Splitting PRE-AMP OUTS.

[JOHN FICKEL]

Can you split the preamp outputs on the back of the receiver ? I have a Yamaha RX -Z9 and I am splitting the preamp outputs to a Yamaha MX-1, and a Mcintosh MC-252. To drive two pair of mains. So I'm splitting the MAIN pre amp outs. Or should I just drive one pair of speakers on the Z9 and the other pair on the Mac 252 Is it a bad idea to split the preamp outs? Thank you

 

[rojo]

Wh... what in the world are you doing to your imaging?

1 pair of mains = Oh, there's a lovely flute solo to the left of the conductor. Well done!

2 pair of mains = Oh, there's a fortissimo flute solo... somewhere.

1 pair in front + 1 pair behind = Oh, I'm in my car listening to a flute solo.

Are you one of those cats with artillery ear who buys high end gear but doesn't really care what it sounds like as long as it's loud?

Uuh, I suppose you can split the line out into two amps if you wish. It won't damage anything.

 

[JOHN FICKEL]

I only listen to all 4, when I have friends over and we are playing pool or something, or having a family get together, NOT. For serious listening, Although all four ON sounds AWESOME. I'm looking for by far a more serious and technical response , for example the MX-1 power amplifier requires it says 1.42 V line level in. My pre-amp outs for the Z9 from what I can find in the manual on the specs page, says the pre-amp outs are( 1v ) (Now if I split that ) is the MX one only getting 500 mA, and Will that Effect quality of the amp ?? From what I've been told that can affect the output of the amplifier and raise the noise floor , is that true. As far as the McIntosh MC 252 I'm not sure what the line level on that is , but I'm sure it's more or similar Gene. Are out out there? Please respond

 

[slipperybidness]

I'm looking for by far a more serious and technical response , for example the MX-1 power amplifier requires it says 1.42 V line level in. My pre-amp outs for the Z9 from what I can find in the manual on the specs page, says the pre-amp outs are( 1v ) (Now if I split that ) is the MX one only getting 500 mA, and Will that Effect quality of the amp ?? From what I've been told that can affect the output of the amplifier and raise the noise floor , is that true. As far as the McIntosh MC 252 I'm not sure what the line level on that is , but I'm sure it's more or similar Gene. Are out out there? Please respond

You've come to the right place for a technical response.

Don't get too caught up on the line level voltages. If it drives to satisfying levels without clipping, then you are fine. You say MX-1 requires 1.42V line level, and I say that is useless information without the extra info----is that 1.42V RMS? Or is that 1.42V peak? Same question for the Z9, are we dealing with Vrms or Vpeak??? It may be that the MX is quoting peak and the Z9 is quoting RMS. Guess what, 1Vrms = 1.42Vpeak.

Next, you ask "(Now if I split that ) is the MX one only getting 500 mA"---where the heck did this come from??? You are talking about voltage signals then you talk about current, but where/how did you do this conversion????

I do assume that we are talking about solid state amps and not tube amps here. The input impedance of a typical solid state amplifier is very high. Off the top of my head, we are talking about an input impedance on the order of 50kohms to 100kohms. What this means is that a typical SS amp requires very little current to drive it. If you connect 2 amps in parallel and they have the same input impedance, then the input impedance "seen" by the pre-amp will be half of the value of each amp's input Z.

So, in general, splitting pre-amp outputs to 2 different amps should not be a problem, assuming that amps and pre-amp are at least fairly robust (ie not some ebay junk). It should not raise the noise floor or harm the amps in any way. If any problems do occur, it would most likely be too much current draw from the pre-amp that may blow a fuse or fry the pre-amp.

If you would like to get an idea of my credentials, take a read on this thread
http://forums.audioholics.com/forums/threads/new-chipamp-project-thread.92513/

 

[JOHN FICKEL]

Thank you for your response. I did talk to Yamaha and he said when you split the 1v off the back of the Z9 , it's being split
, so Each amp is getting half of a volt to each? splitting 1v is 500 ma no? They said I'd be Better to run a pair off the Z9 and run the pre outs to the Mcintosh only. That would be better. And the Mcintosh would perform better. That's where I came up with the 500 mA .. I should have said 0.5 volts . How do I find out whether or not the 1.42 for the MX-1 or 2.5 V for the Mcintosh is peak or RMS.???

