Sub PreAmp Out With Receiver (NAD T762)

John151 · « **on:** 22 Jan 2005, 03:22 pm »

I have two subs, both connected via the RCA SW PreAmp output jacks. With this set up, I am having two issues with my sub configuration.

1) When listening in stereo mode (2 channel), my receiver does not send a signal to the PreAmp Out for the Subs. However, if I select Dolby PL II, or any of the other multi-channel modes, my subs get a signal.

Is this normal? Should I use a different set up for the subs?

2) Because my screen is so larger (front PJ), I don't have a good place to mount the center speaker, and as a result, I prefer the sound when using phantom center. However, when I change the receiver set up to not use the center, the receiver stops sending a signal to the subs. Is this normal? Any idea how to get around this?

You input is greatly appreciated.

John Ashman · « **Reply #1 on:** 22 Jan 2005, 08:21 pm »

What are your speaker settings? If your speakers are set to "large" and subwoofer "yes" you'll not get subwoofer bass for 2.0 stuff.

John151 · « **Reply #2 on:** 23 Jan 2005, 11:15 pm »

Mine was set on Large for the fronts. However, setting them to small did not make the sub work. Is it my imagination, or does the small setting send less bass to the fronts?

TIC · « **Reply #3 on:** 24 Jan 2005, 03:07 am »

John,

I don't know your NAD, but I do know how all of the HT receivers I've owned worked.

First, stereo is 2 channel, not 2.1. The .1 is subwoofer via the LFE/SW output. So, the reason it works with any DSP mode and not stereo mode is the receiver's digital signal processor is smart enough to know that you have a subwoofer attached, because you configured it that way.

One way to make your sub work during stereo playback is to attach it via speaker level output instead of line level output via the LFE/SW output.

Another thing you could try is connecting the subwoofer via RCA outputs from the front L&R outputs. You may be able to set the subs crossover to a low setting so it won't overlap with the low frequency output of you front L&R main speakers.

And YES, setting the front speakers to small produces less bass. That is the whole point. It keeps low frequency information from going to small speakers that can't produce low frequencies anyway and may sound pretty nasty if they try......

Enjoy,

TIC

John151 · « **Reply #4 on:** 24 Jan 2005, 04:02 am »

After revieiwng my manual, and the above posts, I think I have a handle on things.

I don't care that much about using the subs for music, and the subs work great for movies, so I am going to leave it as is.

As for the bass limitation on the front speakers when set to small, I knew the bass was cut off at 80Hz, but I am really amazed out how audible the difference is.

As for my 2nd issue, losing the sub when I turn off the center, this is caused my having the LF set to Large, as the receiver only sends bass content from "small" speakers to the sub.

Thanks for the assistance!

John Ashman · « **Reply #5 on:** 25 Jan 2005, 07:34 pm »

Also, you can do "presets" and have completely different setups for different uses. If you want to use the sub for music, you must set the speakers to small and that should get you bass. You can lower the crossover frequency to as little as 40Hz if needed. If you want the bass only for movies, set the speakers to large. You can have one preset for surround sound with speakers to small and another one for music with the speakers set to large. Or just about any other variation you'd like.

John151 · « **Reply #6 on:** 31 Jan 2005, 01:29 am »

I had given up on the Sub working with 2 channel, and then today, the subs were working. To my knowledge, I haven't changed anything since my last post. Oh well.