[patricklang]

I'm starting my first opamp rolling adventure, how long do you think each of these opamps need to be run before the sound is pretty consistent?

I've been listening to an AD8620 in my Meta42 for the last year and know its sound well. I'm hoping to warm up my K501's just a little bit, so here's what I bought for the journey:

AD8066
OPA2227
OPA2228

The Meta42 that I'm rolling on has 2 EL2001cn's per channel, including ground. Power is a pair of 9v's.

Later this week I'm doing an experiment involving a bass boost based off ppl's design that he ships in the LaRocco PPA. It will hopefully provide that little extra kick I miss from the Grado's on my electronic cds.

 

[Stephonovich]

I'm no genius, but I can't see a digital component needing any warm-up time, barring capacitor charge time. Tubes are one thing; just ask any guitarist who uses a tube amp. But solid state?

 

[Sycraft]

That's one of those weird things in the voodo realm of audio. I've never seen any emprical studies either way. However it's not just a belief of a few hardcore audiophiles, my Hafler amp states that it should be powerd on for an hour before it gives best sound. Well, Hafler is a pretty serious company overall, they made stage and studio gear, not audiophile stuff. They aren't afraid of telling you how their stuff works, and indeed the amps come with a complete circut diagram and parts list.

Now of course that's warm up, not burn in. As for burning, I don't know. I'm skeptical it does anything on electronics. On moving parts, I could see it. It does make sense materials could be a little stiff and need working in.

Who knows? Some people claim there are dramatic differences, some claim they don't hear anything.

I guess I'd say that for those that do think it makes a difference, they might as well as it doesn't hurt anything and, generally speaking, if you think something is hurting sound, you'll get hung up on it and percieve it as bad.

 

[Earwax]

My ears tell me that solid state gear often needs about 5 minutes of warm-up time to settle in to its' normal sound. Which makes some sense if you have components that warm up with current.

I've built a number of DIY amps and I think I've heard "burn-in" changes in the first hour or two of operation. If anything changes after the first couple of hours, it's too subtle for me to pick up.

I've read that capacitors need some number of charge/discharge cycles to reach their normal operating mode. I'm unclear on how that's supposed to translate into minutes/hours of operation or in what cases those changes are large enough to be audible.

 

[patricklang]

Quote:

Originally Posted by Stephonovich I'm no genius, but I can't see a digital component needing any warm-up time, barring capacitor charge time. Tubes are one thing; just ask any guitarist who uses a tube amp. But solid state?

Well, opamps aren't digital

Solid state devices do need to warm up a bit, heat changes the properties of semiconductors, especially increasing resistance. Most reach a relatively stable temperature level after a few minutes.

I've heard reports of Burr-Brown opamps sounding better after a 'burn-in' period, which I might attribute to repeated thermal fatigue from powering up, and cooling down. I've seen this personally when overclocking microprocessors, I hit higher clock rates once the chip was about a month old.

 

[BrokenEnglish]

i know it's hard to believe, but every time i rolled new or even used opamps in my ppa they needed 4-7 days (with 24h/d of music) to get settled in... i noticed bigger changes (tonality, dynamics, depth) in the first 4 days, slighter ones even after day 5. i used to be very sceptical about all that audiophile or audiophilistic habits rumoured around here before that experience... strange thing...

 

[averydonovan]

I found it helps to leave my PIMETA on for a few minutes before I start listening to it. It may have something to do with the fact that the OPA627 opamps are biased into Class A and that the BUF634 buffers are in full-bandwidth mode, so the transistors need a little time to warm up. When I'm using my PIMETA I just tend to leave it on all the time.

 

[roadbuster]

Quote:

Originally Posted by Stephonovich I'm no genius, but I can't see a digital component needing any warm-up time, barring capacitor charge time. Tubes are one thing; just ask any guitarist who uses a tube amp. But solid state?

As patricklang already mentioned, op-amps are not digital in nature. While
they can be used to amplify a "digital" signal, they're inherently analog
amplifiers. As well, since the resistance and junction capacitance of an
op-amp are temperature-dependent, they *do* have a warm-up time.
Whether this warm-up time is significant for the op-amp's performance is
debatable, however. That said, the rest of the capacitors in the amplifier are
temperature-dependent, as well, and it's sometimes a good-idea to let those
get warmed-up before performing any amp comparisons. If you have a room
temperature of 25°C and the operational temperature of your film capacitors
is 75°C, and your film capacitors are rated at P220, they're going to have a
1% higher capacitance after warm-up. Does 1% matter? Considering the fact
that people here are willing to pay $15 for a pair of RCA jacks, I'd say that at
least a few of you would consider a 1% variation to be significant.

 

[jnewman]

Quote:

Originally Posted by roadbuster Does 1% matter? Considering the fact that people here are willing to pay $15 for a pair of RCA jacks, I'd say that at least a few of you would consider a 1% variation to be significant.

$15? There are RCA jacks out there that cost almost $100 a pair

.

And also people who match things far beyond 1%.

 

[bpribadi]

Interesting! Let's see if your finding matches mine:
http://www6.head-fi.org/forums/showthread.php?t=84519

From my experience, the discrete components sounds better after around 3 - 10 hours burning in. But Op-Amp almost no difference, probably very little.

 

[roadbuster]

Quote:

Originally Posted by jnewman $15? There are RCA jacks out there that cost almost $100 a pair . And also people who match things far beyond 1%.

There are a lot of suckers out there, too.

BTW, what I was talking about isn't a matching issue. For example, if the
capacitors are already matched and have the same thermal coefficients, then
they'll both remain matched if they remain at the same temperature. It's more of
a question of, "how is a 1% higher capacitance going to change the
performance of this circuit? Will -3dB roll-offs change? Will the differences be
audible?" and so on and so forth.

Ideally, you would have just about every component at 25°C, and all wires &
resistors at absolute zero.