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

[hydrovac]

Hydrovac, Heck even your car mechanic will take a test drive of your car and will then make some fine tuning before finally giving it to you. Right?

I think there is an optimum temp at which an amplifier will perform at its best..... As the amp heats up the bias points align somewhat. Voltages stable etc etc. The DC bias on the output stage does change after it warms up. This effect is basic semiconductor physics, and all solid state amps will do it. Especially if they have electrolytic caps in the signal forward or return path. Also, the gain curves of transistors are temp dependent... Resistors have temp curves too.... Everything has a temperature Coefficient. It is more a question of how impactful its affect is...and not a question of the temperature has effect.

The effect this has on the audio waveform is also measurable, and shows up the most as a change in IM distortion, so it's not some snake oil theory. In reality I would expect it not to be audible. A 100% distortion increase from 0.001% to 0.01% is still not audible and any modern amp that drifts that much (in a quiescent state that is) has a circuit problem.

"Bias" is to your amp like "idle" is to your car. The bias is adjusted when the amp is warm and not playing (Input shorted), and the idle is adjusted when the engine reaches running temperature and is not moving (no motion). This has a great effect on operating performance.

Why? Is it the waiting time that bothers you or do you believe something is wrong with it if it needs to warm up? Just curious.

Cheers

 

[kanwar]

The design of some low priced digital amps involves some kind of AC-based variable gain device to drive the speaker output. I don't know a lot about it other than it's comprised of transformer coils. Transformers like this are made of very long copper windings and known to be heat sensitive components that settle in when they are first put into service. I could be butchering this explanation but that's my short version of a plausible explanation seen somewhere.
Cheers

Hydrovac,

What kind of explanation is that? Its grossly incorrect.

Can you elaborate more on the source, from where have you got this?

 

[john_k_antony]

Hi John,

Hum is not a good thing to have! Does the hum increase with the volume raised? Is it audible when music is being played? Does the hum go away after a while post warm up period? Does the amp have a 3 pin mains power cord?

Take the amp to Mr. Siva ASAP as he will be right person to diagnose best since the amp is made by him.

BTW, what pre amp have you paired the AP power amp with???

1. Hum doesn't increase with the volume.
2. Hum is not audible with music played. However I started to notice some disturbance during the first few minutes and it goes away after 2-3 songs. After 10 minutes, everything started to sound good and it reaches its best performance after 30 minutes.
3. Yes the amp has 3 pin power cord and I tested the grounding for my house electric circuit and its properly grounded.
4. I am not using any pre-amp now. I am using my Oppo-105 as the pre-amp as its got a simple pre-amp built it with volume control. The pre-amp is active when you use the analog outs and I am directly connected the dedicated stereo analog out form Oppo to AP amp. I will be adding the pre-amp soon as I am in the process of building the pre-amp myself. Its a DIY Pass-B1 pre-amp.

Thanks,
John.

 

[john_k_antony]

Why? Is it the waiting time that bothers you or do you believe something is wrong with it if it needs to warm up? Just curious.

Cheers

I was under the impression that SS devices doesn't need any "break-in" or "warm-up". I wasn't bothering it too much until I started to notice the hum in the speakers while no signal is fed. I was just wondering if the hum has something to do with the "warm-up" time required by the amp to reach its optimal performance. I was thinking if there is any bad Cap that needs a replacement.

Any way, I will take the amp to Shiva soon. It had been a while I met him and there is an audition pending at his place. So I will make a trip to listen to his new setup and also get my amp tested for the hum mainly .

Another OT dump question. Do you guys feel that your system sounds great on some days and other days you feel that "Hey this is not sounding good and I need to upgrade". Again the next day you feel that "Hey my system is sounding superb" .

Thanks,
John.

 

[manniraj]

Another OT dump question. Do you guys feel that your system sounds great on some days and other days you feel that "Hey this is not sounding good and I need to upgrade". Again the next day you feel that "Hey my system is sounding superb" .

Thanks,
John.

Oh yes I do feel that with my music playback, sometimes I feel that I am very satisfied with the music that is being played and on some days it looks like something is missing. I am not sure how but the feeling is right there, good that you brought it up :lol:

 

[john_k_antony]

Oh yes I do feel that with my music playback, sometimes I feel that I am very satisfied with the music that is being played and on some days it looks like something is missing. I am not sure how but the feeling is right there, good that you brought it up :lol:

All right there you go ... Glad to know that I am not alone .

