Separate Amplifier Quandry

[gcmarshall]

Hi,

I am down to these choices for my home theater/2 channel music listening set up (7.1). I watch movies and listen to music on the same system and enjoy crisp, crystal clear powerful movies and music.

1) B&K 200 series amps (200.1, 200.2 and/or 200.5; it looks like the 200.3 is no longer sold; the ".1" for example indicates it's a monoblock, ".2" = 2 channels, and so on))

2) Rotel RMB-1095 (5x 200) and/or RB-1080 (2x200)

Note - I have 2 audiosource amp one/a's which will drive my 2 surround back speakers, so i only want additional amplification for my 5 other speakers (3 speakers across the front and 2 surround sides).

Here are my concerns. All input, criticism, tips, etc. are appreciated.

I have come to believe that listening to 2 channel music with a 5 channel amp driving the front LR speakers will not be as good as listening to 2 channel music with a 2 channel amp driving the front LR speakers. however, i also want my front three speakers to be driven by identical amps for more seamless movies audio.

since the two companies above do not make a 3 channel amp, it seems that a 5 channel amp is the only one that meets the criteria of having an equal presentation across the front three speakers. but, then i get back (in a circular problem) to not having a 2 channel amp hooked to my front LR speakers for 2 channel music.

am i splitting hairs? will a B&K 200.5 driving 2 channel music sound effectively the same as a 200.2 driving 2 channel music? or is a 5 channel amp only suited to a theater application, while giving up something on 2 channel music performance?

 

[Duffinator]

Great question and I've had similar concerns as I comtemplate an external amp for my system. I've also noticed that many of the manufacturers have stopped making 3 channel amps and have wondered if you have a seperate amp for just the two fronts will you notice a difference in the center channel? But if you buy a 5 channel amp you could always use the two extra channels to bi-amp your fronts. I don't think it makes much of a difference but if they are there you might as well use them. And bi-amping is different then having more wattage available, bi-amping is not additive in the sense that 200+200 watts does not equal 400 watts.

 

[MDS]

I have come to believe that listening to 2 channel music with a 5 channel amp driving the front LR speakers will not be as good as listening to 2 channel music with a 2 channel amp driving the front LR speakers. however, i also want my front three speakers to be driven by identical amps for more seamless movies audio.

I don't see the distinction. If you were to use a single 5 channel amp, but then play your source in stereo, you would only be using two channels of the amp.

 

[gcmarshall]

MDS-

the distinction (or proposed distinction) is that, for example, a dedicated monoblock amp driving the left speaker and another driving the right speaker is the ideal (though not the most cost effective) setup if critical music listening is important. by that same logic, i was proposing that a 2 channel amp seems better for 2 channel music than a 5 channel amp for 2 channel music. the more channels a single box drives, the more hardware you have to place inside the box, the more the power supply gets divided up, and it seems that some tradeoffs have to be made in order to get 5 amplifiers in a box. whereas, alternatively, a monoblock amp or a 2 channel amp has more space and less going on internally, thus possibly allowing better sound presentation and fewer tradeoffs.

so, you are correct, listening to 2 channel music with a 5 channel amp only uses 2 of the amps, but that is the heart of my thread. does the nature of the tradeoffs used to build a 5 channel amp reduce a 5 channel amps ability to play crystal clear 2 channel music relative to how well a dedicated 2 channel amp from the same product line would be able to play 2 channel music? i guess i want the best of both worlds and that may not exist. i want the best 2 channel music experience i can afford and i want the best 5.1/7.1 movies i can afford, but all from the same system. thus, my quandry.

 

[gcmarshall]

it seems to me it would make sense for manufacturers to make monoblocks and amps wth 2, 3, 4, 5 and 7 channels. this would give consumers every possible options. however, by not offering 3 channel amps, the logic must be (from the manufacturers perspective) that most people will pay up for a 5 or 7 channel amp rather than buy only a 2 channel amp for fear of having inconsistent soundstage across the front during movies. if the manufacturers i am looking at sold a 3 channel amp, that's all i would need. i don't need a brand name for my rears. my cheap audiosources will drive the surround effects just fine. as it stands, the only locally-sold 3 channel amp i can find is a krell, and that costs almost as much as my son's annual private school tuition.

