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clipping or overexcursion?

R

Rose_of_Sharyn

Jun 1, 2005
51
0
New egypt, NJ
www.myspace.com
#1
Alright. Well I just got a Carvin B1500 and I love it. Only problem is, my Amp clip led light is coming on when I play lower strings (B,e...)

I have an 8 ohm ashdown mag410t that is rated at 450 watts and the carvin is putting 700 watts out at 8 ohms, so theoretically I should be fine ( just about twice the rms rating )

Only thing is, when I play I see my spekers sort of "jumping out" or really pumping hard it looks like. Now I never observed my speakers before hand so maybe thats just how they are supposed to be, but since my amp clip led is coming on im thinking there is a problem.

In my manual, it says that if the amp clip led comes on to turn down the volume, but my volume is at 2... and my drive is at about 5. I did notice that when i turn my drive down or almost all the way off that I dont see the clipping much at all but for the music kind of music we play I like a little overdrive to it.

I also have an fender 5 string jazz bass that has active electronics in it. I also noticed that this bass is SUPER LOUD, ive never played a bass louder for some reason..

so my question is, if I buy say a 15in cabinet would this solve the whole clipping and overexcursion problem? And how bad is clipping anyway? Could it kill my speakers?
 
#2
Here's an uninformed guess (surely someone here knows more). The head doesn't know what the speaker is doing. If the clip light is on, the amp is clipping. The speaker can also be suffering overexcursion, and probably is if a clipped signal is being sent to it. Speaker-fart (if you're getting that) results from some signals the speaker can't track. This is very hard on speakers.

As a dumb question, do you have the active/passive switch set to active? If not, that's a problem. My experience with the Carvin BX1200 is that the drive knob isn't that useful; you'd probably be better off with an overdrive pedal.

(Incidentally, I think you have your ratings backwards. If the speakers can take 450 watts and you're driving them with 700, this can also damage speakers.)
 
#4
Rose_of_Sharyn said:
Well, as for the active/passive switch. I actually didnt have it set to active... this was just because I got a much louder sound from it when I turned the active switch off... I didnt think it would have made a huge difference in the clipping area but now I see your point. Ill try it turning it to active next practice.
Click to expand...

And besides doing that you don't need to turn your active bass up to full volume. The active basses I have are all capable of putting out way more levels than I really need. With active basses, I usually set their volume control about 2/3 wide open or to match the level of my passive basses. That will help prevent the amp from clipping and the bass will run a bit cleaner too.

Speaker over excursion is something else. Watch you don't use too much bass boost. That can kill the speakers fast. If the speakers sound like they're in distress, back down on the volume. Get an extension cabinet to spread out the work they have to do.
 
#5
As Flintc says, the clipping light has nothing to do with the speakers. Depending on how the manufacturer has designed the amp, it is telling you one of two things:

a) that your active bass is sending too large a signal to the input of your amplifier, causing the pre-amp stage to clip. Answer: make sure the amp's input is set to "active" (you have an active bass - why else do you think that switch is there?) and if it still clips, turn your bass down.

or

b) that your Carvin's pre-amp stage is putting out too large a signal, causing the power amp to clip. Answer: turn your amp's master volume control down (assuming it has one).

I suspect that it's the first of these that is happening. If you really were driving a 700 Watt solid-state power stage into clipping, it would sound like Satan's chainsaw and your ears would be bleeding. :eek:

Also, if that clipped 700 Watt amp was being used to drive a cab that is rated to handle only 450 Watts maximum, then by now you'd have fatally damaged your speakers by driving them too hard. This why my personal preference is to make sure that my speakers can handle more power than the amp can provide. I know this goes against the very popular "amp twice as powerful as speakers" body of opinion, but that's how I like to work. At the end of the day, you can't put a quart in a pint pot.

No doubt by saying this, I'll have triggered another TB "overpowering/underpowering" mud-fight. (Yawn)
 
#7
Espidog said:
Also, if that clipped 700 Watt amp was being used to drive a cab that is rated to handle only 450 Watts maximum, then by now you'd have fatally damaged your speakers by driving them too hard. This why my personal preference is to make sure that my speakers can handle more power than the amp can provide. I know this goes against the very popular "amp twice as powerful as speakers" body of opinion, but that's how I like to work. At the end of the day, you can't put a quart in a pint pot.

No doubt by saying this, I'll have triggered another TB "overpowering/underpowering" mud-fight. (Yawn)
Click to expand...

I'm not into the overpowering/underpowering thang, but I'll say this: having 2 times the power for SR cabs isn't uncommon - but the mains are protected from overexcursion by the crossover frequency choice, and the subs are usually made for long excursion. The RMS of either is usually 1/2 of what they can handle for shorter periods, thus the 3 dB of headroom can actually BE USED, and not just admired ; }

For bass rigs, so many of the available cabs have used their xmax by the time a wattage ONE HALF of their RMS rating has been reached - or even much less. But. Compounding the difficulties in accessing full output of a bass rig is the observation that many players do not know how to maximize/properly use their gain structure - pregain and postgain and maybe master volume in the preamp section (and matching the bass's output to the input for that matter), mixed with radical EQ gain or loss, and then the additional "gain" knobs on a power amplifier.

