"Don Pearce" wrote in message
...
On Tue, 22 Aug 2006 11:13:57 +0100, "Keith G"
wrote:


"Don Pearce" wrote in message
.. .
On Tue, 22 Aug 2006 00:22:20 +0100, "Keith G"
wrote:


"Don Pearce" wrote in message
. ..
On Mon, 21 Aug 2006 08:40:31 +0100, Rob
wrote:



One of the few (obviously!) things I remember from physics at school
is
that you should use the appliance switch if it has one to avoid
damage,
rather than the socket switch or pull the plug. Is there any truth to
this?

Rob

It depends. If the appliance switch is simply turning off the incoming
mains (the traditional way to do it), then pulling the plug or
switching off at the socket is exactly equivalent. If the appliance
switch works through some electronic function, then it isn't.

But whatever the case, there should be absolutely no danger of damage.


???

You never seen a wall socket with one hole a bit bigger than the other,
with
blackened edges....???



Errrrmmmm..... No.



Errrrmmmm..... Really?

I have on a number of occasions.

How about seeing a flash when pulling a plug out? (Like even through the
white plastic?)


Maybe when unplugging something really meaty - but never anything like
a Hi Fi.


I did a projector swap the other evening using the same kettle lead that was
already plugged in and got a little 'plip' as I plugged the thin end into
the PJ - thus, I suspect, nearly reducing myself to *two* frazzled PJs at a
stroke!! I have no idea how many times I've heard fizzing/pops/cracks
pulling plugs out (audio gear) over the years - usually because I was in an
awkward position and not able to do it quickly and cleanly....

On Tue, 22 Aug 2006 12:43:41 +0100, "Keith G"
wrote:

I did a projector swap the other evening using the same kettle lead that was
already plugged in and got a little 'plip' as I plugged the thin end into
the PJ - thus, I suspect, nearly reducing myself to *two* frazzled PJs at a
stroke!!

Why do you suspect that?

"Laurence Payne" lpayne1NOSPAM@dslDOTpipexDOTcom wrote in message
...
On Tue, 22 Aug 2006 12:43:41 +0100, "Keith G"
wrote:

I did a projector swap the other evening using the same kettle lead that
was
already plugged in and got a little 'plip' as I plugged the thin end into
the PJ - thus, I suspect, nearly reducing myself to *two* frazzled PJs at
a
stroke!!

Why do you suspect that?



Because the PJ I wuz swapping out had (apparently) been rendered dead by a
10 minute power cut the night before and there I was, zapping the second
one....

(The first PJ *is* rendered dead by a blown lamp - sez so in the manual...)

Dave Plowman (News) wrote:
In article ,
Rob wrote:
I take it your physics teacher had a degree in physical education? Because
it's basically rubbish. Although some devices like projectors have cooling
fans which are meant to run after powering down, but I'll bet he wasn't
thinking of those.


No, she (it was a 'she', Dave, and not a 'he' - Ms Lyons, class 3C, BVGS
Birmingham 1976) was/is a physics graduate although she didn't have a
PhD - or at least she didn't use the title 'Dr' (most of the other
staff did). I'm afraid I can't remember if she was a member of any
chartered or similar organisation - sorry.

I was trying to remember last night - I asked her 'why?', and I'm pretty
sure the answer had the word 'surge' in it, and tailed off into a 'this
doesn't apply to everything but as a rule you shouldn't switch a
switched device on or off at the mains. Device first, mains second'. I
tried it with my system - 3 valve amps, TT and CD, and left them
switched on at the appliance and just flip the switch at the mains.
Mighty convenience, but hell of a thump at the speakers when it's
switched on, fine when switched off.

That's rather different as there's no way you could switch all the devices
simultaneously except at the socket.


Indeed - it would be tricky - 6 switches!

But I'd be worried if a valve power amp produced a thump at the speakers
when powered up.


No, that's the curious thing - just a little 'blip' when the main supply
is switched in/on at the appliance. I'm not sure of the reason when
they're all put on at once, although I could easily isolate the rogue. I
have a feeling it is the power amp though - the guy who serviced it said
it's best to switch on the standby first, wait a minute, then switch on
the main thing.

