[avahifi]

Double blind amp testing is useful, only if it is done properly.

The general method is to share inputs from the source and switch outputs from one amp to the other.  Switching inputs can cause large transient pops and destroy speakers.

The problem is that shared inputs share the distortion of both amps under test which appears at the inputs of the amps and is easy to see on a test bench.

Do the amps sound the same under those conditions, of course, you are hearing the mix of the distortion of both amps combined with either amp, and generally nothing sounds really good at the session.

I have not seen DB testing done properly, with both input and output connections seamlessly switched.

In house we get around this by simply doing preliminary testing of new circuit ideas in mono.  One channel original, other channel with new ideas in place.  Then randomize speaker cable and source connections.  Use two identical speakers side by side and switch channels with the balance control.  Make written notes with each test.  Can you hear a difference?  Is it a better or worse difference?  Are your findings consistent over a variety of source materials?  Did you identify the channels "correctly"?  If we can consistently identify a "new idea" as actually being better musically, then we proceed to stereo listening, and evaluations on a variety of speaker loads.  Sometimes a "new idea" turns out to be a bad idea.  Its nice to catch these before we start selling them.

Break in does not enter into the process, except for letting vacuum tubes settle down for a few hours.  When I listen to a unit that was shipped out two years ago and returned for upgrade or repairs, it sounds exactly the same as brand new unit of the same design, just off the test bench in final listening testing before shipping.

There are a number of people who think we build pretty good equipment, good enough that if many hours of use was improving the equipment, we should be able to hear that here.  Either that or we are really stupid and deaf.  Of course its hard to build Absolute Sound recommended equipment if you are stupid and deaf. 

Regards,

Frank Van Alstine

Regards,

Frank

[TheChairGuy]

Frank,

Gooble-di-gook.

I owned one of your 240/3 ex's for a time.  The difference from the time I first turned it on to the couple hundredth hour was enormously beneficial.

I commented in your circle a few years ago that it was one dang impressive amp for the reasonable money charged. You agreed ('natch ) and mentioned that one that you had been using in your video system seemed to be improving over time.

So, you were either stroking me for leaving a nice message for me in your circle.....or you've experienced break-in yourself yet alternatingly don't believe it.  Which one is it?

I could find the related statement(s) again...it would take a while in the archives, tho. 

I'm really not trying to bust your balls, I consider your presence here at AC an honor given your history as a designer in high fidelity audio over the past 3+ decades, but your incongruous statements over the years on break-in are puzzling.

John

[Pez]

What I find rather confounding is that Both Wayner and Frank are stating repeatedly this idea that only "mechanical things" break in.  Things like drivers and what not. Then there seems to be this grey area that includes tubes because they are "mechanical things" can one of you slap some sense into my thick head and tell me what part of any piece of equipment is not a "mechanical thing" because it seems to me that everything from A to Z falls into this category. Does it involve moving parts? Like a motor. Or is there some other explanation to these rules?

And what parts would you expect to break in and what parts would not break in. Also what is the logical explanation for such a divide between things that do and things that don't. Does a capacitor not take a while to properly "form", so to speak, a proper capacitance (which measurements prove it does) or is a capacitor one of those magical items that do not require break-in under these conditions? For now lets disregard whether one can hear the change or not, what I want to establish are the ins and outs of what you have claimed as certain things needing break in and certain things not needing break in.

[Wayner]

Audio dealers may have experienced differences between like models and believe they have witnessed "break-in". I quess I can't blame them, but I think what they are hearing is tolerance differences between pieces. We all know that resistors, capacitors, transformers all have tolerances. Some are going to be on the high side of the "perfect value", others on the low side. So if we imagine this assembly line making power amplifiers, to some very small degree, they could all sound different as the components within them have tolerances that are all over the place and hense, a slightly different sound.

Over time, things corrode, wear and build up crude (like in volume, balance, tone controls) and affects the sound. This, again is not break-in, but break down.

I have 4 Dynaco A25XL speakers and they all have a slightly different sound. Maybe the wood cabinet on one has a loose piece or the capacitor on another has aged and changed value. It's a huge puzzle that at first thought confuses the senses.

On the topic of "eye witnesses" hearing the changes, I have several attorney friends that will tell me that "eye-witnesses" are not reliable. They all see things or hear thing or think things from a different perspective. DNA is much better!

Anyway, this is a great discussion and I'm sure I won't change any minds and that's OK. We all have our belief systems. I use mine until it's proven wrong and then I jump to the next one.

The one thing I'm sure of is that the more I learn the more I don't understand. We certainly live in a very complex world.

Wayner

[Browntrout]

Break in can be explained quite simply.
 
   If a resistor or capacitor is made from a material that has not had a potential difference applied across it then when one is applied the material changes.
 
  Those that say break in does not occur are in fact incorrect it does occur and is easily heard. Such things as polarisation, magnetisation and alignment together with structural breakdown as the result of voltage spikes are well documented and proven within the electronics industry.
   Without meaning to be rude I don't really understand why there is a debate about this, it is known, proven and mostly understood.

