Breaking in new tubes, what will change?

[Flevoman]

Hello, 

 

I just bought a (almost) new tube amp. 

The Melody MDA2 with the 2A3 tubes. 

So far it has played for about 20 hours. 

How many hours of break in time need these tubes do you think? 

And what can I expect in terms of sound that will change? (if there will be any changes at all) 

 

Cheers 

 

[jjptkd]

1 hour ago, Flevoman said:

Hello, 

 

I just bought a (almost) new tube amp. 

The Melody MDA2 with the 2A3 tubes. 

So far it has played for about 20 hours. 

How many hours of break in time need these tubes to you think? 

And what can I expect in terms of sound that will change? (if there will be any changes at all) 

 

Cheers 

 

Never had those exact tubes but between my last two Carver tube amps they actually settled in quite nicely over the span of 200-300 hours. They started out just a little bit "bright" or slightly harsh with some material but slowly smoothed out over time. Also with my VTA-20 bass response became noticeably better. 

[Flevoman]

Thank you. 

These are exactly the points that I have some difficulty with now. I hear more detail, more of a 3D sound, perfect.. but the sound as a whole seems to be lifted 1 step more to the bright side . As a result, the bass is thinner and the music  can sound a bit shrill sometimes. But apparently this can still improve . 

[Flevoman]

By setting the bias colder or warmer, can you make the sound less shrill? 

If so. Should you change the bias more towards the cold side or towards the warm side. 

[jjptkd]

13 hours ago, Flevoman said:

By setting the bias colder or warmer, can you make the sound less shrill? 

If so. Should you change the bias more towards the cold side or towards the warm side. 

 

 My Carver 275 had adjustable bias a single point for all tubes factory set at 100 on the meter I read that some prefer less at 80 I experimented and thought that it lost some detail at lower settings I believe I ended up leaving mine around 95? 

 

 The 275 took months to burn in as I didn't really know what to expect if any changes over time at around 100 hours things got more acceptable and I was less concerned with harshness, by 200 hours things were smooth sailing and I was very happy. I did not wait with my new tubes in the VTA-20 I turned that thing on first thing in the morning and ran it all day 12-14 hours for a couple weeks to rush the burn in and it helped but took a little longer about 300 hours to really sound its best. 

[Flevoman]

As you describe it, I hear it myself. 

With a higher bias, the music sounds a bit fuller and more dynamic. 

As far as harshness is concerned, I don't hear much of a difference with a colder or hotter bias. 

But my preference clearly has a hotter bias 

 

I am now on 40 hours of break in time and the music seems to sound a little less sharp. 

The amp sounds very good and I can hear a lot of improvement compared to my other amp, this is only my second amp that I own and I had no idea what to expect. 

But an amplifier can clearly have a lot of influence on the sound. 

[henry4841]

Changing the bias can have a huge impact on the sound. As much as swapping output tubes as many do on this forum. A higher bias does increase the power. Just be sure and not red plate the tubes. With too high a bias the tube plates will develop red spots or glow all over. The plates of the tubes are the largest part in the tube closest to the glass for those that do not know. They should never show any red, hot spots. 

[Flevoman]

Thanks for explaining this. 

In the manual they are talking about 30/35 for bias. 

How hot can I set the bias without causing harm? For example, is 40 really too much or can I try this in a safe way to hear what the audible difference is. 

And the same question for a cold bias. Can I safely set the bias to, for example, 20 to hear what the differences are? 

[TubesGlo]

I wouldn't over think the bias set point. Best practice is to stay with manufacturers specs. They've designed, tested and evaluated the amp to perform best at their recommended setting. Lowering the bias too much will increase distortion, increasing it will run the tubes hotter and out of their comfort zone.

[henry4841]

TubesGlo pretty much said what I was going to say. Stay within the range recommended by the manufacturer. They probably, should have, done all the research on the proper range of bias for their particular amplifier. 

[Flevoman]

OK, understood 👍🏻

[Curious_George]

On 5/27/2022 at 4:46 AM, Flevoman said:

Hello, 

 

I just bought a (almost) new tube amp. 

The Melody MDA2 with the 2A3 tubes. 

So far it has played for about 20 hours. 

How many hours of break in time need these tubes do you think? 

And what can I expect in terms of sound that will change? (if there will be any changes at all) 

 

Cheers 

Unless you can at least measure distortion, it is almost impossible to tell, just by listening, how your tubes are "breaking-in". During break-in the tube elements will expand and contract in cycles until a "natural state" (Chief Bone Head used this term, and I think it is accurate) is achieved. This natural state could reduce distortion or increase it depending on how the other tubes in the circuit also break-in. All the tubes (plate curves) will interact with one another in the circuit, add or subtracting distortion. 

 

I know a lot of people rely on their ears to hear these differences during break-in and in some cases, it is audible, but most times it is not. 

 

 

[KT88]

On 5/27/2022 at 10:46 AM, Flevoman said:

Hello, 

 

I just bought a (almost) new tube amp. 

The Melody MDA2 with the 2A3 tubes. 

So far it has played for about 20 hours. 

How many hours of break in time need these tubes do you think? 

And what can I expect in terms of sound that will change? (if there will be any changes at all) 

 

Cheers 

 

 

If it's a brand new amp then I would also take into account that all the components need to settle in, not just the tubes. Also some capacitors can sound shrill at the beginning and need some time before they sound "round". But if you suspect the tubes, then the small preamp tubes and their change often cause the biggest differences in sound. But I personally just would let it play for several months.
I agree with everyone who mentioned it one should stick to the factory specifications. A too high idle current stresses all components. 

[jimjimbo]

28 minutes ago, KT88 said:

 

If it's a brand new amp then I would also take into account that all the components need to settle in, not just the tubes. Also some capacitors can sound shrill at the beginning and need some time before they sound "round". But if you suspect the tubes, then the small preamp tubes and their change often cause the biggest differences in sound. But I personally just would let it play for several months.
I agree with everyone who mentioned it one should stick to the factory specifications. A too high idle current stresses all components. 

Not so sure I agree about the capacitors "settling in", but otherwise I would say 100 hours or so will be just fine, and agree with the rest of the above post.  Enjoy.

[pnort]

As a retired scientist I wonder about this tube-break-in mythology. Has anyone measured the amplifier spectrum as a tube ages? Not that I imagine that peoples ears get used to an amplifier over time... just asking for a friend.

 

Peace be the journey

[billybob]

May be more a phenomenon. Think you will find most to all believe...

2 hours ago, pnort said:

As a retired scientist I wonder about this tube-break-in mythology. Has anyone measured the amplifier spectrum as a tube ages? Not that I imagine that peoples ears get used to an amplifier over time... just asking for a friend.

 

Peace be the journey

"Go in peace and you will never be out of season"

[seti]

I look at it like this. I put in new tubes or I roll tubes they sound great. If there is breakin they just sound a bit better. When I build a new amp or get a new piece of gear I just let it play for a week without turning it off. That way I know it is stable...