Using a 2 Channel amp in a 5.1 system

[karlusmagnus]

I have a Marantz SR7005 receiver, and a Rotel RMB-1080 2 channel amp.
The 2 fronts are Axiom M3 Bookshelf speakers. I happen to have picked up some Thiel CS floor standing speakers at a local antique store and they are nice, but my wife does not want to look at them (aesthetic reasons as the room is our living room), and relegates them to rear speakers if I want to use them there (where she says they will not dominate the room). I could pick up an Axiom VP-150 center speaker (matching the 2 fronts).
My question is if there is any issue with pushing the the 2 fronts with the Amp, and the center and rears with the receiver? The Marantz is no slouch.
Ideally I would put the Thiels up front, and the bookshelves at back, but that is something that will take time to convince my wife on the aesthetics (and then i might be wiser to hold off on a center until that time, but I would like to clean up dialogue on movies, and the center should do that for me).

The room is about 26x18. We listen to music for the most part (40% classical, 30% jazz, 30% RnB and rock and everything else), but watch movies, and would like to improve the aural experience when watching them.

Any helpful thoughts are appreciated, as I know little enough about this, except from what I have found through searches.

 

[ahblaza]

Thiels

What model Thiel CS's do you have, I'm just curious and will try to address your query soon after.

 

[j_garcia]

I would just leave the Rotel out of the picture until you can get the Thiels up front, because the M3s probably don't need 200W. It should not damage them though. IMO, the Thiels are going to outclass the Axioms by a lot, and probably won't match perfectly with the Axiom center (without hearing them together it is hard to say how close it might be). That is how I would sell the Thiels up front - since it sounds like music is a factor, then the best speakers should be up front.

Once calibrated properly, there should be no issue between using the Rotel in your setup with either of the speakers. I've run my Marantz with many different amps powering some or all of the speakers at various times.

 

[karlusmagnus]

What model Thiel CS's do you have, I'm just curious and will try to address your query soon after.

Thanks.
I believe them to be CS 2.2's

 

[Adam]

Welcome to the forum!

There's no problem with using a two-channel amp to run two speakers in a 5.1 setup. I've done it myself, as have others here. In fact, it's recommended fairly often because taking the load of the front two speakers off of your receiver frees up power for the other speakers, so some find that they don't need a multi-channel amp to get the performance that they want.

Do you know the impedance of your new Thiels? If not, let us know which model you got (as asked above), as we can look into it. Your Rotel is rated for speakers down to 4 Ohms nominal, but your Marantz is listed only down to 6 Ohms. That might impact which speakers you want to connect to the amp, but my guess is that you'll still want to use it for the front speakers.

EDIT: You answered the question as I was typing. Looks like the 2.2s are 4-Ohm speakers.

 

[karlusmagnus]

I would just leave the Rotel out of the picture until you can get the Thiels up front, because the M3s probably don't need 200W. It should not damage them though. IMO, the Thiels are going to outclass the Axioms by a lot, and probably won't match perfectly with the Axiom center (without hearing them together it is hard to say how close it might be). That is how I would sell the Thiels up front - since it sounds like music is a factor, then the best speakers should be up front.

Thanks. Yes, sometimes it takes someone else to spell out what makes perfect sense. You are indeed correct. My thought was that if I picked up a center for not a lot of cash, I could resell it afterwards without losing much in the equation, once i had moved the Thiels upfront.

 

[j_garcia]

My speakers are 4 Ohm as well and the amps for the front three speakers in the receiver haven't been used in years

Nice speakers. I personally feel they are pretty good looking too

 

[karlusmagnus]

Thanks Adam. I didn't expect such a prompt answer to my question, and yourself and j_garcia pretty much answered everything that was popping around in my head.

 

[ImcLoud]

Use the amp, that will fre eup the power of your avr...

 

[ahblaza]

Thanks. Yes, sometimes it takes someone else to spell out what makes perfect sense. You are indeed correct. My thought was that if I picked up a center for not a lot of cash, I could resell it afterwards without losing much in the equation, once i had moved the Thiels upfront.

Sorry my friend and welcome, I had to leave the computer for a minute, as expected John and Adam came to the rescue, I don't think I can add anything that has not already been suggested, nice Thiels, use them as mains, your wife will thank you in the end.......

 

[j_garcia]

Use the amp, that will fre eup the power of your avr...

LOL. That receiver could drive those M3s with no issues all day long, so the amp is sort of just gravy. The Rotel on the other hand, will power them without breaking a sweat while riding a unicycle and juggling chainsaws

 

[karlusmagnus]

LOL. That receiver could drive those M3s with no issues all day long, so the amp is sort of just gravy. The Rotel on the other hand, will power them without breaking a sweat while riding a unicycle and juggling chainsaws

Sort of like bringing a shipping container to a tupperware party, so i guess

 

[PENG]

Can you ask your wife if she can make the Thiels look good enough to go up front? I (could have said we) just can't tell you it is okay to put them at the back if 40% of the time you listen to music and enjoy classical music. The M3's belongs to the side or rear. The Thiels need the Rotel, not much doubt about that and if they are in good working condition they will impress you.

 

[JerryLove]

My question is if there is any issue with pushing the the 2 fronts with the Amp, and the center and rears with the receiver?

Rather than try to match volumes across the front three with two different amps, and also run your lowest ohm speakers (the thiels) on your AVR while putting a big amp on some bookshelves... Why not just run your rears off your amp and the front three off the Marantz?

 

[ImcLoud]

LOL. That receiver could drive those M3s with no issues all day long, so the amp is sort of just gravy. The Rotel on the other hand, will power them without breaking a sweat while riding a unicycle and juggling chainsaws

yah but with the amp helping it can do all that while balancing a no armed midget on its nose...

As far as which speakers to run, most likely the rear will be easiest, although you should be able to use your avr to balance the front amp to run the l r channels. I know I had a marantz running a 5.1 with 2 mono blocks powering the front left and right and it was easy to balance with a cheap spl meter...

 

[karlusmagnus]

If I was to put the vintage thiel's up front, what center would be a reasonable match and relatively inexpensive?
There is a Boston Acoustics VR 12 nearby for less than $100, for example.
Thanks.

 

[Bryceo]

Currently running a 400 watt mono block amp off my main speakers
The center and 4 rear surrounds run off my receiver

 

[j_garcia]

I've run my mains off a variety of amps and never had a problem level matching them. I would not consider that an issue.

 

[ahblaza]

I've run my mains off a variety of amps and never had a problem level matching them. I would not consider that an issue.

I definitely concur, what issues (OP) do you think you may encounter using the amp for mains (Thiels) and the Marantz for everything else, maybe I missed something...........

 

[ahblaza]

Currently running a 400 watt mono block amp off my main speakers
The center and 4 rear surrounds run off my receiver

I hope you mean two mono blocks...