# Active vs passive power difference?



## JH1973 (Apr 21, 2017)

Right now my components(5.25 Polk) are getting 75w RMS per set with passive crossovers.If I was to get another exact model of my amp,go active and have an amplified channel on each component(tweeter-mid) would there be a big power difference? It seems like a dumb question but I'm wondering with my current set up getting 75 to each,how much is going to the mid and how much is going to the tweet after the crossover does it thing?Hope someone knows where I'm coming from.Thanks for any input!


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## gijoe (Mar 25, 2008)

A crossover splits frequencies, not power. Unless the tweeters have a resistor for attenuation then they have the same power available as the mids. So, at the moment, both the mid and tweet could be receiving the same power.


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## JH1973 (Apr 21, 2017)

gijoe said:


> A crossover splits frequencies, not power. Unless the tweeters have a resistor for attenuation then they have the same power available as the mids. So, at the moment, both the mid and tweet could be receiving the same power.


So with that answer it seems I wouldn't gain much by doing it?


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## Marky (Nov 15, 2011)

If you went active you would need amplifier channels for every component. But the gains in sound quality is tremendous. I can't say that you would have more output power but the difference is night and day. Clarity and accuracy is off the scale as long as you are using nice equipment.


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## JH1973 (Apr 21, 2017)

Thanks for the comment.I am currently using my HU crossover for all frequencies but you're saying that going active is much more superior in terms of sound quality and accuracy.I'm really on the fence about what to do next.Honestly I'd like more power all around as right now my total RMS is 450.I think if I could double that while going active and without having to upgrade my electrical system then I'd be satisfied.


Marky said:


> If you went active you would need amplifier channels for every component. But the gains in sound quality is tremendous. I can't say that you would have more output power but the difference is night and day. Clarity and accuracy is off the scale as long as you are using nice equipment.


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## gijoe (Mar 25, 2008)

Let's be clear, you need more than a couple extra amp channels to go active. You need the ability to set proper crossover points for the mid and tweeter, which means you need a HPF for the tweeters, and a band pass filter for the mids. For it to be an improvement, you need time alignment, and hopefully some decent EQ.

So, if you can do this properly, then yes going active can be a step up. An active setup does not automatically sound better, you need a DSP with some tools (TA, flexible crossover points and slopes, decent EQ, and the knowledge to use these correctly) otherwise a passive set will sound just as good.


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## Marky (Nov 15, 2011)

JH1973 said:


> Thanks for the comment.I am currently using my HU crossover for all frequencies but you're saying that going active is much more superior in terms of sound quality and accuracy.I'm really on the fence about what to do next.Honestly I'd like more power all around as right now my total RMS is 450.I think if I could double that while going active and without having to upgrade my electrical system then I'd be satisfied.


You don't loose any power when running active. You can turn the volume up almost 100% when you have a good clean system. So in those terms you will have more volume because its tailored to each driver. 
I went passive at first on my last old school build and I just could not hit the " YEA THATS IT" point.
Gave up went active and yea it was all there all the way. High volumes were just as well behaved as moderate levels.

By all means go for it if you love music and power.

I have lots of pics under my profile on that system as well as what I'm putting together now. I was even using old school electronic crossovers and it sounded Awesome. Not comparable to passive, not even close.

I say go for it, you wont look back.


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## t3sn4f2 (Jan 3, 2007)

A passive setup will/could draw a _significant_ amount of the available power for itself. And since we perceive louder as sounding better, active would then inherently sound better over passive on the same setup. Assuming a proper active tune.



Oliver said:


> Abmolech, excerpt about power, power as it relates to speakers
> 
> The reason for so many watts is to allow for dynamic range. If your listening to 80 dB at 1 kHz (not unusual in a moving car) then you require around 86 watts at 80 Hz.
> So 1 watts without allowing dynamic range.
> ...





Abmolech said:


> Assuming your driver is rated at 92 dB at 1000 Hz, 1 watt at 1 meter, then to play 100 Hz at 92 dB will require 100 watts.
> 
> The sensitivity is rated at 20 % Celsius, a normal driver can easily exceed 200 degrees during normal operation.
> Resistance of copper = +0.393 % per 1 degree.
> ...





