Phase Linear 700b transistors

Slake

New Around These Parts
Joined
Jul 7, 2025
Messages
6
#1
I have asked a few questions about 700b transistors but forgot to ask if it is possible or necessary to find matched transistors?. I plan on using MJ21196G's and RCA 410's as drivers.

thanks
 

Hexis22

Chief Journeyman
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Dec 28, 2022
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Wisconsin
#2
I have asked a few questions about 700b transistors but forgot to ask if it is possible or necessary to find matched transistors?. I plan on using MJ21196G's and RCA 410's as drivers.

thanks
Although it’s nice to have all output devices from the same lot and matched specs, it’s not necessary as the emitter resistors swamp out component differences and promote current sharing.
 

mlucitt

Veteran and General Yakker
Joined
Jun 24, 2011
Messages
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Jacksonville, FL
#3
According to Joe at White Oak Audio Design, https://www.whiteoakaudio.com/estore.aspx
It used to be a good idea to match the hFE, or Forward Current Gain, of the output transistors to make the amplifier more efficient.
Today, with modern robotic construction, better design, and higher quality materials, the consistency of modern, new power transistors makes gain matching unnecessary.

When I order 100 MJ21169G Output Transistors, they all have the same date code. I spot check the Gain of maybe (10). They are all within one or two units of Gain measurement on my Sencore TF151A Transistor Tester.
 
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