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Power amps on switched outlets.

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May 7, 2004 4:35:39 AM

Archived from groups: rec.audio.tech (More info?)

Will switching the amps on and off be bad for it?

I don't have any popping going on (amps last on, first off), but i'm
still wondering if this could be harmful to the amps themselves.

tia,

--
cyrus

*coughcasaucedoprodigynetcough*
Anonymous
May 7, 2004 4:53:36 AM

Archived from groups: rec.audio.tech (More info?)

In <invalid-9C02AE.17404906052004@newsclstr01.news.prodigy.com>, on
05/07/04
at 12:35 AM, cyrus <invalid@i.like.spam> said:

>Will switching the amps on and off be bad for it?

>I don't have any popping going on (amps last on, first off), but i'm
>still wondering if this could be harmful to the amps themselves.

The power switch on many preamplifiers is not robust enough to switch a
power amplifier and the switch will fail. As far as power amplifier
life is concerned, it's a complex situation.

There are many failure "clocks" ticking in any power amplifier. Some
run faster at higher temperatures, some run faster if the amplifier is
not used, and some are related to the number and depth of the
temperature cycles. Eventually, one of the clocks times out and the
amplifier fails.

Turn-on is one of the more stressful events in your amplifier's life.
There is a sudden inrush of current and a new temperature cycle begins.
If your amplifier runs hot, and most of the better sounding amplifiers
do, then the output transistors will fail after a certain number of
ON/OFF cycles. This number could range from a few thousand to tens of
thousands of cycles. Leaving the unit on all the time will certainly
minimize the number and depth of the temperature cycles, but this will
accelerate the "clocks" that are sensitive to long hours at elevated
temperatures.

You are dammed if you do and dammed if you don't.

My strategy is to turn a unit ON when I first need it on a given day
and keep the unit ON for the rest of the day. I avoid multiple ON/OFF
cycles in a day. This will limit the number of temperature cycles to
one per day. This may not seem like the minimum energy strategy, but
one should also consider the energy and pollution costs of
manufacturing a replacement unit.

This strategy has served me well for many years. I tend to have much
less trouble with electronics of any kind than most people I know.

-----------------------------------------------------------
spam: uce@ftc.gov
wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13> (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------
Anonymous
May 7, 2004 7:06:19 AM

Archived from groups: rec.audio.tech (More info?)

cyrus wrote:
> Will switching the amps on and off be bad for it?
>
> I don't have any popping going on (amps last on, first off), but i'm
> still wondering if this could be harmful to the amps themselves.
>
> tia,
>

Since many amps are plugged into preamps and switched on/off by the
preamp, there is no reason to believe that controlling an amp with some
other switched outlet should be a problem.

Exactly what are you trying to do?
Related resources
May 7, 2004 10:45:32 AM

Archived from groups: rec.audio.tech (More info?)

In article <L2Dmc.49025$Xj6.832926@bgtnsc04-news.ops.worldnet.att.net>,
Robert Gault <robert.gault@worldnet.att.net> wrote:

> cyrus wrote:
> > Will switching the amps on and off be bad for it?
> >
> > I don't have any popping going on (amps last on, first off), but i'm
> > still wondering if this could be harmful to the amps themselves.
> >
> > tia,
> >
>
> Since many amps are plugged into preamps and switched on/off by the
> preamp, there is no reason to believe that controlling an amp with some
> other switched outlet should be a problem.
>
> Exactly what are you trying to do?
>

Multi amp setup (tri-amped+sub amp). Trying to figure the easiest way to
power it all down at once. For ease of use basically.

--
cyrus

*coughcasaucedoprodigynetcough*
May 7, 2004 10:50:31 AM

Archived from groups: rec.audio.tech (More info?)

In article <409b1ce5$1$avgroveq$mr2ice@wcnews.cyberonic.com>,
zzzz@zzzz.zzz (Barry Mann) wrote:

> In <invalid-9C02AE.17404906052004@newsclstr01.news.prodigy.com>, on
> 05/07/04
> at 12:35 AM, cyrus <invalid@i.like.spam> said:
>
> >Will switching the amps on and off be bad for it?
>
> >I don't have any popping going on (amps last on, first off), but i'm
> >still wondering if this could be harmful to the amps themselves.
>
> The power switch on many preamplifiers is not robust enough to switch a
> power amplifier and the switch will fail. As far as power amplifier
> life is concerned, it's a complex situation.
>
> There are many failure "clocks" ticking in any power amplifier. Some
> run faster at higher temperatures, some run faster if the amplifier is
> not used, and some are related to the number and depth of the
> temperature cycles. Eventually, one of the clocks times out and the
> amplifier fails.
>
> Turn-on is one of the more stressful events in your amplifier's life.
> There is a sudden inrush of current and a new temperature cycle begins.
> If your amplifier runs hot, and most of the better sounding amplifiers
> do, then the output transistors will fail after a certain number of
> ON/OFF cycles. This number could range from a few thousand to tens of
> thousands of cycles. Leaving the unit on all the time will certainly
> minimize the number and depth of the temperature cycles, but this will
> accelerate the "clocks" that are sensitive to long hours at elevated
> temperatures.
>
> You are dammed if you do and dammed if you don't.
>

