Powering a center channel with a two channel amp

Marantz 6015 manual

Page 23

@vacerator 

If I understand correctly what you want to do. Did you try connecting an RCA interconnect cable from the PRE OUT CENTER channel jack on the rear panel on the Marantz 6015 to one channel input jack on the  MC352 amp?

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Um, what?? 

Anyway I can interpret this it all seems too complicated.  

The center is NOT the sum of the L and R signals, whether we are talking Dolby ProLogic or 5.1.  The center out from your AVR is the only viable input.

As for amps, you could get a stereo amp and bridge it or a mono amp or perhaps a 3 channel amp to poewr the center and surrounds. 

Yeah, I should have looked at my amps manual before posting.  I was going off a theater sound installers advice, which he said to just use one channel of the amp to power the center, and when I searched that, it wasn’t an option.

I learned that I can run my MC352 in either parallel or mono, to power my center.  My only concern is that when doing that, it cuts the impedance of the amp in half.  So the amp would be 4 ohms and the speaker is 8, with 3 being the lowest.

Is there a reason why you can't run the MC352 using only one channel of the stereo pair?  Correct me if I'm wrong, but the MC352 is solidstate and not class A?  If so, it should be able to run without a load on one of the stereo channels.

I’m using a crown xls 1502 powering a center channel, one side is for the tweeter and the other side is for the full range side. Just remember to set the crossover to the correct spec for the center channel frequencies.

@jeffbij +1

Huh, well, I guess I’ll have to talk with my McIntosh guy about that.  Everything I read on the web suggested or said that center channel audio couldn’t be amplified correctly with a left or right channel from the amp.  My take off was that a left channel would pull left channel audio and not the full center audio sound.  I have absolutely no education in this area, as to how the amp actually amplifies sound.  If an amplifier purely amplifies sound, which is what I originally thought, then what Jeffbig should work.  Not sure how muvluv’s set up would work correctly, I guess if you ran a 2 to 4 rca?

I got an email back from Mike, from Audio Classics, and he iterated the proper set up being parallel and mono.

@vacerator 

If you own a MC352 and want to use it for a center channel it won’t matter if you use only the Left Ch or only the Right Ch for the center Ch speaker. Both are exactly the same.

Look at the specs for Marantz 6015

The amplifiers specs are all the same.

The Left ch, Right ch, and Center ch are the same, as the rest of the amplifiers channel’s specs.. 

What’s different is the digital processor in the preamp section.  

Google AI response:  Just for 3 channel, Left ch, Center ch, and  Right Ch.

A digital audio/video multi-processor (often shortened to "DSP" or digital signal processor) for a Left, Center, and Right (LCR) channel setup is crucial in home theater and professional audio environments

. It acts as the "brain" of the system, taking in audio signals, processing them digitally, and then directing them to the appropriate amplifiers to speakers to create a cohesive and immersive soundstage. 

 

Here’s how it generally works

• Input and Digitization: The processor receives audio signals from various sources (Blu-ray player, streaming device, game console, etc.). If these signals are analog, the DSP converts them into a digital format.
• Decoding and Processing: The DSP decodes the audio information, especially if it’s in a multi-channel format like Dolby Atmos or DTS:X. It then applies various algorithms and processes to each channel (Left, Center, Right) individually and in relation to each other. This can include:
  • Equalization (EQ): Adjusting the frequency response of each speaker to compensate for room acoustics and listener preferences.
  • Time Alignment (Delay): Ensuring that the sound from each speaker reaches the listener’s ears at the same time, despite different distances and speaker placement.
  • Crossover Filtering: Dividing the audio signal into different frequency ranges and sending them to the appropriate drivers (tweeters, mid-range, woofers) within each speaker.
  • Dynamic Range Compression: Balancing the loudness of the audio to prevent sudden loud passages from being jarring and ensuring dialogue is clear.
  • Room Correction: Analyzing the acoustics of the listening environment and applying filters to correct for reflections and inconsistencies.
• Spatialization and Image Creation: The processor plays a key role in creating the soundstage, ensuring sounds appear to come from the correct direction and depth.
  • Center Channel: This channel is dedicated primarily to dialogue and sounds that should appear directly in front of the listener. The DSP ensures these sounds are clearly focused in the center.
  • Left and Right Channels: These handle the bulk of the stereo and surround information, providing a sense of width and directionality.
  • Panning: The DSP uses panning to place individual sounds anywhere between the left, center, and right channels, creating a seamless and realistic sound field.
• Output and Amplification: After processing, the digital signals are converted back to analog (if necessary) and sent to the power amplifiers, which then drive the speakers (Left, Center, Right). 

