Do DACs need a running in period?
- Thread starter avole
- Start date
sergeauckland
pfm Member
Quite so. New electrolytic capacitors, if they have never had voltage applied, might take a few minutes to form, but I would expect any piece of electronics to have been at least tested, so the capacitors would have formed.
Valves, especially power valves might need a few minutes to gas fully from new, but that's about it. Nothing else needs any "running in" as nothing changes in a few hours.
The cynic in me suspects that the 200 hour burn-in is a way of protecting the manufacturer or their dealers from people bringing stuff back...."You don't like the sound, take it back home, you haven't run it in yet, come back after 200 hours"........"You don't like the sound, well sorry, I can't take it back now, as it's not new any more".....
S.
Valves, especially power valves might need a few minutes to gas fully from new, but that's about it. Nothing else needs any "running in" as nothing changes in a few hours.
The cynic in me suspects that the 200 hour burn-in is a way of protecting the manufacturer or their dealers from people bringing stuff back...."You don't like the sound, take it back home, you haven't run it in yet, come back after 200 hours"........"You don't like the sound, well sorry, I can't take it back now, as it's not new any more".....
S.
onlyconnect
pfm Member
I suspect most "burn-in" is to do with our ears/brains becoming accustomed to the sound.
Tim
Tim
Do a preamplifier need running in? A dac has a built-in preamplifier...
tof
pfm Member
agreed !
Cereal Killer
432
Personally, I think running in does exist in a few things but it can't make a crap product sound good. It may make something like a 5-10% improvement. It is more apparent with speakers though.
JohnW
pfm member
I can say that OUR CD / DAC's DO need running in - there a substantial change after about 12 hours that appears to happen very rapidly over 1 - 2 CD tracks. The unit continues to improve over then next 24 hours.
As the effect is quite drastic - I can only put it down to changes in the capacitors. We use organic capacitors within our design - I wonder if these go though some internal physical / chemistry change.
The ESR of capacitors becomes lower and flatter / more extended as they are warmed-up - but this would hardly explain the "rapid" change that happens at around 12 hours – as “thermal changes” have a slow gradient in the longer term – within a couple of hours the unit reaches its “thermal equilibrium” – its operating temperature.
Typically, a cold unit will sound - well COLD! Hard and bright, closed in sound stage.
It happens repeatably, that there’s no question in my mind to its existence - rather what’s its cause.
I do suspect it related to ESR of Capacitors, as when upgrading a design to low-ESR capacitors, the effect is not so pronounced (the "12 Hour rapid change"). But changing to Low ESR caps. also effects many other parameters of the capacitor and indeed the circuit, so it’s hardly a "Controlled test".
But I will say that a run-in / warm up period is VERY important for my own designs (and I'm sure others) - But I cannot say for certainty why.
Once a unit has been “Run-in” and is used “often” then they seem to warm up within 30 minutes to an hour. I don’t normally switch off my units – only if we are leaving for an extended period.
John
As the effect is quite drastic - I can only put it down to changes in the capacitors. We use organic capacitors within our design - I wonder if these go though some internal physical / chemistry change.
The ESR of capacitors becomes lower and flatter / more extended as they are warmed-up - but this would hardly explain the "rapid" change that happens at around 12 hours – as “thermal changes” have a slow gradient in the longer term – within a couple of hours the unit reaches its “thermal equilibrium” – its operating temperature.
Typically, a cold unit will sound - well COLD! Hard and bright, closed in sound stage.
It happens repeatably, that there’s no question in my mind to its existence - rather what’s its cause.
I do suspect it related to ESR of Capacitors, as when upgrading a design to low-ESR capacitors, the effect is not so pronounced (the "12 Hour rapid change"). But changing to Low ESR caps. also effects many other parameters of the capacitor and indeed the circuit, so it’s hardly a "Controlled test".
But I will say that a run-in / warm up period is VERY important for my own designs (and I'm sure others) - But I cannot say for certainty why.
Once a unit has been “Run-in” and is used “often” then they seem to warm up within 30 minutes to an hour. I don’t normally switch off my units – only if we are leaving for an extended period.
John
It begs the question as to why you would choose not to run them in before you release them. I don't know of any manufacturer who does this either which would indicate that 'cold' products are not going to hinder sales.
sergeauckland
pfm Member
John,
This, coming from someone with your reputation, offers some valuable information. Have you measured what the changes are? Can you put some numbers to what changes?
My own design experience goes back many years to the '70s, when I never found any change in performance with burn-in although for reasons of reliability, we soak-tested everything for several days defore despatch so our products were down the bathtub curve of failures.
I recently had an experience with a large electrolytic capacitor that I found in my junk-store. This capacitor was unused, but had been stored for 30+ years. I put it on a bench power supply and measured the leakage, which took some 48 hours to reduce to a very low level, typical of electrolytics. After that it was fine. However, this is unusual, and different to what we're talking about here.
A 30 minute "warm-up" seems very long, something is obviously changing, if the sound changes, it would be interesting to find out what it is....and design it out.
S.
tomek
pfm Member
Pete the Feet
pfm Member
I experienced the same with a Rega Planet cd player years ago. The dealer at the Audio Counsel warned me about it and said it wouldn't sound like the one in the shop when I got it home and he was right. Two weeks he reckoned of "normal" play and it would be okay. After 3 days of "continual" play with the volume off the difference was unbelievable.
After the initial burn in had been done it didn't take long to warm up from cold though.
If all suppliers were to run the product in then I think the price of said product would double.
After the initial burn in had been done it didn't take long to warm up from cold though.
If all suppliers were to run the product in then I think the price of said product would double.
So why are CD players or DACs different, then? How come amps and preamps don't need running in?
sergeauckland
pfm Member
This is what mystifies me about John's designs, which he himself, as the designer, says need a period of burn-in, then 30 minutes warm-up. What changes in that time, and why? Shouldn't it be identified and then designed out?
S.
Steven Toy
Accuphase newbie
There was quite a dramatic change midway through a track about 40 minutes after switching on my CDQ following its OLED/transformer upgrade.
Serge,
Embrace the possibility that we have not yet found a way to measure all that we reliably and repeatably can hear.
Serge,
Embrace the possibility that we have not yet found a way to measure all that we reliably and repeatably can hear.
sergeauckland
pfm Member
Nonsense. If we can hear it, we can measure it. If a change is audible, then some parameter has changed, whether distortion, noise, frequency range or whatever, but something must be different. Consequently, it can be measured.
S.
john dolan
pfm Member
Burn in is real ive heard it many times with different products.
Ive got a old dac in a box that takes a age to come on song and its not just dacs.
My Tom Evens pre takes days to sound good and also made a few passive preamps with stepped pots that take many hours to lose the hard shiny edge they have when new.
Ive got a old dac in a box that takes a age to come on song and its not just dacs.
My Tom Evens pre takes days to sound good and also made a few passive preamps with stepped pots that take many hours to lose the hard shiny edge they have when new.