Amplifier Burn In

Hello Everybody,
I have just joined this forum yesterday. Great to be here. Come with a question. Do Semiconductor Amplifier need 'Break In'.
Let me have your replies.
Thanks in advance

Well, I am on my second avr, both yams, i dont think solid state electronics need burn in.

Amplifier burn-in is as controversial a topic as burn-in of any other audio component.

In tubes, a 30 minute warm up is needed for the tubes to be ready to play. But I have not read anywhere about a burn-in for tube amps.

In solid state, the transistors, resistors and other components use low voltage DC current. If a stable power is delivered, they should sound the same as always. Nelson Pass, a legend in amplifier design, says that, during production, his amps are adjusted for bias after about an hour of being on for the first time. This is done over a few days to ensure that the amp sounds the same always. Once it reaches the user, it is ready to be used from the first minute.

Excepting for a warm up requirement, I don't think amps need any burn-in.

Cheers

My amp sounded real grainy for the first 10 hours of play. Then in a weeks time it improved. Thats +1 for break-in

Then i once left my amp on for 15hours ( I fell asleep and the lights didn't go away ) ... and my!! Did it sound sweetly delicious? It was heaven! There was a drastic improvement in SQ . +1 for warm-up

So I am inclined to believe SQ is affected ... so much for theory.

Regards

Since you fell asleep then, are you sure you did not hear those "sweetly delicious" sounds in your dreams?

Just kidding...

Short answer: it depends.

A lot of amps use thermal tracking to set the output stage bias and then, yes, the amps need to reach thermal equilibrium for optimum bias. You will frequently hear some manufacturers mention that their amps should not be switched off, and if switched on, be left on a while to reach full performance.

NP usually runs high bias, so the optimum bias points are probably in the transistor's sweet spots for a long time, and therefore can be 'set and forget'. There will be a minor variation in the bias, but since it is is near optimum range anyway, the changes will be minimal. He uses MOSFETs most of the time, and in almost all cases uses their natural properties to prevent thermal disaster (I think the F5 was an exception, but I can't be sure right now).

For more marginal circuitry, expect the amp to sound a bit better as it warms up, as long as the rest of the chain has the resolution to show it. Class A amps, for example, will typically need very little warmup, tubes need the warmup as filament temperature has a direct correlation to the performance of the tube.

Specific passive components can have long settling times, such as found in high-end systems. I don't like that very much, but that's the way it is - sometimes the performance difference is worth it, and sometimes it isn't. Your ears also need time to get used to tonality of your system as opposed to what you were hearing earlier, and that is also part of the break-in/burn-in process.

Finally, some amplifiers and receivers do not need any burn in at all, they always sound terrible. There are too many variables, there's no single right answer. You are advised to talk to the manufacturer, look at other owner experiences, try it yourself, and reach your own conclusions.

Sincerely thank you guys for your replies.
By the way has anybody done any tests which shows the difference betweeen the units before and after burn in.
I guess this it is more of getting 'familiar and used to' effect.
If there are any such test reports would be glad if someone can share it here with us.
Thanks

Burn in of tubes and SS amps is mainly due to the way the amplification is driven. To me, there are 2 things that need to be at the optimal state : some of these are instantanous and some take a few hours - These are tubes (can feel the sound differences when you start from cold state) and capacitors (cannot feel the difference) even though they go through reactions in order to run at full capacity.

+1 to that.

Ah ha !!! I caught this extremely loaded statement only after I ready Cranky's post a few times.

More than anything else, I firmly believe that it is the human ears that adjust to the sound coming in, more than a system breaking-in. A system's sound stage could change, but I doubt if it for the better. Even if it does change for the better, it will be a very marginal amount within the first few hours.

Whatever warm up adjustments are needed should be complete during the testing phase at the factory itself. I am sure some of the better brands run their systems for a couple of hours at least, and that should be enough.

Someone compared the burn-in of electronics to that of a car. In the days of Ambassador and Fiats, the machining capabilities of the manufacturers were not so good, so the tolerances in the pistons, the crankshaft, and other parts were rough. In a mechanical device, when two parts rub against each other there is wear and tear. In the initial stages, since the fitting and tolerances are low, this actually leads to an improvement with the reduction of friction. But, as the usage increases, the wear and tear actually leads to decay and and a gradually worsening of performance. It is because of this that those manufacturers would recommend gentle usage in the initial stage so that parts fit into each other well and friction get reduced.

Modern cars are a different matter altogether. Using robotised machining, the tolerances are measured in micro millimetres and. a brand new car can be driven and abused without any worry immediately after you drive it out of the showroom. But, with usage, you will only see a worsening of the performance - more noise, lowering of pickup, slight reduction in mileage, etc. You will not see any improvement whatsoever.

Modern solid state electronic circuitry is similar. If designed and manufactured well and tuned properly, using high quality parts, a modern amplifier, barring a few minutes to reach stable state after power on, should perform as well from day one. Whatever improvement we 'hear' could possibly be more psychological and in our heads rather than something that can be measured as coming from the system.

Consider me a skeptic if you want, but all matter decays in time and with usage.

Cheers