[Pez]

Audio dealers may have experienced differences between like models and believe they have witnessed "break-in". I quess I can't blame them, but I think what they are hearing is tolerance differences between pieces. We all know that resistors, capacitors, transformers all have tolerances. Some are going to be on the high side of the "perfect value", others on the low side. So if we imagine this assembly line making power amplifiers, to some very small degree, they could all sound different as the components within them have tolerances that are all over the place and hense, a slightly different sound.

Ahh but the claim is NOT whether one hears a difference between component A and component B, the claim is that component A @ 0 hours sounds different than component A @+1,000.  Also it is odd that you would claim a component would have a "very  small degree" of difference in tolerance and that is something one can pick up on, yet one is incapable of hearing the way a single component shifts over time. Yes I agree that sometimes someone may attribute a change because their own ears and mind are deceiving them into thinking there is a change, but I cannot say this is a reasonable thing to assume will be the case everytime as you seem to claim.

Over time, things corrode, wear and build up crude (like in volume, balance, tone controls) and affects the sound. This, again is not break-in, but break down.

Ahhhh so things "Break Down" but not "Break In" I have never once seen a baseball mitt go from working perfectly the second you buy it to suddenly just failing many years later. There is a break in period to loosen the leather and conform to the wearers hand. A crude example I know, but apt when you consider the topic at hand. Tubes definately burn in to my ears. Cables definately burn in to my ears.  Sibilance that I find absolutely unlistenable on new cables goes away after 300+ hours. And that's with me leaving them running while I go do other things. Did I suddenly learn to love the horrifying sound of sibilance in that time frame despite the fact I didn't give them the time of day for several hundred hours? Did the dry climate in Colorado suddenly become a sweltering 90% humidity? Or is it possible my baseball glove analogy is more apt than I initially gave it credit for?

On the topic of "eye witnesses" hearing the changes, I have several attorney friends that will tell me that "eye-witnesses" are not reliable. They all see things or hear thing or think things from a different perspective. DNA is much better!

Yet eye witness testimony is still admissible as evidence. Why? Because the human experience regardless of how flawed it is still matters. Not to mention DNA cannot tell you motive (at least most of the time anyway).

Anyway, this is a great discussion and I'm sure I won't change any minds and that's OK. We all have our belief systems. I use mine until it's proven wrong and then I jump to the next one.

The one thing I'm sure of is that the more I learn the more I don't understand. We certainly live in a very complex world.

Wayner

And that is something we can ALL agree on. 

[Tone Depth]

Would it be possible to quantify the results of "break-in" of a piece of elecrical equipment by making before and after digital recordings at the output at the equipment, using the same source and upstream equipment?  Then the two signals could be compared, subtracted, to see if there are any measurable results.  Similarly, the two recordings could be played back, switching back and forth between the two, to see if there are any audible differences.

[Danny Richie]

Come on people, the Earth is round already. It's round damn it! 

[Wayner]

Where do you make the recording from? The output of the preamp or the speakers? And to Pez's point of view, did the recording instrument break-in and is it's data is now not reliable, corrupt because it is not broken in yet?

We should all be in a debate class at Yale. If I could only spell. Damn engineering. We usually only work with numbers. Letters are just in the way (unless they describe a view or datum plane!).

W

[Pez]

Where do you make the recording from? The output of the preamp or the speakers? And to Pez's point of view, did the recording instrument break-in and is it's data is now not reliable, corrupt because it is not broken in yet?

I know that was meant in jest, but who knows, maybe it would need to break in!

And I could afford to go to Yale if I didn't spend so much on equipment. 

I think I need a drink. 

[tanchiro58]

Hello,

Each of you has your own opinion about "break-in" or "burn-in" in your system. Everyone has his own right to discuss about to believe or not to believe in break-in.

Let's read other expert's opinion about this concept:

http://www.michaelgreenaudio.com/new/HTML/public_html/systemtuningframe.htm

Here is another one:

http://www.gcaudio.com/resources/howtos/breakin.html

Have fun on your debates.

[Wind Chaser]

Come on people, the Earth is round already. It's round damn it! 

According to historians it started off flat, but it is now round as consequence of having been broken in. 

[JackD201]

Come on people, the Earth is round already. It's round damn it! 

According to historians it started off flat, but it is now round as consequence of having been broken in.

I believe it's called a paradigm shift!
 

[rockadanny]

I think I recall (but I do have the CRS disease) that there was a device(?) which would do just that - record (via speaker output(?), compare results, and display differences in frequency and amplitude?, I think?). Of course, I cannot recall what it is or where I read it. There you go. Glad I could help.  (Maybe my wife is right about me.)

