'Burn in' when there's nothing to burn

Posted by: Dave***t on 06 November 2015

Just wondered if this seemed familiar to others.  Obviously some people scoff at burn in, but I've heard it with my own ears, and most here accept and embrace it.

 

But what if there's nothing which should be burning in?  I installed a glass shelf on dome nuts underneath my 172 today, and spent a couple of hours listening afterwards.  It was largely because I thought I'd like the look, but I did also hear a change, and not necessarily for the better.  The details don't really matter for the point I'm making, but there seemed to be more detail higher up the frequency range, but a bit more congestion in mid-bass, and a bit of boom in the bass.  This was over a few hours, so unlikely to have been to do with having switched off for 5 minutes to install the shelf.

 

I left Radio Paradise playing while I went out for a few hours, and when I got back, things seemed to have improved somewhat.  Getting used to a new sound could be part of it, but I was away from the system in the meantime, and immediately thought it sounded better when I got back in.

 

So, apparent burn in from a glass shelf?  Shouldn't be a factor, surely.  Ridiculous, even.  But if there's one thing I've learned about hifi it's to trust one's own ears.  Weird.  Anyone else had similar?

Posted on: 07 November 2015 by Willy
Originally Posted by Innocent Bystander:
Originally Posted by Morton:

Personally I have never understood why adding a glass shelf would be a good idea.

People talk about isolation, but surly most vibration your 172 will see will be airborne from the loudspeakers. Adding glass plate on dome nuts will, I would have thought, only add to the problem as this plate will now also vibrate.

It will certainly not damp any vibrations from the floor, for which you would need rubber AV mounts.

If the plate is not for isolation, apart from looking nice, what is its purpose?

Depending on the shelf dimensions and other physical characteristics it can pick up airborne vibrations more so than the equipment sitting on it, and so transmit through the equipment feet to the equipment! acting as a 'sounding board'. Meanwhile vibrations via the floor can be significant especially with a suspended wooden floor.

 

in laboratories, three different approaches apply to isolating sensitive equipment such as balances from vibration from different source: very solid (typically stone or concrete) table tied to  to solid building foundations foundations, where that isn't possible, solid high mass table or slab on resilient vibration absorbing isolating material (eg feet), and an enclosure to protect from draughts, which may be an acoustic enclosure where airborne noise is a possible source of vibration. 

 

When end I had a turntable, clearly the item most susceptible to vibration, I used it on a concrete slab on a metal frame spiked to the (solid) floor, inside a cupboard lined with damping pads on all panes to minimise their vibration and hence transition into the cupboard, and I acoustic absorbent material inside as well to minimise reflections. Clearly not a full sound isolation booth, but I believe it is an effective supplementary approach - and wonder why others don't do likewise if concerned that vibration is a significant issue for any or all of their equipment, or is it just that no-one else has thought of it?

 

Whilst ventilation holes can be judiciously arranged to provide adequate airflow for low powered components while still providing a fair degree of acoustic isolation, the same is unlikely to be true for power amps so serious consideration of ventilation would be necessary if they are contemplated - but as signal levels are higher the power amp should be the item of least vibration concern anyway.

You're welcome to come round and suggest this to my spouse. I'll observe from a safe distance

 

Regards,

 

Willy.

Posted on: 07 November 2015 by Simon-in-Suffolk

when you placed your 172 on the shelf, did you disconnect the signal lead to the amp? I find physical connections do change the sound subtly over a short time after being re-connected.. I suspect it's about mechanical contact stresses resolving to a more natural state, (I think this is also the thinking behind the Hiline floating connector) and it is through this contact the electrical signal is passing through.. And of course at the microscopic level a contact is typically many contacts of differing micro resistances and capacitances.

Simon

 

Posted on: 07 November 2015 by Huge
Originally Posted by Huge:
Originally Posted by George Fredrik Fiske:

My favourite ground coffee is “Lazy Italian” produced in Harrogate [Yorkshire] by Taylors and all you need in is a cafitierre

 

Less than £10 to buy a cafitierre for coffee almost as good the magic they make in France ...

