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How can these be "matched" power tubes

86.10.108.253
Posted on November 3, 2009 at 05:10:12
The Decameron
Audiophile

Posts: 28
Location: UK
Joined: February 18, 2006
 I ordered two "matched quads" of output tubes from a reputable source selling through eBay. The package arrived and inside were 8 'unmarked' boxes containing 8 'unmarked' tubes.
Any other time I have paid a premium for 'matched' tubes, they carried markings to demonstrate this had been done.
Also if what I bought were two matched quads all packed together and unmarked, how can I tell which are members of each 'matched quad'? Maybe I have bought a magic matched octet instead! all eight tubes matched to each other? What do people think?

How can we know & help?, posted on November 3, 2009 at 06:16:11
Allen Wright
Manufacturer

Posts: 4729
Location: Schaffhausen
Joined: January 31, 2002
 You have to ask the seller.

Regards, Allen

RE: How can these be "matched" power tubes, posted on November 3, 2009 at 06:02:43
Neff
 Eight matched tubes must have been sorted out of 50 or likely more tubes. Perhaps matched means same date codes from this vendor? I find matched to be unscientific statement without actual readings at the audio system operating voltage.

When I sell (rarely sell) matched tubes, readings are posted on each tube and numbered in pairs only even if a quad or more was sold.

RE: How can these be "matched" power tubes, posted on November 3, 2009 at 13:00:24
Michael Samra
Dealer

Posts: 13108
Location: saginaw michigan
Joined: January 30, 2005
Contributor
  Since: June 24, 2005
 Neff
Excellent points. There are so many opinions that formulate matching and many are so silly,you wonder how they get away with it..I match the way you do and basically thats putting the tube under dynamic conditions and that way you know how the tube will operate.
I like to match with voltage and current of identical types as the emission or transconductance is usually pretty close when the plate and control grid voltage is the same and the setting of the bias pot is the same as the other.
If the power supply waveform isn't pretty,neither is the sound in most cases.

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