Warm up times

[Alrainbow]

in trying to not have stuff on when I am not home I turn my system off. It has many components
5 nas drives and many other devices. It's all fed from a 10 kva ISO transformer that does 208 to 125 volt completely isolated from the house. I found that the quiescent current is about 6 Amps with almost nothing running
no Amps just the nas and my msb stack
so my question is when I turn it on it takes way more than an hour to settle in. This includes my caps but it's not the caps that's bad sounding
my system is compleltmy solid state except for one dac
and I have found that tubes seem to be fine in just 15
mins

but it seems solid state takes much longer. Any advice or other opinions of time for warm up ?

[kcin]

Well, solid state devices have different thermal coefficients and different amps have varying bias schemes that impact the stasis of the amp at different times with different thermal management systems. And if you have mosfets their transconductance actually varies with temperature so there are two variables at play there.

So not only do caps need forming but your solid state devices will be affected by temperature as well. While I run mostly tubes, my Bedini class A is very affected by operating temp and sounds like dreck until it gets hot enough to cook on.

[1morerecord2clean]

I don't turn mine off generally. My Pass Labs amp is in standby and my ifi Phono has no on off switch so it is intended to be on all the time. Of course if you are away on long biz trips then you could be inclined to turn off power. Yes, I find SS gear often has a long warm up period.

[Alrainbow]

Thanks all
some of this is just to keep what little sanity I have left lol. To say it's horrible is an understatement
and in this maddening hobby I often wonder how much is real and how much is fantasy.
Thanks

[kcin]

Hi, thermal stabilization is very real for solid state devices . It is definitely not your imagination. If you go over the Pass labs DIY site with Nelson Pass and do a search you will see his thoughts on the subject .Many of us will have varying opinions on his designs but there is probably little argument that he has a very good understanding of consumer based audio amplifiers and design principles that he has been willing to share over many years- for that he has my respect.

[cpp]

I generally leave my DACS and CD's players on all the time unless we have a regular power failure. My amp, pre-amp, TT and phono I turn them on about 1 hour before I play any tunes. Why a hr, not sure, it seemed like long enough for tubes and internal SS electronics to get to an operating temperature.

ps: good topic

[Alrainbow]

Thanks I owned and built a few Amps of his. For headphone use. He is a very tslented man. Unfortunately his sound type of Amps is not neutral so for headphones it was not for me. He had ones that were constant current as well something not many Amps do. His stuff is large and very cool
looking lol.
my msb dac takes a little time too. But my lampi does not seem to take much at all.
now I also use small personnel Amps and caps they don't seem to need as much time really none at all in most cases. This makes me wonder why ?

[Rust]

Al - a small amplifier has fewer and smaller components to thermally stabilize on startup compared to a honking big piece. The more parts, the more things change until things thermally stabilize, that is warm up to operating temperature.

As mentioned in a previous post, transistors are affected by temperature, their transconductance characteristics change with temperature. One new trend in transistor amps has been the use of thermal tracking transistors to adjust bias to suit the temperature of the transistor in real time. Temperature can change rapidly from soft passages to loud peaks. I don't know how much difference that might make, the only way to tell would be to review/test such an amplifier modified so that feature could be enabled/disabled as needed for comparison.

I think that in the case of some amplifiers with a large number of transistors in parallel in the output stages, the transistors do not warm up at the same rate and thus have slightly different transconductance curves. Circulating currents? Slightly different rise times/slew rates? I don't know. I believe it is Gamut which uses two very large MOSFET transistors per channel to minimize such interactions which certainly makes sense on paper.

But I suppose all of that is why there are so many brands and multiple designs even within a brand, no consensus of a single best solution exists.

[Alrainbow]

I can say this of the many times I posted such findings yours and others here have really made me understand it.
Now of ok may I ask what is your thoughts on burn in or run in. And before you answer consider this why is it always better lol.

[MylesBAstor]

I think it depends on the equipment and it depends upon the equipment.

