Leaving your Amp ON 'all the time'

[kanwar]

Hi Guys,

There is a lit bit of technical aspect related to this thing also.
The AC mains normally we have in our homes is contaminated usually with noise spikes, Semi clipped waveform containing harmonics and dreaded of all the DC bias present on it due to non linear loads connected.

Out of the above mentioned three , the dc bias can give your transformer[if equipment is fitted with a transformer in it, provided not in standby mode]
a real hard deal. When transformer is idle, the eddy current losses rise up sharply with the presence of DC bias in mains AC and the core of transformer starts heating up from inside to an extent that it will heatup the transformer windings to very high degree[though the wire enamel if Class-F is rated above 180C], also you might hear a buzzing sound from the transformer in that case.

And when you listen to the music[giving a job to amp to do what it is suppose to do.]
In case of transformer being loaded slightly the eddy current losses diminish to a smaller extent and the reluctance kicks in due to current being used up by circuitry in the amplifier thereby it will generate less heat in that case. Only if loaded fully the heat generation will exceed the limit in idle cases.


So technically its not advisable to leave the equipment in ON mode all the time which is having a 50-60 hz transformer in it, SMPS is exception.


My 2cents,

Kanwar

 

[malvai]

Hi Guys,

There is a lit bit of technical aspect related to this thing also.
The AC mains normally we have in our homes is contaminated usually with noise spikes, Semi clipped waveform containing harmonics and dreaded of all the DC bias present on it due to non linear loads connected.

Out of the above mentioned three , the dc bias can give your transformer[if equipment is fitted with a transformer in it, provided not in standby mode]
a real hard deal. When transformer is idle, the eddy current losses rise up sharply with the presence of DC bias in mains AC and the core of transformer starts heating up from inside to an extent that it will heatup the transformer windings to very high degree[though the wire enamel if Class-F is rated above 180C], also you might hear a buzzing sound from the transformer in that case.

And when you listen to the music[giving a job to amp to do what it is suppose to do.]
In case of transformer being loaded slightly the eddy current losses diminish to a smaller extent and the reluctance kicks in due to current being used up by circuitry in the amplifier thereby it will generate less heat in that case. Only if loaded fully the heat generation will exceed the limit in idle cases.


So technically its not advisable to leave the equipment in ON mode all the time which is having a 50-60 hz transformer in it, SMPS is exception.


My 2cents,

Kanwar

I absolutely agree with you! though, many a audiophile believes that keeping the amps on at idle keeps them "warm" and hence makes the music sound smoother from the get go!

 

[venkatcr]

I absolutely agree with you! though, many a audiophile believes that keeping the amps on at idle keeps them "warm" and hence makes the music sound smoother from the get go!

That is certainly valid for tube amps as the tubes take a bit of time to warm up. You usually switch a tube amp at least 30 minutes before playing time. But this is not valid for amps using transistors and ICs, as they do not have any warm up time.

Cheers

 

[kanwar]

I absolutely agree with you! though, many a audiophile believes that keeping the amps on at idle keeps them "warm" and hence makes the music sound smoother from the get go!

Yeah, Audiophiles and their myths

 

[kanwar]

That is certainly valid for tube amps as the tubes take a bit of time to warm up. You usually switch a tube amp at least 30 minutes before playing time. But this is not valid for amps using transistors and ICs, as they do not have any warm up time.

Cheers

Tubes are different phenomena and they need a warmup time for sure, its inherent to their way of operation.


cheers,
Kanwar

 

[Bobby]

One of my audiophile friend has plinius 9200 and claims that there is a day night difference when he leaves the amp on standby mode for 5 hours before his listening session

 

[gobble]

Even the humble bad 325 sounds great after 10 hrs on leaving on.

 

[nshankar]

^ nad 325?

 

[captrajesh]

bad 325

Was that deliberate or the Chill" um effect?

 

[crewcut]

The pass through functionality serves a totally different purpose for me. It now allows my younger one to watch Pogo without having to get through the complexity of working the Denon.

Of course, the master switch goes off when no one's watching/ listening.

 

[askii2]

One of my audiophile friend has plinius 9200 and claims that there is a day night difference when he leaves the amp on standby mode for 5 hours before his listening session

5 hours is an exaggeration. 10-15 minutes of power-on should help amp reach it's optimum temperature.

