ok moon, ear, or any knowledgeable ones...

[ekbriggs]

Here is the current setup:

Rf-3's in the front and back, rc-3 center, 2 subs (not important).

Hk avr-525 reciever (as my pre-amp), Hk Pa-2000 amp (bridged running the fronts)and Hk Pa-4000 (bridged running the center and rears).

Here is the problem:

After continuous playing with both movies and music, during which both amps sound marvelous (great extension, control, etc..over the efficient Rf-3s). When i got to power off the system everything shuts off fine until i get to the amps. Which ever amp i shut off first, no matter which one, will emit a fairly loud pop out of my front speakers (its very fast but moderately loud) or rear depending on the amp. Then when i shut off the other amp it turns off just like normal. When i only have the Pa-2000 in the system everything is fine, likewise with just the 4000...it only happens when both are used and then turned off.

I am not sure if this pop is harmful or not, nor am i sure how to get rid of it. It just seems odd that it only comes from the first amp that i turn off, of the pair. Both are plugged into a Monster hts-2000 surge so i know its not out of the wall, and both powerup and play wonderfully for me so i dont think the problem is in the actual amp?

Any thoughts on the subject will be both helpful and greatly apreciated as i try to track down the cause of this in my system. Thanks to all that apply.

-Eric

[IndyKlipschFan]

First off relax...

I get this too from my sub when it is turned off..

You might try this though... Turn the volume all the way down wait like 3-5 seconds then turn it off. This might help.

As long as it is not too loud, you should be fine. Most people when they turn down the volume knob still get it.. But at a lot less voume wise. Hope this helps!

[Dale W]

Does your 2000 not have a cascading shut down ? ( switched and unswitched )

[ekbriggs]

Nah, it just a manual turnoff and on. It seems now that i am still playing with it that when i wait a few minutes after i turn amp 1 off to turn off amp 2 that the pop is not quite as loud (and by loud i am sure that the horn loading of the sound that is most likely coming through the tweeter only magnifies what i hear). Will continue to experiment...and thanks Indy it helps to know that someone else has something similiar to what i am experiencing....will remember to brreeaaathhh.

[m00n]

Woah. I have no idea. Are you stacking one on top of the other? If so, have you tried to sepparate them? Do you have any kind of an insulator between them? Not saying that will help but it if they are touching, I guess there could be a chance that there is some static build up or something..

I wish I could be of more help.

[chops]

That's what you get for running cheap equipment! just kidding!

Are the power plugs on the amps polarized? Meaning, is one prong wider than the other? If not, have you tried flipping one or both of them in the outlet? I know this can sometimes help with hum coming through the speakers, but maybe it might help in your situation as well.

Also, do they still "pop" if you shut one of them off before anything else in the system? As a general rule, it is always best to shut down your amps before the rest of the system, to reduce the chance of getting those pops through the speakers.

One more thing, have you tried turning both amps off at the same exact time?

Hopefully, maybe one of these little tricks might solve you problem. Good luck!

[Doc Robin]

Try plugging them into different power source's. I think it is the change in the load on the power strip. I may be wrong but it sounds like that is what it is. Bill

[JohnA]

Shutdown should be power amps first, then work back up the signal chain (start-up is the opposite, source first, amps last). If you do that, what happens?

[ekbriggs]

Let me start by saying thanks to all that put in their thoughts. I wanted to reply to all of you right away but i realized that i would be a little trigger happy if i did so without a little more through testing. Thus i have surmised the following;

1. When i turn off the first amp and wait 20-30 seconds before i turn off the second one everthing is perfect (no pop, no nothing...other than the usual sound i get when cutting the power to my speakers)

2. Shutting things off and powering up as you all suggested yielded perfect results as well. In powering up 1. Reciever then 2. Hk Pa 4000 3. Hk pa 2000. When powering down: its everything described above in reverse.

3. It seems that there is only the persistent popping when i turn the amps off consecutively one after the other, thus i will wait for a short time before i power down the second one.

Lastly, do others experience a slight sound through your speakers when powering up your amps, not loud just a sound like the amps are ready to send in the power when the signal is sent to them?

Second, is there any benefit to having my 3 channel amp power the Main L/R and center and 2 channel power the rears vs. letting my 2 chanel power the main L/R and the 3 channel power the rears and center? (i used configuration one as its easier to just have one amp on during stereo listening).

