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post #1 of 21 Old 08-12-2014, 11:20 AM - Thread Starter
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Question About Pre-Outs

I just ordered a pair of Magnepan MMG speakers. I also bought a used ROTEL RB-980BX amp to drive the speakers. I plan on plugging the Rotel Amp into my Marantz SR5005 AVR's preouts to power the speakers.

I have never used pre-outs before. My question is, will the speakers acquire the sound fidelity from the Rotel or from the Marantz AVR? If this is a stupid question, I apologize in advance.
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post #2 of 21 Old 08-12-2014, 11:34 AM
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The speaker gets the power from the Rotel amp. The Marantz is basically being used as a preamp. The tone settings, Audyssey room calibration, crossover settings for the sub (if you have one), sound modes (stereo, dolby digital), etc all come the Marantz.

I hope that answers your question.

Is this only a two speaker setup? Any subwoofer or other speakers?

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post #3 of 21 Old 08-12-2014, 11:35 AM
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Passes the sound signature of the pre-amp, in my experience. Had two pre amps, two power amps and tried mixing and matching.

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post #4 of 21 Old 08-12-2014, 11:49 AM - Thread Starter
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Quote:
Originally Posted by afrogt View Post
The speaker gets the power from the Rotel amp. The Marantz is basically being used as a preamp. The tone settings, Audyssey room calibration, crossover settings for the sub (if you have one), sound modes (stereo, dolby digital), etc all come the Marantz.

I hope that answers your question.

Is this only a two speaker setup? Any subwoofer or other speakers?
Thank you. Right now I have Polk center and surround speakers. As for the sub, I have two Def Tech fronts with the 300 watt built in subs. Once I hook up the MMGs I'll try using the two Def Techs just for the subs, see what happens. If that sucks, I can sell the Def Techs and buy a new sub. Of course, the center may also be a problem because the Polk mixes very well with the Def Techs but may not work with the Maggies. I guess I could also keep the Def Techs and use them when playing movies, and just use the MMGs for music. I could probably keep both sets of speakers wired, shut the Rotel amp when playing movies, or unplug the Def Tech's when playing music.
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post #5 of 21 Old 08-12-2014, 11:50 AM - Thread Starter
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Originally Posted by fatbottom View Post
Passes the sound signature of the pre-amp, in my experience. Had two pre amps, two power amps and tried mixing and matching.
That's what I figured thank you.
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post #6 of 21 Old 08-12-2014, 12:02 PM
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Quote:
Originally Posted by pandy4 View Post
I just ordered a pair of Magnepan MMG speakers. I also bought a used ROTEL RB-980BX amp to drive the speakers. I plan on plugging the Rotel Amp into my Marantz SR5005 AVR's preouts to power the speakers.

I have never used pre-outs before. My question is, will the speakers acquire the sound fidelity from the Rotel or from the Marantz AVR? If this is a stupid question, I apologize in advance.
The preouts from the AVR are basically a DAC. DACs have two advantages over an amplifier. One, they don't have to interact with speakers - their output is into an amplifier's input stage which is high impedance. The other advantage is that unlike many amplifiers using class AB topology they don't have crossover distortion. They do have the problem of converting digital to analog but that seems to be a well solved problem. Obviously DACs have excellent specs and it's not clear to me why one would be better than another.

Amplifier sound seems mostly insignificant compared to other factors and based on various blind tests. As amp sound has been debated countless times I won't bother to debate it here.

It seems me that amplifier sound would be more of a factor than DAC sound as the amplifier is connected to speakers where there DAC is connected to a high impedance input.

In summary, personally I would never worry about a preamplifier's sound as such a thing seems to elusive to define or address. I suppose if a person had excellent hearing and open mind and a lot of time they might be able to properly evaluate it. But most people seem happy to buy on price an features. As the amplifier interacts with speakers if there is some sonic factor or factors with the amp you would have to evaluate that in house (connected to the speakers to be used with it.) Or buy based on price and features and quality and accept that amps will sound more alike than different and address sound with speakers and room treatments.