 

[The13thGryphon]

There are still some amps being manufactured with single channel amp modules that will allow you to configure an amp with 2, 3, 4, 5, and sometimes even 6 or 7 channels. The ATI 2000 series is one example. The Theta Dreadnaught is another... although that one might be a little more money than the average person would want to spend.

However, you can purchase a 2-channel AT2002 for $1,495 (mfg. list), and add a third 200 watt amp module for an additional $300 (list).

Look around on the Internet and you're bound to find a few additional brands that will also allow similar customization.

Personally, I do use a 2-channel amp for my main left and right, so when I'm listening to stereo music I get the most out of my equipment (my 2-channel amp is a dual-mono design). I also have a second amp from the same company, so that my center channel will be powered by similar amplification and not sound different as things pan across the front three channels. Works great in my opinion.

However, I think that if you're using a quality amp like the B&K or Rotel you won't really notice a difference on 2-channel music. Some amps, like the ATI referenced above provide individual power transformers for each channel. Others use a single large transformer for all channels... which does mean that there might be a small drop in watts per channel if all channels are being hit with high-power demands simultaneously... which really doesn't happen that often.

When running such an amp in 2-channel mode the transformer only has to supply power tot he two channels that are being utilized, and therefore the chance of running out of juice is substantially minimized.

Obviously the type of music you listen to, the efficiency of your speakers and their ease or difficulty in being driven, the size of your room, and other factors -- like how loud you like to listen -- will ultimately determine whether an amp like the B&K will suffice or not... but I'd bet it would work out very nicely.

 

[highfihoney]

maybee i missed it but i didnt see if you mentioned a budget of if buying used gear is an option for you.

i have owned 5 & 6 channel amps that i ran the front 2 channels for stereo with & ive found out that a dedicated stereo amp or in my case dedicated monoblocks were able to drive my fronts with much more authority over equal wattage multichamps with the extra channels not being used.

if you dont mind buying used i have a few specific amps that i could reccomend that i have tried in 3 channel that were excellent amps.

 

[Nick250]

.

(snip)

am i splitting hairs?
(snip)

Yes, big time. IMO you are throwing money at problems that do not exist. And you are getting crummy advise from the other posters. Hell, no one even asked what speakers you are using. What ever the least amount of money you are willing to spend is the way to go. There will be no audible differences in your different solutions.

IMO, YMMV, yadda, yadda

 

[mtrycrafts]

Yes, big time.

Hell, no one even asked what speakers you are using.

There will be no audible differences in your different solutions.

IMO, YMMV, yadda, yadda

Yep, that seemed strange to me too and was about to ask but you brought it up first.
Interesting, critical issues are overlooked and a solution looking for a problem is offered.

 

[Buckeyefan 1]

I agree with the last two posts. First off, what type of speakers are you using, and what are the specs (spl/ohm)?

13th G makes a good point:

Some amps, like the ATI referenced above provide individual power transformers for each channel. Others use a single large transformer for all channels... which does mean that there might be a small drop in watts per channel if all channels are being hit with high-power demands simultaneously... which really doesn't happen that often.

You also need to consider the capacitors that store power for those demanding peaks. How large are they? How many per channel?

Finally, if it's a class A or A/B amp, and you plan on playing music at reference levels, how large is the heat sink? What is the weight of the unit compared to the number of channels? The better the amp dissipates heat, the lower the thd once the unit starts acting like a small furnace.

 

[gcmarshall]

i appreciate all the advice. correct, no real problems exist. in fact, the thread was not about any problems, but instead about differences in performance of 2 ch versus 5 ch amps for 2 ch music (in general, and not with my specific speakers, thus the reason i did not provide such details).

 

[highfihoney]

i appreciate all the advice. correct, no real problems exist. in fact, the thread was not about any problems, but instead about differences in performance of 2 ch versus 5 ch amps for 2 ch music (in general, and not with my specific speakers, thus the reason i did not provide such details).

i understood what you were asking about differences in sonics when switching between ht & critical listening 2 channel & i think your on the right track looking at seperate amplification,the more shared channels in the amplifier the more cross talk between channels,more useless hardware, more signal seperation, more signal loss,more drain on the transformer & caps,multichamps are not too unlike running a stereo amp in bridged mono the more you increase the demand on the amplifier the more unwanted everything.

others may dissagree but from my experience you will get better performance running as much seperate amplification as possible.