[hmen]

I use a BAT 31VK preamp with a 140 step volume attenuator that has a digital readout. I usually listen between 70 - 80 decibels at the listening position, which usually meant that the volume would be set between 60 - 70 on the readout depending on time, music, etc.
I installed a cryoed Hubbell outlet. When I hooked it up I listened for a while at my regular volume and I didn't notice much difference in the sound. Even after a few weeks, at a rate of probably 40 - 50 hours of use a week, there was no tighter bass, blacker background or faster transients, nothing.
But about  month and half later I discovered something. I was listening at the same volumes but the volume setting on the preamp was about 8 -10 steps lower. Apparently, (at least to me and I might be wrong) I was getting more juice through the outlet after it broke in. It was the only thing I changed during that time so it's the only explanation that I have. I definitely listen at lower volume settings on my preamp since the outlet broke-in, or at least since about a month and a half after I installed it, and I achieve the same volume as before.
Unfortunately, I have no scientifically reliable measurements to prove this. There are too many variables and I didn't keep records but I do notice that I have the volume set lower on the preamp than I would have had it set in similar situations before. The only thing I can attribute this to is the outlet working better after a few weeks. My friend who dog sits for me noticed the same thing (independent verification!).
While I think a lot a break-in stuff I hear is over-hyped I think break-in does exist and the way I think I witnessed it is probably more straight forward and easier to describe than the usual explanations that talk about sound qualities, which are not only subjective, but also involve the repeated use of auditory memory during the break-in period.
Does anyone know of any experiments that have been done which demonstrate break-in?                         

[Slowdown]

Not beyond an hour or two, no.

[JackD201]

Loudspeakers and vacuum tubes, both being made of a bunch of mechanical parts fitted and fastened together in some sort of way, likely will require a bit of break in time, but how much of this you can really hear has not been examined carefully with double blind testing methodology as far as I know.

Frank I can't imagine how it can be done at all. Impossible to do an A/B/A/B test much less a blind test. There's just B for before and A for after. Take into account Wayner's "break-down" theory along with the QC questions and even the Mono vs. Mono has lots to be desired.

Here's a test that seemed to prove break-in at least to me. I assembled an entire system with gear and cables straight out of their boxes. I let it run for four hours and called my wife to have a listen. Now this woman cares noting about gear but she does like her music. I cued up one of her favorite songs. She walked in, sat for a minute and said "Sorry babe, It kinda sucks." Trying to lead her, I asked what sucked. She replied "I don't know, it just does". Clearly even after 20 years together her audio vocabulary is still non existent. After leaving the system playing for 5 days straight, I called her back in. I asked her what she thought. She said "Oh this is much better, glad you got rid of the other stuff you dragged me in here to hear".

Hmmm go figure, she couldn't even recognize the stuff by looks alone. I was rather expecting her to ask what I changed at the very least. I pretended to just agree. The less she knows, I figure the better she stays as my "blind test". 

Okay, granted the speakers were new too. Big 'ol true ribbons to boot. I also agree that transducers have the most marked difference over time. MC cartridges and Speakers in particular. I'm pretty sure that the biggest difference she heard was in the speakers. Yet, my own experience especially with teflon caps is that they do change in time. That sound change isn't linear either. In a pair of speakers I had that used V-caps the upper register did a roller coaster on me over a period of two months. On the third month differences were less (more like a kiddie coaster) and by the fifth month and for the next year and a half, there were no noticeable changes. "Break Down" would imply a linear degredation until it reaches a point of failure.

[alan m. kafton]

Why does anyone need to "prove" they're enjoying music?

Unless you require validation, having to prove what we hear to others is folly. Trust your ears. No one else is paying for them, nor your equipment.

[Wayner]

Alan, your talking about acoustic memory. We can recognize voices over a crummy phone. I think that is really awesome. But recalling a tone or texture to a particular piece of music on a system that you think has had the break-in phenom happen to it, is one tremendous skill. I certainly couldn't do it. I will agree with you on one part that systems have "sonic signatures". That might be  another discussion.
 
Here is my real problem with you guys and the break-in theory. I'll bet you guys are all just like me and are constant fiddelers. You can't leave things alone. So how do you know you did or didn't do something to alter the sound of the system and perhaps didn't even know it, like change a tone control or move a speaker. I've had my systems sound "off" and sometimes I'm puzzled why things have gone sour. But soon, after some jiggling, things come around. Then I wonder if it wasn't the barometeric pressure or the humidity. I just don't know.
 
Wayner

[Pez]

I am a constant fiddler, and that is how I KNOW when something is different/good/bad/wrong.  Much of that is direcly related to the way a system images/soundstages. Sometimes you will make a change and suddenly the whole system sounds more 3D, a pretty good indicator that something you changed is "better". Also being a musician determining tonality has become second nature to me especially in vocals. If something I change causes some sort of timbre change or overall tonal change I've grown keen to determining what/where that change has occured.

Wayner, just like an excellent engineer can often diagnose an issue BEFORE they pull out the ol' multimeter or wine connoisseur can name the area of the world and what year a wine came from just from tasting it, one's auditory sense can be used to determine the most minute changes in a system with years of practice and appreciation. I truly believe you are not giving the human ear the credit it deserves.