hype; IMHO. Go with either a set of SED's or JJ 6L6GC's.

[OscrDGrch]

I'm running the amp primarily in Class A/B. But trying different tubes like Grimace and slider313 mentioned is a good idea.

[Johnny Z]

I test and my own tubes and service my own amps and I like Ruby 6L6GCMSTR tubes. I wasn't sure I would like them at first but they have held their own in my "hottley biased" Reverend Hellhound with a fixed bias setting. Way better than the original EH tubes held up, I play serious Jazz and need a clean sound, I think they sound better too.

[Johnny Z]

I would stay away from the Groove Tubes,first as they are higher priced than most and, second they are not any better than the brands that are out there. Marketing hype; IMHO. Go with either a set of SED's or JJ 6L6GC's.

Hype! How true, I'm glad someone besides me feels that way, no offence to Aspen, he's just a damn good salesman. :nono

[KevinOConnor]

Hi Guys!

You could change the 470-1W screen resistors to 1k-1W flame-proofs. This will protect the tubes and allow use of any grade. It is not high-voltage killing the tubes it is screen-over-heating. Aspen copied Fender's mistake here.

[OscrDGrch]

Thanks again gents. I'll take it to the amp tech with this information.

Cheers,
McE