hehe Indeed. I leave my power amps on most of the time unless they won't
be used for a day or so. The on/off cycle thing was mentioned to me
about power supplies for large format recording consoles. Seems it would
apply to other components but i didn't know the specifics.

> My strategy is to turn a unit ON when I first need it on a given day
> and keep the unit ON for the rest of the day. I avoid multiple ON/OFF
> cycles in a day. This will limit the number of temperature cycles to
> one per day. This may not seem like the minimum energy strategy, but
> one should also consider the energy and pollution costs of
> manufacturing a replacement unit.
>
> This strategy has served me well for many years. I tend to have much
> less trouble with electronics of any kind than most people I know.

The situation has come up that somebody not so technically inclined can
switch the amps with a single throw of the finger.

Thanks for the info.

>
> -----------------------------------------------------------
> spam: uce@ftc.gov
> wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
> 13> (Barry Mann)
> [sorry about the puzzle, spammers are ruining my mailbox]
> -----------------------------------------------------------
>

--
cyrus

*coughcasaucedoprodigynetcough*
Anonymous
May 7, 2004 2:58:43 PM

Archived from groups: rec.audio.tech (More info?)

cyrus wrote:

> Will switching the amps on and off be bad for it?

Not if done within reason. Power cycling often puts several hours worth of
wear on the equipment being power cycled.

> I don't have any popping going on (amps last on, first off), but i'm
> still wondering if this could be harmful to the amps themselves.

I'd be more worried about the switch that is controlling the outlets.

I have a BIG mongo 50 amp 120 volt relay in a well-made box that controls
the power downstream of the preamp. It's plugged into the preamp, not the
equipment. I've had it for about 25 years. I originally scarfed it out of a
electric dryer. Who knows how many power switches lives it has lengthened.
Anonymous
May 7, 2004 6:18:04 PM

Archived from groups: rec.audio.tech (More info?)

cyrus wrote:

> In article <L2Dmc.49025$Xj6.832926@bgtnsc04-news.ops.worldnet.att.net>,
> Robert Gault <robert.gault@worldnet.att.net> wrote:
>
>
>>cyrus wrote:
>>
>>>Will switching the amps on and off be bad for it?
>>>
>>>I don't have any popping going on (amps last on, first off), but i'm
>>>still wondering if this could be harmful to the amps themselves.
>>>
>>>tia,
>>>
>>
>>Since many amps are plugged into preamps and switched on/off by the
>>preamp, there is no reason to believe that controlling an amp with some
>>other switched outlet should be a problem.
>>
>>Exactly what are you trying to do?
>>
>
>
> Multi amp setup (tri-amped+sub amp). Trying to figure the easiest way to
> power it all down at once. For ease of use basically.
>

Use a power strip. A preamp probably won't like switching as much power
as you are using.

I added surge a suppressor circuit to my amp and have no concerns about
turning it on and off. It would not be a good idea to rapidly cycle
(on/off) any electronic device including light bulbs. Also any device
has a limited operating life. You need to decide whether there is more
wear and tear caused by constant use or switching a device on.
Personally, I think it is both silly and wasteful to leave equipment on
when it is not in use.
Anonymous
May 7, 2004 6:37:36 PM

Archived from groups: rec.audio.tech (More info?)

> Turn-on is one of the more stressful events in your amplifier's life.
> There is a sudden inrush of current and a new temperature cycle begins.
> If your amplifier runs hot, and most of the better sounding amplifiers
> do, then the output transistors will fail after a certain number of
> ON/OFF cycles.

Is this dictated by the switching though? For a class A/B amplifier, a
thermal cycle will be dictated by use, since the bias alone is not
substantial enough to maintain the temperature.
May 7, 2004 9:16:25 PM

Archived from groups: rec.audio.tech (More info?)

I'm looking for an actual scientific study, so please, no opinions. I'm sure
this subject has been the object of flamewars and endless threads.