-Eric

[DrWho]

The pop you get when you turn off the second amp "too quick" is most likely due to a grounding issue...when you turn the amp off, the capacitors and crap discharge and I can see the ground getting a slight charge on it...and then when you turn the other one off, the ground isn't a true ground and thus provides you with a nifty little pop...I might suggest you try a gound lift on one of the amps and see what that does for you, or even bypassing your special powerstrip doohickey on one of the amps. If those two things don't do anything, then all my talk about grounds is most likely a bunch of crap But just so you know, that pop really isn't that big of a deal (unless of course it's very loud). too loud would be about the sound a book makes when you drop it flat on the floor from about 3 feet up.

as far as the hum when you turn your amps on...that is perfectly normal and just about every amp makes that sound to some extent. All you're hearing is the capacitors loading (which causes a little bit of current to flow in the process).

as far as your two amps, if they're of the same family and have all the same specs and stuff, then there should be no problem with running the 2 channel for the mains and the 3 channel for the center and rears...just remember that a timbre matched front array makes a world of difference. So basically, if you can't here any difference between the two amps, then totally go for what's easiest to work with.

[ekbriggs]

Good to hear that all of my worries are just overreactions for the most part. Not only does it help me immensely with reassurance, but it also helps to iron out (quickly) any of these problems that i might see in my or a friends own system.

Oh and Dr. Who do you know the official name of that first coincidence about the grounds discharging when turned off one after the other? Is that similiar in theory to back induced Emf on a speaker?

Also yes the amps are essentially the identical make and model all from the same family. They are just 8 and 4 channel native amps that i have bridged to 4 and 2 channel amps. The main reason that i got them was because of really good deals and the same matched front 3 speakers.

Thanks again for all the advice and help.

-E

[colterphoto1]

hey ek,

I remember this phenomena from my PA days. The rule was, in order to keep the signal spikes from damaging your speakers (we're talking massive tri-amped systems here), you always turned the amps ON last and OFF first. This way, if your mixer or any processing gear created a 'spike' when powering up/down, it would NOT be amplified and sent to speakers as the massive 'POP' like you are experiencing.

So my advice to you might be to turn your receiver or preamp off first, then shut down the amps. If the POP is being created by the amp switch itself, there might be a fix through HK. This situation is not only bothersome, but could possibly cause speaker damage, so I definitely would not just ' live with it'. Hope this helps.

[the plummer]

My experience is to concurr with the turning off the amps first to let them discharge power before turning off the pre-amp. I don't know how to do that if you are running a receiver though.

To save you from having to remember shut down order, or heaven forbid your significant other just shutting the system off and damaging your speakers, ADCOM makes a nifty AC line enhancer that when you power off your Pre-amp it automaticly shuts the amps off first. Then it shuts everything else down about thirty seconds later. I have used this with great success for 15 years now and have never damaged any speakers. Good luck.

[IndyKlipschFan]

Colterphoto said...

The rule was, in order to keep the signal spikes from damaging your speakers (we're talking massive tri-amped systems here), you always turned the amps ON last and OFF first. This way, if your mixer or any processing gear created a 'spike' when powering up/down, it would NOT be amplified and sent to speakers as the massive 'POP' like you are experiencing.

So my advice to you might be to turn your receiver or preamp off first, then shut down the amps.

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John Albright

Shutdown should be power amps first, then work back up the signal chain (start-up is the opposite, source first, amps last). If you do that, what happens?

============================================================

I think Colterphoto meant turn the AMPS off first ... Just got it mixed up.

Mike, look at this again, I think you were just backwards... Look at your second paragraph.

Roger

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I was taught this too.. Turn the Mixing board (In your case the pre amp) on first, wait a few seconds make sure all volume nobs are down, then turn amps on...

Later after the show, or in your case after your done listening or watching/listening to your system, turn volume knobs down, then turn the amps off first, then (in your case the pre amp) mixer boards...off.

[colterphoto1]

Hey Indy, please reread my post. I concurred with John A, create power spikes with other equipment with AMPS OFF, saving speakers, by switching amps ON LAST and OFF FIRST. This is in agreement with your theory.