So some people buy more power than is needed without necessarily using it all, and others would be in danger if given that much power because they are already maxing the available gain at the preamp and can very easily keep a power amp at clipping deeply, well above the sweet spot of "occasional" clipping.

Really, it's not what you have, it's how you use it.
 
#8
I see that someone else mentioned to try the 'active' input setting, so I erased that part of my post. That might help if you play aggressively. Also, remember that the setting of the master volume control has nothing to do with the amount of power the amp puts out... with a very hot input signal (that drive control adds a lot of gain to the signal), you can easily clip the amp with the master control set at what seems like a very low level. Using the active input setting would at least give you more range on the master volume taper to set you final volume level..

However....IMPORTANT... the lowest bass control on that amp is brutal... almost sub bass. When you mentioned your speakers jumping about, my guess is you might have that control above flat. That control is very, very powerful, and cranking it even to the 1 or 2 o'clock level will result in a huge amount of deep bass going into your speakers... making them 'piston' like you describe, and eating up a ton of power from your amp resulting in the amp 'clipping' sooner than it should. On the B1500, you should really use the 'low mid' knob similar to other amps' bass controls, and only use the 'bass' control very slightly to add or subtract deep bass from your sound depending on the room acoustics.
 
#11
^Kjung

there is no doubt in my mind that it is a great head. Like i said, I only had the volume at 2! And I play in a really loud metal band, like really loud, and this was at the exact same volume level that my ashdownmag300 head was at when the ashdown was set at like 8! and it sounds so great, I can get any tone I want out of it.

If I try everything everyone says and it still clips on the low notes, it will ultimatley destroy my speakers right?
 
#12
Rose_of_Sharyn said:
^Kjung

there is no doubt in my mind that it is a great head. Like i said, I only had the volume at 2! And I play in a really loud metal band, like really loud, and this was at the exact same volume level that my ashdownmag300 head was at when the ashdown was set at like 8! and it sounds so great, I can get any tone I want out of it.

If I try everything everyone says and it still clips on the low notes, it will ultimatley destroy my speakers right?
Click to expand...

Well, there's clipping and then there's 'clipping'! If the amp clip light comes on only occasionally when playing the loudest low notes, you are probably OK. If you drive the amp to 'clip' constantly combined with playing at high volumes and pumping more power into your cab than it's rated for... that is probably not a very good thing!

I think you will be fine though if you watch that low bass control and pad down the input level a little bit.

The good news for you is that eventually you can add another 8ohm cab... this would result in the wonderful situation of getting more power from the amp (a whopping 1250 watts) and having more speakers to move more air.... an additional cab will make your rig MUCH louder if you find the single cab is not doing it for you.
 
#13
I just got my odb-3 overdrive pedal and I plugged it in, sounds great. and the clip light did not come on once!? Why is this? Did I bypass the main thing or something? Because normaly withought the pedal the Amp Clip led comes on every so often, but once I plugged in the pedal, everything was fine. Is this normal, or could it still be clipping and I wont know bc I bypassed the thing somehow?

btw im the original poster
 
#15
Flintc said:
The speaker can also be suffering overexcursion, and probably is if a clipped signal is being sent to it. Speaker-fart (if you're getting that) results from some signals the speaker can't track. This is very hard on speakers.
Click to expand...

This is just plain incorrect. Can the speakers "track" a distortion pedal? Can they "track" a synth pedal? Yeah, they can. Do some more research on the effects of clipping. Drivers aren't damaged by the shape of a waveform. What's hard on speakers is too much heat or too much excursion.
 
#16
Rose_of_Sharyn said:
Alright. Well I just got a Carvin B1500 and I love it. Only problem is, my Amp clip led light is coming on when I play lower strings (B,e...)

I have an 8 ohm ashdown mag410t that is rated at 450 watts and the carvin is putting 700 watts out at 8 ohms, so theoretically I should be fine ( just about twice the rms rating )

Only thing is, when I play I see my spekers sort of "jumping out" or really pumping hard it looks like. Now I never observed my speakers before hand so maybe thats just how they are supposed to be, but since my amp clip led is coming on im thinking there is a problem.

In my manual, it says that if the amp clip led comes on to turn down the volume, but my volume is at 2... and my drive is at about 5. I did notice that when i turn my drive down or almost all the way off that I dont see the clipping much at all but for the music kind of music we play I like a little overdrive to it.

I also have an fender 5 string jazz bass that has active electronics in it. I also noticed that this bass is SUPER LOUD, ive never played a bass louder for some reason..

so my question is, if I buy say a 15in cabinet would this solve the whole clipping and overexcursion problem? And how bad is clipping anyway? Could it kill my speakers?
Click to expand...

I don't think it's been clarified, but is this a preamp or a power amp clip LED?
 

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