Quick question about multi-channel amps

**imprezive one** · 08-06-2004, 01:30 AM

Okay, so I will admit that I am a car audio n00b. However, I will also say that I am learning a great deal, and I've been reading up on it a ton in the past few months since I'm ready to put together my carpc. Mostly getting my information from here.. www.bcae1.com

Basically, my audio setup is as follows:
Speakers - Infiniti Kappa components - front & rear
Subwoofer - 10" Kenwood w/ self-enclosed 100w amp (going to upgrade later)
Soundcard - Creative Soundblaster Audigy 2 NX
Amplifer - trying to decide

I've had a question that I haven't been able to answer by researching it on my own... so here it is. Say you have a 4 channel amp and you are using all four channels to power four different speakers (RF, LF, RR, LF). What is the advantage/disadvantage of doing this over using only 2 channels to power front and rear? Also, if you have four speakers and a subwoofer, what is the advantage/disadvantage of using 2 channels to power the 4 speakers (F,R), and then bridging the last two to power the sub vs. buying another mono amp just for the subwoofer?

I'm slowly expanding my understanding of all of this so any help you can give would be great. Thanks.

If an amplifier is rated at say 100w X 4, does that mean for each channel it can push 100watts for a total of 400w?

**christmaspie** · 08-06-2004, 02:05 AM

What is the advantage/disadvantage of doing this over using only 2 channels to power front and rear?
The advantage is that you will have fade and balance for all four speakers. If you used 2 channels for four speakers you would lose either your fade or your balance depending on how you set it up.

Also, if you have four speakers and a subwoofer, what is the advantage/disadvantage of using 2 channels to power the 4 speakers (F,R), and then bridging the last two to power the sub vs. buying another mono amp just for the subwoofer?
The same comment I made earlier about fade/balance for the speakers. As far as the sub is concerned, a mono amp is always a better choice for subs (IMO) as they are designed to amplify only the lower frequency spectrum and are much more efficient than a typical class AB amp design. Most mono sub amps tend to be Class D amps.

If you want 4 speakers and a sub each speaker needs individual amplification. Trying to parallel your lefts to a 2 ohm load and then trying to run the fronts on a 4 channel to your left and etc. is just not a good idea. It is definitely do-able in theory (but hell, so is socialism) but I wouldn't recommend.

If an amplifier is rated at say 100w X 4, does that mean for each channel it can push 100watts for a total of 400w?

An amplifier rated @ 100W X 4 into 4 ohms will give you 4 seperate channels that produce "100" watts at 4 ohms. As you may notice from the quotes I consider most power ratings to be marketing tools and would recommend you ignore them for the most part. I always love the guy who asks about the 1800W 2 - channel BOSS amp for like 40 bucks and they say it has more power than an RF or kenwood with a "little more" of a conservative rating. Side note: I'm waiting to see whether or not this new CEA-2006 rating standard means anything. We'll see.

**sssssss27** · 08-06-2004, 02:21 AM

Originally Posted by christmaspie

The same comment I made earlier about fade/balance for the speakers. As far as the sub is concerned, a mono amp is always a better choice for subs (IMO) as they are designed to amplify only the lower frequency spectrum and are much more efficient than a typical class AB amp design. Most mono sub amps tend to be Class D amps.

If I remember correctly the reason Class D amps are only for subs is they have a bad sound quality to them but at the lower frequency's it's an inaudible sound degradation.

He pretty much covered all the basic advantages and disadvantages. I'd probably just go with a two amp setup, make things easiest.