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Discussion in 'Fred's Barcalounge' started by radd, Nov 7, 2019.
When was the last time you bought tubes??
It could also be due to the new tubes being closer in spec to the bias point. All performance tolerances vary. As it's a Class AB amp, a matched set of output tubes should be used. It's an imperfect world, and tubes are 100 year old tech, so there easily could be an issue with the tubes. Glad you had some that worked for you.
ahh 12 months ago
Prices have gone up I see but Doug still has many 12ax7 preamp tubes around $10-15 each
Power tubes are always more expensive but Doug presently has these Sovtek EL84 for only $12.50 . Great price on an excellent power tube.
Different power tubes of the same type (6V6 in this case) can sound different, especially if the amp isn't re-biased when you switch them. But I've NEVER had new power tubes (re-biasing or not) be different enough that I had to adjust my pickups. The amp controls maybe one notch here or there, but never the pickups....
BTW- with that amp under a table like you have it (I have a similar setup), and against a wall, that will increase the bass response.... altho putting on your little riser might help negate that, but amp placement can definitely play a role in low-end frequencies...
Microphonic tube, I have not had a booming one but it is possible microphonic combined with the right resonant frequently and bias could easily been the perfect mix for you issue. I haVe pulled noisy tubes and they have never worked in another amp so I tossed them. My last set of xxx head tubes failed. Turned her on warmed her up hit one big chord and after the initial attack silence! The threw them all out and put in new. Tubes can do some frustrating things at times!
And unless the bias is way way off, I've never seen bias make a big difference like that.
To learn more about tube amps, look for a podcast called The Truth About Vintage Amps. It's related to The Fretboard Journal. Terrific info from a guy who has been fixing tube amps for decades.
Which is why I said...
I deserved that.
I guess I was trying to highlight the extremes. I've swept my bias pot from one extreme to the other and it never made much if any difference in tone.
My last 3 amps were solid state... I'm just saying.
I'm surely digging my Roland Blues Cube Artist... (altho that didn't keep me from buying a Bad Cat soon after )
Love my Roland Blues Cube Stage. However, I have found that my Strat and Tele sound simply glorious through my Princeton Reverb. I think Fender tube amps love single coils.
Something else different with the two new power tubes. I would get occasional crackling that would come and go. That is gone. I gotta think one of, or both, the tubes were bad
In the '50s, most tubes averaged between $5 and $10, with some even cheaper. Tubes were used in all electronics, and were common and available. You could find them at the grocery and drug stores. Now, they're niche items, only used by audiophiles and guitarists. Prices aren't that bad, considering.
yeah agree Bertotti
I've seen bad tubes make all kinds of weird noises that surprised me - buzzes, screams clicks etc. Extreme boomyness is no surprise to me.
Thanks for that! I've been listening and really enjoy it.
Even minor bias adjustments on some amps. A teacher I got a couple lessons from has a Marshall, he was a huge AC/DC fan, so he had whichever Marshall did it for that. But it had no clean headroom at all. I took a meter to it and Cooled off the bias a bit. Not much and honestly I can’t remember how much I changed it but the tone change was dramatic. He was happy because now that doggone Marshall had a very good clean tone and with a bit of Knob tweaking still got his AC/DC break up and more. I just remember it was a very minor change in bias.