The worst offender on the switch on thump syndrome is the CD - a
throoughly modern Marantz. I tend to switch that on first, followed by
everything else, finsihing with the power amp.

Rob

Keith G wrote:
"Rob" wrote in message
news
Don Pearce wrote:
On Mon, 21 Aug 2006 08:40:31 +0100, Rob
wrote:

Trevor Wilson wrote:
"Serge Auckland" wrote in message
...
I would suggest that our domestic consumption is typical, even lower
than average as our children have left home, so if more people turned
off stuff on standby, the power saving would be very considerable.
There is the anecdotal evidence that equipment left on standby or
permanently on seems to be more reliable, but I'm happy to take that
chance.
**A common misconception. The killer for most permanently powered items
are capacitor failures. Turning stuff off and on as required does
several things:

* Capacitors last longer.
* The product is shielded from unnecessary spikes on the mains.

I always turn stuff off (except for the obvious stuff, with clocks)
unless I actually want to use it.

One of the few (obviously!) things I remember from physics at school is
that you should use the appliance switch if it has one to avoid damage,
rather than the socket switch or pull the plug. Is there any truth to
this?

Rob
It depends. If the appliance switch is simply turning off the incoming
mains (the traditional way to do it), then pulling the plug or
switching off at the socket is exactly equivalent. If the appliance
switch works through some electronic function, then it isn't.

But whatever the case, there should be absolutely no danger of damage.

d

That's grand - thanks.


Except that it's not (see my posts alluding to burnt sockets).......

Also, do not be tempted to plug in a 'kettle lead' with the mains end
already plgged in - I've done that many times in the past, but had a little
'pop and flutter', once or twice recently.....


Well, yep - it's a bit tricky having being told there's no danger of
damage, but I'll stick to my old habits of appliance first, mains second
for the pure and simple reason that I paid for the switches so I'm
bloody well going to use them :-)

Rob

On Tue, 22 Aug 2006 14:17:01 +0100, Rob
wrote:

Dave Plowman (News) wrote:
In article ,
Rob wrote:
I take it your physics teacher had a degree in physical education? Because
it's basically rubbish. Although some devices like projectors have cooling
fans which are meant to run after powering down, but I'll bet he wasn't
thinking of those.


No, she (it was a 'she', Dave, and not a 'he' - Ms Lyons, class 3C, BVGS
Birmingham 1976) was/is a physics graduate although she didn't have a
PhD - or at least she didn't use the title 'Dr' (most of the other
staff did). I'm afraid I can't remember if she was a member of any
chartered or similar organisation - sorry.

I was trying to remember last night - I asked her 'why?', and I'm pretty
sure the answer had the word 'surge' in it, and tailed off into a 'this
doesn't apply to everything but as a rule you shouldn't switch a
switched device on or off at the mains. Device first, mains second'. I
tried it with my system - 3 valve amps, TT and CD, and left them
switched on at the appliance and just flip the switch at the mains.
Mighty convenience, but hell of a thump at the speakers when it's
switched on, fine when switched off.

That's rather different as there's no way you could switch all the devices
simultaneously except at the socket.


Indeed - it would be tricky - 6 switches!

But I'd be worried if a valve power amp produced a thump at the speakers
when powered up.


No, that's the curious thing - just a little 'blip' when the main supply
is switched in/on at the appliance. I'm not sure of the reason when
they're all put on at once, although I could easily isolate the rogue. I
have a feeling it is the power amp though - the guy who serviced it said
it's best to switch on the standby first, wait a minute, then switch on
the main thing.

Are you sure? The usual way is main first, then standby later.
Switching on the standby first does nothing until the main is on.


The worst offender on the switch on thump syndrome is the CD - a
throoughly modern Marantz. I tend to switch that on first, followed by
everything else, finsihing with the power amp.

Rob

It sounds like the amp is the common factor here, and thus also the
problem.

d

--
Pearce Consulting
http://www.pearce.uk.com

Don Pearce wrote:
On Tue, 22 Aug 2006 14:17:01 +0100, Rob
wrote:

Dave Plowman (News) wrote:
In article ,
Rob wrote:
I take it your physics teacher had a degree in physical education? Because
it's basically rubbish. Although some devices like projectors have cooling
fans which are meant to run after powering down, but I'll bet he wasn't
thinking of those.

