QUESTION about Installing "Matched" Tubes

Thanks.  Well, after yogiboy's post I just slammed 'em in there and biased.


Atmosphere, maybe after a listen, tomorrow I'll re-arrange them.


So for each 4 tubes per amp, I just select the transconductance with the closest value number, correct?

Yeah, I'm going to have to take the amp in to the local shop now.
BTW, the sudden loud ripping distortion then silence, amp no longer on, burning smell....does that sound like a fuse?
Would a tube dying suddenly cause that and if so would the tube look obviously burnt or anything?

Hi oldhvymec.   (And others...thank you!)



Yeah, I was wary of that one number being extra high.  That comes from a replacement tube.   I'd bought two matched quads, but one tube turned out to be bad, and I guess that's the best replacement the proprietor could find.


Another thing:  I'm surprised at the nature of the change in sound this brought to my amp. 



Up until how I'd stuck with whatever CJ recommended at the time, which 6 years ago where the modern Tungsol 6550s.   So that's what I'd used until recently.  I started hearing creeping grain/distortion in my system and figured it was likely tubes.   I've had the CJ Premier 12s since the late 90's and never replaced the small input tubes either!   So I figured it was time just in case.  The original were GE tubes, one 5751
two 6FQ7 per amp.


I ordered the Svetlana Winged C 6550 NOS tubes, and wanted to try tube rolling for the input tubes.   Bought these:


5751 super low noise:


http://www.tubeaudiostore.com/57suplownois.html


And these Mazda 6CG7 / 6FQ7:


https://upscaleaudio.com/products/mazda-6cg7-6fq7


My research on the Svetlana Winged C 6550 NOS tubes suggested they had a rep as a linear-sounding tube, tight bass etc, not overly tubey.Which I was kind of going for.


The results have been, first off, a total lack of distortion and grain, so that problem was fixed.  Utterly gorgeous, smooth, velvet texture and tone.


BUT...an increase in the "tubey-quality" - the bass is less defined, bigger, a bit woolier, less air on top, a teeny bit thinner upper midrange.  And most of all a mellowing of dynamics, punch and density.  In effect it now sounds more like a slightly underpowered tube amp - gorgeous in tone, but lacking some drive and aliveness.   That part is a bummer.


So I'm wondering if it's the 6550s or the input tubes changing this character.    I've heard input tubes can change an amp even more than the bigger output tubes.


Thoughts?  (Anyone?)

Well.   My amp just blew.

Sudden loud sound, distortion then silence.   Slight burning smell from amp.   Same amp as the one tube that went bad that I had replaced.


That didn't last long.

Sigh...

Thanks for the input fellas!


The idea of shipping the Premier 12 kills me.  First, I'm not sure I even have a shipping box and these are super heavy.  It would be damned expensive and likely a long time before I got them back.


I'm taking them in to the local shop again to see what they have to say, as the other places I tried were busy.


If it needs more particular care I believe there are some specialty tube amp techs within my city area who, I hope, can do a pretty thorough look over.

atmosphere:  I bought these:

https://www.dougstubes.com/power-tubes/6550-kt88-kt90/svet-winged-c-6550.html

As I understand it, that's a reliable place for tubes and he measured each before they went out to match.   Does that not indicate working tubes to begin with?

Thanks atmosphere.
I'm rolling the dice one more time taking it in to the local shop.  If things fail again I'll have to escalate my efforts.