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Do Solid State stereo amps needs "warm up" time to sound good?

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Old 14th October 2013, 09:45 PM
 
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Do Solid State stereo amps needs "warm up" time to sound good?


Friends,

Do Solid State stereo amps need a good warm up every time you "cold" start it? Meaning you switch it on after they have been kept off for a while (more than 8 hours) and you have to play it for 30-45 minutes before it sounds good?

I have an Acoustic Portrait SS power amp and it needs a good 30-45 minutes of playing to start sounding good. When I do a "cold" start , it sounds very thin and bright. The bass and mid range shows up after 30-45 minutes .

I also noticed that I can hear a feeble humming sound from the speakers when no signal is fed, like a tube amp. The humming/distortion sound is heard from both the speakers.

Does the above symptoms sound like there might be a leaking / weak Cap in the amp that needs replacement?

Thanks,
John.
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Old 14th October 2013, 10:33 PM
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

While it is true that solid state circuits have a warm up period, the aural effect is negligible, as all of the components have stabilized at their nominal operating parameters within about a minute of being turned on. However, unless the circuit is being used in a lab to take measurements that are of microscopic magnitude, the time between when the circuit is charged, to when it reaches full equilibration, is not important. The changes just cannot be heard by most people. Furthermore, if there is a very noticeable change in the quality or magnitude of the sound during warm up, then it's likely there may be a problem with that circuit to begin with.

So, are there measurable differences in the output of a solid state amp from the time it's turned on, to the time it has thermally stabilized? What is the engineering basis for this if there is?

Caps values and ESR shifts when it heats up??? And this is because of capacitors charging and transistors coming up to temp? As for the warm-up time, most transistors are likely to be operating well within their margins, so they will probably heat up slowly to the steady state operating temperature.

So leaving it on all the time is a good practice. Amps also take time to break in - may be months! Leaving it on also stabilizes the operating point. So when you want to listen, it is ready. The only negative thing about this is that in countries where the power fluctuation is very bad it might kill the amp if you get spikes or high voltage often. So you will have to do this judiciously.

My contribution to this thread is that I suspect that a "cool" amp is less sensitive compared to a "hot" one. So, experiment for yourself. If you hear a difference in the sound after the amp has "warmed up," then go with what you hear, and not with what I say. Your ears are the final arbiter in this discussion.

Cheers.
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Old 14th October 2013, 11:01 PM
 
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

Thanks for the excellent explanation. I do hear a significant difference. But I have to make sure if its my ears getting used to the original sound after 30-45 minutes or there is a difference. I will have another pair of ears access the same. I would attribute the difference in the quality. I feel the sound is getting more 'beefier' after the first 30-45 minutes. When it starts, it plays pretty 'thin' and 'bright'. The magnitude / volume level is not changed when the amp is warmed up. And the speakers are also old and they have properly run in. I felt the same issue with multiple sources. Initially I thought it was my new Oppo 105 taking time to warm up. I tried it with my 3 yr old Project TT -> Denon and Denon Pre outs -> AP Amp and felt the same behavior.

Also I hear a humming / distortion sound from the speakers when there is no signal. I think I should talk to Shiva from AP and find out whats going on.


BTW, the amp is quite old and has been properly run-in. I bought it used from a FM and I think i am the 3rd or 4th owner .

Thanks,
John.
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Old 14th October 2013, 11:30 PM
 
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

Quote:
Originally Posted by hydrovac View Post
Amps also take time to break in - may be months! Leaving it on also stabilizes the operating point. So when you want to listen, it is ready. The only negative thing about this is that in countries where the power fluctuation is very bad it might kill the amp if you get spikes or high voltage often. So you will have to do this judiciously.

My contribution to this thread is that I suspect that a "cool" amp is less sensitive compared to a "hot" one. So, experiment for yourself. If you hear a difference in the sound after the amp has "warmed up," then go with what you hear, and not with what I say. Your ears are the final arbiter in this discussion.

Cheers.
While I could understand the heating up concept I can not reconcile to the fact that a number of people recommend breaking in of solid state Amps!

What could be the technical reason - there are no moving parts?
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Old 15th October 2013, 12:00 AM
 
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

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Originally Posted by jagdish_p View Post
While I could understand the heating up concept I can not reconcile to the fact that a number of people recommend breaking in of solid state Amps!

What could be the technical reason - there are no moving parts?
I mean this as a genuine question and not a "comment". I've tried to understand the rationale and basis of "breaking in" and in many cases, it makes sense. Mechanical and electrical components can have changes in their specifications and characteristics as they are used.

