Amplifier Burn In

I think the amplifier break-in issue is very amplifier specific. It has mostly to do with the components used in the power supply section. The final amplifier sound has much to do with the power supply. Especially black gate caps and such. These kind of amplifiers take a while to break in. Most average amps just sound the same always. Like cranky said, “terrible”

It is not in the mind because we have checked out burnt in and non-burnt in amps of the same brand side by side to understand this phenomenon.

Count me in your skeptic's anonymous group.
Particularly liked the analogy to cars.

In fact I believe that there is no speaker-break-in as recommended by speaker manufacturers. The manufacturer has got all the time during the quality check / testing to actually break in.

Its our ears and mind that really requires breaking in to find something acceptable, and its a tactic by manufacturers to buy enough time to make their products acceptable to customers who might be in split minds while auditioning.

Venkat,

I am completely with you on your observations on system burn-in, However, your statement on new cars is one I cannot agree with.

I know many car manufacturers (Honda being one of them) who do recommend easing the accelerator and break during the first 500 miles or so, till the car is "driven in" (their term, not mine). Honda also states that mileage will pick up after this. We can drive from showroom in a new car but there is still a break-in period during which the company recommends we go a little more gently. This is not for gears meshing together in older cars but for the piston rings to conform to cylinder walls and friction between all moving parts to reduce. Even though the process is greatly reduced and the requirements less stringent, there is a break-in period. All this is well documented in Honda and Toyota user manuals.

That being said, in audio, I believe solid state requires no burn-in. Speakers I may accept since there are moving parts which can soften over time. Tubes, I don't really know since I am not familiar with tube design methods.

For the most part, it's all in our heads (and hearts) rather than in our equipment specification. (Funnily enough, I believe the same thing is true of love and s** as well )

-Ajinkya.

Quite possible. Strangely I have never read the manual of any car that I have purchased including a Honda City. Old cars used to have a block on the accelerator that would stop you from speeding beyond some 40KMPH.

Cheers

I don't know about Indian Honda manuals but I know that UK and US manuals are very detailed and worth a read. There is a lot of practical information in them. Some even have an index and a glossary
Yes, I remember my father telling me about the "regulator" on his ambassador that needed to be taken out after first few months of use. How times have changed! Reliable electronics, reliable mechanics, reliable performance...only constant is unreliable politicians. Well,...actually they are reliable in being unreliable...

-Ajinkya.

Dear Venkat,
It is very much there in all the Honda vehicle manuals i have. It also goes to say the first few thousand Kms are crucial and will determine the performance of the vehicle in the long run.
What u guys are talking about on old cars was called a GOVERNOR. That is hardly ever used anymore except on rebuilt engines of old/vintage cars.
Rgds

I am really a novice and am curious to know of any basis for the statement above, especially the reference to "a couple of hours".

I would like to know

1) Why is a time interval of that order (2 hours) relevant here? Why not 20 hours, or 200 hours? Is there a scientific reason that sets the scale here?

2) Why isn't a period of 2 hours considered a break-in?

There is a possibility that I have not made myself at all clear here. I am introducing a notion called "orders of magnitude". For example, an ant has a length of the order of a cm, a human being has a length (usually called height) of the order of a meter, a football ground has a length of the order of 100 meters; up to very large distances like astronomical distance scales of megaparsec (1 parsec is 31 trillion km). Now the point is that all the above are lengths, however small or large. Any of them can be relevant depending on the scale of our observation. There exists this notion of order of magnitude with all physical quantities.

With the above explanation of the notion of order of magnitude of a given quantity, now my concern is two fold, as above: 1) if you say, there exists a 2 hour break-in, that is to be considered also a break-in, though a relatively short one and 2) what sets the scale here? Once we agree that there is a break-in, the question naturally arises as to what in an amp determines whether the break-in will be achieved in 2 hours or 10 hours or 20 hours?

Since the time I have owned stereo separates, I have owned 4 amps: Technics (model forgotten), HK 6300, Nad c325bee and Leben CS300. All these amps have had a break-in period. This is of course a subjective statement, but I can say only the stuff that I myself have noticed, and I would not like to theorize or speculate here, just stating the facts I have perceived them to be.