•  

In essence, a digital audio processor in an LCR setup meticulously analyzes and manipulates the audio signals for each channel, ensuring that each amplifier, speaker receives the optimal information to create a balanced, clear, and spatially accurate sound experience tailored to the specific listening environment and content. 

I added :

amplifiers to

amplifier

.

+1 @jea48 and @muvluv

@vacerator 

You are over thinking things.  Your Marantz has preamp RCA outputs for each channel.  Left, Right, Center, and surround channels RCA connections. 

Connect the:

• Marantz left preamp output RCA's to the left input on the MC352 amp #1,
• the Marantz right preamp output RCA's to the right input on the MC352 amp #1,
• the Marantz center preamp output RCA's to the left input on the MC352 amp #2

That will leave the right input RCA's on the MC352 #2 amp connected to nothing, which is fine.  Then connect the speaker cables to the MC352 connections to the approperiate speakers.  You may need to go into the Marantz setup menus and tell it you are using the off board amps for the front 3 channels (L/C/R).  

Ok, I’m impressed with the quantity and quality of the responses.  Thank you so much!  I’m back to what I was originally recommended to do by the audio guy that I’m working with, in building a million + dollar home theater, in a 48 million dollar house.  I’m doing the wood work.  I wanted to confirm his recommendation, and AI just screwed with my head.  Thanks again!

@vacerator posted:

Huh, well, I guess I’ll have to talk with my McIntosh guy about that.  Everything I read on the web suggested or said that center channel audio couldn’t be amplified correctly with a left or right channel from the amp.  My take off was that a left channel would pull left channel audio and not the full center audio sound.  I have absolutely no education in this area, as to how the amp actually amplifies sound.  If an amplifier purely amplifies sound, which is what I originally thought, then what Jeffbig should work.  Not sure how muvluv’s set up would work correctly, I guess if you ran a 2 to 4 rca?

I got an email back from Mike, from Audio Classics, and he iterated the proper set up being parallel and mono.

I’m not sure why you posted this thread on Agon. You should just follow the advice you got before posting your thread. Wrong advice, IMO, but you should just follow your gut.  

You didn’t mention the speakers you are using. The center ch speaker is probably considered the most important, followed by the L&R ch speakers.

FWIW, IMO, the Marantz SR6015 digital processor is more than likely the weak link in your multichannel system. The  Marantz SR6015 would be considered mid-fi, not high end. 

Jmho, it hardly does justice to a McIntosh 352 power amplifier.

I see the SR6015 has been discontinued. Note, the SR6015 was made in Vietnam. 

You might want to step up to a Marantz Cinema 40. It’s made in Japan. IMO, this AV receiver would be considered high-end. 

Huh, well, I guess I’ll have to talk with my McIntosh guy about that.  Everything I read on the web suggested or said that center channel audio couldn’t be amplified correctly with a left or right channel from the amp.

@vacerator 

I’ve been involved in cinema sound long before home theater existed and my experience is that’s not correct.  There’s no such thing as a Left, Center or Surround amplifier.  They are all just amps subject to the same ratings and limitations of any other amplifier.  The labels of Left and Right or Center are just convenience.   You might as well number the amps 1, 2, 3, etc.  instead.  

In cinemas, before Dolby Digital, we would use 2 stereo amps, one channel each for Left, Center, Right and Surround.  Yep, we often used a single amp for the entire surround speakers with judicious parallel/serialization.  Back then the Surround channel was 1, not 4 or whatever it is now with Atmos. 

