Do these CMoy amps really need a burn in period?

[Matt Scarlett]

Something that caught my eye with Bozz's CMoy amp is this statement

This  BOZZ Headbangers Amp has been burned in and play tested for hours to ensure that the amp is in good working order upon shipping to winning bidder!

Do these amps really need a burn in period, and if so how long do they need?

[Bozz Amps]

Yes and no...

As with most electronics, if anything will happen, it will be when first "turned on" or power is applied.

I like to play test... meaning, I take it to work and use it.  Opening the lid, removing the battery, closing the lid.  The caps are rather large and can cause a problem if not properly placed.  I try to make sure there is no short that can be caused.

Thanks for the interest!!!

[Aenn Seidhe Priest]

Here's what Lynn Olson said...

Q: How exactly do amps burn-in?

Headphones and speakers have their rigid parts soften, but what about
amp components? Which parts exactly benefit from burning-in, and in
what way?

A: Capacitors, especially electrolytics, can exhibit subtle changes with time and temperature - enough so that electrolytics need to be routinely replaced after 20 years, whether they've been used or not.
I suspect nearly all "burn-in" changes are due to electrochemical effects - that would be consistent with the time constants of 5~100 hours that people report.

[SharpyWarpy]

An old post I know, but I'm new here so forgive me.
Chips don't need burning in.   The only difference you may perceive after some time of using the amp would be you and the amp becoming acquainted.

[Aenn Seidhe Priest]

With much gear it's actually both... And pretty much anything that changes signal latency will also change the sound. It's a common misconception that humans somehow listen to frequency ranges... In reality, humans listen to phase and latency; human hearing is echoic, so it is the intensity of echoes and shape of reverberant waveforms that humans listen to (across a very wide frequency range; it's a different matter altogether that not all of what's listened to is heard consciously). Latency, quickness of waveform update, matters too - especially in the high frequencies, which are related with spatial perception. Basically if the high frequency range (10-20 KHz) isn't updated quickly enough by the amp/cable/headphones/speakers, a recording doesn't sound lifelike enough. This is also why Denon thousand-series and Grado headphones sound so exciting - dynamics allow them to draw the "spatial range" relatively accurately. This is also why the sound reprodution of amps changes subtly over burn-in time - dynamics over different frequencies change slightly. And yes, thank-you-very-much, there're people who distinguish between their own perception and a physical change.

It's a question whether chips can change much with burn-in, but capacitors, and all electrochemical components, as Lynn wrote, do change subtly; they have to, as they're not made of diamonds or other hard substance.

[SharpyWarpy]

So maybe we shouldn't buy new stereo equipment? Only used?  I mean, what good is it to shop for stereo stuff if you're not really hearing what it's gonna sound like?  If there is an  actual physical change in sound quality after a certain "break in" period it doesn't say much about the quality of the parts used, especially if it's the chips that are changing.   And if that's the case, how can we believe the specs in the datasheets?  If it's the caps that are changing that much maybe we should remember caps come in a wide range of tolerance anyway, 5%, 10%, 20%.   

[Aenn Seidhe Priest]

Again: nothing's stable. Even metals change over time (oxydation, etc.). Any parts have to change in some way, especially electrolytics.

Please point out where it was written that caps change "that much". Lynn's comment (Lynn is a longtime amplifier/speaker maker, http://www.nutshellhifi.com/ ) was that electrochemical components change subtly.

Headphones do change with burn-in, materials, recable, etc. Even headphones in a stock configuration change after serious burn-in, the usual effect is a "relaxation" of the sound, as diaphragms are manufactured stiff; they need some time to "flex" out. And yes, this is why some people prefer seriously burned-in headphones to fresh new stock.

Again, no material's hard and stable like a diamond.

[SharpyWarpy]

I thought we were talking about the amps, not the headphones.

[Aenn Seidhe Priest]

For starters, it might be appreciated you didn't try to exaggerate and pervert the original post.

You've been trying to exaggerate and pervert the original meaning out of any proportion; why? What kind of madness is that?

Have you noticed the meaning of the original reply?

It's a question whether chips can change much with burn-in, but capacitors, and all electrochemical components, as Lynn wrote, do change subtly; they have to, as they're not made of diamonds or other hard substance.

To that, you have replied with a coarse exaggeration:

So maybe we shouldn't buy new stereo equipment? Only used?

Perhaps you might admit your wrongness and rudeness first?

