How to fit a subwoofer in to my current setup. [Archive] - Audio & Video Forums


View Full Version : How to fit a subwoofer in to my current setup.

03-05-2007, 02:26 PM
I currently have a NAD 3020i powering Tannoy Mercury M3's. But there is not enough low end in this configuration. So how do I hook up a subwoofer do I take it from the pre amp and hook it up to its own amp? Or is there a more proper way?

03-06-2007, 08:19 AM
does the nad have a pre out or a sub out?

most subwoofers are active, this means that they already have an amplifier in them.
if your nad haves a pre out, or a sub out, then connect the sub to it.

Keep them spinning,

03-06-2007, 09:09 AM
The amp has a pre-out but it is bridged in to the amplifier to run the loudspeakers. The amp has no sub-out.

03-06-2007, 09:10 AM
fortunately for you, most NAD integrateds allow you to (functionally) separate the preamp from the power amp.

If it's just a couple of jumpers on the back, it's really easy. Check there for these.

What you now need is a pair of "Y" connectors with two male RCA plugs and one female RCA jack.

Remove those jumpers and replace them with those "Y" connectors. You should have the two female jacks hanging out doing nothing.

Now, this very important... When buying a powered subwoofer, make sure it's got two line level inputs, one for the right channel and one for the left channel. It it;s only got one line level input, forget it. You can't use it with your setup without more expensive gear.

Now, simply get a stereo interconnect and connect it from those dangling female jacks to the line level inputs on the subwoofer. You'll now be feeding the full range signal to both your main speakers and your subwoofer. Adjust the subwoofer's crossover and level control so the sub's contribution starts right where your main speaker's start to drop off. It may take a few attempts over a few days to get it right, but it's not hard and doesn't cost anything.

An possible alternative: Some subs also offer line level outputs. These will return the signal' without the lows, to your power amp. For this you don't need those "Y" connectors but you will need two stereo interconnects, one to the sub and one from the sub back to the power amp. You may prefer this but, at least in most subs I've seen, the return frequency is not adjustable and wastes too much of the main speaker's capabilities. Personally, I prefer the first method but this world is full of choices.

03-06-2007, 09:18 AM
I'm guessing your NAD doesn't have pre-outs for the sub due to it's age. As basite said, most subs are active so all you'll need to do is run a pair of speaker wires to the speaker level inputs on the sub and utilize the built-in X-over. A basic rule of thumb is to find out where your speakers start to fall off (i.e. 30hz @ -3dB) and set the X-over a bit higher. Tweak until you get it right. The idea is to blend your sub with your mains, not overpower them. A well integrated sub allows the listener to believe all of the sound is coming from the same stage.

Sub integration is a bit tricky as room acoustics wreak havoc on the long wavelengths. An old trick is to place the sub in your seating position and then crawl around the room on your hands and knees until you find the where the bass is the most even. That's where your sub goes. I'd also highly recommend you do a search on this site for Richard Greene. Doc was the sub guru here and authored a few threads that should be required reading for anyone with a sub. They'll tell you all about room modes/nodes and how to compensate. Great stuff.

Hope this helps.

EDIT: I was typing while Mark posted. That's pretty cool that old NAD integrateds have pre-outs. If true, definitely go with the splitter. That's how I did it with my 2ch rig and it's a lot easier.

03-07-2007, 01:20 PM
But in my NAD the pre-outs are bridged in to the main-in because its an intergrated amp. Or do I split them and run one set back in to the main. Another thing I see is that the bridge links the inside part of the RCA inputs. But an RCA will bridge the outer terminal and inner terminal. Does this make a difference?

03-07-2007, 01:30 PM
I can't find your exact amp, but does your back panel look like this one?

Yes or no.

the impotant part here is those four jacks on the right of the jack panel that are joined by jumpers. How are these implemented in your setup? Do you have anything connected to the preamp out jacks?

Ultimately, your goal is to put the sub between the preamp and the power amp. Think you can figure out a way? Once you can see how to do that, it's all downhill from there.

03-07-2007, 03:14 PM
oh, and it doesn't matter if its just the insides of the RCA jacks are are connected, the signal will still be the same. I'd go with the Y splitter thing, would probably work better...

But wouldn't the pre-amp signal be then cut in half? thereby diminishing the output volume of the entire rig?

03-07-2007, 03:47 PM
But wouldn't the pre-amp signal be then cut in half? thereby diminishing the output volume of the entire rig?The load on the preamp is still of high enough impedance that you don't hear any signal loss. I've run this way for years.

03-07-2007, 06:32 PM

This is the amp

03-08-2007, 02:26 PM
The proper way to do it is to place the sub in line with your power amp. In your case you would separate the pre and power amp stage in the NAD, take your pre out on the NAD to the line in on the sub, line out of the sub back to the power amp in on the NAD. Set the cross on the sub about an octave above the lowest response point of your mains. The sub and your mains will be a single unified system and the sub will provide the cross for it. Plus, your sub will always be active, even with a stereo program.

This makes for a smoother integration of the sub and the rest of your system.