 

[gcmarshall]

hifihoney,

thanks. yes, i agree. even with my cheap audiosource amps run in bridged mode, i heard distinct improvements in nearly all of my well-recorded DVD's versus my receiver alone. bono's voice in the Slane Castle DVD was previously muted and weak. with the amps, his voice sends chills down my spine. as someone who is generally cheap, i certainly appreciate the few previous posts from mtry and nick suggesting that separate amps may be throwing money to the wind. but, i am a convert and am lucky to be in a position to buy some serious adult toys (and i don't mean the kind that use AA batteries sold from a store with darkened windows).

anyway, mainly for the price, local availability, and the generally positive feeling i get about it, i am probably going to end up with the Rotel RMB-1095. if after some use feel that it's 2 ch performance is lacking, i can always add a 2 ch amp (RB-1080) bringing me up to full 7 channels with separate amplification. until then, i will let my yamaha drive my surround backs or use some cheap audiosources. my current audiosources are going to be reassigned to drive some in walls in my living room and dining room for background music for entertaining.

 

[Leprkon]

it seems to me it would make sense for manufacturers to make monoblocks and amps wth 2, 3, 4, 5 and 7 channels. this would give consumers every possible options.

I know you were down to just two companies, but have you looked at the Outlaw monoblocks ? they might fit your needs.

http://www.outlawaudio.com/products/2200.html

 

[gcmarshall]

leprkon,

yes, i've looked at outlaw. thanks. i am trying to minimize the number of plugs i have. and i want to buy locally.

 

[pearsall001]

gcmarshall

In a way I think you answered your own question. If the Audiosource was good enough to "send chills down my spine" then I doubt spending the bucks on either Rotel will get you a "better chill". I myself love the pro amps. I have 2 Behringer A500's running in mono - talk about chills - with the performance I'm getting from them I see no need to spend big bucks on another amp & getting nothing better in return IMO.

 

[zumbo]

3-channel Adcom
http://www.adcom.com/amplifiers/gfa5503.htm

http://www.adcom.com/dealerlocator.htm

http://cgi.audiogon.com/cgi-bin/auc.pl?ampsmult&1138932730 used

http://audiophileliquidator.chainreactionweb.com/product_info.php?cPath=35_24_54&products_id=225&osCsid=28e7b232a2bdc643a46b8da8900ab476 new

2-channel Adcom:
http://www.adcom.com/amplifiers/gfa5500.htm

http://cgi.videogon.com/cgi-bin/cl.pl?amps20ch&1141678422 used

http://audiophileliquidator.chainreactionweb.com/product_info.php?cPath=35_24_25&products_id=227&osCsid=28e7b232a2bdc643a46b8da8900ab476 new

My baby below!

 

[zumbo]

 

[highfihoney]

http://www.adcom.com/amplifiers/gfa5503.htm

http://www.adcom.com/dealerlocator.htm

zumbo,i see you like adcom,i do too,if you ever get the chance to try the gfa 565 monoblocks jump on them,300 wpc @ 8 ohms & 600 wpc @ 4 ohms,they usually go for right around $500 each used,ive got 1 pair of the white face models sittin in the closet while i wait to find a 3rd with the white face for an all white adcom rig for the master bedroom.

the 565 monoblocks are damm good compitition for krell,levinson & mcintosh amps at a fraction of the cost.

 

[zumbo]

zumbo,i see you like adcom,i do too,if you ever get the chance to try the gfa 565 monoblocks jump on them,300 wpc @ 8 ohms & 600 wpc @ 4 ohms,they usually go for right around $500 each used,ive got 1 pair of the white face models sittin in the closet while i wait to find a 3rd with the white face for an all white adcom rig for the master bedroom.

the 565 monoblocks are damm good compitition for krell,levinson & mcintosh amps at a fraction of the cost.

I saw one of those recently, I am looking now. I could just see 600w on my poor little quarts.