# can inadeqate power cause clipping?



## deadenddude (Jun 3, 2009)

Like if your battery and alternator aren't proving enough power to the amps? When I run a two ohm load on my amps, and to a lesser extent a 4 ohm load, I get periodic clipping at high volumes. I was thinking that perhaps the amps aren't getting adequate power to drive lower impedance's because they can drive 8 ohms fine with no clipping.


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## TREETOP (Feb 11, 2009)

deadenddude said:


> Like if your battery and alternator aren't proving enough power to the amps? When I run a two ohm load on my amps, and to a lesser extent a 4 ohm load, I get periodic clipping at high volumes. I was thinking that perhaps the amps aren't getting adequate power to drive lower impedance's because they can drive 8 ohms fine with no clipping.


Yep.


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## Luke352 (Jul 24, 2006)

It's kinda obvious isn't it. Say you have a 4 ohm load and your amp with 13.8volts going to it and it just clips during a certain dynamic demand, now lower it's input voltage to 12volts now play that same dynamic passage now the amp isn't going to be able to produce the same amount of power because of the lowe input voltage so obviously it will clip harder whereas if you can provide it with 14 volts that dynamic passage where it was just clipping with 13.8 volts will probably be fine with 14 volts. The other thing to consider is that when your electrical system is incapable of providing a a nice high stable voltage supply, then during the stages when the voltage starts to sag under load it means your amp will try to pull even higher current to produce the same amount of power and cause even greater voltage sag.


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## deadenddude (Jun 3, 2009)

Luke352 said:


> It's kinda obvious isn't it. Say you have a 4 ohm load and your amp with 13.8volts going to it and it just clips during a certain dynamic demand, now lower it's input voltage to 12volts now play that same dynamic passage now the amp isn't going to be able to produce the same amount of power because of the lowe input voltage so obviously it will clip harder whereas if you can provide it with 14 volts that dynamic passage where it was just clipping with 13.8 volts will probably be fine with 14 volts. The other thing to consider is that when your electrical system is incapable of providing a a nice high stable voltage supply, then during the stages when the voltage starts to sag under load it means your amp will try to pull even higher current to produce the same amount of power and cause even greater voltage sag.


Well, I wasn't sure if you could get clipping unless you dropped to really low voltage. I've had some people tell me you would have to drop below 11 volts before you'd get clipping. That didn't sound right to me though. Should I upgrade the alt or the batt, or both? Also, should i put bigger gage wire from the batt and ant?


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## Luke352 (Jul 24, 2006)

Just look at the difference in power ratings some amps have @ 12v, 13.8v, and 14.4v.


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## Oliver (Jun 25, 2007)

quote>

24 Kinetic batteries and three Ohio Generator 250-amp alternators, producing more than 24,000 watts of power.

quote>

Musta had money to burn 

2006 Car Audio and Electronics Magazine September News

Some of the guys here get this loud with their wives car stock electrical system :surprised:

quote>
179.5 dB and 180.3 dB and 177.2 dB and 174.6 dB 
quote>

Oh yeah...don't forget about corner loading the subwoofers :laugh:


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## MarkZ (Dec 5, 2005)

The system voltage may not be your issue here. It shouldn't be terribly dependent on whether or not your load is 4 ohms or 2 ohms. If you're clipping more often running the 2 ohm load, it could be because that speaker is less sensitive or the losses are within the amplifier itself.


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## tspence73 (Oct 14, 2008)

deadenddude said:


> Like if your battery and alternator aren't proving enough power to the amps? When I run a two ohm load on my amps, and to a lesser extent a 4 ohm load, I get periodic clipping at high volumes. I was thinking that perhaps the amps aren't getting adequate power to drive lower impedance's because they can drive 8 ohms fine with no clipping.


When your amps don't have sufficient current to create a peak bass hit for instance, then I would imagine the result would be a very soft clipping effect where the impact itself would be less powerful. This is where I think some people get the description I've heard like, "it hits harder now". Power upgrades have been known to get responses like that.


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## deadenddude (Jun 3, 2009)

tspence73 said:


> When your amps don't have sufficient current to create a peak bass hit for instance, then I would imagine the result would be a very soft clipping effect where the impact itself would be less powerful. This is where I think some people get the description I've heard like, "it hits harder now". Power upgrades have been known to get responses like that.


That's basically what I get, a soft clip on bass hits. Would I benefit more from a high amp alternator, or an Optima Yellow Top?


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## sqshoestring (Jun 19, 2007)

If the amp has an unregulated PS like most, the input voltage dictates the output. Lets say an amp produces +/-28V rails on 14v input, in simple theory that is the transformer doubling if we ignore losses/sagging/etc. So at 12v you get 24v rails. That rail voltage is the peak + or - voltage sent to your speaker; once you ask for more you get a clipped wave. Can't ignore power compression in the sub, that will have a similar effect of it wanting to clip sooner.

