Do a preamplifier need running in? A dac has a built-in preamplifier...Just idle curiosity, that's all. I can't see that they do, but have read reports that some need up to 200 hours. If that is so, I'd love to know why.
I suspect most "burn-in" is to do with our ears/brains becoming accustomed to the sound.
Tim
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 ours 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 theres no question in my mind to its existence - rather whats 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 its 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 dont normally switch off my units only if we are leaving for an extended period.
John
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 ours 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 theres no question in my mind to its existence - rather whats 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 its 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 dont normally switch off my units only if we are leaving for an extended period.
John
Once a unit has been Run-in and is used often then they seem to warm up within 30 minutes to an hour. I dont normally switch off my units only if we are leaving for an extended period.
So why are CD players or DACs different, then? How come amps and preamps don't need running in?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.
So why are CD players or DACs different, then? How come amps and preamps don't need running in?
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.