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Matched pair?

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Kenneth Friis DK
Posted on Friday, April 08, 2005 - 02:23 pm:   

Hi I hope you can help me with a tube question.
One of my friends found some philips El34 tubes in a closed cinema. and has offered me 2 to try in my music man 65 212 combo. the ones currently installed are also El34. I�ve just read the phrase "matched pair" and was wondering if it means that 2 tubes are matched for each other or it means something else?
I�m not shure if I can find two tubes matched for each other, they are packed individually.

Hope you understand my question, and that you can help.
Kind regards
kenneth
Anonymous
Posted on Monday, April 11, 2005 - 01:59 pm:   

Matching is accomplished using a speialized tester. When these amps were built, matching was less of an issue. Since the tubes your friend found is of unknown quality, it may not be all that advantageous to try 'em in your amp.
Sometimes they go BOOM.
Kenneth Friis DK
Posted on Thursday, April 14, 2005 - 10:55 am:   

OK i think I�ll drop it then, not worth the risk..
thanks for the reply:-)
jj
Posted on Friday, April 15, 2005 - 06:36 pm:   

I'm new to tube amps too. If the tubes are not matched is the worst thing that can happen is the tubes will blow?? Will it hurt the amp itself?? OR.. will it just sound bad?? If the tubes are all from the same lot (and tested) are they matched (my guess is no).
Anyone want to set me straight.
michael kaus
Posted on Saturday, April 16, 2005 - 07:14 am:   

Tubes absolutely matched is not really needed. I've run my amps with unmatched tubes on purpose as a n experiment. They seem to sound differant when unmatched. The key is in getting the bias set so that the HOTTEST tube is not pulling too much current. This keeps you from red plating a tube and going into runaway. THAT'S BAD. You should have the tubes matched within 10% though as a rule just for safety's sake. Same batch means nothing. They have to be matched for current draw at a specific WORKING voltage. Mike.