However, I must say in all these cases, the break-in period was not large, between 20 and 30 hours. In the case of the Leben, the statement is not accurate, it's more of a guess (also based on inputs from Sridhar and Leben users), because I also had a brand new IC that was connecting the CDP to this new amp.

I also would like to share with you another relatively recent fact. Three years ago my 20 year old HK amp developed some problem with one channel. There is a very experienced person (Sri Rajesh Tanna) in Kolkata who in his spare time repairs amps, speakers etc and he has a special interest in old HK amps and also holds them with very high regard. He repaired and serviced my amp and claimed that it needed a few cap changes. His explanation was also consistent with my guess, because I suspected that after so many years of running the dielectrics of the caps had to give in and they better get replaced. But when I got the amp home, although it was fully operational, I did not like the sound at all, it sounded very harsh to me, and sounded very much unlike the amp I had owned for such a long time. At that time I already bought my Nad amp, and hence I was listening mostly to the Nad amp in my setup. However, the sound of the HK amp quickly improved and in about 20 hours at the max, it sounded beautiful again, and perhaps with more dynamics than what was there before the amp started giving problems.

The capacitors need a time of the order of milliseconds to get them fully charged. So contrary to many forum discussions (in forums across the globe), I concluded that the improvement could not be due to charging of the new caps, rather it must have had something to do with stabilization of the electric response properties dielectric material of the caps, assuming of course that the new caps were of course of the correct specification. Experienced and knowledgeable people, please explain my observations and confirm or reject my conclusions above.

Please note that I have been specific to break-ins of amps only, no sources, speakers or cables.

In addition, I like to point out that I did not find anything in Cranky's post that says that the amps do not have break ins. He obviously has also added to the subject the new issue of the listeners' ears and subjective adjustments.

Regarding cars (excuse me moderator, since this has been brought up), I have personally bought 11 cars so far in my life (7 of them new) and still do own 2 of them (the rest were sold as and when they got 'old') from early 80's models to last years models, from entry level cars to mid level and I have driven quite a number of relatively high end cars. As I have some interest in the matter, I have gone through the owner's manuals of most of those (even rented cars in the US). All those owner's manuals (irrespective of brands) say very very clearly that for the first X kms one should be careful, shouldn't do this and that and so on. My personal experience (after driving of the order of 10 lakh kms so far in my life, without being a truck driver) has been something like this: 2500 kms is a good average after which the car becomes very smooth in handling (especially pick up). But I must say I do not find any similarities between a car break-in and an amp break in.

I'm sorry if my statement led you to believe that amplifiers do not need burn-in. They do, almost all of them. Whether your equipment can reveal the extent of change due to burn in, or indeed if your hearing is good enough to distinguish it, is another question. We all love a glass of wine now and then, but not all of us can distinguish between wines easily, only some of us are wine tasters or connoisseurs...

Anyway, I do believe that ears also take time to adjust to tonality. I do not make the mistake of sticking to any extreme stands.

All passive components require settling time, specially capacitors (arguably, resistors too, drift with time and temperature). The process of an electrolytic capacitor is not in the manufacture, but in the formation of the oxide layers inside the cap to permit the capacitor to create its capacitance. And that takes voltage, which needs to be applied for a while (say 2 hours) before the cap settles in.

Also, a typical mass-market manufacturer turns out at least a hundred amplifiers or speakers a day. They don't usually run more than a two minute QC check, and that's it. Two hours is unheard of, nobody puts that much time into testing anymore, unless it's a boutique manufacturer.

And speaker break-in was being mentioned by someone as unnecessary. Nothing could be further from the truth. It is a measurable, repeatable and audible fact that the suspension of drivers need to be exercised for quite a while (between 4 and 40 hours) before the driver settles into its specified performance. Typically Qts and Fs both come down with some heavy massage, specially for mid-premium lines like Seas Prestige or SS Revelator speakers.

Since there is a continued suspension of belief, I am proposing that someone buys two monoblock amplifiers, connect only one block and run it in mono for a week, preferably with a small panel of friends to listen occasionally. After a week (say, 100 hours), connect the other one and use the balance control on the preamp to check for differences between the channels. No further testing is required. Cheap Ahuja monoblocks will obviously not do, so one will have to hunt down suitably cheap products. If there are members buying two identical amps and live in the same city, comparing a brand new unit against a previously run in unit should provide adequate proof.