 

ATB from George

George,

 

Is that a 50/50 mixture of Taylor's 'Lazy Sunday' and Taylor's 'Rich Italian'?

I just realised I'd forgotten the perverse subtleties of Nordic humour!  May the Italians forgive you.

Posted on: 07 November 2015 by Huge
Originally Posted by Willy:
...

The small contact area between glass and ball bearings results in a very high loading(N/m**2) at the contact point. Over time this will cause deformation of both materials and a gradual increase in the contact area. Maybe that breaking these contacts and resetting to a smaller contact area with higher loading accounts for the perceived benefits of a periodic Fraim build?

 

 

Regards,

 

Willy.

I can envisage creep occurring in the glass at these loads but in a years time-scale rather than hours or days.  However I'd be very surprised if these loads exceed the elastic limit of steel, particularly the type of steel used in ball bearings!

 

Indeed the effect forces on the glass could be a reason for Fraim re-builds becoming necessary, as could the slow relaxation of toughened glass.  I still don't see how it accounts for a 'burn-in' type of effect though.

Posted on: 07 November 2015 by Willy
Originally Posted by Huge:
Originally Posted by Willy:
...

The small contact area between glass and ball bearings results in a very high loading(N/m**2) at the contact point. Over time this will cause deformation of both materials and a gradual increase in the contact area. Maybe that breaking these contacts and resetting to a smaller contact area with higher loading accounts for the perceived benefits of a periodic Fraim build?

 

 

Regards,

 

Willy.

I can envisage creep occurring in the glass at these loads but in a years time-scale rather than hours or days.  However I'd be very surprised if these loads exceed the elastic limit of steel, particularly the type of steel used in ball bearings!

 

Indeed the effect forces on the glass could be a reason for Fraim re-builds becoming necessary, as could the slow relaxation of toughened glass.  I still don't see how it accounts for a 'burn-in' type of effect though.

The thing to bear in mind is that although the steel and glass look ever so smooth to the naked eye at a atomic level their surfaces are veritable "mountain ranges". Contact between the glass and steel will be very very small, potentially single numbers of atoms at initial contact. Under these conditions both materials will deform and both will continue to creep for some time. Over time as the contact surface area continues to enlarge, reducing the loading, the rate of creep will decrease.

 

Regards,

 

Willy. 

Posted on: 07 November 2015 by Innocent Bystander
Originally Posted by Willy:
Originally Posted by Innocent Bystander:
 

 

When end I had a turntable, clearly the item most susceptible to vibration, I used it on a concrete slab on a metal frame spiked to the (solid) floor, inside a cupboard lined with damping pads on all panes to minimise their vibration and hence transition into the cupboard, and I acoustic absorbent material inside as well to minimise reflections. Clearly not a full sound isolation booth, but I believe it is an effective supplementary approach - and wonder why others don't do likewise if concerned that vibration is a significant issue for any or all of their equipment, or is it just that no-one else has thought of it?

 

 

You're welcome to come round and suggest this to my spouse. I'll observe from a safe distance

 

Regards,

 

Willy.

Happy to - where do you live?

 

actually, my spouse liked it because with all except the power amp enclosed in a cupboard with a wide base and bookshelves at the top, CDs filling the shelves, it looked, and I quote approximately "much better than that mess of wires I used to hate". So domestic bliss as well as form and function!

Posted on: 07 November 2015 by Morton
Originally Posted by Huge:
Originally Posted by Morton:

Personally I have never understood why adding a glass shelf would be a good idea.

People talk about isolation, but surly most vibration your 172 will see will be airborne from the loudspeakers. Adding glass plate on dome nuts will, I would have thought, only add to the problem as this plate will now also vibrate.

It will certainly not damp any vibrations from the floor, for which you would need rubber AV mounts.

If the plate is not for isolation, apart from looking nice, what is its purpose?

Hi Morton,

 

A toughened glass plate supported on ball bearings or dome nuts can act as an isolation system, but the method of operation of this isn't obvious.

