Amplifier Power tubes - important to sound?

@rel LMFAO...

Curious, I read herein that the feedback level related to the amplifier is important to consider for purposes of evaluating whether it really makes much of a difference to tube roll power tubes. Anyone know why that would be?

Further, I am biamping with mc 901 monos and since the solid state part of it handles the bass drivers maybe power tubes are not that important since it appears it impacts the bass area more so.

But since I love spending so much money on everything audio even the slightest change might be worth considering. Maybe power tubes would impact the mid driver.

@emergingsoul 

Agree with @dogearedaudio - feedback does not free us from the impact of tube rolling on sound. Lessens it some - but never completely gone, in tube land!

Even if those MC 901 push bass frequencies with the SS section (really nice looking amps, btw) - most of the "music" lives in the midrange, and the sonic fingerprints of your components and tube choices will sum up and reveal themselves here. It's not just a matter of raw power; amps each have their own "sound" even when loafing  - but they'll certainly strain and sound more colored when pushed hard, so having more headroom is an asset. 

@immatthewj 

It's not just about producing max power IMO. The parallelization smooths out imperfections in each PP pair, and more importantly gives headroom at lower levels. There is an effortless sense of power, finesse and grip with my larger Master / Statement level VAC amps compared to the Signature 200iQ (to be fair there are other improvements too, besides more PP pairs & power). On a good day, the 200iQ sounded wonderful. On other days, the treble seemed a little aggressive. On others, the bass sounded either a bit lean or too loose / bloated. Even on a "bad" day, the Master and Statement amps will outperform the 200iQ's best days. 

@mulveling

RE: Master II - I misspoke. I meant Signature II. You’d think for as long as I’ve been considering one I would know that. And I do. But my grey matter keeps getting greyer as I throttle down the on-ramp to being an official Geezer. I don’t have an AARP card which means I’m not licensed to fart on airplanes just yet, but I sure do feel my synapses misfiring from time to time. Which frankly often smells the same. This is what I get for not eating all that broccoli as a kid. Which makes it twice I’ve been wrong in as many sentences. But don’t worry, I’m not done being wrong yet. The only reason this whole Internet thing exists is because it feeds off of wrong. It’s what fuels forums like this. Without enough emerging souls to satiate our hunger to be right we’d all starve to death from malvalidation. And I can’t have y’all going starving because then I’d have all the vacuum tubes to myself, which at first blush has many merits. But if you sit with all of it for minute, for long enough anyway, you eventually come to realize there’s a special, irrevocable loneliness that comes with having it all. 

Despite how many tubes I look after, having them all is not why I got into tubes. In fact, it is entirely counter to why and how I became a traveling vacuum tube salesmen. Which, like our friend Kevin at VAC, is not something I ever intended to do. All I really wanted to do was hustle a few tubes to some friends in need to start paying off the mortgage on that pair of mismatched RCA 7025s I bought from the clowns over at TubeDepot. But it happened and when it happened it happened suddenly and it happened without warning. One minute I’m minding my own business, next thing you know I’ve accidentally started a business I need to mind — and I can’t be left alone with old jukeboxes or I’ll give into to the overwhelming urge to tear them apart with my barehands to see what kind of tubes it might have in it. I’ll save you the trouble, the hand injuries and the trips to small claims court: If it’s after the early 1960’s don’t bother. You know why, transistors. And frankly, by default, I don’t hold tubes made after the 1960s with too much regard anyway. But the best mC1s I’ve ever heard came out of a mid 1950s Wurlitzer. That’s the how of it.

The why of it is that I wanted to be an archaeologist as a kid. Maybe I still do, and in a sideways kind of way, tubes scratch that itch for me. Studying them. Knowing them. Being able to determine by the most forensic of evidence who made what for who when. Like someone authenticating a painting by identifying the brush strokes of the master who painted it. That sense of discovery when you find something that was overlooked by generations of people for going on seventy-five years because to them it didn’t matter, it was history not History. Worse, it’s just nostalgia or distortion. I often read sanctimonious comments that preach with righteous vitriol about how buying old vintage gear is just buying nostalgia — like it is some kind of cardinal sin. And why is that inherently bad? Who gets to decide that for everybody else? A bunch of guys with solid state amps, chips on their shoulders and $25K record players? We buy old cars. We play old music. We make grandma’s recipes. We do those things because it helps us connect with and understand where we came from so we can see more clearly who we are and where we need to go. Nostalgia is defined by longing, an unrequited longing for something every rational part of us knows we can’t have while our emotional side finds comfort in anything that brings us closer to being able to have it -– to go back in time. Tubes make for good medicine.

