Metropoulos Forum

my friend just got a brand new pair of gtkt66hp's
he put them in a jtm45 reissue and biased them and found one
was at 30 ma and the other at 36 ma
he aked me what i thought and i said my pair were allmost
identical and after 5 months were only separated by 1.5 ma
i thought they were way to far apart for new. he switched tubes
and the diff. follwed the tube. he emailed g t and myles rose
told him this was ok, and said 10 to 20 % differance was ok
because of all the other matching peramiters that were checked
i was very surprized by this reply i thought these had to be very
close if tubes were matched. i know you had probs with these tubes
what do you think

Not George here, but Mike

A 6 mA difference is not my idea of a 'matched' set so the letters BS in your subject title pretty much say it all. However, that's not to say that tubes that are 6 mA apart won't sound good! The quad of GE 6CA7's I currently have in my plexi are 5 mA apart and they sound awesome! Who knows you might actually appreciate the sound of your KT66's.

Mike

There was a long thread about this at PP. Like everyone else I buy matched sets but do they sound better? Apparently the whole mania behind mathcing tube sets for 'guitar' amps is a more recent thing that started way after plexis had their vogue. There was a lot of people chiming in about their preference for the tone of more unmatched sets vs the more (linear I guess) sound of matching. Obviously thats why hifi wants matched sets. But reading that thread it hit me that there have been times I thought Ive noticed better tone though I was put off by how far off they were. Theres a limit obviously. You cant have one 10mA higher then the rest and watch it cook. But I wouldnt get my panties in a bunch about it either. But it is BS. Better sounding or not they advertise as matched- thats why GT are so damn expensive (the supposed reason anyway) and their not even that! Ive never found GTs to be better matched then any other brand.

yes mr batz that is the point. when i pay the extra bucks
these should be very close in ma. the pair i got when i built
my jtm45 were very close but my friends are 6 ma apart
what the extra money for

They claim that the ma match is not the sole parameter they use. They also check for distortion curves, etc. That all being said, I haven't bought Groove Tube outputs for years. There's just no point in it.

In there ad's from the late 70's early 80's in Guitar Player in the full page ad's they claimed ,"how we go threw 1000's of tubes just to get a matched pair"and give some Rock Star free tubes forever, to say how GRRRR-eat! Asshole Pittman is. Back in the early 80's ALL of these Guys thought there shit didn't stink,would look down at you even in the music stores the pricks thought "They" were rock gods,Thanks God for maken Grunge Musicians and even those Gay Boy bands helped, they took the arrogant grin off many a My Rack dick is bigger than yours, Music Stores and AMP techs.Everbody thought they were the next EVH. Do I sound bitter

I buy whatever sounds best. I dont get crazy if their not matched because unlike what marketing would have you believe, I dont notice a better sound from my amp with tightly matched sets vs loosely matched sets. Whichever brand and type sounds best to me is what I go with and I prefer to not use GT on principal if I can help it. Its not like all other companies arent the same souless cash whores as GT but they arent as blatent anyway.

New Sensor has to have raised the mark for souless cash whores...

Technically, audiophiles get credit for pushing the importance of matching tubes. GT just adapted the idea to guitar amps.

FWIW if you took an old set of tubes out of your favorite sounding vintage amp, chances are you'd be surprized how "matched" they are.

If you pay for "matched" tubes now a days, it reasonable to expect them to be matched within 4-5mA. Otherwise, why pay more for them?
If a vendor claims that they are "good enough" then you make up your own mind.

If you do have a set that are off by several mA, try putting the hotter ones on the PT side of the output section. The phase invertor in Marshall circuits drives the OT side harder. This will help balance performance.

George

You could always use that trick of seperating the junction point of the two V3 plate resistors and put a 10k trimmer between them to balance the two sides, the wiper getting the B+ and the two sides attached to the two ends of the plate resistors.

FWIW if you took an old set of tubes out of your favorite sounding vintage amp, chances are you'd be surprized how "matched" they are.

I don't think the RCA 6V6's in my sorta-TrainWreck amp were within 5mA, more like 7 or 8, and that's supposed to be the pinnacle of the tube construction era. I just don't think they payed that much attention to these things. And I'm sure not gonna pay for a matched set of JJ 6V6's to put in their place.

I've 2mA difference between two output tubes.
i've TAD premium selected tubes.
I don't think these (2,5,10mA) is audible difference.... who knows

Sub

I run my main amp with unmatched SED EL34's which sound better to me than matched. For unmatched, I pull one tube from each matched pair that have different ratings. This way I don't chance getting matched pairs by accident.

Somewhere out there in the internet is a sound check of a bunch of EL34s, current production and NOS. Some of the tests include a pair of different EL34's (some brand paired with a Mullard NOS), and that Mullard with a 6l6. This is a real eye-opener which I suggest listening to.

I believe that match pairs and quads are an effective means of separating more of one's money from their wallet. Perhaps, this is a phase and next year I will think the world of matching power tubes.

Edited to Add: I would describe the unmatch pairs as more singing and 3D sound. Subtle, but there. Beats my match pairs of RFT/Siemens and NOS Telsa. Somebody send me a pair of XF2's so I can prove these are better.