Newbie Preamp out question

 

New member
Username: Ebizboy

Post Number: 1
Registered: Oct-05
I have just finished setting up a new HT in my living room but now I want to connect my AVR to a stereo receiver that feeds speakers throughout the rest of the house because I want to be able to take advantage of all the sources on the AVR. My AVR is a NAD T753 and it has multi-source pre-amp outputs. I was under the impression that I could simply connect the pre-amp out to an input such as CD or video 1 on the stereo receiver then just pick that source on the stereo receiver and I would be good to go. Unfortunately, when I try that I get a very loud humm from the stereo. I can hear the AVR source but the humm far outweighs it. Should I be able to do that or am I misunderstanding what the multi-source preamp is supposed to do? Thanks.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 6069
Registered: May-04


Pre amp out is "PRE AMP OUT"!

Pre amp out places the output from that connection behind (after) the volume control on the original pre amp. In this case the original pre amp is in the NAD. If the volume control is set to be the master for all levels it will control the volume for all power amps after (following) its output. If the NAD has the ability to switch the multi-source/multi-zone (?) pre amp outputs to fixed level you will get better results. Otherwise advance the volume on the NAD to get a signal level from the pre amp outputs. This can present problems since the main system may be playing too loudly for comfort by the time you get sufficient volume in the second room.



In any case it is not advisable to run one pre amp's output into another pre amp's input. In this case the second pre amp is in the second zone/room receiver. The potential for ground loops has increased by enormous amounts when you try this connection as the two systems will not normally be at the same ground potential.

To make this connection work properly you can try two different connections. First, a pre amp's output is meant to drive a power amp's input. If your secondary receiver has pre and power amp separation (jumpers on the back panel), you should run the main (NAD) pre amp outputs to the power amp inputs on the secondary receiver. This eliminates the volume control on the secondary receiver but is the least likely to cause hum problems. If this connection still hums, it is due to different ground potentials of the two outlets which the two systems are running from and a qualified electrician will be needed to correct the situation.

Secondly, you can try running the NAD tape outputs to the AUX input of the second receiver. To get sources switched you will use the tape output selector on the NAD. This is far less convenient than the first arrangement but should give you a clean signal.

I think I would either; first, read again the NAD owner's manual (which is fairly pathetic at explaining anything) or, second, consult the shop where you bought the NAD for assistance. There are instances where an on site survey of the problem will be the best solution to problems which might arise. It is not uncommon for a remote source based system to require a secure ground connection for all AC outlets which can only be done by a qualifed electrician. If you live in an older home where
outlets have been added to the service panel, this is particularly true.




 

New member
Username: Ebizboy

Post Number: 2
Registered: Oct-05
Jan, thanks for your quick response. Unfortunately, the stereo receiver, a low end Sony, does not have power amp inputs. It doesn't even have an Aux input. However, the NAD's pre amp out is actually a 2nd zone so it's volume is separately controlled. I did try to up the volume on the NAD 2nd zone but it did no good. I still go the hum.

Since, if I get this hooked up the way I want, I will only be using the second receiver to power the speakers throughout the rest of the house, perhaps I would be better off just replacing it with a power amp. Since the other speakers throughout house are only used for background music I like to keep the budget down. Any recommendations?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 6076
Registered: May-04


Not really. Look through the classifieds on line for a good deal.


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