Do you leave your DAC powered on all the time?

[esldude]

At one time good DACs seemed to need to reach an equilibrium to sound best.  Some said it was the clock stabilizing and jitter reducing as a result.  There are other possible effects.  It sure seemed to matter with some I have had in the past.  They seemed to take a couple days to warm up to equilibrium.  I may have been the audiophool then, a couple seemed to take a week.  When power went out I groaned for it would take days for my best sound to return.

 

I have had other gear, power amps or preamps that might take a half hour or even a few hours, but DACs seemed the worst.  In those days I just accepted it as so. 

 

Seems modern DACs are less touchy about this though not completely turn on and have top sound in two minutes. 

 

I have measured using a Jtest and seen that cold the first couple minutes DACs do have a bit more jitter, and some have a tiny bit more distortion.  The newer ones seem to reach final stable levels after about 30 minutes.  I haven't been rigorous about this.  When I checked and a Jtest was clearly worse cold vs 15 minutes later it looks to be at least plausibly true though the apparent jitter levels still should be inaudible.  Then 30 minutes seemed as good as it gets.  I do have one older DAC and it does take about an hour for its jitter to fully calm down.  Again I wouldn't think it has enough to matter even cold.

 

So in my audiophool days it seemed real and I believed it. There is at least a grain of objective truth devices need to warm up for stable function.  Can we really hear that?  I don't know.  If people took part in listening tests I would put up files recorded dead cold vs one week on.  Just for discussion and entertainment.  I have found people like to argue about what they hear more than simply listen and choose.  They seem intimidated by actually choosing with the risk of being wrong. Even though the only downside to choosing wrong is a little loss of face paired with really learning something.  Seems like a good bargain to me.

 

When I have recorded various files for people to argue over, I don't do any recording until everything has been on for two hours. 

 

Yet when I record people playing music, I have at times needed to setup, get ready, and start recording when the gear has only been on a few minutes due to time constraints.  It hasn't been worse that I can tell.  Usually the second take by the musicians is a much bigger improvement.  Maybe they should warm up for 30 minutes.

[esldude]

I did some measures of warming up gear from cold today.

 

I started both an ADC and DAC from a dead cold start.  Ran some measurements immediately and then at 35 minutes, 63 minutes, and 114 minutes later.

 

The first surprise is timing and jitter.  Cold while I have no way to measure absolute clock speed, the clock rate difference between ADC and DAC was 81 ppm.  At 35 minutes it was 79 ppm and stayed at that speed. Using a quarter sample rate tone the sharpness of the tone and observable jitter sidebands changed not at all even dead cold compared to 114 minutes later.  I may post graphs of those later on.

 

The noise floor did drop nearly 5 db from cold to 114 minutes later. I guess analog circuits care more about warmup!

 

The 3rd harmonic of a 1 khz tone was -97 db cold, - 99.5 db at 35 minutes, 99.7 db at 63 minutes and 99.9 after 114 minutes.

 

The 1 khz difference with a max level 18 khz and 19 khz tone for testing IMD was -112.5 db cold, -114.5 db at 35 minutes, -115.4 db at 63 minutes and -115.9 db at 114 minutes. 

 

So it looks like analog circuitry benefits from some warm up at least for two hours.  Though the differences are not at all likely audible.  The big surprise is timing and jitter change very little and apparently stabilize quickly or at least less than 30 minutes time.

 

So my suggestion would be turn your DACs off.  No need to leave them on forever.  One less thing to obsess over.

 

 

[esldude]

I said I would post some graphs of jitter levels in my prior post.  I listed differences between warmup and 2 hrs of operation which mostly looked to be in the analog circuitry.  I expected clocks would be picky about settling down.  There was a minor change in clock rates over the first half hour.  I was surprised the quarter sample rate tone which will make some types of jitter visible showed no change between cold and 2 hrs later.

 

First is a 128K FFT of that tone covering 10 khz to 14 khz with the frequency of the tone centered on 12 khz. There are a couple spurs one at 300 hz above and below the tone, and one that fluctuates 392 hz above and below the tone.  Red is give or take a few seconds 2 minutes after turn on.  Green is two hrs after turn on (actually 114 minutes).

 

 

 

Here is a view close in that covers 12 khz plus or minus 50 hz.  A fairly good result.  10 hz away from the central tone the level is already down to about -100 db.  It is -80 db down at only 2.5 hz either side of the tone. Again red is cold and green nearly 2 hrs later.

 

[esldude]

To give an idea of what the last FFTs are showing here is one with red being the previous gear used for the warm up testing.  The green is all the same gear except a different DAC.  It has tighter control near the center of the 12 khz tone with less spreading at the base, but it has numerous spikes either side of it.  Though low in level they would be signal correlated.  First is the 4 khz wide view and then the close in 100 hz wide view.

 

 

 

 

 

[esldude]

30 minutes ago, STC said:

ESLDude, perhaps you could add the sound sample and let us hear the difference itself. Hearing is believing.

 

Like that has ever done anything other than cause arguments here on CA.

 

So are you wanting samples of the two different DACs (which actually I have already done in the past)?  Or the sound of cold vs 2 hours later?

 

Maybe I could do this one differently.  Post the two DACs, tell you which is which, and chances are few have heard either much less both.  Then people could describe the differences they hear.  In addition I could post a cold file and one 24 hours later for each and we could describe which one warmed up better. 

 

 

[esldude]

2 minutes ago, Ralf11 said:

label one A, the other B

 

Let people guess which is which - see what happens

Perhaps you missed when I posted two identical files and a copy of those.  Only to have people argue the two identical files sounded dramatically different.  One of them sounding much like the copy.  One not at all.