Can anyone point to tests which address this theory? "Power cycling often
puts several hours worth of wear on the equipment being power cycled."
Anonymous
May 7, 2004 9:16:26 PM

Archived from groups: rec.audio.tech (More info?)

> I'm looking for an actual scientific study, so please, no opinions.

Heh, sometimes there's no difference.
Anonymous
May 7, 2004 9:16:26 PM

Archived from groups: rec.audio.tech (More info?)

Jeff wrote:
> I'm looking for an actual scientific study, so please, no opinions.
> I'm sure this subject has been the object of flamewars and endless
> threads.

> Can anyone point to tests which address this theory? "Power cycling
> often puts several hours worth of wear on the equipment being power
> cycled."

I just did a search on google using the following words:

power cycle stress

This yields a number of scientific studies of the effects of thermal cycle
stress.

Here's a typical hard drive spec sheet:

http://www.superwarehouse.com/Western_Digital_Raptor_36...

Note that near the end of the page, the reliability of the drive is
specified in operational hours and stop/start cycles.
Anonymous
May 8, 2004 1:46:31 AM

Archived from groups: rec.audio.tech (More info?)

"Barry Mann" <zzzz@zzzz.zzz> wrote in message
news:409b1ce5$1$avgroveq$mr2ice@wcnews.cyberonic.com...
> In <invalid-9C02AE.17404906052004@newsclstr01.news.prodigy.com>, on
> 05/07/04
> at 12:35 AM, cyrus <invalid@i.like.spam> said:
>
> >Will switching the amps on and off be bad for it?
>
> >I don't have any popping going on (amps last on, first off), but i'm
> >still wondering if this could be harmful to the amps themselves.
>
> The power switch on many preamplifiers is not robust enough to switch a
> power amplifier and the switch will fail. As far as power amplifier
> life is concerned, it's a complex situation.
>
> There are many failure "clocks" ticking in any power amplifier. Some
> run faster at higher temperatures, some run faster if the amplifier is
> not used, and some are related to the number and depth of the
> temperature cycles. Eventually, one of the clocks times out and the
> amplifier fails.
>
> Turn-on is one of the more stressful events in your amplifier's life.

**Not necessarily.

> There is a sudden inrush of current and a new temperature cycle begins.
> If your amplifier runs hot, and most of the better sounding amplifiers
> do, then the output transistors will fail after a certain number of
> ON/OFF cycles. This number could range from a few thousand to tens of
> thousands of cycles.

**Nope. More than THIRTY YEARS AGO, RCA identified this issue and began
constructing their (steel cased) power transistors to cope with in excess of
a million hot/cold cycles. Back then, plastic encased power transistors
experienced failure after a mere 10,000 cycles. Aluminium cased power
transistors (Motorola, et al) exhibited failures after around 100,000
cycles. Better materials and technologies has extended this range
dramatically. I've not seen the numbers, but I'll betcha it is in the same
order as the devices RCA was producing in the mid 1970s. IME, modern plastic
pack devices exhibit reliability figures well in excess of the aluminium
cased devices, but, perhaps not quite up to the level of the steel cased
devices. I have no figures to back this claim. It is a gut feel, based on 30
years of audio service work.

Leaving the unit on all the time will certainly
> minimize the number and depth of the temperature cycles, but this will
> accelerate the "clocks" that are sensitive to long hours at elevated
> temperatures.

**And there's the biggie. In modern equipment, it is the electrolytic
capacitors which are subject to the most wear. Leaving equipment powered up
will wear caps out and leave the equipment open to line surges. And let's
not even get into the environmental vandalism aspect of the issue. Leaving
equipment on is dangerous, stupid, ill-considered and wasteful.

>
> You are dammed if you do and dammed if you don't.

**Nonsense. Turn it on when you need it. Turn it off when you don't.
Equipment which cannot cope with repeated turn on/turn off cycles is faulty.

>
> My strategy is to turn a unit ON when I first need it on a given day
> and keep the unit ON for the rest of the day.

**Extremely wasteful. I would suggest that if you will not use the equipment
for more than (say) one hour, then turn it off.

I avoid multiple ON/OFF
> cycles in a day. This will limit the number of temperature cycles to
> one per day.

**And will prematurely age the electrolytic caps.

This may not seem like the minimum energy strategy, but
> one should also consider the energy and pollution costs of
> manufacturing a replacement unit.

**One should consider purchasing equipment which is properly and
conservatively designed and built, in the first place.


>
> This strategy has served me well for many years. I tend to have much
> less trouble with electronics of any kind than most people I know.