[SharpyWarpy]

I'm not trying to be rude, just real.   The exaggeration was to make a point, that if the difference in sound quality is THAT large why buy new if you don't know what you're getting?

[Aenn Seidhe Priest]

How exactly isn't an exaggeration and perversion of the author's meaning rude? It is terribly coarse and akin to libel. Even worse, it's an offense. And how exactly is an exaggeration "real"? On the contrary, it perverts a description of reality and destroys any links to reality.

Where exactly was there a mention of any substantial difference in sound quality? Lynn's original reply was:

Capacitors, especially electrolytics, can exhibit subtle changes with time and temperature - enough so that electrolytics need to be routinely replaced after 20 years, whether they've been used or not.
I suspect nearly all "burn-in" changes are due to electrochemical effects - that would be consistent with the time constants of 5~100 hours that people report.

(emphasis added)

Simple school physics tell that molecular links are not stable; materials' properties change over time. Under stress, a new capacitor or headphohe diaphragm, any physical material except perhaps really hard structures like diamonds, will change subtly (or even not-so-subtly). Whether op-amp chips are affected by burn-in is another question. And that's what the post was about - electrochemical amp components like capacitors will exhibit subtle changes, other components like op-amps likely aren't affected enough by stress.

So depending on an amp's design, it may or may not be affected by burn-in - amps with electrochemical components (especially electrolytic capacitors) will exhibit certain (subtle, according to Lynn, but perception varies) changes, simpler designs won't change much. But, even a different rechargeable battery can change the sound in a "subtle yet noticeable" way, especially dynamics.

[SharpyWarpy]

So I'm rude, perverted and full of madness.   And what was that about "libel"?
I just think way too much is made of "burn in".   All reports I've ever read about it say the sound quality improved.   That tells me the listener is just becoming acquainted with the machine.   
If we're going to accomplish anything with all this rhetoric we have to stop wearing our feelings on our sleeves.

[Aenn Seidhe Priest]

Nobody said anything about you being rude or perverted. Just you perverting the topic of this thread in a rather mad and coarse way - with exaggeration and without having paid attention to previous posts. People often "change" to trollish when posting on Internet forums.

Burn-in is a physical effect, but often it can be attributed by a listener to a change in his own perception; that may tell the listener isn't very conscious of his own perception. But just the same, any material will change over time (a thirty-years-old amp usually requires replacement of some electrochemical parts, as noted). The solution is, of course, an observation of the changes with the help of monitoring gear (in the case of an amp there might be a test rig set up with a precise soundcard and high-quality interconnects) and a better consciousness and self-awareness by the listener. The first, ironically, might be easier to provide for many people than the second.

In summary:

Matt asked whether CMoy amps require burn-in;
Lynn Olson, of Nutshell Hi-Fi, had the question forwarded to him;
his reply is shown above - electrochemical components exhibit subtle changes over time, and he suspects that is what people hear change over a period of 5-100 hours.

A CMoy amp, depending on construction, may have electrochemical components like capacitors that will change noticeably (perhaps "subtly", but still change). Op-amp chips, on the other hand, shouldn't change much over time.

[Aenn Seidhe Priest]

Libel is implying the author has written a falsety.

Such as:

So maybe we shouldn't buy new stereo equipment? Only used?

Has anyone in this thread (except you) called for only used equipment to be bought?

[SharpyWarpy]

Oh, whatever.   All this is a waste of my time.   You're an administrator, do me a favor, remove me from this forum.

[Aenn Seidhe Priest]

If you suspect listeners mix up the results of burn-in with changes in their own perception, why not write so? Why offend by exaggerating and perverting the meaning of someone else's post?

Besides, there are people who do have an awareness of what they perceive and what are the changes in how an amp (or any other device) reproduces music. Yes, there are many people who may mix up a lot simply by judging instead of perceiving. But not everyone will be attributing their own getting accustomed to gear to burn-in.

Mind it, just pay attention to what others write...

[Aenn Seidhe Priest]

There was a nice old surrealist tale about a traffic policeman who's fined a fellow crossing to a red light. The traffic policeman was smelling a rose; so he told the guy: "I shall punish you. I won't let you smell this rose".

So no, no "favours". You live; you affect others.

[Aenn Seidhe Priest]

Just respect what others write; don't try to impose any coarseness or ignite flames by perverting the writing of others. Oh, and. There's no "we". It's a delusion. There's no crowd. There're many individuals.