"But this one goes up to 11"
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post #7 of 21 Old 08-12-2014, 12:49 PM - Thread Starter
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Thanks for the input. I guess I probably made a good choice with the Rotel amp. It should have more than enough power at 120W at 8ohms (240W at 4ohms) to power the MMGs speakers and it seems as if that's the most important thing if you're using an AVR's pre outs. The Marantz SR5005 has excellent sound.
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post #8 of 21 Old 08-12-2014, 12:59 PM
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http://www.stereophile.com/content/r...r-measurements

Can't find power output it's in there somewhere.

Krell Evolution 900e x 7

Bose Jewel speakers.

 

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post #9 of 21 Old 08-12-2014, 01:08 PM - Thread Starter
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I'm confused on how I set it up to run the 4ohm MMG speakers. Do I set it to Stereo or Bridge (mono)? once I plug it into the Marantz AVR's preouts?
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post #10 of 21 Old 08-12-2014, 01:24 PM
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Leave it in stereo mode

Krell Evolution 900e x 7

Bose Jewel speakers.

 

Jealous of my speakers?

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post #11 of 21 Old 08-12-2014, 01:54 PM - Thread Starter
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Originally Posted by fatbottom View Post
Leave it in stereo mode
I thought these amps had switches to switch from 4 to 8 ohms. I guess by keeping it in stereo mode it will automatically power the 4 ohm Magnepan speakers?
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post #12 of 21 Old 08-12-2014, 01:58 PM
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Read up on bridging. You gain power but I believe ability to drive low impedance speakers is compromised.

Krell Evolution 900e x 7

Bose Jewel speakers.

 

Jealous of my speakers?

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post #13 of 21 Old 08-12-2014, 02:20 PM
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Quote:
Originally Posted by MichaelJHuman View Post
The preouts from the AVR are basically a DAC. DACs have two advantages over an amplifier. One, they don't have to interact with speakers - their output is into an amplifier's input stage which is high impedance. The other advantage is that unlike many amplifiers using class AB topology they don't have crossover distortion. They do have the problem of converting digital to analog but that seems to be a well solved problem. Obviously DACs have excellent specs and it's not clear to me why one would be better than another.

Amplifier sound seems mostly insignificant compared to other factors and based on various blind tests. As amp sound has been debated countless times I won't bother to debate it here.

It seems me that amplifier sound would be more of a factor than DAC sound as the amplifier is connected to speakers where there DAC is connected to a high impedance input.

In summary, personally I would never worry about a preamplifier's sound as such a thing seems to elusive to define or address. I suppose if a person had excellent hearing and open mind and a lot of time they might be able to properly evaluate it. But most people seem happy to buy on price an features. As the amplifier interacts with speakers if there is some sonic factor or factors with the amp you would have to evaluate that in house (connected to the speakers to be used with it.) Or buy based on price and features and quality and accept that amps will sound more alike than different and address sound with speakers and room treatments.
The preamp outputs are just an analog preamp level signal, similar to a head phone jack, they aren't DAC's at all.The DAC inside the unit is what converts digital signals to analog, but it's a completely different thing than the preamp outputs. Units that preamp outs, are no different than units without them, other than they give you access to the preamp level signals to drive separate amps, but it's really not much added circuitry.
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post #14 of 21 Old 08-12-2014, 02:51 PM
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Quote:
Originally Posted by 89grand View Post
The preamp outputs are just an analog preamp level signal, similar to a head phone jack, they aren't DAC's at all.The DAC inside the unit is what converts digital signals to analog, but it's a completely different thing than the preamp outputs. Units that preamp outs, are no different than units without them, other than they give you access to the preamp level signals to drive separate amps, but it's really not much added circuitry.
AVRs typically go through DSP to DAC to amps. If a person was connecting a stereo only device using some bypass mode, I agree with you

But, the normal path is to use the bass management and room correction (if they are present on the AVR) even if using stereo analog inputs. MC inputs used to bypass everything almost except for some sort of buffer and volume control before the amp section.