The 12AX7 was born in 1949, just as we turned the corner out of a world war and into a brave new decade that brought with it a nation doubling down on being the greatest. The 1950s were a golden era — definitively, thee golden era for tube production. It was a special time. With the right kind of ears you can hear the same voices that sang along to these tubes sixty or seventy years ago singing along with them today, their voices imbued into every tube from that era. There’s a soundtrack of warmth, sweetness, joy, pride, an optimism that the world was healing and becoming a better place. Sometimes when the music stops playing before the next song begins, listen carefully and you can hear the loud silence of an entire generation sharing a collective awe at the magnificent new technology that brought a unprecedented realism of life to our relationship with the past — photography, film, music – major advancements in recording and playback allowed us to go to new places by providing a way to revisit old places and relive old lives with brilliant fidelity. Never before could we do that. How many are old enough to remember getting their first  color TV? I am, and I remember how much more alive everything felt, how much more connected I felt to what I was watching. I was more alive somehow. Tubes are unique in that they themselves glow with their own life, a life that anyone that sees them cannot help but feel in some way they breathe right back into the music. 

Tubes of this era — the 1950s are just the best, in large part because whoever was making them wanted them to be — and as such, spared no expense in making them. Cheap, efficient, economical weren’t on the menu —yet. Audio tubes are a real a cautionary tale in many ways. They started out at their peak and just started skidding downhill and couldn’t stop as more and more people got to stick their nosy little fingers in the pie to the point that what was supposed to be dessert ended up looking like something that should be exorcised and buried with protective spells in the deepest part of Earth. 

By the 1960s the acronyms began to take over. The MBAs got together and did two things; first those smarty pantsed masters of business started hacking away at tubes to make things more efficient, more economical, last longer, produced quicker, produced using cheaper parts with less labor intensive processes. And they spent just about as much time to doing that bit as they did on calculating just how much their brilliance would equate to on their bonus checks. Because that’s what they cared about, saving the company money, because the more money saved, the more they got paid. They didn’t care that short plates didn’t sound as good as long plates because what sounded good was a bigger bonus. They didn’t care that black plates cooled better and thus were more musical, because the only music then wanted to hear was the sound their checks being cashed made. They didn’t care that welded plates sounded better than rivets because what was most riveting was themselves. Me, my money and I.

And with no one looking, the transistor came along like a daisy cutter and blew everything up. Our minds want to equate progress with better, but it isn’t always that way. Progress just means you’ve moved forward. And forward doesn’t mean better, either. You could move from a turd swamp to a beach or a beach to a turd swamp and both are forward movement, by definition progress. In the chaos and frenzy for something ever newer nobody stopped to ask if it was actually better. And they didn’t notice either when the transistor snatched the life from our music, tucking it away, locked up inside a box which by any other name is a prison. At least Intel told us they did it.

Thanks for reading and have a wonderful day.

@darkblacksmoke 
Lovely, entertaining read! Agree / relate with most of that - though I am a young kid in this hobby (mid 40s) and only caught the tail end of analog tech (film, tape, CRTs) in my youth. Thanks for clarifying on the Signature II. Also don't forgot when they went from those artfully bent square and "D" getters to stamped out halos. Though the structure itself probably has no impact on sound, the earlier square / D getter variants always sound better. Also RIP triple micas and smoked glass :( 

@mulveling 

I agree. Nearly all of my favorite tubes have D-Foil getters. I just found a pair of code matched Valvo 45° Long Plate Getter D-Foil 12AU7 that were sold to me lumped in with a bunch of Bugle Boys because they were labeled Bugle Boys. They are excellent, wonderful tubes. Very simiilar to my Valvo mC2s.

I run GEC Triple Mica Black/Welded/Long Plate A2900s exclusively in my MC275s (both for 12ax7 and 12at7, so 7 per amp) and then I use them as my default tubes in my soon to be upgraded Mc C22 preamp. The GEC A2900 is my hands down favorite tube of all time. Nothing beats it.