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PA cliping light, what does it actually mean?

C

callingltu

Jan 18, 2011
112
0
#1
Hey,

I've got Alto mac 2.2 PA, which is 800w @ 4omhs. I use alembic pre, when i set alembic pre almoust at max ant PA volume at about quarter everything is fine, but when i turn volume about at half red clipping light starts to blink. Does this mean that my PA is too powerfull for cabinets or what? I have mag 410 and behringer bb115. They should handle those 800w
 
#3
Assuming PA means Power Amp, not the front of house PA?


Your Alembic Pre is putting out more signal than the Amp can handle. I've never ran a preamp at max. Ever.

The power amp doesn't care what it's doing to your speakers, it just puts out the volume of signal that you tell it to whether the speakers can handle it or not.

No clue on the Alto Mac 2.2 power amp.
If running high volume you're probably beating the living hell out of that Behringer 115 paired up with a 410. IMHO. That one speaker will be getting WAY more power than each of the 410's.
 
#5
The clip lights mean you are maxing out the power amp.

On a power amp, you can be hitting full power way before you have the knobs turned up due to an overly hot signal being fed into it.

You need to turn your pre way down.

Looking at the amps specs, you are only pushing 300 watts per side @ 4 ohms.

If your clip lights are coming on, and you are not loud enough - time for a bigger/better amp.
 
#8
callingltu said:
http://audio.manualsonline.com/manuals/mfg/alto/mac_222324.html?idRes=535471 heres the amp.

So how do i know when preamp output is optimal? Should i put PA at max and adjust alembic volume untile PA clipping light goes off? :)

Well, they should both getting 400w each, behringer says its 600w, which i know it isnt, but at least 400w i hope :D
Click to expand...



You should really never run each maxed. Gear sounds best when it worked, but not maxed... IMHO.

As above mentioned. If you're not getting enough volume... you need more power, or everyone else to turn the **** down.

Sounds like you're running into the 410, then out of hte 410 into the 115, the single speaker will be getting much more power than the 410's. The 410 is capable of being quite a bit louder than the single 115.
 
#9
If the poweramp is clipping it means it's at it's limit. Don't run your pre so hot. Turn the poweramp all the way up, the use the pre volume to adjust overall volume. The clip light flashing once in a while on a hard note is ok, more than that you need to turn down. And yeah, get ready for a blown 15 cause sooner or later that's what you're gonna have. It's a poor combination to run one with a 410. If you must use it, stack the 15 on top so you can hear when it's straining, it's the weak link, no matter how many watts it claims it can take.
 
#10
Hi.

NILFISK???

Or Nimbus for Harry Potter fans.

:D

Unless the vacuum guys have done something very strange, the power amp doesn't have a volume control. It has an input attenuator. The clip light is either for the input or the output, can also be for both, but the main thing is that the signal is too strong and something has to be done. That something is to either get more (/sensitive) speakers or a more powerful amp.

I'm from the school that runs power amps unattenuated and adjust the output from the pre/mixer. There's other schools as well...

Regards
Sam
 
#12
According to the Manual - it seems that you have clip lights that indicate when the distortion is greater than 0.5%.

Clip - indicates that the PREAMP is clipping - Turn down the output of your preamp it is overdriving the input of the amp.

Sig - indicates that the OUTPUT is putting out a signal. There is no indicator for clipping the output - use your ears!
 
#14
will33 said:
If the poweramp is clipping it means it's at it's limit. Don't run your pre so hot. Turn the poweramp all the way up, the use the pre volume to adjust overall volume.
Click to expand...

I don't know where this myth came from. It's just dead wrong. edit: the diming the amp part. Clipping is the amp hitting its limit.

[Invalid or Expired Link Removed]

The signal entering the amp should be as hot as possible, while ensuring adequate headroom, in all preceding gear. Volume should be set primarily with the amp's gain controls.


will33 said:
I
The clip light flashing once in a while on a hard note is ok, more than that you need to turn down.e.
Click to expand...

Agreed. Except on sub amps in an actively crossed system then more frequent clip light blinking by itself is OK. Assuming the speakers can take it, and it still sounds good. But, bi-amping PAs is another story.
 
#15
Hi.

callingltu said:
But then why clipping light comes only when i turn PA volume up ? :D
Click to expand...

Because You don't have a volume knob on the amp, you have a signal ATTENUATOR. When You decrease the attenuation, ie. "turn the volume up" like you think you're doing, the signal level on the input stage of the power amp rises.

Bassamatic was kind enough to RTFM for You, and if you re-read his post (or the manual), you should understand what the clip indicator monitors.

regards
Sam
 
#16
I'm seeing square waves...

You should (depending on the power rating of your speakers!!) have your amp turned all the way up to full and adjust your volume at the input of the pre.

If your amp is clipping at halfway, though....I'd check the THD graph in your amps manual (that's if there's one printed in there). A true THD graph can reveal a lot about an amp's performance.
 
#17
In addition to what everyone else said...

As has been mentioned, the 410 can take a lot more power than the 115. You should run each of the cabs off one side of the power amp. This way, you can feed more power to the 410 than the 115, increasing your maximum volume.

And if that isn't enough, buy a bigger power amp or a second 410, depending on what's the overall limiting factor (and protect your ears ;) ).
 
#18
ulrich said:
I don't know where this myth came from. It's just dead wrong. edit: the diming the amp part. Clipping is the amp hitting its limit.

[Invalid or Expired Link Removed]

The signal entering the amp should be as hot as possible, while ensuring adequate headroom, in all preceding gear. Volume should be set primarily with the amp's gain controls.




Agreed. Except on sub amps in an actively crossed system then more frequent clip light blinking by itself is OK. Assuming the speakers can take it, and it still sounds good. But, bi-amping PAs is another story.
Click to expand...

Spot on. You have to strike a balance betweenst the pre's volume and power amp's attenuators. As a general rule-of-thumb, I'll run a pre's volume at ~50% (whatever that is) and adjust the attenuators so I achieve the necessary volume and near-stable / steady signal indication with no red-lights.. Once the relationship is established, you can make minor changes with the pre's volume control and still maintain nominal signal / noise ratio. Same holds true for mixer / amp PA rigs. Once set, subsequent volume tweaks ("you guys are too loud!") are done with the mixer's main sliders...we don't go running to the power amp bank each time we need to make a volume change. The idea is to maintain a quasi-linear relationship between your pre and power amps, IOW the power amp should respond smoothly, efficiently, and predictably when adjusting the pre's volume.

Still not loud enough? You may need to add speakers.

Riis
 

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