 

Vibration transmitted into the stand finds it's way into the shelf (which is relatively soft compared to the steel supports).  From there it's transmitted fairly efficiently into the steel supports as the small compliance of the shelf couples them at audio frequencies.  From the steel supports to the glass there's little compliance (they are both very rigid materials - hence using toughened glass); however the velocity of sound is different in the two materials and this results in reflection of the sound waves at the interface.  Acting together with the very small  contact patch (typically a few square microns) this limits the amount of energy transferred into the glass.

 

However, personally I don't see a mechanism by which this can significantly change in hours or days time-scales.  Perhaps someone else can suggest something?

Hi Huge,

 

Even if this is true, I still think properly selected AV mounts would do a better job for a fraction of the price.

 

Might not look too good though!

 

Also if the rack was sat on a concrete floor, it would do nothing to stop the major cause of the vibration into the electronics, which is airborne.

When I look at some of the more expensive hifi racks, including Fraim, I can’t help but think that this could be a classic case of over design.

Posted on: 07 November 2015 by Morton
Originally Posted by Innocent Bystander:
 

When end I had a turntable, clearly the item most susceptible to vibration, I used it on a concrete slab on a metal frame spiked to the (solid) floor, inside a cupboard lined with damping pads on all panes to minimise their vibration and hence transition into the cupboard, and I acoustic absorbent material inside as well to minimise reflections. Clearly not a full sound isolation booth, but I believe it is an effective supplementary approach - and wonder why others don't do likewise if concerned that vibration is a significant issue for any or all of their equipment, or is it just that no-one else has thought of it?

 

Concrete is an excellent way to damp vibrations, we once used it at work to isolate a sensitive vacuum chamber from a vibration inducing rotary pump by encasing a section of vacuum pipe in about a cubic foot on concrete, it worked perfectly.

I’m not sure this sort of thing works well in a living room though.

Posted on: 07 November 2015 by Huge
Originally Posted by Willy:
Originally Posted by Huge:
Originally Posted by Willy:
...

The small contact area between glass and ball bearings results in a very high loading(N/m**2) at the contact point. Over time this will cause deformation of both materials and a gradual increase in the contact area. Maybe that breaking these contacts and resetting to a smaller contact area with higher loading accounts for the perceived benefits of a periodic Fraim build?

 

 

Regards,

 

Willy.

I can envisage creep occurring in the glass at these loads but in a years time-scale rather than hours or days.  However I'd be very surprised if these loads exceed the elastic limit of steel, particularly the type of steel used in ball bearings!

 

Indeed the effect forces on the glass could be a reason for Fraim re-builds becoming necessary, as could the slow relaxation of toughened glass.  I still don't see how it accounts for a 'burn-in' type of effect though.

The thing to bear in mind is that although the steel and glass look ever so smooth to the naked eye at a atomic level their surfaces are veritable "mountain ranges". Contact between the glass and steel will be very very small, potentially single numbers of atoms at initial contact. Under these conditions both materials will deform and both will continue to creep for some time. Over time as the contact surface area continues to enlarge, reducing the loading, the rate of creep will decrease.

 

Regards,

 

Willy. 

Thanks,

 

You've just answered my earlier question "However, personally I don't see a mechanism by which this can significantly change in hours or days time-scales.  Perhaps someone else can suggest something?".

 

Yes, I'd only been thinking down to the μm scale.  You're quite correct, in the nm scales and at those pressures, even steel will anneal a bit even at room temperatures as the crystal boundaries shift slightly. The glass will have surface micro variances below 100nm (above that they're visible) and those will flow quite readily.

Posted on: 07 November 2015 by George F
Originally Posted by Huge:
Originally Posted by George Fredrik Fiske:

My favourite ground coffee is “Lazy Italian” produced in Harrogate [Yorkshire] by Taylors and all you need in is a cafitierre

 

Less than £10 to buy a cafitierre for coffee almost as good the magic they make in France ...

 

ATB from George

George,

 

Is that a 50/50 mixture of Taylor's 'Lazy Sunday' and Taylor's 'Rich Italian'?

Well spotted!

 

I meant Rich Italian! Not so fond of Lazy Sunday!