 

[JOHN FICKEL]

Thats my bad. 1000MA is 1 amp. So splitting 1v would be 0.5 volts to each amp

 

[slipperybidness]

Thats my bad. 1000MA is 1 amp. So splitting 1v would be 0.5 volts to each amp

NOPE!

When you connect in parallel, the voltage does not get split! The current gets split but not the voltage.

If you connect in series, then the reverse holds true--the voltage is split but not the current.

 

[PENG]

for example the MX-1 power amplifier requires it says 1.42 V line level in. My pre-amp outs for the Z9 from what I can find in the manual on the specs page, says the pre-amp outs are( 1v )

You can't rely on the specs in the manuals because manufacturers typically don't provide enough details. They also seem to use different standards (if there is any) You will end up comparing apples to oranges.

Bench test data, such as this one:

http://www.milleraudioresearch.com/avtech/index.html

or this one:

http://www.audioholics.com/av-receiver-reviews/rx-z7-7.1/rx-z7-measurements

more often than not, showed the preouts of AVRs, including the Z series far exceed their typically stated 1.2V n their manuals and spec sheets.

 

[JOHN FICKEL]

Thank you both. So with all that being said, what would you do ? Would you split the main pre-amp out , to both power amps or should I run one pair on the Z9 which is rated at 170 watts from 20hz to 20khz at 8 ohms at 0.015 % THD so it's a good amp. And the other pair on the Mcintosh Mc -252 or would you run both amps? The speakers are 101db sensitivity . I just wonder would the Mcintosh perform better not splitting the main pre-out. Thanks again

 

[slipperybidness]

Thank you both. So with all that being said, what would you do ? Would you split the main pre-amp out , to both power amps or should I run one pair on the Z9 which is rated at 170 watts from 20hz to 20khz at 8 ohms at 0.015 % THD so it's a good amp. And the other pair on the Mcintosh Mc -252 or would you run both amps? The speakers are 101db sensitivity . I just wonder would the Mcintosh perform better not splitting the main pre-out. Thanks again

Re-read post #4

Running 4 main speakers with a stereo signal is not a good idea, but the reason that it isn't a good idea has nothing to do with the concerns that you are stating.

 

[JOHN FICKEL]

Ok. So I'm getting that it's not a good idea because if anything I could fry my Z9 if the amps draw to much from the Z9 pre out ? I would imagine to do that you probably have to really be cranking the hell out of it , but again I can use the MX-1 somewhere else, if anything maybe the Z9 is even more capable than MX-1, not comparing power but overall fidelity

 

[JOHN FICKEL]

The MX-1 your right says not only 1.42v / then 20k- ohms input. The Mcintosh MC-252, says 1.6 v / 10,000 ohms unbalanced input. When I called Mcintosh he told be the amp is looking for 2.5v. ??

 

[JOHN FICKEL]

So Peng is right the manuals are not accurate at all?

 

[slipperybidness]

Ok. So I'm getting that it's not a good idea because if anything I could fry my Z9 if the amps draw to much from the Z9 pre out ? I would imagine to do that you probably have to really be cranking the hell out of it , but again I can use the MX-1 somewhere else, if anything maybe the Z9 is even more capable than MX-1, not comparing power but overall fidelity

Re-read post#2

 

[KEW]

John,

To summarize what has been said in one sentence:
There is no concern for your electronics; however, running multiple speakers in the same room with the same signals significantly degrades sound quality.

The additional info you are offering does not change the above statement, and nobody likes to get in an endless cycle of repeating themselves. Slippery knows his stuff and gave you your answer. You can second guess all you want, but we are just reading and thinking "you can lead a horse to water..." If you don't want to drink, don't! But don't expect us to keep pushing your nose into the water!

The best argument for running multi speakers (with same signal) is for a large room where you want to turn the volume down very low (low background music) so the sound has some fullness without having it loud near the mains. It is not a bad idea for a quiet party where you want easy conversation, but still want music in the background. The signal is not loud enough, or is too blocked by bodies, such that the interference between speakers is not an issue.
You should definitely get rid of the extra speakers if you want to listen without loss of sound quality.

I should also confess to running multi-channel stereo in my living room. The room is central to my home and while I constantly pass through it, unless I am listening to music or watching TV, I never actually spend time in there. I find running multi-channel broadcasts the sound better throughout my home (into the adjoining rooms, like my office or the kitchen). It is also low-fi, but I haven't yet set up the zones to have good sound in my main rooms. However, when I actually sit in the Living Room, I switch back to Stereo for music or 5.2 for HT because it sounds better. Listen, you will hear.

