2. amps-preamps
  3. 1185461401

Do tubes "burn in"?

My preamp (octal tubes; cathode-follower outputs) came with two NOS RCA 12SN7GT tubes and I really like the sound I get. Just for grins I picked up a slightly used pair of GE 12SX7GT (U) JAN tubes (Canada) to try. Straight off they were more prolific in the bass and more golden in the mids and highs. I enjoyed these attributes. But the more I listened, the more I noticed the vocals were pushed further forward and the clarity was missing in the mids (vocals, saxophone) when compared to the 12SN7's. I disliked these attributes. The 12SN7's seem to be more evenly balanced throughout. My questions are: Do tubes "burn in" and improve with use? And, can the negative (for me) attributes I described for the 12SX7's improve with burn in (better clarity, less emphasized vocals)?
rockadanny

Showing 1 response by hagtech

hagtech
176 posts
 
I've found that tubes don't really benefit much from burn-in. The first few hours might have a slight bump up in emission, but otherwise they don't seem to change much. And like the other guys said, it's a long road downhill from there. Fortunately, this can be very slow.

You'll hear much more effect by removing the tube and plugging it back in. In other words, cleaned contacts are significant.

jh
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