 

[captrajesh]

I will be adding the pre-amp soon as I am in the process of building the pre-amp myself. Its a DIY Pass-B1 pre-amp.

Trust me, you will be happy you built it.

I once paired the B1 with AP Power amp. It sounded very good.

 

[john_k_antony]

Thanks captain. I read your old thread on that and that gave me the inspiration to actually try the build .

Will let you know once I finish it and play around with it with my AP power amp.

Thanks,
John.

 

[hydrovac]

Thanks captain. I read your old thread on that and that gave me the inspiration to actually try the build .

Will let you know once I finish it and play around with it with my AP power amp.

Thanks,
John.

Hi John,

Wish you all the best and looking forward to your B1 build.

Cheers
Krishna

 

[captrajesh]

I read your old thread on that and that gave me the inspiration to actually try the build .

Will let you know once I finish it and play around with it with my AP power amp.

Great to know that. Looking forward to your build.

 

[Tanoj]

Hi John

All the Best for your Pass B1 Build, i am using it since about a year now, and still going great

Reg the Burn-in topic, i would like to share my exp, sorry that it may sound little off topic

suppose if i think/wish to listen to new LP like Rang de basanti or sufiana etc.. i dont play this disc if my system starts from cold,

i mean i turn the system on and play some other Lp, which is not that popular , once both sides of Lp is done then only i play the disk which i actually intend to play ( Rang de basanti or sufiana )...

the reason is, i feel that the sound starts to open up and becomes airy after a while of playing .... now it can be everything in the chain, so cannot say which is the one which actually taking the time

it can be the cartridge , the turntable, the phonostate, B1 pre amp, or power amp , or may be my AP speakers

But i can bet it does sound an feel different and after 3-4 disks it gives me a feeling as if the needle is actually floating and not touching the record.

Regards

Tanoj

 

[john_k_antony]

Very interesting to know that I am not the only one who has experienced the need for "warm up" with SS devices paired with analog and digital sources.

I have absolutely no issue to wait for them to "warm up".

Another question, I think it might have been answered before but just to confirm, whether the SS components get the "warm up" just by keeping them in stand by mode or you actually have to play them at the the desired volume to get them warmed up? I will try this experiment myself, but just checking your experience.

Thanks,
John.

 

[hydrovac]

Very interesting to know that I am not the only one who has experienced the need for "warm up" with SS devices paired with analog and digital sources.

I have absolutely no issue to wait for them to "warm up".

Another question, I think it might have been answered before but just to confirm, whether the SS components get the "warm up" just by keeping them in stand by mode or you actually have to play them at the the desired volume to get them warmed up? I will try this experiment myself, but just checking your experience.

Thanks,
John.

It depends on the thermal design. Some amplifiers don't have much idling current until they warm up; others have a bit too much. It's true that the bias characteristics will change with junction temperature. The outputs and the drivers will flow more electrons at higher temperatures, having a positive temperature coefficient. The bias circuit will also have a positive tempco and will conduct more at higher temperatures. When the bias circuit heats up, the output bias current goes down, because the voltage spread across the drivers bases gets lower.
So the answer is, it depends. If you really want to know for a specific amplifier, put it on the bench and see what it does cold and hot. You could plot THD vs. time and output device temperature to find a specific answer.

For my own system, as it is, it takes a full hour to really wake up after the initial turn on. The preamp needs only a couple minutes, and the same goes for the CD player. The consequences of listening before everything has really settled in, at least in my experience, can usually be summed up in the word "empty". Everything has a noticeable blandness and lack of character.

Cheers

 

[asliarun]

"Bias" is to your amp like "idle" is to your car. The bias is adjusted when the amp is warm and not playing (Input shorted), and the idle is adjusted when the engine reaches running temperature and is not moving (no motion). This has a great effect on operating performance.

Why? Is it the waiting time that bothers you or do you believe something is wrong with it if it needs to warm up? Just curious.

Cheers

No no, the warm up time doesn't really bother me. Just wanted to get a better understanding of the whole thing. I want to understand what is valid and what is not.

What does frustrate me is that basic engineering and basic electrical stuff (that people wouldn't even normally bother about) acquires this cloud of mystery and alchemy. You know - Merlin the magician performing his dark arts and actually causing electrical amplification to happen!

Sure, I get that some things in the audio world are truly unique. Usage of vacuum tubes for example (well, if not unique - then archaic).