 

[slipperybidness]

I should also confess to running multi-channel stereo in my living room. The room is central to my home and while I constantly pass through it, unless I am listening to music or watching TV, I never actually spend time in there. I find running multi-channel broadcasts the sound better throughout my home (into the adjoining rooms, like my office or the kitchen). It is also low-fi, but I haven't yet set up the zones to have good sound in my main rooms. However, when I actually sit in the Living Room, I switch back to Stereo for music or 5.2 for HT because it sounds better. Listen, you will hear.

+1

When I'm working around the house, I put my AVR into "7 channel Stereo" and let all 5 of my speakers play. That is when I "prefer quantity over quality".

When I'm actively engaged in listening, it's 2.0 or 2.1 ONLY.

 

[JOHN FICKEL]

First and foremost , I would like to thank everyone who took time out of there day to respond to me THANK YOU !! I bought 4 RF-7ii's so when I was entertaining or walking around the house I didn't have to run one pair LOUD. 99% of the time if I'm doing any serious listening only one pair is on, however this may be just personal preference but I do like to have all four on once in a while. I guess what I have gotten from this is I should be able to run both Amps without any problems, however I'm just wondering now if my RX-Z9 would be better quality then my MX-1 . Another thing I've taken from this is just because I'm splitting those pre-amp outs on the back of the receiver , my amplifiers are still running at the fullest quality, or their to their fullest potential . One weird thing ... I brought my question to this site because both Yamaha and McIntosh labs, both stated I should not split the preamp out , because I will drop 10 DB of amplification because Im splitting the voltage..( Which I find is not true)

 

[PENG]

So Peng is right the manuals are not accurate at all?

I did not say the manuals were not accurate.

I said in post#8: "You can't rely on the specs in the manuals because manufacturers typically don't provide enough details. They also seem to use different standards (if there is any) You will end up comparing apples to oranges." I am quite confident the Z9 has high enough preout voltage to drive your Mc amp to its rated output without audible distortions.

The reasons why you cannot rely of them is not because they are not accurate, but because they don't provide enough details or follow one same standard for you to compare apple to apple.

slipperybidness had given you the reasons not to do what you wanted to do but if you are not concern about sound quality then you can do it either way without risking damaging your amps.

I have no idea why Yamaha and McIntosh told you what they told you. Sometimes tech supports are not all that technical and they might just want to error on the safe side.

 

[slipperybidness]

because Im splitting the voltage..( Which I find is not true)

Just think about this logically for a minute.

Voltage is a measurement of POTENTIAL energy. You can never take a voltage measurement at a single point, voltage measures the difference in potential energy between 2 points.

Now, to connect in parallel, the output of the pre-amp will have a + connection and a - connection (just looking at 1 channel). For RCAs, the middle pin is + and the outer jacket is -. Now, if the + is connected to different points, then those 2 points MUST be at the same potential (you connected them with a short). Same holds true for the - connection.

So, you have now forced the + on the pre, on amp 1, and on amp 2 to be at the same potential. When you connect the - in the same manner, those are now forced to be at the same potential as each other (but possibly at a different potential than the + connection). Therefore, the potential difference (ie voltage) between the + and - is the same regardless of where you take a voltage mesurement (all your + are the same point and all your - are the same point--they are connected by a short so they have been forced to the same voltage as we just discussed)

The "techs" that you talked to are ignorant!

 

[JOHN FICKEL]

Just think about this logically for a minute.

Voltage is a measurement of POTENTIAL energy. You can never take a voltage measurement at a single point, voltage measures the difference in potential energy between 2 points.

Now, to connect in parallel, the output of the pre-amp will have a + connection and a - connection (just looking at 1 channel). For RCAs, the middle pin is + and the outer jacket is -. Now, if the + is connected to different points, then those 2 points MUST be at the same potential (you connected them with a short). Same holds true for the - connection.

So, you have now forced the + on the pre, on amp 1, and on amp 2 to be at the same potential. When you connect the - in the same manner, those are now forced to be at the same potential as each other (but possibly at a different potential than the + connection). Therefore, the potential difference (ie voltage) between the + and - is the same regardless of where you take a voltage mesurement (all your + are the same point and all your - are the same point--they are connected by a short so they have been forced to the same voltage as we just discussed)

The "techs" that you talked to are ignorant!

Thank you .