2. amps-preamps
  3. 152633-72263

"Matching" of dual triode tubes - how close?

I'd like to understand how matching affects the sound & performance of dual triodes. 6SN7s are of particular interest, but I suppose it could apply to any dual triode. There are several aspects to this question - probably closely related, but maybe not:
1. If a tube is not closely matched - let's say for the sake of discussion that the two triodes are within about 20% of each other, under what conditions will the difference be audible? How will it impact the sound? Frequency response? Extension at the extremes? Imaging? Noise?2. In an exchange of messages on a different forum someone told me that the tube matching wouldn't really make a difference - that is, the tubes he was selling were "close enough for all practical purposes". Is this just an attempt to pass off poorly matched tubes? Or is it true?Thanks,Markus
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Showing 1 response by armstrod

armstrod
602 posts
 
The 6SN7 is my favorite tube, and I've used them extensively in at least 3 different preamps. My experience is matching within 20% is more than enough, but here's something else to consider: some (maybe many?) preamps only use 1 of the 2 triodes for each channel. This true for my current Modwright LS100, confirmed by Dan Wright, who said you could use tubes until they were below nominal for one triode and then swap them and use the other triode. In that case, it wouldn't matter that the triodes in the same tube matched, only that triode 1 of one tube and triode 2 of the other matched, and vice versa.

So the takeaway is I mostly agree with millercarbon. Buy tubes that are close and don't sweat it. And if you buy tubes from private parties, invest in a tube tester. I'm glad I did.
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