Remember the amp has lots of power to send to the speaker, the speaker's ohms of resistance limits the power that goes through the speaker and thus through the amp. That is why a low load blows amps up, too much power is let through like a short. Also when you run lower ohms (allowed loads) an amp tends to be less efficient just by design. So running 2 ohms instead of 4 will take more power (let more through) but also the amp can be less efficient so it takes more power per watt. So you might get 80% more power at 2 ohms through the speaker, but the amp might take 100% more power (amps of draw on your 12v) to run. I'm just picking numbers, I have seen amp tests on the net showing this. Other amps don't do that, they might give 25% more power to the speaker and get hot and pop fuses like crazy at low loads. The heat means they are getting inefficient. Given class D is more efficient and that loss in efficiency is less. Either way an amp will draw more power getting louder at a lower load, delivering more watts to the speaker. Drawing more power is naturally when you will see a deficiency in your supply or wiring, via lower supply voltage at the amp it is easy to check.


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## MarkZ (Dec 5, 2005)

deadenddude said:


> That's basically what I get, a soft clip on bass hits. Would I benefit more from a high amp alternator, or an Optima Yellow Top?


You would benefit most by not listening to tspence.



sqshoestring said:


> If the amp has an unregulated PS like most, the input voltage dictates the output. Lets say an amp produces +/-28V rails on 14v input, in simple theory that is the transformer doubling if we ignore losses/sagging/etc. So at 12v you get 24v rails. That rail voltage is the peak + or - voltage sent to your speaker; once you ask for more you get a clipped wave. Can't ignore power compression in the sub, that will have a similar effect of it wanting to clip sooner.
> 
> Remember the amp has lots of power to send to the speaker, the speaker's ohms of resistance limits the power that goes through the speaker and thus through the amp. That is why a low load blows amps up, too much power is let through like a short. Also when you run lower ohms (allowed loads) an amp tends to be less efficient just by design. So running 2 ohms instead of 4 will take more power (let more through) but also the amp can be less efficient so it takes more power per watt. So you might get 80% more power at 2 ohms through the speaker, but the amp might take 100% more power (amps of draw on your 12v) to run. I'm just picking numbers, I have seen amp tests on the net showing this. Other amps don't do that, they might give 25% more power to the speaker and get hot and pop fuses like crazy at low loads. The heat means they are getting inefficient. Given class D is more efficient and that loss in efficiency is less. Either way an amp will draw more power getting louder at a lower load, delivering more watts to the speaker. Drawing more power is naturally when you will see a deficiency in your supply or wiring, via lower supply voltage at the amp it is easy to check.


But most modern day amplifiers aren't unregulated. They ramp up the switching duty cycle to be able to control for losses within the amplifier. The problem, ultimately, is that if you're drawing more current from your output stage (and therefore, more current from your Vrails), then you'll cause the Vrails to sag. This is an INTERNAL loss, rather independent of the electrical system. The clue in his situation is that 8ohm seems fine but 2 ohm doesn't. That tells me that the issue is probably with the amp (or speaker, or ears) and not the electrical system.


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## sqshoestring (Jun 19, 2007)

I suppose it depends on the amp. For example many old MRV alpines are rated about 25% less output on 12v than 14.4v. They do have a regulated power supply but it actually regulates only for high voltage. If the PS goes above what about 14v makes, it lowers the PWM to protect from overvolt of internal components. Once under load the PS runs full power and does make less max power on lower supply voltage. If you fire the amp up idle the PWM will pull right back until a load is placed on the amp. Most amps do not regulate the PS fully because to have it run at less PWM all the time on 14v is inefficient. I know some do, but I don't know every amp and have tested few if any of those. Many amps I have checked the PWM runs WOT (50%) all the time it is running.

I don't check this, but have been told most newer amps have better PS and less of a problem with sagging than older amps. They are smaller and more powerful, higher frequency. Yes, all depends on a specific amp of course.

I should add that you could well be right, the amp may sag at lower loads. Some seem to be made to and others not. Would be easy enough to check the supply voltage at the amp under load. On the other hand some amps don't make much more power at 2 ohms than 4 while a few amps actually do double. But they all consume more power at lower load excepting the few amps with regulated or switchable output.


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## MarkZ (Dec 5, 2005)

sqshoestring said:


> I suppose it depends on the amp. For example many old MRV alpines are rated about 25% less output on 12v than 14.4v. They do have a regulated power supply but it actually regulates only for high voltage. If the PS goes above what about 14v makes, it lowers the PWM to protect from overvolt of internal components. Once under load the PS runs full power and does make less max power on lower supply voltage. If you fire the amp up idle the PWM will pull right back until a load is placed on the amp. Most amps do not regulate the PS fully because to have it run at less PWM all the time on 14v is inefficient. I know some do, but I don't know every amp and have tested few if any of those. Many amps I have checked the PWM runs WOT (50%) all the time it is running.
> 
> I don't check this, but have been told most newer amps have better PS and less of a problem with sagging than older amps. They are smaller and more powerful, higher frequency. Yes, all depends on a specific amp of course.
> 
> I should add that you could well be right, the amp may sag at lower loads. Some seem to be made to and others not. Would be easy enough to check the supply voltage at the amp under load. On the other hand some amps don't make much more power at 2 ohms than 4 while a few amps actually do double. But they all consume more power at lower load excepting the few amps with regulated or switchable output.