DACs take at least 24 hrs to start to sound right.
Tube gear depends upon the design. cj takes about an hour to sound good but for instance the GAT sounds better being left on overnight. The biggest change I hear with the cj tube gear is the appearance of air and space. Cold, not so much; after an hour, you know why cj is so special. But not going to wear my tubes out. Designs with interstage coupling transformers took hours to sound good. Don't know about the newer models but the old VAC Renaissance and Audio Note amps took about 3-5 hrs to sound their best.
Cartridges usually an hour of playing.
SS never turn off. There was a sizeable difference in sound for example between the AF amps cold and 24 hrs later. Among other things, the amps sounded much warmer (NPI). Also much smoother.
Electrostats take 24 hrs in general to charge up and stabilize. Before that very thin and undynamic.

[Rust]

Al - Burn in, run in, break in usually refers to new components.

Speakers definitely break in. Danny Richie wrote an article on it. He took new drivers out of the box and measured their electrical characteristics while being driven. As hours of operation increased their electrical characteristics changed. This was attributed primarily to mechanical changes to the spider and surround "breaking in". When turned off with relatively few hours on them, the speakers started to revert to their original condition although they did not fully revert. With more hours on them they reached an new equilibrium, not a point per se but more of a general area.

Capacitors to me are problematic. In certain power plant control equipment left powered down for long periods of time, electrolytic caps can loose their "form" which is a problem unless voltage to the equipment is very slowly ramped up to full operating voltage to reform, they let out the magic smoke on which they operate. Tantalum capacitors are much more reliable and preferred in this regard. Electrolytic caps also have a tendency to leak due to thermal cycling (expansion and contraction). Their values can also change over time. Of course more expensive exotic caps are better in this regard. In audio equipment the final arbiter is sound quality so the tradeoff may be better sound over warmup/forming time or even long term reliability. Finally a lot of capacitors do break in, that is reach their final electrical characteristics as they fully form.

Inductors change their characteristics too. Primarily from heat, but I can positively state that they can degrade over time, the permeability of the core can change over forty years. Long story, not audio equipment but very large magnetic amplifiers and if you don't know what one that is an entirely different conversation.

But I believe that the bottom line is things age or cure from a new condition to a long term stable condition. Not to be confused with going from a cold start to a warm operating condition. I also believe that in many instances break in is overstated and that often it is the ears acclimatizing to a new sound. YOMV (Your Opinion May Vary).

[JCOConnell]

On my second system, which I listen to the most of the time and is all solid state, I just leave the preamp and pwr amp on all the time.

[Alrainbow]

Thanks all.
For me first hand caps do change as I have rolled caps in headphone Amps and dacs to fine tune the sound scape I like. Mundorf caps be it silver , copper and in general have a type of sound thats not hard but still is dynamic
now I do have a theory on burn in too so I will post it now
in haveing many types of devices rolled in my systems I feel its not just the device burning in. I also feel it's us.
When i receive a new dac per say it takes me a while as in days to completely hear what has changed
it's fairly easy to hear some changes but to get it all takes a bit. Rolling many tubes has shown me this. Tubes that are nos have long been burned in and while a simple quick change yields many clues it takes some time for my small brain to completely zero in. Does anyone else feel this way ?

[MylesBAstor]

I can say this of the many times I posted such findings yours and others here have really made me understand it.
Now of ok may I ask what is your thoughts on burn in or run in. And before you answer consider this why is it always better lol.

These were my thoughts. I now have the newer Cable Cooker that treats the cables in less time.

Oh and BTW, I used the cable cooker to burn-in capacitors too. You just treat them as if they were speaker cables. So instead of having to wait a couple hundred of hours, the capacitors are ready to be soldered into the board say in 2-3 days.

Same goes for phono cables and tonearm wiring that without burning in is never fully ready for prime time.

[Barry]

It took a week to burn in these big Duelund Cast Pio speaker crossover caps on a Cable Cooker. That was after trying to run them in with 500 hours of listening which did not work.