No, she (it was a 'she', Dave, and not a 'he' - Ms Lyons, class 3C, BVGS
Birmingham 1976) was/is a physics graduate although she didn't have a
PhD - or at least she didn't use the title 'Dr' (most of the other
staff did). I'm afraid I can't remember if she was a member of any
chartered or similar organisation - sorry.
I was trying to remember last night - I asked her 'why?', and I'm pretty
sure the answer had the word 'surge' in it, and tailed off into a 'this
doesn't apply to everything but as a rule you shouldn't switch a
switched device on or off at the mains. Device first, mains second'. I
tried it with my system - 3 valve amps, TT and CD, and left them
switched on at the appliance and just flip the switch at the mains.
Mighty convenience, but hell of a thump at the speakers when it's
switched on, fine when switched off.
That's rather different as there's no way you could switch all the devices
simultaneously except at the socket.

Indeed - it would be tricky - 6 switches!

But I'd be worried if a valve power amp produced a thump at the speakers
when powered up.

No, that's the curious thing - just a little 'blip' when the main supply
is switched in/on at the appliance. I'm not sure of the reason when
they're all put on at once, although I could easily isolate the rogue. I
have a feeling it is the power amp though - the guy who serviced it said
it's best to switch on the standby first, wait a minute, then switch on
the main thing.

Are you sure? The usual way is main first, then standby later.
Switching on the standby first does nothing until the main is on.


Yes, I'm sure. It's a Beard P100. The amp was originally fitted with a
'soft start', that would actually amplify, albeit at low volumes. The
problem was that owners kept them in this 'standby' mode all the time,
and early valve failure was common. Mine has been rewired so that
standby does something (all the valves light up but no sound), and power
brings with it sound.

The worst offender on the switch on thump syndrome is the CD - a
throoughly modern Marantz. I tend to switch that on first, followed by
everything else, finsihing with the power amp.

Rob

It sounds like the amp is the common factor here, and thus also the
problem.


Yes, I think it is the amp, but if the only way is to follow the
suggested power-up routine, then life goes on.

Rob

"Rob" wrote


seven indents is too much for me....


Except that it's not (see my posts alluding to burnt sockets).......

Also, do not be tempted to plug in a 'kettle lead' with the mains end
already plgged in - I've done that many times in the past, but had a
little 'pop and flutter', once or twice recently.....


Well, yep - it's a bit tricky having being told there's no danger of
damage, but I'll stick to my old habits of appliance first, mains second
for the pure and simple reason that I paid for the switches so I'm bloody
well going to use them :-)


There used to be a saying that you switched the kit on like the amp was the
MD - last in and first out. Having been one for over a decade (MD that is,
not amp...) you can take if from me that that is exactly the wrong way
round!

.....A good MD gives 'em time in the morning to correct the cock-ups made the
previous day 'unnoticed' before he arrives and stays on long enough in the
evening to discover what cock-up there will need to be surreptitiously (and
swiftly) corrected before he arrives the next morning!! ;-)

And to think all I did was ask about a tuner that doesn't forget when
the mains is off!


I built a 100Wpc dual-mono MOSFET power amp and wanted to switch it
from the pre-amp - at the time a Quad 33. I got a 30A solid state
relay, fitted it inside the amp, and switched it from the low voltage
supply from the pre-amp. Never had any thump or anything like.

The reason? Solid state relays only switch on at the zero crossing of
the mains, so there can never be any inrush current per se......


--
Woody

harrogate3 at ntlworld dot com

In article ,
harrogate3 wrote:
I built a 100Wpc dual-mono MOSFET power amp and wanted to switch it
from the pre-amp - at the time a Quad 33. I got a 30A solid state
relay, fitted it inside the amp, and switched it from the low voltage
supply from the pre-amp. Never had any thump or anything like.

The reason? Solid state relays only switch on at the zero crossing of
the mains, so there can never be any inrush current per se......

I sincerely hope the 'mains inrush current' doesn't get to the speakers on
any amp...

--
*We are born naked, wet, and hungry. Then things get worse.

Dave Plowman London SW
To e-mail, change noise into sound.