I recently rewired my Ushers, but we left one with the old wiring and ran A/B for the last two days. The differences were astonishing, you should be able to read more about it on Wednesday when the article goes up, but in short they sounded like two different speakers from two different companies, such was the difference. There is no substitute for checking results out yourself, it can shatter quite a few beliefs.

I agree largely with Asit. The science of human hearing is largely unexplained. We know the mechanism, but the big DSP inside your head that is decoding everything is quite a mystery.

The car analogies are irrelevant, in my mind. Cars have not changed at all since the days they were first manufactured, they just have gotten better at isolating the occupants from the pollution they are creating. Amplifier technology has taken huge strides forward, in my mind, and a lot of it in the last thirty years when we are able to improve distortion by thousands of degrees of magnitude. If we were to progress at the same rate with cars, we'd have landed one on the moon ten years ago. In an hour.

Unfortunately a lot of these developments will not hit the commercial mainstream, and will remain in the DIY and boutique segments. There are about sixty or seventy methods of getting 30 watts into 8 ohms. It is not right to cast blanket judgements on what the best way to do that is, and then, what the nature of that amplifier is, without ever having experienced it.

From what I know, the oxide layer coating the anode is formed during the manufacturing process itself. So where does the question of break-in for capacitors play any role? I am assuming you're talking about electrolytic caps.
Resistors drift with temp. but that does not mean that burn-in is required to get them to the 'right state' since temp. drift will occur throughout the lifetime of the resistor. It is not a process which goes to some value and stops. So again I cannot see any reason for burn-in here. Similarly for an inductor (taking into account its non-ideal resistance). I could be missing the point of what exactly you're explaining.

That is not true. The first Ford car, the Model T had to be hand-started (cranked up). The mechanical engine used was vastly different from the computer-controlled fuel injection engines used today. There are about 50-100 embedded controllers in a modern car, monitoring every aspect of it's drive along with cruise control, anti-lock braking, stability control, active suspension damping, along with mechanical things like crumple zones, airbags...all these things make the modern car a distributed computer system on wheels, something which is orders of magnitude more sophisticated than old cars.

Yes, we still use petrol/diesel as primary fuel but now electric hybrids are changing that scene as well. I think as far as cars and airplanes are concerned, there have been monumental leaps forward in the last 50 years, especially in passenger safety and ride comfort. Cars will soon drive themselves, as witnessed by the recent Urban Challenge held in the US by DARPA.

Comparing this to reducing distortion levels in amplifiers is, in my opinion, comparing apples to cherries. Yes, amplifiers have gained a lot from strides in reducing tolerances on all components, aside from minituarization and VLSI design. But the stride is not comparable to placing a car on the moon. If that was the basis of comparison, amplifiers today should be able to adjust all their individual component characteristics to match the current listener's tastes and mood, all in real-time, apart from being able to adapt tonally and electrically to whichever speakers and source they were connected to, at half the cost of today's budget amps. And all these components (CDP,Amp, Speakers) should be connected wirelessly, without signal interference over a room length. That would be an amplifier equivalent to a "car on the moon".

-Ajinkya.

Electrolytics idling on a shelf or moving in transit, or lying in switched-off equipment, lose their oxide layer, it dissolves in the electrolyte. They need to be reformed, and this happens only when current is applied. This effect is minimised in solid capacitors like Panasonic FC series, and polymer capacitors, but exists in all electros.

As for resistors, the degree of drift changes with age. I'll look up references for you, but IIRC the initial drift is pretty rapid, and then the drift changes with time at a slower rate, depending on ambient temperature and voltage, until the resistor reaches failure mode.

Inductors have no aging/break-in/drift phenomenon AFAIK, and given operation within parameters, should retain their properties indefinitely, unless it encounters stress beyond its specifications.

As for cars, the IC engine has basically remained the exact same for the last 80 years. Everything around the the engine performs auxilary functions, it's equivalent to your couch, to extend the corollary. Even the tie-rod and independent suspension has basically not changed at all, except improvements in the materials and implementation. I do not consider passenger safety and comfort core to the idea of a car in your example, they're purchase-related, not function-related. The idea of burning fossil fuel (which is a very precious, finite and wonderful natural resource) in a chamber to produce expansion is identical to the very first petrol engine.

But maybe just that's the way I look at it.