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devbro
08-14-2007, 08:07 AM
When someone says a pair of tubes is matched, I assume this means they have put them in an amp and measured bias voltage of both and the readings are fairly close, say within 5 MV.

Can tubes be matched on a tester or any means other than an amp?
Blue Strat
08-14-2007, 08:34 AM
Don't assume anything unless they tell you exactly how they "matched" the tubes. Ebay proves this time and time again. Sometimes it means that it's the same tube type and brand (eg, RCA 6L6GC), other times it's a test reading on a tester that doesn't measure plate current (this is very often the case), sometimes it means plate current at low plate voltage (400 Volts is a reasonable, "amp like" plate voltage) and sometimes it's measured on a tester like a Maxi Matcher (www.maximatcher.com (http://www.maximatcher.com)).

ASK!
devbro
08-14-2007, 08:48 AM
Mike,
You nailed it. The guy says they're matched so I asked him how he determined they were a match and his response was his tester. I'm sure glad I asked.

thanks..........
Blue Strat
08-14-2007, 09:04 AM
Consulting bill sent :D
Old Tele man
08-14-2007, 10:24 AM
FWIW--Ted Weber will be soon introducing a DIY-KIT "matcher-testor"
Blue Strat
08-14-2007, 11:00 AM
FWIW--Ted Weber will be soon introducing a DIY-KIT "matcher-testor"

Cool. Got any details?
John Phillips
08-14-2007, 11:57 AM
I really should get around to converting one of the many dead amp chassis in my garage into one...

For guitar amp purposes, it probably only really matters that the plate current is matched at a typical amp plate voltage and bias voltage. You could match other parameters too, but it would really only be important if you were trying to eliminate distortion :).
Old Tele man
08-14-2007, 12:42 PM
...this was Ted's reply to the forum question "Ted, Tell me more about the Tube Matcher" that was posted 03-Aug-07:

"I keep adding features, but it will have adjustable screen and plate voltages, then the bias can be set to view the plate current. It's not going to be a drug store emissions tester, the user will have to know what screen and plate voltages to dial in.

It is also going to test preamp tubes for gain and noise (microphonics)." ...Ted Weber
Blue Strat
08-14-2007, 12:59 PM
but it would really only be important if you were trying to eliminate distortion :).

Who ever does THAT?!?!?!?!? :FM:dude
Blue Strat
08-14-2007, 05:00 PM
...this was Ted's reply to the forum question "Ted, Tell me more about the Tube Matcher" that was posted 03-Aug-07:

"I keep adding features, but it will have adjustable screen and plate voltages, then the bias can be set to view the plate current. It's not going to be a drug store emissions tester, the user will have to know what screen and plate voltages to dial in.

It is also going to test preamp tubes for gain and noise (microphonics)." ...Ted Weber

Can we look forward to lead paint or a fishy odor? :rotflmao
Old Tele man
08-14-2007, 05:12 PM
Can we look forward to lead paint of a fishy odor? :rotflmao...lead paint = CHINA, fishy odor = TAIWANESE
Blue Strat
08-14-2007, 05:51 PM
...lead paint = CHINA, fishy odor = TAIWANESE
I was trying to draw a parallel with the poisoned fish we've been getting from our good friends in China. ;)
Hipster Dofus
08-14-2007, 08:30 PM
Matched tubes do not stay matched in all cases. Just because they are when new means nothing after hard use....

If this is wrong, then why?
Blue Strat
08-14-2007, 08:36 PM
Matched tubes do not stay matched in all cases. Just because they are when new means nothing after hard use....

If this is wrong, then why?

Yes, they do drift over time. Burning them in for 24 hours before matching minimizes drift.