"But this one goes up to 11"

Last edited by MichaelJHuman; 08-12-2014 at 02:54 PM.
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post #15 of 21 Old 08-12-2014, 02:56 PM
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Originally Posted by pandy4 View Post
I thought these amps had switches to switch from 4 to 8 ohms. I guess by keeping it in stereo mode it will automatically power the 4 ohm Magnepan speakers?
Solid state amplifiers usually lack an impedance switch. Some AVRs have an impedance switch that lower the supply voltage for safer operation into lower impedance, but that also lowers power output.

Tube amps often have multiple taps or a selector for impedance

"But this one goes up to 11"
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post #16 of 21 Old 08-12-2014, 03:04 PM
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Quote:
Originally Posted by MichaelJHuman View Post
AVRs typically go through DSP to DAC to amps. If a person was connecting a stereo only device using some bypass mode, I agree with you

But, the normal path is to use the bass management and room correction (if they are present on the AVR) even if using stereo analog inputs. MC inputs used to bypass everything almost except for some sort of buffer and volume control before the amp section.
OK, yeah, the preamp outputs signals are influenced by the internal DAC in a modern AVR if one is using a digital signal such as HDMI, Toslink or whatever, it just seemed strange wording to refer to the preamp outs as DAC's.
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post #17 of 21 Old 08-12-2014, 03:05 PM - Thread Starter
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Originally Posted by fatbottom View Post
Read up on bridging. You gain power but I believe ability to drive low impedance speakers is compromised.
Yes, I did read that in a review.
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post #18 of 21 Old 08-12-2014, 04:32 PM
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Quote:
Originally Posted by 89grand View Post
OK, yeah, the preamp outputs signals are influenced by the internal DAC in a modern AVR if one is using a digital signal such as HDMI, Toslink or whatever, it just seemed strange wording to refer to the preamp outs as DAC's.
I figured, the OP was talking about his Marantz in general, and how it effects the sound. Ignoring any DSP effects, I suppose it could be broken down into-
* DAC circuitry
* Volume/tone control
* Any buffer circuits

So I think I see your point as the DAC is only one part of that

"But this one goes up to 11"
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post #19 of 21 Old 08-13-2014, 09:53 AM
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If he is using the preouts from the Marantz, then it is simply an A/V Preamp/Processor.
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post #20 of 21 Old 08-13-2014, 11:51 AM
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Quote:
Originally Posted by pandy4 View Post
I'm confused on how I set it up to run the 4ohm MMG speakers. Do I set it to Stereo or Bridge (mono)? once I plug it into the Marantz AVR's preouts?
leaving aside questions of whether the amp is rated to run a 4 ohm load bridged, if you bridge it, you can only run one channel (ie one speaker) off it. Onaccounta it's monophonic, not stereo, after you bridge it.

Besides, you don't need more power than you use. THere's this physical law of the universe we occupy (at least our four dimensions) called Ohm's law, and it states that for any voltage swing (ie for any loudness you try to achieve with your speakers) the current (and therefore power)has to be exactly, precisely, unvaryingly the same whether it's a 100 watt amp or a 1000 watt amp. If (and it may be unlikely) a more powerful amp sounds different at the typical one to 10 watts that average listening levels call for, it's not because of the power. Might be because a lower output impedance allows it to drive a difficult load better, but the MMGs present a load much like a resistor - - about as easy as it gets for an amp.

There's lotsa blah blah blah about how the 1.6s (which I used to have) need big power to come alive. Well, number one, if I listen at my normal levels, even the peaks aren't consuming 50 watts regardless of the amp, and a more powerful amp cannot make a difference. I measured the difference between a 50 watt amp and a 250 watt amp in the bass - - there was zero difference despite what people thought they heard. Now, if you listen loudly enough to push the speakers into significant compression, more power will likely mean that the compressed sound doesn't also include amp distortion, and that would be a good thing. But you have, technically, exceeded the speakers' capability already if you are compressing audibly . . . .
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post #21 of 21 Old 08-13-2014, 06:14 PM - Thread Starter
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Thank you.
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