I always remembered it by thinking of the signal flow at the beginning of a gig- you should follow this path in your startup procedure- never turning on a component earlier in the signal path than the last one on.Shutdown at 3 am was always the reverse, if you could think at all!

[burtlively]

ekbriggs,

have you considered leaving the amps on 24/7? i never did this until i read other threads from this and other forums. i never turn off any of the amps i own. i also never have popping sounds when i turn my systems on or off. another upgrade i recommend highly is to replace the outlet with a hospital grade 20 amp outlet.

[IndyKlipschFan]

I think we always did it as I was taught too, top to bottom, bottom to top... Mixer, effects, EQ, Amps... Then after the show, in reverse.

Seeing how 90% of people sit the power amp below the pre amp this should work too.

Top to bottom, bottom to top.

Kinda like how a man looks at a woman when her first sees her walking into a bar! He first looks at her top, then her bottom... OK, sorry, just living it up in here... LOL But maybe will help you remember too.

Or for you accountant types, LIFO - FIFO... Last in, first out... So, Last on, First off... That may help too.

[DrWho]

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On 5/7/2004 12:04:25 AM ekbriggs wrote:

Oh and Dr. Who do you know the official name of that first coincidence about the grounds discharging when turned off one after the other? Is that similiar in theory to back induced Emf on a speaker?

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actually i have no idea what the "grounds discharging" and all that would be called. in fact, it was more or less just a theory i threw out there based on a similar experience i've had in the past with grounds that were holding charge (and i'll be sure to come up with a more akward way to say that too). anyways, i once had an amp connected to a "special-clean-the-signal-bells-and-whistles" power strip and everytime we turned it off, it would create a very nasty sounding pop in the studio monitors...a pop so bad that i was actually afraid to turn the amp off with the speakers plugged in (so we would disconnect the monitor cables and then turn the amp off). needless to say, that got a bit annoying so i started doing some measuring of voltages and stuff. I figured that if i measured the voltage being sent to the speakers to be within the range of normal music playback, then i wouldn't worry about it. but just for kicks, i decided to plug the amp into a different socket first (not on the power strip) to see what changes that made. well there was no more pop, imagine that. then i measured the output coming out of the powerstrip and i had a good sized charge sitting on the ground (i forget the values, but i think it was around 20volts). anyways, to make a long story short...i got rid of the powerstrip and all my problems went away...now that's not to tell you to get rid of your powerstrip because when i installed a new board, i got mega hiss problems that were later fixed by a similar fancy power strip thing...and in between the time of the two power strips, the ground for the electrical socket that the conditioner was plugged into was rewired because that entire outlet box didn't have a good ground. (it was later discovered that the dedicated grounding cables were run near a water pump thing that was installed after the cable was run and it actually induced a voltage on the ground! talk about annoying!) so all that to say, if one of your amps is putting a lot of charge on the ground when it turns off (as it could be doing when the capacitors unload when you turn it off), then it's possible that your conditioner/power strip or your ground in your wall is holding a charge temporarily and causing a pop in the other amp when you turn it off (it's the second amp that's causing the pop, right?)

anyways, that whole story is why i suggested you try a ground lift on your amp. a ground lifting plug only costs 25 cents and if you don't need it now, they're always nice to have around when you're trying something new and you get ugly buzzes and crap. but since you don't have a buzz right now, im pretty sure that putting a lift will actually cause a buzz (which would suck), but it'd be cool to test and see if that got rid of the pop when you turned them off. if the pop was still there, then it has nothing to do with the ground and you can ignore all my ramblings and past experiences as they are totally irrelevant (in which case, i hope i haven't been too boring).

btw, are you still hearing the pop when you turn your equipment off in the right order? (last on, first off) i'd hate to continue my ramblings when you've already arrived at your cause/solution (i've already thought of a few more it could be)

for what it's worth, the amp and speakers that im using with my pc make a pop sound when i turn the amp off (no matter if the pc is on or off). at first it bothered me, but now i just live with it. the speaker and amp combo is around 30 years old and it still works, having popped since the beginning. however, if i turn the pc off first, i get an extremely loud pop and i've actually blown a pair of speakers that i was using as surrounds...i managed to fix them, but it was really annoying (and loud, wow).