 

[prankey]

One of my audiophile friend has plinius 9200 and claims that there is a day night difference when he leaves the amp on standby mode for 5 hours before his listening session

STANDBY MODE is different than keeping idle... Even my AVR is kept on standby most of the time (as it consumes just about 1 watt of power in standby). However, my AVR consumes about 40 Watts when in idle and I NEVER notice any difference in quality doing cold start or warm... Some of us are talking in automobiles terms here (keeping the engine warm to get best performance). While it is true for Automobiles and Tube Amps, it certainly do not make noticeable difference particularly in modern solid state AVRs.

 

[askii2]

Some of us are talking in automobiles terms here (keeping the engine warm to get best performance). While it is true for Automobiles and Tube Amps, it certainly do not make noticeable difference particularly in modern solid state AVRs.

Integrated or pre-power amplifiers -
Transistor (BJFET/MOSFET) characteristics vary with temperature. A good quality amplifier ICs have compensations built into them in form of cancellations. Power amplifiers or preamplifiers which use ICs are immune to temperature variations in those stages where ICs are used. Last stage of a power amplifier is usually a class AB push-pull and has to be transistor pair based. Manufacturers implement include a temperature compensation for last stage. Better an amplifier, which usually implies costlier, the lesser temperature variation it'll exhibit. My guess is integrated amplifiers which cost more than Rs. 50000 should not show noticeable temperature variation.

There are current-dumping class B amplifier designs by Quad which provide near ideal compensation for temperature variations among several other features; these haven't been implemented by other manufacturers. Quad's current-dumping power amplifiers are completely immune from temperature or time variations.

Class T amplifiers (Topping TP20) do not use a push-pull last stage and hence don't suffer from this problem. There are other reasons why they aren't as good for higher powers.

My low cost PACE 5020 stereo integrated amplifier does sound better when turned on for 5 to 10 mins.

AVRs-
AVRs usually implement class D switching amplifiers. These do not use a push-pull last stage and hence don't suffer from this problem. Resistors and capacitors also suffer from temperature variations, although the variation is less. So most AVRs do not sound any different after 5 minutes.

 

[buswal]

The power fluctuations are in the range of 160 to 250 V in many places in India. Hence it is not advisable to leave any electronics gadgets in on mode, when not in use.

Just purchase a voltage meter, connect it directly to the wall socket and monitor the fluctations during different timings like before 8 am, after 10 am, after 5 pm, after 10 pm etc for few days.


cheers,

 

[kanwar]

Class T amplifiers (Topping TP20) do not use a push-pull last stage and hence don't suffer from this problem.

AVRs usually implement class D switching amplifiers. These do not use a push-pull last stage and hence don't suffer from this problem.

Whether its Class-D or Class-T, push-pull output stage is still there, only difference is the nature of operation which is switching operation not a linear like in A/AB stages.

Temperature variation is absent in Class-D because the devices are operated as saturated switches. Whereas in linear Class-A/AB amps the output stage is biased to some quiescent current level.


Kanwar

 

[kayjay]

I agree that in these days of responsible power usage keeping equipment on continuously is criminal.
However, it must be said that all electric/electronic devices are the most vulnerable at switch on and switch off, where heavy surges are the norm.
It was for this and this alone I'd keep my gear on all the time.
That was then.
Now I use a soft start circuit in my power amp and power conditioning on all loads (including the fridge!!) with DC filtering added on certain loads (where, for instance, toroids are in the power chain) to avoid unnecessary stress on the equipment.
That this improves the listening experience is an added bonus!

 

[square_wave]

The odyssey stratos amp I used have earlier needed to be warmed up at least 2 hours for it to sound really good. It sounds nice (much better than any hi-end AVR) from startup but starts opening up and sounds effortless and very analogue without any hard edges after 2 hours or so and continues to improve till some 4 hours or so. This amp is recommended to be kept "on" all the wihile by the manufacturer.

 

[soundofmusic]

My Bryston and My Plinius Integrated sounds better after 45mins and continue to improve time after time.
Heard a Class A Pass Labs amplifier and it was heaven after 2hours. I listen to Music seriously after 1 hour of switching on the amp.

regards

 

[askii2]

With due respect to members posting about substantial improvements after 1 hour: if an amp takes that long to reach it's optimum temperature, it has to have poor heat dissipation.

Some of the amps quoted above are priced very high. I would expect a high priced amplifier to have temperature compensation built into it. My Rs. 7000 amp doesn't have it, but that's ok for the price.