Adding an amp through preout - i dont get it???

[alpina]

hi guys,

can someone please explain this to me.

assuming i have a 7 channel av receiver but want to use a more powerful amp to drive my front speakers, i could use the preout and buy a stereo power amp to drive my front 2 speakers but where would that leave me with my center speaker?. given that the fronts are a matched set, would i just continue to run the centre off the av amp or would i have to get another amp to run the centre (another preout) and if so, what would i do with the spare channel on the amp?

hope this makes sense?

cheers,

julie

[Karma]

HI,
I have done what you are thinking about. The center remains on the receiver and the two abandoned main Left & Right receiver channels are unused. If I had to do it again I would buy a three channel amplifier that would also drive the center.

I will say that this setup works very well. My priorities strongly include stereo music which is why I decided on a two channel amp.

Sparky

[alpina]

thanks sparky,

relatively new to all this - didnt even realise that you could get a 3ch power amp only.

isnt the center underpowered when compared with the fronts?

cheers,

julie

[gcmarshall]

sparky-

same question from me. why do you say you'd get a 3 channel amp if you were doing it again? is the center "off balance" with your mains with just the 2 channel amp across the front? i was thinking of doing this myself and am very curious about your experience.

thanks.

[PewterTA]

Well there's few things going on here when you only add a stereo amplifier.

One thing is the power difference of the Mains vs. Center... The Center will be "underpowered" when compared to the mains. This wouldn't be bad except something like 70% of all sound comes from the center channel, so really the center is the one that needs the power. An amp can (and most likely will) "color" the sound some so that the exact same sound center to the center and to the mains will sound different in some way.

You could look for a three channel amp, or even better yet, 3 mono block amps. Get three nicely powered amps and really enjoy knowing that each speaker is powered identically the same. The other thing you could do is by a normal 5 -7 channel amp and psuedo-bi-amp the mains and still power the center with it (or biamp all the speakers with a 7 channel and have one open channel).

Adding a stereo amp is not a bad starting block...but your center will most likely sound a different than your mains...is it really noticeable? Only you can tell. It's all how the amp "colors" the sound. You might find you can't tell and it's much better of a sound...or you might not like it.

The nice thing to remember is with the receiver not having to push the two main speakers (and hopefully it is really built this way), that should leave more power for the center and surround speakers! So it really is a win-win situation, all in all.

Only downside is if you really listen to multi-channel audio where you might notice the difference in sound quality from mains to center.

[alpina]

The other thing you could do is by a normal 5 -7 channel amp and psuedo-bi-amp the mains and still power the center with it (or biamp all the speakers with a 7 channel and have one open channel).
............ The nice thing to remember is with the receiver not having to push the two main speakers (and hopefully it is really built this way), that should leave more power for the center and surround speakers! So it really is a win-win situation, all in all.

hmmn,

so if i have a 7 channel receiver (yamaha 2600) but am only using 5 (ie 5.1 setup), is it possible to tap into the 2 unused channels and direct them towards my fronts in addition to the 2 channels that are already powering them?

julie

[Karma]

HI julie,
Yes, the center channel does have less power than the Left and Right channels. In my case the L & R amp is a 250W per channel Krell KAV-2250. The center is 120W's from a Denon 3805 receiver. But remember the gain of the center channel can be adjusted to match the mains so volume balance per se is not an issue. I have yet to run out of power on the center channel. But as a wise person said: "You cannot have too much horsepower or watts". I agree. So, I would rather have all three channels match.

As to sound quality, I basically feel that my Denon reciever has better than average fidelity for a receiver. It is true it is not as good as my Krell stereo amp. For me, stereo music is purely a aural experience. Thus, I place great importance on the quality of the components. Movies, OTH, is mostly a visual experience. I kind of go on the philosophy that the small differences are less important to me while I am paying attention to a movie.

Make no mistake, this is a fine sounding system with my 805S's and dual ASW800 subs for either music or movies. Would it be better with all front channels having identical front channel amps? Yes, I think so but just for movies not music.

Sparky

[Stoney]

Having the center channel on an amp with less power will probably give you only a difference in available headroom. You probably rarely run the amp at max power and won't experience a difference in volume after properly balencing the three channels. As was mentioned above, the power supply in your receiver will have 2 less channels to power. My beleif and understanding is that the center channel is usually less demanding than the mains since it is fed mostly dialog related info, the more power hungry frequencies are sent to the mains and sub. I would think that adding a separate two channel amp, although not the "perfect" solution, will be an overall improvement.
As far as trying to channel the unused channels back into the mains, I don't think that is a good idea. Potential damage to the amps I would think.
Edit; I think I misunderstood your question about the spare amps. My first thought was that you wanted to use the main channels in parallel with the external amp. Now I see you are talking about the rear surround amps. I still say it would not be advisable to use the rear surround amps in paralell with the mains, but I wonder if you could use them to bi-amp your mains?

[Stoney]

I have a Denon 7.1 receiver.
The rear surround amps can be set to "multi-room" mode where the original intent is to have speakers in another room. I don't know what signal mix is sent to them though. Is it just the mains signal, or is a combo of the main and surrounds? It might be possible to take the pre-out main signal and feed it into the surround back external inputs and set the amp for multi source input with multi room output and use the surround back amp out as a second amp out for bi-amp on a bi-wirable speaker.

Arrrrghhhhhh- I think I strained something in my brain!!!!!! I'm glad I have surround back speakers and don't have to worry about it. Whatever you decide, I hope you enjoy the results.

[dyazdani]

Another option for the spare channels might be a tactile device or two...

[stewfoo]

when wife gets weirded out when i use my tactile device!
Stew