Combining power amps on 7.1 systems

[markeh]

Apologies if this has been asked before - I've been out of the audio market for a while.. (I still have my Carver TX-11 tuner and AR turntable....)

I'm setting up a new system, mostly for classical and jazz music, but it will also support the occasional DVD or TV show.
Most of the AV systems I have been looking at have 7 power outputs, so 7 power amps. The system I'm planning on setting up will start with 2 front channels plus subwoofer, and maybe a center channel in the future if I feel like it would be useful. No plans for rear or surround speakers.

So if I buy a 7.1 AV receiver, am I throwing money away - will 5 of the amps be sitting idle? Or a better question, if I use only two front speakers can I combine amps to increase the power to those two??

thanks,

 

[TLS Guy]

Apologies if this has been asked before - I've been out of the audio market for a while.. (I still have my Carver TX-11 tuner and AR turntable....)

I'm setting up a new system, mostly for classical and jazz music, but it will also support the occasional DVD or TV show.
Most of the AV systems I have been looking at have 7 power outputs, so 7 power amps. The system I'm planning on setting up will start with 2 front channels plus subwoofer, and maybe a center channel in the future if I feel like it would be useful. No plans for rear or surround speakers.

So if I buy a 7.1 AV receiver, am I throwing money away - will 5 of the amps be sitting idle? Or a better question, if I use only two front speakers can I combine amps to increase the power to those two??

thanks,

Yes, the amps will be sitting idle. No you can not combine the amps. That will blow the receiver up instantly, and void the warranty.

The only way you can resolve this is to use a pre/pro rather than a receiver, and add power amps as you add speakers.

I use a pre/pro, and I can switch in the amps as required. I can bring in right and left front, center, surrounds and rear backs at the flick of switches.

 

[lovinthehd]

The economies of scale somewhat work for you in an avr, though. Buying a pre/pro plus amps is usually quite a bit more money (and if you want multich with bass management the minimum these days is a 5ch unit, 7 ch units are more common now). If you want a 2.1 unit with bass management that will generally cost you, partly again due to economies of scale, not that much demand for such in comparison to avrs. Better avrs can act as a pre-pro, too in case you actually need more amp power (what speakers are you driving?).

I still have my Carver C-1 preamp and two M-500t amps and my Technics SL1200mk2....the Technics works fine on my avr, the other stuff is in storage. YMMV.

 

[markeh]

(what speakers are you driving?).

You've heard of paralysis by analysis?? I'm picking out every element of the system, meaning an almost infinite number of combinations. Speakers included.Eventually (soon) I'll get sick of looking at web sites and downloaded manuals and reviews and pick something.

It just annoys me to pay for 5 power amps that i will never use.

Thanks,

 

[lovinthehd]

You've heard of paralysis by analysis?? I'm picking out every element of the system, meaning an almost infinite number of combinations. Speakers included.Eventually (soon) I'll get sick of looking at web sites and downloaded manuals and reviews and pick something.

It just annoys me to pay for 5 power amps that i will never use.

Thanks,

You'd rather pay much more for just two? That's the usual deal depending what features you want. Especially if you want a center or bass management. Perhaps look at the Marantz or Yamaha slimline 5ch avrs, that way you "waste" less.

The power supply can be used for two ch more effectively with most avrs, too (mine does, at 8 ohm, 170 w/ch 2ch driven, 120 w/ch 5 ch driven, almost 110 w/ch 7 ch driven).

Might want to determine speakers first, then determine amp needs accordingly. If you want your amp power to go further, get higher sensitivity speakers.

 

[KenM10759]

The total system compatibility does depend upon a wide range of variables, including room size and shape, room treatments or not, preferred listening levels and desired features for now and future.

How big is your room and how loud do you think you would like to be able to go?

 

[PENG]

Apologies if this has been asked before - I've been out of the audio market for a while.. (I still have my Carver TX-11 tuner and AR turntable....)

I'm setting up a new system, mostly for classical and jazz music, but it will also support the occasional DVD or TV show.
Most of the AV systems I have been looking at have 7 power outputs, so 7 power amps. The system I'm planning on setting up will start with 2 front channels plus subwoofer, and maybe a center channel in the future if I feel like it would be useful. No plans for rear or surround speakers.

So if I buy a 7.1 AV receiver, am I throwing money away - will 5 of the amps be sitting idle? Or a better question, if I use only two front speakers can I combine amps to increase the power to those two??

thanks,

I don't disagree with TLS Guy in practically sense though as usual, not totally if "combined" means biamp instead of just tie them together. You can get a mid high end AVR such as those from Yamaha, Denon and Marantz, or Anthem that has very decent bass management and are "biampable" using the unused channels. If your speakers are also biampable, then not all of the amps have to sit idle because you can use up 6 of them to bi-amp the left, right and center.

It will not give you double the power per channel(not even close), but depending on the speakers crossover configuration, you may get some gains to various degree when you biamp them. From power usage stand point, you will get minimal gain in 2 or 3 way speakers that has the tweeter on its own once the jumpers are removed. The gain in power usage efficiency is limited by the size of the power supply and the fact that tweeters use much less power than the mid range and bass drivers. Regardless, if I were to use a mult-channel AVR for 2.1, 2.2 or 3.1,3.2 speaker configurations I will biamp for sure instead of letting them sit idle. Some will tell you it is a waste of time, and I will say it depends, and why not..

 

[markw]

It's that "maybe a center channel in the future" that's problematic.

Had you not specified that, a good two channel system would be all you need. Once you indicate you MAY want a center channel, you need a true multi-channel setup. Ain't no growing a two channel system into anything more than that.

But, on the positive side, as lovinthehd pointed out, when using only two channels of a multi-channel amp, it puts out a bit more power.

 

[BlwnAway]

Apologies if this has been asked before - I've been out of the audio market for a while.. (I still have my Carver TX-11 tuner and AR turntable....)

I'm setting up a new system, mostly for classical and jazz music, but it will also support the occasional DVD or TV show.
Most of the AV systems I have been looking at have 7 power outputs, so 7 power amps. The system I'm planning on setting up will start with 2 front channels plus subwoofer, and maybe a center channel in the future if I feel like it would be useful. No plans for rear or surround speakers.

So if I buy a 7.1 AV receiver, am I throwing money away - will 5 of the amps be sitting idle? Or a better question, if I use only two front speakers can I combine amps to increase the power to those two??

thanks,

First off let's consider your main question, "will the amps your not using just go to waste?"
Will they sit idle...yes
Will it be a waste... Maybe not, depends on your speakers, one thing to remember is that modern day AVR's, while they have multiple amp channels, they share one single power supply for those amps, so by not drawing power from multiple channels at once, it leaves more power available for the channels you are using.
Don't forget, amps don't push power, speakers draw power, so the higher the demand from those individual speakers (in either impedance or in volume/db's) The more power is needed and the power is derived from the power supply, not the amp, the amps are rated and built according to the power supply that will be available to them.

Example: an AVR capable of 100w all channels driven, will often be capable of 130+ watts with only 2 channels driven.

Plus, if your thinking about adding a Center speaker in the future, then you've used 3 of those amp channels, plus most modern AVR's come with at least 2 zones, that you could possibly use for future areas in your home.

As far as combining Amps, NO, you can't simply combine amps that would technically be bridging and no current mainstream AVRs allow you to do that.