Mr. Nelson Pass on Amp break-in

[anilva]

Someone asked Mr. Nelson Pass:

"A question. For how long should the amp be
broke in? For the breaking in period, should I play music continuously, or
is it better to turn the amp off for about an hour once a day?"

His reply:

"Thank you, and I have an answer:

I have no idea. Hi Fi equipment seems to settle into a good state over time,
but there is no decisive evidence as to whether it is the equipment or the
listener."

- Cheers

 

[josephjohnt]

Cant say anything more to it Period. :lol:

 

[gopib]

True of all things audio....and maybe even others.....

 

[doors666]

mechanical parts require break in, electronic parts dont. speakers do, amps dont.

 

[GeorgeO]

That's put very welll!

 

[deba]

Mr Pass is completely right, there is no evidence that electronic components will perform better when burned for few days. It is actually the listener whose ear adjusts to the equipments output.

A very simple way to test is to play your favourite audio CD in a different set of Amplifier and speaker and most people will not like it at the beginning but go on listening and after few days you will like it very much.

This is because every amp and speaker combo has its own sound signature which you dont like at the beginning but turns out to be great after few days of listening.

Audio is very subjective since you cannot see it or touch itbut have to feel it .and this subject of feeling is very complicated and debatable.this is the area where most manufacturers play with our hard earned money !!

 

[askii2]

Break-in only applies to equipment with moving parts - speakers, automobiles .
Semiconductors, resistors, capacitors don't require it.

Transformers don't require any break-in, so they "sound" the same, although they "smell" different on first and second days :lol:

 

[Hari Iyer]

Amplifiers when turned on initially will deliver instantaneous power which may be higher than the rated RMS power. After all the components in the amplifier have heated and arrived at the steady state it will deliver continous power which will be less than the instantaneous power. This is true about all amplifiers even when the amplifer is new or old. Hence you would realise that when you turn on your amplifier initially the output will be more and after some time when the steady state of the amplifier is reached the output will become slightly less. This is some kind of a break-in i would say but it happens every time you turn on the amplifier unlike a car.

Cheers,

 

[Hari Iyer]

This is also one of the reason that all good quality stereo amplifier will always quote the continous RMS power of the amplifier and not the Max power. The Max power of the amplifier is the instantaneous power when you turn on the amplifier and the continous RMS power is the steady state power after the initial heat build up.

Cheers,

 

[omishra]

Break-in only applies to equipment with moving parts - speakers, automobiles .

Transformers don't require any break-in, so they "sound" the same, although they "smell" different on first and second days :lol:

+1, agreed

Semiconductors, resistors, capacitors don't require it.

I keep different opinion here. Forgive me for below lecture.

Semiconductors are prepared by doping impurities in pure Carbon, silicon and germanium have a unique property in their electron structure -- each has four electrons in its outer orbit. These impurities each molecule either create one additional electron (n-type) or deficiency of one electron (p-type) material. This is unstable state, offers electric conduction under specific condition. Over the time material tries to get into balanced/stable state. With the time passing, heat and electron conduction make it happen. That's why new transistors' characteristics differ after used for some time.

Electrolyte caps and ceramic caps change property due change into there dielectric properties. Chemical in electrolyte caps dries, getting used (if not leaked). That's why they have life span wrt temperature of use condition. (At room temp. ~25 years). If temperature increased then life decreases. At 85 degree Celsius most electrolytic caps die after ~2000-3000 hrs.

Ceramic looses its internal molecular structure due to AC through it. This means they change minor values.

Now tell me if burn-in happens or not? Its like a car engine. if its life span is 2 Lac KM then performance increases till first 1 Lac KM and decreases further remaining 1 Lac KM. ( conditions apply)

So the burn-in happens.

 

[cricfansd]

+1, agreed


I keep different opinion here. Forgive me for below lecture.

Semiconductors are prepared by doping impurities in pure Carbon, silicon and germanium have a unique property in their electron structure -- each has four electrons in its outer orbit. These impurities each molecule either create one additional electron (n-type) or deficiency of one electron (p-type) material. This is unstable state, offers electric conduction under specific condition. Over the time material tries to get into balanced/stable state. With the time passing, heat and electron conduction make it happen. That's why new transistors' characteristics differ after used for some time.

This phenomenon happens with in microseconds as soon as you apply bias at the p-n junction. There is no time variant steady state etc. If someone designs a circuit which gets to a linear state after the temperature increases in the semiconductor it is a REALLY bad design.

Now tell me if burn-in happens or not? Its like a car engine. if its life span is 2 Lac KM then performance increases till first 1 Lac KM and decreases further remaining 1 Lac KM. ( conditions apply)

So the burn-in happens.

This is a completely mechanical process. The engine becomes less efficient as time goes by due to deposits, mechanical wearing down of the moving parts etc. This is why you need frequent tune-ups. Electrical burn-in is only valid for tube amps not for solid state.

 

[omishra]

This phenomenon happens with in microseconds as soon as you apply bias at the p-n junction. There is no time variant steady state etc. If someone designs a circuit which gets to a linear state after the temperature increases in the semiconductor it is a REALLY bad design.

+1, But Sirjee over the time this pn juction show change of forward resistance. In Datasheet, there values are always defined as 3 columns Max, Min & (typical) where that typical is average one which we consider in circuit design. These are not only manufacturing tolerances. You can measure it yourself. I found hfe changing from 750 to 630 within couple of months time.