 

Best wishes from George

Posted on: 07 November 2015 by Huge
Originally Posted by Morton:
...

Hi Huge,

 

Even if this is true, I still think properly selected AV mounts would do a better job for a fraction of the price.

 

Might not look too good though!

 

Also if the rack was sat on a concrete floor, it would do nothing to stop the major cause of the vibration into the electronics, which is airborne.

When I look at some of the more expensive hifi racks, including Fraim, I can’t help but think that this could be a classic case of over design.

Hi Morton,

 

Viscoelestic damped mounts have been tried with Naim electronics many times.  Unfortunately, the usual perception of the change to the sound is that they interfere with the reproduction of dynamic contrasts in the music robbing it of some of it's vitality.

 

I've not heard of anyone trying magnetic suspension though.

 

 

Incidentally, for my speakers I do use mass loading in their support: Each of my speaker stands sits on a rigid plinth that weighs 35kg.  I've not done this for the rack as yet though.

Posted on: 07 November 2015 by Dave***t
Interesting discussion. Since a couple of questions were asked, CharlieP, I used 3 nuts, two at the front and one at the back. While as I said the motivation was largely cosmetic (that was the purpose, Morton), I figured that I may as well try 3 contact points as a) I believe that's what's used with Fraim racks and b) Huge's recent investigations supported the idea that 3 was best, IIRC.

And yes, SiS, I did disconnect the leads etc, as I was doing it by myself (my partner would probably be kind enough to help, but she already thinks I'm weird enough as it is!). I also un/re-plugged the mains cables a couple of times. Again, just as a matter of received wisdom vs no cost other than 30s of my time.

I suppose that those who doubt burn in, at least in terms of electrical components (hi George), will forever remain skeptical, but I'm happy enough to agree to disagree with them. No one is harmed, either way, after all.

So I suppose in retrospect that any difference (and I insist that there was one, even if it is a delusion) could be down to the plugging. I remain unconvinced about anything else being the cause. But some ingenious technical suggestions/food for thought, too.
Posted on: 07 November 2015 by George F

I am sure that when people report that a change in quality in a given replay system has followed some physical change such as remaking the connections, mounting the equipment on a different support [or moving the equipment about on the support] or even exchanging one component for another [including different connecting wires], that the report of the change is true.

 

In some cases the change would be obvious to someone who did not what change had been made, and in other cases the change might well pass unremarked or even un-noticed. I do think there are times when some changes are really to be put in the category of the placebo effect, but if the effect makes the systems owner happy, then who am I to disagree. I am all for enjoying the simple pleasures in life! 

 

I am not that convinced by the changes brought by running in over months for example. They may exist but whose aural memory is so accurate as to be able to sense such changes given the far wider swings in the state of the listener him or herself? The time of year [dark or light evenings] ambient temperature, the health of the person, the mood of the person and so many factors ...

 

It will be clear that on first turning on a brand new piece of equipment the sound is often rather pinched and hard and soon improves to something much better. After a day or so, I would say that any further changes for the better are most likely outweighed by the factors I mentioned in the previous paragraph.

 

I remember going back ten years I was told that a certain new piece I had would certainly improve over months! I believed it and convinced myself that in spite of the points already mention - but at that time not thought through by me - I could detect this long term improvement, however unlikely it seemed. 

 

Since then I have had two new Naim pieces, and I never considered it as by day two the whole lot had settled down so nicely. I then set about analysing why I could not detect this long term improvement, and concluded that I had forgotten about the possibility, and therefore had not looked for it. 

 

The very act of seeking it out can itself be convincing enough.

 

ATB from George

Posted on: 07 November 2015 by Innocent Bystander

IIRC some manufacturers do a 'soak test for anything from a day to a week. That should take care of any significant initial 'burning in' of components, and I wouldn't expect ANY further detectable change in the short term with such gear. aNd any quality manufacturer of expensive gear should surely do such a soak test, both for the primary purpose of ensuring that any faulty components or joints manifest themselves before supply to the consumer, and to ensure the consumer gets the equipment already at its normal operating standard.

