I added a note to the end of the 6AS7 “Purpleheart” SET amplifier page concerning power tube variability and their use in this amp.
Anyone considering building this amplifier should read the note at the bottom of the page. It’s nothing serious. I just wanted to call attention to one of the idiosyncrasies of using power supply pass element tubes in audio amplifiers.
Matt, on some songs I did notice a slightly lower volume in the right channel on mid to high frequencies. I put the blame on likely poor soldering or something I did or didn’t do. After reading your supplement I changed out the 6080 for a 6n13s (I don’t have a 6as7 yet). I have 2 of these but the first one I tried levelled things out. I think the bass is slightly lighter but there was plenty to start with. The mids and highs are great with both tubes.
Do you find that it is easier to get 6080 tubes than 6AS7 ones?
There do seem to be many more 6080 tubes on the market than 6AS7s. However, my experience has been that if they are not NOS the buyer needs to be wary. There are a lot of “used” 6080 tubes on the resale market which have been overstressed in power supply applications. These are in many cases not suitable for audio. So when I buy 6080 type tubes I attempt to get assurances that they are truly NOS and that the seller takes returns.