However, my question is, if the specifications change with usage, why is it that almost universally, the change happens for the better. In other words, why does the process of break-in almost always end improves the sound and never ends up distorting or worsening the sound?

Conversely, why do manufacturers sell us products that are out of spec? We spend a ton of money buying expensive audio components with the assumption that they will be well engineered. And a well engineered product should be "in spec" when you buy it. Other electronics that are far cheaper are manufactured with much better tolerances and QC.

Imagine if your refrigerator needed to run for 500hrs before it properly cooled and froze your food. It has more mechanical components than your amp (and is probably cheaper too).
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Old 15th October 2013, 12:30 AM
 
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

I dont have any technical explanation but my odyssey stratos amps sounds totally different after being kept on for about 1. 1.5 hours

Everything in sound changes for good. Infact the manufacturer recomends to never switch off the amp. But its not possible for me to do that

What i have read that its something to do with power caps being completely charged snd then the true sound of amp is heard
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Old 15th October 2013, 12:58 AM
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

Quote:
Originally Posted by jagdish_p View Post
While I could understand the heating up concept I can not reconcile to the fact that a number of people recommend breaking in of solid state Amps!

What could be the technical reason - there are no moving parts?
Well, its the people who recommend breaking in of amps, not the manufacturers. If it was required, they would have stated so in the manuals. Sometimes, you would see this breaking in for few days recommended by dealers. You are most likely out of the return window by then.

John: Most of the time, its psycho accoustic playing the tricks. Same way as the car feels smooth after oil change. The only way for you to know if the frequency response is different is measure it - when its cold started and then after the warm-up. So far, nobody has proven it scientifically how it affects. Indeed, if warmup was needed, manufacturers would have mentioned it in the manual.
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Old 15th October 2013, 01:31 AM
 
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

Quote:
Originally Posted by rikhav View Post
I dont have any technical explanation but my odyssey stratos amps sounds totally different after being kept on for about 1. 1.5 hours

Everything in sound changes for good. Infact the manufacturer recomends to never switch off the amp. But its not possible for me to do that

What i have read that its something to do with power caps being completely charged snd then the true sound of amp is heard
You may be right - I don't know. But a cursory google search indicates that capacitor charging and discharging times are in the order of micro and milli seconds. So I'm not sure.

Maybe the circuit operates better at higher temperatures??

It still mystifies me why the sound always changes for the better.

Psychoacoustics cannot be that consistent and that strong a factor, right? I mean, take other examples. Do you feel that the sound in a movie theater or a music concert significantly improves after a period of time?

No, right?
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Old 15th October 2013, 07:51 AM
 
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

Quote:
Originally Posted by asliarun View Post
You may be right - I don't know. But a cursory google search indicates that capacitor charging and discharging times are in the order of micro and milli seconds. So I'm not sure.

Maybe the circuit operates better at higher temperatures??

It still mystifies me why the sound always changes for the better.

Psychoacoustics cannot be that consistent and that strong a factor, right? I mean, take other examples. Do you feel that the sound in a movie theater or a music concert significantly improves after a period of time?

No, right?

I am not at all sure, but with a movie theatre or a concert all the concerned equipment is kept on long before the actual show starts.

Maybe that's why one does not experience any improvement as the show goes on as it has already reached optimum levels

As I said earlier I don't have any scientific backing to prove my point.

But with my regards to my setup, I have experienced it several times in the last almost three years of owning the amp that sound reaches another level after a warm up around two hours
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Old 15th October 2013, 08:15 AM
 
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Re: Do Solid State stereo amps needs "warm up" time to sound good?

Quote:
Originally Posted by rikhav View Post
I dont have any technical explanation but my odyssey stratos amps sounds totally different after being kept on for about 1. 1.5 hours

Everything in sound changes for good. Infact the manufacturer recomends to never switch off the amp. But its not possible for me to do that

What i have read that its something to do with power caps being completely charged snd then the true sound of amp is heard
There are two aspects being discussed here - the improvement in SQ after a warm up period of around 1 hour has been explained by FM Hdrovac in this thread. To me it sounds logical as its a known fact that the characteristics of the circuits change with temperature and the manufacturers design their circuits for steady state operating temperatures.

My skepticism is about the need to break in a new Amp over a period of time for a few hundred hours. I can understand this requirement for speakers as they have a moving coil with very close tolerances but the same should not be applicable to Amps and some people even recommend this for Cables!


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