But if you take any other technical or non-technical hobby/pursuit/vocation, you will find only a fraction of the "magic pixie dust" that happens in the audio field. You can argue that it is because audio and music and especially the "perception" of it is very complicated and hence fragile and hence an inexact science.

Fair enough. But the same can be said about art, performance cars, or even cooking. High end cooking arguable touches upon all the senses so it can be argued that a good omelette is even harder to make than good sound. And it IS difficult if you want to get it "right". In fact most people don't even know how a good French omelette should taste or look.

But it is only "difficult", and with good knowledge of technique and basic principles and with sufficient practice, quality can be achieved. However, there is no "mystery" or dark arts involved.

Sorry for the rant.

 

[john_k_antony]

Wow hydrovac, thank a lot for the very detailed and indepth explanation. Really appreciate your knowledge on this.

Off Topic : I started to remember some of this stuff I learned in my engineering 16 years back. All these class A, class AB amplification, DSP, SSD etc sounded toooo boring way back then . Never paid too much of attention. I wish I did get some of my basics in electronics strong during that time. We were all behind "Java" and "Old Monk" back then . I think its the still the same old Java helps me buy these expensive electronics now .

Thanks,
John.

 

[asliarun]

Wow hydrovac, thank a lot for the very detailed and indepth explanation. Really appreciate your knowledge on this.

Off Topic : I started to remember some of this stuff I learned in my engineering 16 years back. All these class A, class AB amplification, DSP, SSD etc sounded toooo boring way back then . Never paid too much of attention. I wish I did get some of my basics in electronics strong during that time. We were all behind "Java" and "Old Monk" back then . I think its the still the same old Java helps me buy these expensive electronics now .

Thanks,
John.

And Old Monk will make it sound better (than any component upgrade).

 

[sonosphere]

Another OT dump question. Do you guys feel that your system sounds great on some days and other days you feel that "Hey this is not sounding good and I need to upgrade". Again the next day you feel that "Hey my system is sounding superb" .

Thanks,
John.

Hi,
I have experienced this too. Furthermore... the whole setup sounds better after 11pm approx... and no, its not because there is almost dead silence at that time... because I've heard the same quality during noon time on "good days"!

I remember reading somewhere that "harmonics impurities" in AC supply reduce in night time as less equipment's are powered on during night. And reduced impurities in source* result in better SQ. Similarly there may be other reasons why "harmonics impurities" are less during some days ("good days").

*The AC does get converted to "pure?" DC before an amp amplifies it, and then again re-converts to AC audio signal, however the end result supports the theory of "harmonics impurities"

And BTW... My amp sounds better after approx 30 mins of playing music.

There have been times when my system was not played for approx 1 week. The next time I played it... the SQ was almost devoid of bass It took almost 10 hrs of play-time to come back to normal SQ.

All the aforementioned SQ improvements, IMHO, are not psycho-acoustics. It's something real... it's just that we don't have "prove-able /scientific reasons" to support them yet.

Regds,

 

[jls001]

I have absolutely no issue to wait for them to "warm up".

I was bothered enough with the one-hour wait to migrate from tube power amp to SS power amp.

My older tube-FET hybrid preamp didn't have that much variation - the sound from dead-cold start to one-hour of play wasn't very different. But then the tube compliment was just one 6922 dual triode. It didn't produce a whole lot of heat so I guess it may be reaching its ideal operating temperature much faster than my power amp with its four huge 6550 output tubes and four 6922 driver tubes per side.

My current preamp is a hybrid again and has similar characteristics as the above described preamp. Almost nil waiting time. It sounds good right off the bat.

Current SS power amp also does not show much discernible improvement with 30-60 minutes of play. Of course I don't know if this is because it is a class A and the full current flows at all times (whether or not the amp is playing or it is just powered up and idle). It heats up a hell lot. I am guessing it also reaches its ideal operating temperature fast.

 

[hydrovac]

No no, the warm up time doesn't really bother me. Just wanted to get a better understanding of the whole thing. I want to understand what is valid and what is not.

In fact most people don't even know how a good French omelette should taste or look.

Sorry for the rant.

Whoa, sorry for that rant, y'all, We just really have to get that outta us.
Nursing an Old Monk and tossing a couple of omelettes will give sufficient time to warm up the system!? if not make it sound better.

Cheers

 

[Santy]

I am glad that my setup (with active speakers) sounds absolutely same to my ears at 1st minute and 100th minute of playback. And I will most definitely change my system if it takes that long to sound 'nice'. For me, its like my car would not go beyond 60kmph till first 10 km of the day.