I guess the point I was making is a little different from the regulation of the PS. He's saying that his amp seems to be clipping earlier than he would otherwise expect when running low impedance loads, but not with high impedance loads. So, although you're correct that the majority of amps out there will supply more power with higher supply voltage, the voltage isn't really what's being modulated here -- the impedance is. And the impedance (ie. current draw from Vrails, and ultimately the transformer's secondary) shouldn't depend so strongly on the supply voltage, right?

Personally, I think electrical system problems tend to manifest first in light dimming, before your ears will be able to hear distortion products from clipping.


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## deadenddude (Jun 3, 2009)

Thanks for all the informative replies. I'm still not clear whether upgrading my power supply will help. To be more specific, if I wire my dual voice coil Alpine type Rs to 8 ohm, I can turn the head unit all the way to 35 and the subs pound hard with no clipping. When I wire them to 2 ohm, I can't get the head unit past 27 before I get a clipping popping sound through the subs.


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## MarkZ (Dec 5, 2005)

I think the most likely culprits are either the sub bottoming out or the amp's internal losses. What's the amp anyway? What are its 8 ohm and 2 ohm ratings?


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## deadenddude (Jun 3, 2009)

MarkZ said:


> I think the most likely culprits are either the sub bottoming out or the amp's internal losses. What's the amp anyway? What are its 8 ohm and 2 ohm ratings?


They're diamond audio d 7152's. They're rated at 150 X 2 at 4 ohms and 300 X 2 at 2 ohms. It doesn't give the 8 ohm rating.


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## sqshoestring (Jun 19, 2007)

MarkZ said:


> I guess the point I was making is a little different from the regulation of the PS. He's saying that his amp seems to be clipping earlier than he would otherwise expect when running low impedance loads, but not with high impedance loads. So, although you're correct that the majority of amps out there will supply more power with higher supply voltage, the voltage isn't really what's being modulated here -- the impedance is. And the impedance (ie. current draw from Vrails, and ultimately the transformer's secondary) shouldn't depend so strongly on the supply voltage, right?
> 
> Personally, I think electrical system problems tend to manifest first in light dimming, before your ears will be able to hear distortion products from clipping.


The amp will draw more current at low loads, so if the supply to it is inadequate it will be more so. That only takes a $10 meter on the amp supply to find out. If so it could be the wiring to the amp, or the car just plain can't supply the amp due to alternator and if it drops under 12v the batteries too.

Far as how good the amp's internal PS is...who knows. Some amps don't make much more power at low load that also depends on the amp design.

So yes it could be the 12v supply, could be the amp PS, could be the amp does not perform well at that lower load some don't.

For the last OP post, you have to set your gain. If you swap 8 to 2 ohms the amp will be putting out much more power at 2 and the gain will have to be lowered. Some amps are more stable at highers ohms, but likely this is an issue of power. If that is a larger amp this just might be all the subs can take...since I don't know what amp you are talking about. 2 to 8 ohms load would be well over double the power difference maybe 3-4 times.


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## deadenddude (Jun 3, 2009)

sqshoestring said:


> The amp will draw more current at low loads, so if the supply to it is inadequate it will be more so. That only takes a $10 meter on the amp supply to find out. If so it could be the wiring to the amp, or the car just plain can't supply the amp due to alternator and if it drops under 12v the batteries too.
> 
> Far as how good the amp's internal PS is...who knows. Some amps don't make much more power at low load that also depends on the amp design.
> 
> ...


Gain isn't the issue here, it still does it with the gain all the way down on a 2 ohm load. i have two alpine Type Rs that are rated 500 RMS each so I'm sure I'm not overpowering them, my amp is only rated at 300 RMS x 2 at 2 ohms.


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## 89grand (Nov 23, 2006)

Are you running the amp in mono to two subs? If so, I wouldn't wire those subs in parallel for a 2 ohm load. That Diamond amp isn't rated to handle a 2 ohm mono load. Rewire it for 8 ohms before you ruin the amp.


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## deadenddude (Jun 3, 2009)

89grand said:


> Are you running the amp in mono to two subs? If so, I wouldn't wire those subs in parallel for a 2 ohm load. That Diamond amp isn't rated to handle a 2 ohm mono load. Rewire it for 8 ohms before you ruin the amp.


No, I'm not bridging it. It's running stereo, one channel to each sub. It's rated to handle two omh loads in stereo mode.


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## 89grand (Nov 23, 2006)

deadenddude said:


> No, I'm not bridging it. It's running stereo, one channel to each sub. It's rated to handle two omh loads in stereo mode.


Oh ok well then nevermind.


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