turning off the computer with active speakers still on, how bad?

[Starmonger]

That's twice i've done that now- by mistake turning off the computer when the active monitors are still on, it causes a loud thump. How bad is this for the speakers?

[TheReson8or]

Not good! ALWAYS......SPEAKERS OFF FIRST!!!!

[Steve Hill]

Once or twice you will - probably - get away with it. But not good.

Go and resolve to behave better to your monitors in future!

[Shivanand]

I'm sure a loud "thump" is not doing the speakers any good at all but why is this happening? I always shut my PC down first, then switch off everything else (including the active speakers) with a single master switch. No thumps, no problems.

[Starmonger]

I think it's my soundcard (RME HDSP 9632), it just means I have to switch off the active speakers first otherwise its like turning on a mixer when the amps allready on.

Its annoying as it will probably happen again at some point, even though I mean to switch them off first, I guess I'll forget again

What happens to speakers when this happens? what get's damaged? I've only just bought these speakers.

[Shivanand]

I'm surprised that an RME does this, TBH it is a most unprofessional behaviour! My previous (high end but domestic Sony) amp used to send a thump to the speakers if it was switched off at the master power switch but the Genelec actives power down gracefully whatever I do to them! FWIW I'm using as Echo Audiofire PC interface and that doesn't do anything naughty at all.

[oggyb]

I have KRK RP5#2 monitors. One of them thumps when I turn it of at its own master switch, the other is gracefully silent. Neither is malfunctioning though I suspect the thumpy one isn't having a great time.

Just thought I'd mention that.

Occasionally I restart my computer with the monitors on and it thumps when the bios re-engages after shutdown. Interesting.

I find it is setups that have two big red "1" and "2" master switches that promote good behaviour, and those are hard to come by. Here I just have extension cables and individually switched equipment.

[James Perrett]

What happens to speakers when this happens? what get's damaged? I've only just bought these speakers.

Most modern amplifiers and preamps work on dual power supplies - one supplying the positive supply and one supplying a negative supply at the same voltage as the positive supply. + and - 15 to 18 volts is common for preamps while power amps will often be higher.

The current drawn from the + and - supply will be roughly but not exactly equal. When you turn something on or off the supplies don't go up or down at the same rate which will cause temporary offsets in some parts of the circuit. It is these temporaray offsets that cause the switch on thumps. In some gear these offsets will be small enough to not cause problems while in other gear these offsets could reach close to the supply voltage so you could be sending an 18 volt spike to your speakers.

What happens to this spike depends on how well protected your speakers are. Most professional gear won't mind but hifi gear or computer speakers probably won't like this sort of voltage on the input. The exact nature of the problem depends on the particular gear that you are using - I suspect that I may have blown a driver transistor in a Quad 405 by doing this once (although the amp had other problems too).

Cheers

James.

[Starmonger]

Thanks for answering that James. My speakers are AE22 active monitors. They seem pretty well built.

[Peter Conz Connelly]

My Yamaha MSP10 Studio monitors have "thumped" many a time when shutting down my PC (when I forget to switch them off first), which is connected to a Delta 1010. When I had... dare I say it... Behringer MX8000A desk connected, I had a problem with the PSU that caused HUGE thumps to my monitors. Touch wood, everything is still good with them though, apart from the crumpled tweeter mesh which I'm sure my curious nephew disturbed. No one, 3 years on, has owned up to that yet!!!

Cheers,
Peter

[Hugh Robjohns]

If the sound card is in the computer then there is a good chance you're going to get a heavy transient when the power goes down in the PC. Some designs will be better than others, but it is quite common.

Always, always, always turn off the speakers (or mute the inputs) before turning off whatever is feeding them.

And when powering up, always turn the speakers on last.

Standard studio practice.

Hugh

[Peter Conz Connelly]

Always, always, always turn off the speakers (or mute the inputs) before turning off whatever is feeding them.

And when powering up, always turn the speakers on last.

Standard studio practice.

Hugh

Unfortunately late nights, typical human error or getting older sometimes get in the way of protocol

P

[jayzed]

The monitors weren't active (80s) but if I'd switched off anything in the audio path before the power amp as a tape op it would have been the last thing I did. In the studio, anyway. Along with dropping mics, this was one of the first things we were told would be a career ender!

