[Daryl Zero]

So I have my tube integrated, Rogers High Fidelity 65v-2 for my Spatial Audio X5s. It comes with either two KT88s or EL34s. I chose the EL34s because I heard that they have a great midrange sound and I figured since the X5s' subwoofers have their own class D amplifier, I only need to concentrate on the mids and highs.

In triode mode the mids with the EL34s are very full and sound pretty good. But I'm a bit tube curious and research that the KT88s and EL34s are sort of on opposite ends of the spectrum from each other. The KT88s are more powerful but more clean and less tubey whereas the EL34s are more sweet tubey goodness.

I do a bit of research and see that there are two other tubes that work: 6CA7EH and KT77s.

I've spent maybe 70 hours with the EL34s and I haven't heard any real change in they sound.

I've switched to the 6CA7EHs and they sound sort of how I expect KT88s to sound. Much cleaner and the triode mode doesn't sound a ton different than the ultralinear mode.

I'm a bit anxious to hear the KT77s as my research showed that they'd be a mid-point between the EL34s and the KT88s and I think that may be the ultimate sweet spot depending on how much of the mid-sweetness they retain.

However, I'm wondering whether I'm being too ADD (attention deficit disorder) on the whole thing and not giving the tubes a chance to develop since there is so much talk about burn in, etc.

So this is a long winded way to ask whether there actually is tube burn in (I think but I'm not sure that the EL34s from Rogers (Mullard) came with some pre-burn in) and whether I am way too early to judge how any of these tubes really sound? If so, is there a burn in process and how long should they be played or left on in order to achieve their actual selves?

[FullRangeMan]

In triode mode the mids with the EL34s are very full and sound pretty good. But I'm a bit tube curious and research that the KT88s and EL34s are sort of on opposite ends
So this is a long winded way to ask whether there actually is tube burn in (I think but I'm not sure that the EL34s from Rogers (Mullard) came with some pre-burn in) and whether I am way too early to judge how any of these tubes really sound? If so, is there a burn in process and how long should they be played or left on in order to achieve their actual selves?

I doubt Rogers or Mullard had made the initial burn in, so with 70 hours use you already made your amp test pilot and the getters already had being activated and no prob surfaced.

The break-in to sound settlement are greater than 70 hours though.

[opnly bafld]

I have experienced tube burn in just a couple times and the change happened within a few songs.
FWIW, YMMV, etc.

Amplifier run in is another topic. 

[Daryl Zero]

I doubt Rogers or Mullard had made the initial burn in, so with 70 hours use you already made your amp test pilot and the getters already had being activated and no prob surfaced.

The break-in to sound settlement are greater than 70 hours though.

So do you just use the amp normally or do you keep it on all night to get the hours in on them or something else?

[JackD]

If you've got 70 hours on the Mullard's they are broken in and not likely to change anymore.  The Gold Lion KT-77's are a good alternative if you want to try something different. 

[FullRangeMan]

So do you just use the amp normally or do you keep it on all night to get the hours in on them or something else?

Normally, a few hours 3/4 hours in the winter.
Tube amps cant be run around the clock due over heat,
not to mention the electric bill.

[Daryl Zero]

If you've got 70 hours on the Mullard's they are broken in and not likely to change anymore.  The Gold Lion KT-77's are a good alternative if you want to try something different.

They are on deck. I want to give the 6CA7EHs a fair listen prior to "burning in" my thoughts about them.

[SteveFord]

Use it normally, don't leave tube gear running around the clock.
You should have a good idea of how they're going to sound after an hour or two, if there's a weird "glare" to the sound that will be a matter of time to get rid of that.

[I.Greyhound Fan]

Tube burn it is a real thing and varies among tube type in my experience.  I found 6CG7's to take about 30-50 hours.  My 8x6H30's took about 75 hours.  The sound change can be subtle or dramatic.

[Chewbacca]

They certainly change within time, but my experience is mainly with sources and preamps. For me, I've noticed the biggest changes happen within the first hour (maybe 80%), then they seem to settle after 10-20 hours (maybe 95%). To me, after that it's hard to tell. I just run them normally. I never run my tubes overnight, or when they're not playing (maybe besides a small warmup). My battery preamp will die out before the tubes get too hot, so that's my timer

Guitar amps I usually run on standby for about (5) 1 hour sessions after changing them out (Current amp has: 4x 12AX7, 1x 12AT7, & 2x 6N14N (EL84)). Then play lower volume for about another 5-10 hours. Then let them loose into being overdriven after that. New tubes in guitar amps can get ruined without proper break-in. Totally different world though, audiophiles want the smallest distortion possible. With guitarists, distortion is part of the sought after sound.

[Daryl Zero]

If you've got 70 hours on the Mullard's they are broken in and not likely to change anymore.  The Gold Lion KT-77's are a good alternative if you want to try something different.

I'm now on the KT77s and I think they are as advertised, in the middle. I think I'm getting an initial glare as some have described it so I'm going to see if that clears out over time.

[Daryl Zero]

I'm now on the KT77s and I think they are as advertised, in the middle. I think I'm getting an initial glare as some have described it so I'm going to see if that clears out over time.

The KT77s have stayed bright and actually difficult to listen to. I'm back with the EL34s with the rich mid-tones and feel like I've wasted money trying these other two tubes other than the 6CA7s make the amp sound close to a solid state, very clean.

[Les Lammers]

The KT77s have stayed bright and actually difficult to listen to. I'm back with the EL34s with the rich mid-tones and feel like I've wasted money trying these other two tubes other than the 6CA7s make the amp sound close to a solid state, very clean.

Changing/rolling the EF86 tubes in your amp will change the sound. Since you are new to tubes, I suggest contacting a reputable and knowledgeable dealer and discussing EF86 options. Your ears will thank you.

https://www.audiotubes.com/

https://tubeworldexpress.com/

[jazzbo]

I have encountered significant change on some tubes after break-in, burn-in.

I'm currently using two pair of Wathen Speakers "Cryotone" tubes, one a pair of JJ 6SN7 and the other a pair of Russian 615P-EV. The latter seem to "be all they can be" after about 40 hours, the former seemed to take about 100 hours to mature and dispense with a brightness I didn't really like. These are cryogenically treated tubes and I will admit that they sound somewhat transformed as a result from the untreated versions--a bit more depth to the sound stage and an endearing midrange clarity.

[Tom Bombadil]

I have used a good number of new power tubes and even conducted comparisons by buying two sets of tubes and then comparing them after 100 hours vs new in the box.   In both of those comparisons, I heard little to no difference.  In a couple of other instances I perceived slight changes after maybe 20 hours.  No additional change after that. 

I believe that most of the perceived difference is the listener becoming more acclimated to the change in the sound from their previous tubes.  That is say something like substituting new Gold Lion KT77 in for a vintage set of EL34.   The new tubes will have a bit more bite / aggressiveness to them.  But after listening to them for 100 hours, people tend to be more used to that extra energy and perceive that the tubes have mellowed a bit.

[SteveFord]

Today I get to burn in two new Sovtek 6550s in a VTL amp.
One Winged C was doing the snap crackle pop thing so I replaced that and another Winged C wouldn't bias so in go two Sovteks.
A bit of a project setting the bias on 8 tubes in that amp but I got it.
Two hours later, back to the tunes!