Outboard amp for only two channels; any probs? Timbre differences? (1 Viewer)

[MichaelDDD]

I had a conversation...OK, an argument w/someone today. Anyway, here's the scenario.

You can't afford outboard power amps for all five channels, so you purchase a single two channel amp and power your main front (L/R) with it. The idea is that you have more power for two-channel stereo listening.

The receiver still powers the Center and Surrounds.

I say that you'll have problems getting levels to match b/c under transients, the outboard amp will provide much more kick than the receiver will to the other three speakers.I also say that the outboard amp will color the sound...not necessarily in a bad way, but the front L/R will sound different than the other three.

He says that's totally incorrect. As long as the power amp is "a good one" you wouldn't hear any difference. And once you "match" the levels on all the channels, it's matched.

Who is correct?

 

[Tom Grooms]

He is. A good two channel amp can only help your 2 channel and 5.1 movie experience....

$0.02

 

[MichaelDDD]

He is. A good two channel amp can only help your 2 channel and 5.1 movie experience....

OK, I learned something new today.




But what about the "channel matching" and different power characteristics of the two amps? Doesn't that factor in, particularly with movies? All five channels (3 from receiver and 2 from outboard amp) are being used, but all five channels are not duplicates of each other. I'm confused. *crowd yells "YES, you are!"*

 

[Doug_B]

Michael,

Do you have the same speakers all around?

Doug

 

[Tom Grooms]

As long as you are using a decent A/V receiver you shouldn't have a problem with level matching the 2 channel amp powered mains. And freeing up the A/V receivers amp could have a positive effect on how it handles the other 3 channels.

Down the road you could always get a 3 channel amp (or a 5 channel amp is you have a huge room for 7.1) and it might be that much better for your movie viewing. But the 2 channel music sources will definitely benefit from off loading the amp duties from your A/V receiver....

$0.02

 

[MichaelDDD]

Hmm, interesting stuff guys.

Currently, I don't have the same size/model speakers all around...I have cheapie Kenwoods.

Buying an Ascend or Axiom system soon...most probably WON'T have the same speakers all around then, either.

 

[Claude M]

Here's my 2 cents. I used an Anthem MC3 to power 3 marble Norhs in the front and a 2 channel vintage MA5002 Soundcraftsmen power amp for the rear Norhs. The 5002 is a beast of an amp with 250W/side and the Anthem is 175W/side (all channels driven). After about 1 year I decided to use the 5002 for the front L&R channels. For music I hear a difference, for HT I can't tell any changes were made.

 

[MichaelDDD]

Thanks, Claude M. That's good stuff.

I will cede my defeat...obscurely. Don't want this guy to get a superiority complex...or make me look too dumb.

 

[Claude M]

I think the timbre match is mostly for speakers. But even when you have all speakers the same they still sound different because of room placement. My center one has a sheet of glass directly below it. The right one has a wall on the right side while the left one has another room to the left of it. You do your best then live with it (or go nuts).

 

[Geno]

MichaelDDD,

as far as "channel matching" volume wise, allways calibrate your system. so even if your receiver only puts out 50 watts a channel and the external amp puts out 200 watts a channel, after calibration, you know you will have the same power being USED in each channel. As far as the receiver amps sounding different than the external amp, well you wont notice it with your mix and match kenwoods anyway so dont worry , no seriously, there are discussions about that, I would say your receiver colors the sound more than the external. If you can tell a difference or it bugs you 6 months later, just purchase matching external amps for all your speakers .

"timbre matching" is a whole different beast. theoretically, the fron three should be as close as equal as possible. the surrounds arent as important.
what is your music/movie ratio.
I guess my suggestion is that you prioritise your speakers. like the mains are the most used, then center, then surrounds. I, like you have a mx and match speaker system, and budget is what restricts me from having matching speakers all around, but I dont think about that when Im watching movies. When I can afford new speakers, then I will consider my options.

hope this has helped

 

[Rachael B]

Michael, I suggest you consider a 3-channel amp for the front 3 channels.

 

[Steve Adams]

I have an old nikko 220 amp, if I run that for my fronts, and use my pioneer for the rest will the rest have some more power to them because I took off the mains?

 

[Geno]

steve, I have one word, calibrate.
that is about the most important thing you can do when you have mismatched power ratings and/or mismatched speakers.

once you calibrate [with an aftermarket disk and not the test tones from a receiver].

yes, you will gain some power in the rest of the channels, or you can look at it as there are less amps within your receiver drawing power AWAY from each other.

PS I run my sub thru a Nikko Alpha II amp, and I love it!

 

[MichaelDDD]

Oh, I'm a calibrating madman. Both the TV and the receiver/speakers get done about twice a year.

Most times, nothing gets changed, but I do check.

I don't really have a "mix and match" set of Kenwoods. They are all timbre matched to each other. The center uses the same mids and tweet as the towers.

The surrounds use different drivers than the front, but power handling wise are an good match for the front three.

Great comments and advice here. Thanks.

I'm getting new speakers soon. Calibration time.