Abmolech said:


> Depending on the voice coil size and magnet assembly it would take around ½ minute to reach 200 degrees.
> Consider our example of a 4 ohm driver, having a DC resistance (DCR) of 3 ohms at 20 degrees Celsius
> 
> The ratio of nominal impedance (Z) to DCR is 4 / 3 = 1.33:1
> ...


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## JH1973 (Apr 21, 2017)

350w for a 6.5 driver? Most mid-range drivers that I've looked at are rated at 100w RMS give or take.This guys saying you can put 3 1/2 times that ?Is this information true?


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## DC/Hertz (Nov 27, 2011)

JH1973 said:


> 350w for a 6.5 driver? Most mid-range drivers that I've looked at are rated at 100w RMS give or take.This guys saying you can put 3 1/2 times that ?Is this information true?


You have to look at the way RMS is measured. It's taken over a long period of time on full range noise. 
With music you also have dynamics and ohm rise with lowers the amplifiers power. 
You rarely if ever get rated power from any amplifier and you don't listen to noise for 10 minutes straight


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## gijoe (Mar 25, 2008)

JH1973 said:


> 350w for a 6.5 driver? Most mid-range drivers that I've looked at are rated at 100w RMS give or take.This guys saying you can put 3 1/2 times that ?Is this information true?


You need to understand the difference between the amount of power that is available, and how much the driver is getting. 

In this case they are talking about passive crossovers and how much power can be wasted by them. The driver won't get all 350 watts. I'm not convinced the passives waste that much power, but it is absolutely true that for every 3dB you increase in output you need twice as much power.


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## DC/Hertz (Nov 27, 2011)

3db by doubling power on paper. Rarely ever works that way. Power compression and heat fight back. We've built SPL cars that went from 5k to 15k to gain 3db. It's a downward spiral the more power you add.


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## JH1973 (Apr 21, 2017)

Wow,you guys are impressive with your knowledge.Its going right over my head.You've obviously been studying car audio for quite a while.


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## gijoe (Mar 25, 2008)

Like DC clarified, doubling the power gives you 3dB AT BEST. The point is to show that the difference between your 75 watt amp and one with 150 watts per channel isn't really that much at all. There are plenty of reasons to buy as much power as you can, but understand that breaking the bank for a few extra watts isn't really the best choice. A 75 watt per channel will get plenty loud, the tweeters will never need that much power, and the mids will rarely use that much. If you went out and spent money on a 100x4 amp, you'd have almost no perceivable increase in output.


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## JH1973 (Apr 21, 2017)

What if I bridged the 2 main channels and turned 75 into 200.Would that be worth it?


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## JH1973 (Apr 21, 2017)

Ok,scratch that.According to what you guys are saying,doing that I might gain 4db.Ivkinda get it now.This is very interesting stuff.Thanks for all the input thusfar.


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## DC/Hertz (Nov 27, 2011)

3db is not a bad gain. It's a few more clicks on the volume knob and could be needed when it's time to roll down the interstate with all 4 widows down. That choice is on your needs. 
It's nice riding 80mph without a lose is audible output.


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## LostnEye (Feb 18, 2016)

DC/Hertz said:


> 3db is not a bad gain. It's a few more clicks on the volume knob and could be needed when it's time to roll down the interstate with all 4 widows down. That choice is on your needs.
> It's nice riding 80mph without a lose is audible output.


True. It's all in what you are looking to accomplish and where you are starting from.


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## gijoe (Mar 25, 2008)

While 3dB is noticeable, it's not significant. It's widely accepted that a 10dB gain is perceived as being twice as loud. That first 3dB is usually reasonable, going from 75 watts to 150 watts isn't usually that expensive, going from 150 to 300 and 300 to 600 starts to get very expensive without little to no perceptible gain. 

I've said it before, yes headroom is nice, but when most people are using far less power than they realize, 75 watts will get plenty loud and the amp will have plenty to cover dynamics. Don't be fooled into thinking a bit extra power is going to increase the sound quality. It will increase the output potential, and will increase dynamics, but even moderately powered systems have plenty of power to cover dynamics. 

Remember, you are in a car, and unless you are sitting in a silent garage with the engine off, and an award winning system, those millisecond dynamic peaks that you're striving to reproduce are inaudible anyway.


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