So, yes, you may use 1 channel of a stereo amp for your center channel so long as the amp and speaker are otherwise a good match for impedance, sensitivity, power, etc. 

It’s sad to waste an amp though so not uncommon to see it bridged if the amp supports it.  Note that minimum impedance is usually higher for amps when bridged.   Otherwise, if your center supports bi-amping it’s another option for fully using a stereo amp. 

Since the invention of HT however the idea of a 3-channel amp to enhance a stereo amp has become popular as well... the idea being that you can power 2 surround channels plus the center.  Again, there’s absolutely no difference in the electronics.  It’s just a 3 channel amplifier.  

Of course, what you should be doing is using 7 monoblocks.... Hahahaha.  Just kidding, but it would work too. :) 

Having said all of that, the input to whatever amp is connected to your center speaker should come from your HT receiver/processor’s center out.  Not any other source.  There have been a number of mini appliances in the past to create a center channel from L and R outputs... but I can’t think of a reason to use them in the 21st century unless you are trying to recreate 3 channel stereo from the early recording days. 

Hey Jea48,

I’m curious what you mean, wrong advice?

One thing I never do is fallow feelings or gut.  I’m looking for correct information.

in reference to the 6015, yep, one thing at a time.  I do have an INNUOS ZENMINI MK3 MUSIC SERVER-STREAMER and a INNOUS POWER SUPPLY, and Kaleidescape for movies.

B&W CM10 LR & matching B&W CM Center 2.  I’m currently testing a HTM71 S3, and haven’t been able to make a decision between the two.  The vocals are definitely more pronounced on the new center, but not sure about blending in with my LR.  I’m waiting for my new amp to make that decision.

Thanks for that Erik!!

So, what Muvluv said was correct then.  You can use the left for the tweeter and mid, and right for the bass.  Currently, I have a bi wire cord, so I’ll have to change that.  I like this idea better than bridging, mainly for the reason of impedance.  I don’t even know how many cords I’ve changed out now, because of various changes 🙃

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+1 @jea48 and @muvluv

@vacerator 

You are over thinking things.  Your Marantz has preamp RCA outputs for each channel.  Left, Right, Center, and surround channels RCA connections. 

Connect the:

• Marantz left preamp output RCA's to the left input on the MC352 amp #1,
• the Marantz right preamp output RCA's to the right input on the MC352 amp #1,
• the Marantz center preamp output RCA's to the left input on the MC352 amp #2

That will leave the right input RCA's on the MC352 #2 amp connected to nothing, which is fine.  Then connect the speaker cables to the MC352 connections to the approperiate speakers.  You may need to go into the Marantz setup menus and tell it you are using the off board amps for the front 3 channels (L/C/R).  

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As previously posted recommendations, I am in agreement. 

just simply look at your back panel and all is there. at the most, you may just have to use 1 channel of MC352 and leave the other unused. I am doing in my home theater setup too.

https://forum.audiogon.com/posts/2824647 I actually took left and right from both channels used a cable to make into 1 channel to feed my amp, than set the amp to y mode so one input now puts out the same signal into both outputs that is why I said you have to set the crossover correctly so the center channel sounds good

Very true amps don’t care about the signal, what matters is where the signal is coming from not what actually is amplifying the sounds

I have 50 years in audio sales and system design, with early adoption of home theater…of necessity.  I also am a cheap sob, so I hate waste.  The idea of using a second MC352 as a center channel amp appalls me.  I agree that your front end is weak…get a new one.  A Sony STRZA3000 or above is hard to beat for bleeding edge AV tech.  Run the L/R pre-outs into your MA352.  Then if you want a McIntosh SS amp that runs in mono, find a restored MC2100 at Audio Classics or elsewhere.  Otherwise, get any 200-300w mono amp you like.  Running surrounds off the receiver is fine in most cases, although maybe not yours. We don’t know enough about your whole HT config to be more specific. Maybe a McIntosh MC205 is the best option…5 channels of 200W each.