For caps, its sure they change values, (capacitance decreases over time)

This is a completely mechanical process. The engine becomes less efficient as time goes by due to deposits, mechanical wearing down of the moving parts etc. This is why you need frequent tune-ups.

That is why there is line "conditions apply" in my statement

Electrical burn-in is only valid for tube amps not for solid state.

Why not for solid amps? I noticed & measured MOSFET, HEXFET and BJT before & after 3 months usage in circuit. Our general thought is - never open a working circuit. For my current stereo amp, I build 2 mono blocks each after 6 months gap. I found earlier one was sounding nice and new one is muddy. I kept matched pair of MOSFETs. There I desoldered and measured the parameters again because on same bias current older one was running cooler than new one.

 

[cricfansd]

+1, But Sirjee over the time this pn juction show change of forward resistance. In Datasheet, there values are always defined as 3 columns Max, Min & (typical) where that typical is average one which we consider in circuit design. These are not only manufacturing tolerances. You can measure it yourself. I found hfe changing from 750 to 630 within couple of months time.

For caps, its sure they change values, (capacitance decreases over time)

That is why there is line "conditions apply" in my statement

That is the device level variation as wafers cannot be identical. There is a band gap carrier lifetime which changes over time but T_l is much higher than couple of months time. This is not the right forum but if you are interested you are welcome to read chapter 5 of "Semiconductor Power Devices: Physics, Characteristics, Reliability". It talks about what you are describing but the time variant nature of devices are much higher otherwise most circuits will be useless after few months/years.

 

[sonosphere]

Hi,
I guess the burn-in phenomenon of amps is a mix of both reasons, i.e change in electronics circuit's performance, and the listener's ability to hear "refinements", after a period of time.

Electronics example: In early days when music synthesizer were made primarily out of analog circuits, they used to lose frequency-tuning after some day/months, similar changes were observed in behavior of "oscillators" and "filters" that created textures in sound (this happened with ALL companies... not a specific model related issue). Frequency drift in those synths is an obvious and measurable difference.... nothing to do with listener hearing refinements. So I wouldn't be surprised if sonic character of an analog amp changes over time.

Listener's ability example: Really long ago, when music of Boney M was my first exposure to HiFi recordings... I used to hear same tracks on two different systems, and the only difference i could make out between them is that the "bigger" one could be driven louder without hurting ears. At moderate volumes they sounded same to me. After sometime I started discovering some sounds in the bigger one that the smaller system didn't reproduce.

The two factors above probably combine to create the burn-in improvement impression in amps.

Regds,

 

[omishra]

That is the device level variation as wafers cannot be identical. There is a band gap carrier lifetime which changes over time but T_l is much higher than couple of months time. This is not the right forum but if you are interested you are welcome to read chapter 5 of "Semiconductor Power Devices: Physics, Characteristics, Reliability". It talks about what you are describing but the time variant nature of devices are much higher otherwise most circuits will be useless after few months/years.

No problem buddy! No offense in either way. I don't want to read physics (left since graduated in 1994). My first love of Electronics still keeps me busy. Since I have background of MW/Satellite signal experience, it may not completely fit to audio electronics. Anyway thanks for hard discussion which is refreshing and reminded those days. BTW, it also reminded me that my PHD is pending for this subject.

 

[captrajesh]

Disclaimer: No offenses to anybody and pun is unintentional.

Even Nelson Pass seems to be unsure of his statement but many of our learned FMs are categorical in their statements.

 

[Hiten]

There must be a reason why Mr. Nelson Pass

said what he said.

Replacing caps on 10/20 years old amps is common practice. So logic tells us components do change over time. Now question is how much they change over 1/2 months compared to 20 years ? And can we notice the change in SQ in that period ?
Regards

 

[cricfansd]

Disclaimer: No offenses to anybody and pun is unintentional.

Even Nelson Pass seems to be unsure of his statement but many of our learned FMs are categorical in their statements.

May be some of us do have the credentials and the experience to talk It is agreed upon that component's characteristics change over time but it needs a long time not 100 or so hours mentioned in the reviews etc and not often for the good.

 

[captrajesh]

May be some of us do have the credentials and the experience to talk It is agreed upon that component's characteristics change over time but it needs a long time not 100 or so hours mentioned in the reviews etc and not often for the good.

Though it is proven that human mind can conjure up imaginative things based on specific situations, quantum physics is still a very active field of research and the atom has not yet been understood fully. So 'break-in' might not be an imaginative thing after all.


Talking of my personal experience in the past one and half years, I've made several changes in my system. I purchased a new CDP, replaced several capacitors in a vintage amp, bought a valve pre and SS power amp and bought tower speakers and changed their ESL panels.

I've clearly noticed the phenomenon of 'break-in' while listening to the CDP, the vintage amp and the ESL panels but did not notice it with the pre and power amps.

 

[anilva]

Though it is proven that human mind can conjure up imaginative things based on specific situations, quantum physics is still a very active field of research and the atom has not yet been understood fully. So 'break-in' might not be an imaginative thing after all.


Talking of my personal experience in the past one and half years, I've made several changes in my system. I purchased a new CDP, replaced several capacitors in a vintage amp, bought a valve pre and SS power amp and bought tower speakers and changed their ESL panels.

I've clearly noticed the phenomenon of 'break-in' while listening to the CDP, the vintage amp and the ESL panels but did not notice it with the pre and power amps.

Are you referring to Electrostatic Louspeaker panels when you say ESL? If not what is ESL?

Thanks.