# powering midranges off of a headunit vs multi channel amplifier?



## jockhater2 (May 9, 2011)

is it better sound or what?
just curious because I see a lot of midranges run off of multi channel amps.

and I have 4 mids and 2 tweets right now running off of my headunit and they get more than enough power. I have to set the high pass to 100 because 125 is too much.

so is their any reason or just preference?


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## sqshoestring (Jun 19, 2007)

A HU can only make about 18rms/ch. It would be a real challenge to play to just 80Hz and overcome road noise in some cars. If that is enough power for you that is great, for many it is not. My 4x50 is far nicer and it does not go that loud, but fairly loud. I can get by with 4x50 on highs no problem, but will be putting a larger amp in soon.


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## trojan fan (Nov 4, 2007)

jockhater2 said:


> is it better sound or what?
> just curious because I see a lot of midranges run off of multi channel amps.
> 
> and I have 4 mids and 2 tweets right now running off of my headunit and they get more than enough power. I have to set the high pass to 100 because 125 is too much.
> ...




Talk about a no-brainer


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## jockhater2 (May 9, 2011)

i don't notice a difference. thats why i ask.


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## antikryst (Feb 26, 2011)

jockhater2 said:


> i don't notice a difference. thats why i ask.


there is a big difference. im new to all this and i though powering them off the HU was good enough. added an amp and it was night and day difference.

maybe your speakers are crap (no disrespect intended) so giving them more power... they still sound like crap.

the speakers i powered werent the most wonderful speakers out there... they were infinity reference speakers about $99 a pair. when i amped them... it sounded way better than just HU power.


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## jockhater2 (May 9, 2011)

well my alpine were 130. so i know they are decent.

ive always read that you an amp is their to give you the power you need.
if i am getting enough power from my headunit. why would i need an amp?


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## antikryst (Feb 26, 2011)

jockhater2 said:


> well my alpine were 130. so i know they are decent.
> 
> ive always read that you an amp is their to give you the power you need.
> if i am getting enough power from my headunit. why would i need an amp?


i got a lot more detail off the infinities when they were running off an amp. more mid bass too. night and day difference.

without an amp... the same speakers sounded muddy. it cleared out when i put in an amp.

hope this helps.


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## envisionelec (Dec 14, 2005)

jockhater2 said:


> well my alpine were 130. so i know they are decent.
> 
> ive always read that you an amp is their to give you the power you need.
> if i am getting enough power from my headunit. why would i need an amp?



The short answer: _you don't.

_A bigger amplifier doesn't make a speaker suddenly sound better. A bigger amplifier lets you play louder without distortion.

These threads' answers are just horrible. Isn't this DIYMA? I wonder where I am sometimes...


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## Chaos (Oct 27, 2005)

envisionelec said:


> *A bigger amplifier doesn't make a speaker suddenly sound better. A bigger amplifier lets you play louder without distortion.*



Which could be defined as "better"  - but you're absolutely right.


OP: If you are satisfied with the sound you have with the power from the head unit, then good for you.


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## jockhater2 (May 9, 2011)

i was just curious if there was a difference. thats all. thank you envisionelec. your answer helped a lot


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## sqshoestring (Jun 19, 2007)

envisionelec said:


> The short answer: _you don't.
> 
> _A bigger amplifier doesn't make a speaker suddenly sound better. A bigger amplifier lets you play louder without distortion.
> 
> These threads' answers are just horrible. Isn't this DIYMA? I wonder where I am sometimes...


True, if you can overcome road noise in a car with 18rms. It would likely only sound better because now you can overcome it. This will be worse in the bass region which requires more power to reproduce.

I guess my cars tend to not be that quiet.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

I'll add this. The pos sony I had in my car did 17 watts a channel before clipping. I bought a cheap amp, and it did about 18 watts a channel before clipping. The external amp sounded significantly better then the headunits internal amp did, at the same volume. Both the point at which the headunit and amp clipped were verified by my dad on a scope, and the fact that the external amp sounded better by his ears. FWIW, my dad designs power supplys for components that nasa and the military uses, along with many other commercial companies, like honeywell.

I'm going to say that the dedicated amp had lower noise and lower thd than the head units amp did.


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## jockhater2 (May 9, 2011)

hmmmm. makes a lot of sense.
wow then. I got really lucky. Because I o-scoped my headunit and it doesn't clip until 56/62

so I can turn my volume up to 55. so the mids are really loud. I actually have to turn down the Mids and Highs because at the moment I only of 1 12 and it doesn't make enough bass to over come the mids and highs.

i am glad I got lucky with a good head unit


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## SACRAMANIAC916 (Apr 9, 2011)

get an amp!!!!


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## envisionelec (Dec 14, 2005)

TOOSTUBBORN2FAIL said:


> I'll add this. The pos sony I had in my car did 17 watts a channel before clipping. I bought a cheap amp, and it did about 18 watts a channel before clipping. The external amp sounded significantly better then the headunits internal amp did, at the same volume. Both the point at which the headunit and amp clipped were verified by my dad on a scope, and the fact that the external amp sounded better by his ears. FWIW, my dad designs power supplys for components that nasa and the military uses, along with many other commercial companies, like honeywell.
> 
> I'm going to say that the dedicated amp had lower noise and lower thd than the head units amp did.


But he doesn't design amps. 

If your cheap amp clipped at 18W on a 4 ohm load, its operating supply was the battery and the outputs were BTL - _just like the headunit._ No step up. So, if it sounded better, it was not due to "better power".

Music's crest factor is around 10dB (4 to 8 for highly processed music like an MP3). 

So let's break this down. Say you're listening at 5W average (pretty loud). A peak of just 8dB comes along and the amplifier is commanded to produce 31.5W. Whoops - we just clipped hard on that headunit. 

Now, your external amplifier is going to need a power supply of 25V (+/- 12.5V) to accurately reproduce this signal without clipping.

If you can give me the model number of the "cheap amp" you used, we can discuss apples to apples.



To the OP. The reason I objected was the "pile on" that people were saying an outboard amplifier is ALWAYS better sounding: net-net. It's just not the case.


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