Newbie question...

[desmo900rider]

If you have a 75w per channel amp that is 7.1, but you only use it in a 5.1 setup, where does the extra power go? As in...


75w x 7 channels is 525 total

so if you use that amp in 5.1, does it then become

525w total/5...so 105w per channel?

I have heard of bi amping, but I'm not clear in that yet...still learning...


Thanks for helping the new guy out...


Mike

 

[markw]

Not quite.

First off, that 75 X 7 spec is a bit exaggerated. Each channel might put out 75 wattts individually, but they will not all put that out simulteneously.

The reason is that they all share one common power supply and it distrubutes the power as needed working on the premise that, at least with HT, not all channels will be called upon for the maximum output at the same time.

So, that "extra power" allocated for the non-used two channels is not just sitting idle. It's being distributed to the five working channels as needed and actually affords you a little extra headroom on them, and that's a good thing.

 

[desmo900rider]

Thanks, that helps...the reason I ask is that the set I am looking at (KEF 2005.2), according the KEF, should have 100w per channel. I understand that Sony/Kenwood, etc power does not equal Adcom/Rotel power, so I'm trying to decide what will be enough...I am looking at a Denon that puts out 75w per channel in 7.1, according to the spec sheet. All the reviews that I have read on the KEF system say that the system needs as much power as you can afford, I just don't know if the Denon's 75w is enough...

I rarely watch HT or listen to music at very high volume if that makes a difference, but I also do like to turn things up enough to hear them...

 

[markw]

Decisions, decisions...

About the best advice I can offer is to make sure that whatever receiver you wind up buying has preamp outputs, at least for the front channels. That way, if it lacks the oomph the KEF's need for your listening levels, you can always augument it with a behemoth amp.

 

[skizzerflake]

If you have a 75w per channel amp that is 7.1, but you only use it in a 5.1 setup, where does the extra power go? As in...
75w x 7 channels is 525 total
so if you use that amp in 5.1, does it then become
525w total/5...so 105w per channel?
I have heard of bi amping, but I'm not clear in that yet...still learning...
Thanks for helping the new guy out...
Mike

First, be wary of power ratings. Most AV receivers have a maximum amount of power they can put out and it isn't quite as much as the watts/channel X number of channels figure. They assume (correctly) that you will probably never drive all channels to the max at once.

Secondly, don't worry too much about minor differences in power output. You have to double amplifier power in order to make a 3 db difference (barely louder) in output at the speakers. 100 WPC is probably better than 50, but probably not discernable from 75 or 90. If you have a powered subwoofer and can relieve your main speakers of the low frequencies, this is even more true since low frequencies use up most of your power.

If you are not listening to loud music, you are probably using a couple watts per channel at most. I recommend paying more attention to features and sound quality and ignoring power unless is is at least double.