 

which leads me to an interesting query: if the process is not predominently psychological, whether that be getting used to and accepting the different sound. Any other psychological explanation, why invariably is it reported that changes are for the better? Surely if it is components changing value slightlymor even mechanical shifts, it is likely to yield a proportion of cases where the result is a deterioration, yet i have never heard such a report?????

 

Posted on: 07 November 2015 by Dave***t
I seem to recall DB's long term Statement reports, which I enjoyed reading, mentioning periods of deterioration mixed in with the positive improvements. And I mentioned that the changes I heard upon messing about with things weren't entirely for the better. So perhaps not exclusively positive reports, but you're right, in the main it's one way street according to most people.
Posted on: 07 November 2015 by Ebor
Originally Posted by George Fredrik Fiske:

The very act of seeking it out can itself be convincing enough.

 

I am sure that can be true. However, George, do you think it possible that the reverse could also be true? That you convincing yourself that burn-in after an initial day or so is impossible means that you convinced yourself that there were no changes in the sound? After all, if auditory memory is as fickle as you suggest (and I'm sure it can be), surely any claims of being certain there are no audible changes should be treated as skeptically as those that claim the opposite.

 

Mark

Posted on: 07 November 2015 by CharlieP

Interesting hobby, this...

Posted on: 08 November 2015 by Simon-in-Suffolk

Indeed i think a fair amount of the burn in or bedding in over an extended period of time is in the mind..

Sure there are initial significant changes as components warm and charge, and clocks stabilise and reduce their noise, and physical connections and cables become de stressed.. But in my experience, other than with speakers, this usually happens within 3 to 4 days... and applies to new and often old equipment.

Thereafter once the components are in their 'quiescent state' there will continue to be changes as ultimately both the electronic and mechanical systems are dynamic, but it will be usually subtle and just as likely to be for the negative as positive.

Simon

 

Posted on: 11 November 2015 by Dave***t
Just as a coda to this thread, despite some initial improvement, the glass had to go. Seems that in my case, bare IKEA Corras is better.

So, given that trying it under my 250 seemed too much of a faff, the shelf is now serving as a purely aesthetic platform for my (seldom used) turntable. Still, worth trying it out. Just goes to show that racks etc can make a difference.
Posted on: 11 November 2015 by George F
Originally Posted by Ebor:
Originally Posted by George Fredrik Fiske:

The very act of seeking it out can itself be convincing enough.

 

I am sure that can be true. However, George, do you think it possible that the reverse could also be true? That you convincing yourself that burn-in after an initial day or so is impossible means that you convinced yourself that there were no changes in the sound? After all, if auditory memory is as fickle as you suggest (and I'm sure it can be), surely any claims of being certain there are no audible changes should be treated as skeptically as those that claim the opposite.

 

Mark

Dear Mark,

 

I am sorry to reply rather late! I have only just seen your post.

 

The one thing that I am not certain of is any absolutes in this. More than ten years  - fifteen actually, where does the time go! -  ago I first bought some new Naim and was assured that if I really liked them now, just wait a few months!

 

Of course I was so pleased with my new Naim pieces and I duly noted the improvement over months. When I bought my V1 and NAP 100 soon to be three years ago, I was delighted from the start. Certainly by day two it simply wonderful. I forgot to notice any improvement over months, though I have always noted that on a nice day when I am not tired and in good condition, the music is always better enjoyed. One thing I am sure of is that the condition of the listener is far more important than any noticed or not noticed improvement over months from new.

 

I am not being dogmatic, but rather working from experience of my own twice running in Naim pieces from new. Of course there is something else I have just thought of. First time I was also running in new speakers, and I am prepared to believe that physically moving cones may be subject to more obvious improvements than electronic pieces over weeks at least - possibly longer if you are not a loud music person!

 

This may be the reason why this time it was delightful after only a day. The ESLs were, shall we say, in the first bloom of youth after a service four years ago and so were completely run in at the the the time the V1 and NAP 100 arrived more than twelve months later ...

 

I think that explains the difference in all probability!

 

Thanks for your point made!

 

Very best wishes from George