[Hugh Robjohns]

Unfortunately late nights, typical human error or getting older sometimes get in the way of protocol P

True... but that's the whole point of being taught the correct way of doing things and having it drummed in from an early age -- so that it becomes an automatic thing that doesn't require any active thought, like putting on your seat belt as soon as you sit in a car, or flushing the loo....

Hugh

[TheReson8or]

Dont flush your computer speakers down the loo!!!!

[Peter Conz Connelly]

Dont flush your computer speakers down the loo!!!!

I dropped my brand new Nokia N97 down the toilet not too long ago. Weeing and texting, simultaneously, is not recommended!!!

[Steve Hill]

A rather wealthy client and friend dropped his mobile (containing "his life") off the back of a boat in the Thames estuary. We were all obliged to dive for it. He got his life back.

Anyway, if you don't have a proper monitor controller try an SM Pro Audio Nano Patch (about £38) and always turn it down or hit the mute button before shutting down. I use one on my "home" computer.

[Starmonger]

I've emailed Acoustic Energy to see if they say that my speakers will be ok (looking for reasurance that i havn't damaged 'em). will see what they say (if they even reply haha).

[Steve Hill]

I've emailed Acoustic Energy to see if they say that my speakers will be ok (looking for reasurance that i havn't damaged 'em). will see what they say (if they even reply haha).

You may well find the designer is not a million miles from being a very regular contributor to this forum...

[Starmonger]

I've emailed Acoustic Energy to see if they say that my speakers will be ok (looking for reasurance that i havn't damaged 'em). will see what they say (if they even reply haha).

They are beutiful speakers

[ef37a]

Two different things going on here to this old brain..

IMHO modern amps should NOT make a loud pop at switch on or off. My Tannoy 5a's make a rather muted click at switch off and an even softer "ffrpp" as they come on( I have a home built 60watter using 2 V old ILP modules and that gives a good old crack into a pair of crap Pioneer speakers I have hooked up to them, we should be doing better 20years on?)

Second point...

The Tannoys are fed from a small mixer and I can power up/down the whole system without any untoward noises. I trust the monitors are NOT fed directly from the soundcards outputs?

Dave.

[ef37a]

Steve H,

Were I 45 years younger and able to swim like Sharon, (never learned)NOTHING would convince me to go into the Thames just to find some rich *&^%s fekking mobile!

Dave.

[Hugh Robjohns]

IMHO modern amps should NOT make a loud pop at switch on or off.

I agree... but it appears not to be the amp that's making the loud pop, but rather the sound card in the computer when the PC powers down.

Of course, there are still ways and means of designing a soundcard to power up and down gracefully too, but I suspect such niceties weren't on the design wishlist... and if normal power up/down practices are adopted it doesn't matter anyway.

I doubt the power-off thumps have done any damage....
you'd already know if it had because you'd hear it when playing music. But I would do something to prevent exposing the speakers to thumps in the future.

hugh

[ef37a]

Yes Hugh,
I was just pointing out that there could be two strands to this thread.

Op amp topology is of course much the same as a PA and suffers the same problems, I find the otherwise very useful TL0 series gives switch off thumps. It can sometimes be as simple as not providing a dischage path for the output coupling cap to save .01p per unit. Thus at switch on/off that cap charges thru' YOUR kit!

But yes, correct fader drills save everybodies ears and possibly cones!

Dave.

[James Perrett]

Of course, there are still ways and means of designing a soundcard to power up and down gracefully too, but I suspect such niceties weren't on the design wishlist...

Warning - a bit of a rant follows...

I hope Focusrite are listening - I don't understand how anyone reputable could design a serious interface with a dedicated monitor out that gave out large spikes not only when powered up/down but also when the sample rate is changed. I don't care that they've fixed it on the new model - a company that is supposedly well respected in professional audio should never have released such a badly designed product in the first place. While I've had other interfaces that make noises at power up/down, everything else I have owned has been totally silent when changing sample rates.

Cheers

James.