**And I turn my equipment on and off as I need to. My only exception to this
rule, are computers. And that is because the boot time is so damned long.
The oldest piece of equipment I own is a Marantz Model Eighteen receiver. It
was built in 1968 and has served me well on my workbench, since 1978. I turn
it on and off around 10 times per day. Apart from the CRO, I have had to
replace one set of output devices, during that period. I expect it to last
another 35 years. I will continue to turn it on and off, as needed, as that
is what the Marantz design engineers intended. It's power switch is
adequately rated for the job.

This whole leaving equipment on, is an old wive's tale. I have been
servicing equipment for more than 30 years. I can always tell when equipment
has been left on for extended periods. Electrolytic caps dry out
prematurely. Every time.

Don't believe me? Go talk to a video tech and ask them what fails in most
VCRs (apart from the mechanical stuff). He/she will always tell you that it
is the electrolytic caps in the (permanently powered) power supply. They
stay warm and they dry out.

--
Trevor Wilson
www.rageaudio.com.au
Anonymous
May 8, 2004 1:48:07 AM

Archived from groups: rec.audio.tech (More info?)

"cyrus" <invalid@i.like.spam> wrote in message
news:invalid-9C02AE.17404906052004@newsclstr01.news.prodigy.com...
> Will switching the amps on and off be bad for it?

**No. And on the contrary, leaving an amp switched on, will hasten its
demise. Filter cap wear and tear and possible mains line surges may kill an
amp. ALL filter caps will eventually wear out. Heat accelerates that wear.

>
> I don't have any popping going on (amps last on, first off), but i'm
> still wondering if this could be harmful to the amps themselves.

**Nope. It is far and away the best method to do it.


--
Trevor Wilson
www.rageaudio.com.au
Anonymous
May 8, 2004 2:17:14 AM

Archived from groups: rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in message
news:0aqdnZS8Dqv-fAbdRVn-hQ@comcast.com...
> Jeff wrote:
> > I'm looking for an actual scientific study, so please, no opinions.
> > I'm sure this subject has been the object of flamewars and endless
> > threads.
>
> > Can anyone point to tests which address this theory? "Power cycling
> > often puts several hours worth of wear on the equipment being power
> > cycled."
>
> I just did a search on google using the following words:
>
> power cycle stress
>
> This yields a number of scientific studies of the effects of thermal cycle
> stress.
>
> Here's a typical hard drive spec sheet:
>
>
http://www.superwarehouse.com/Western_Digital_Raptor_36...
>
> Note that near the end of the page, the reliability of the drive is
> specified in operational hours and stop/start cycles.

**Which, of course, has nothing to do with non-mechanical components.


--
Trevor Wilson
www.rageaudio.com.au
Anonymous
May 8, 2004 2:36:59 AM

Archived from groups: rec.audio.tech (More info?)

"Jeff" <nospamthanks@pacbll.net> wrote in message
news:JvPmc.6145$hz7.1805@newssvr27.news.prodigy.com...
> I'm looking for an actual scientific study, so please, no opinions. I'm
sure
> this subject has been the object of flamewars and endless threads.
>
> Can anyone point to tests which address this theory? "Power cycling often
> puts several hours worth of wear on the equipment being power cycled."

**Without some extensive and expensive tests, this comment cannot be
justified. In a purely electronic device, there are several failure modes,
due to various factors.

1) Leaving equipment powered for extended periods:
* The equipment is open to any mains borne spikes and surges, which may
damage various elements in the product.
* Elevated temperatures will dry out electrolytic caps (most domestic
equipment uses caps rated at 85oC). more heat = more wear.
* Elevated temperatures will lead to gradual failure of solder joints.
Curiously, I have only ever noticed this effect in certain Asian brands. I
suspect either poor soldering techniques.Hand soldered joints almost never
fail in this way.

2) Turning equipment on and off, as required.
* Power switch failure. Clearly, a design fault. Not acceptable. Good design
precludes such problems. Solid state switches (available for around 40
years) completely eliminates such problems.
* Thermal cycling of active devices. This has not been an issue, for around
30 years. Modern semiconductors tolerate large numbers of thermal cycles.
* Rectifier failure. This can occur when the product is switched on at the
top of the AC waveform. Large currents can flow. Good designers make
allowances, by choosing appropriately rated (transient current) rectifiers.
Else a 'soft-start' mechanism should be implemented. Either way, it boils
down to good design.

If equipment needs to be left continuously powered, then it is a function of
poor design and such designers should not be supported with consumer's
money.


--
Trevor Wilson
www.rageaudio.com.au
May 8, 2004 12:50:22 PM

Archived from groups: rec.audio.tech (More info?)

Thanks for the comments and ideas guys.

--
cyrus

*coughcasaucedoprodigynetcough*
!