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Subwoofer connection conundrum

Need some help, as I'm in over my head. I've got a new NAD C 298 power amp -- a gift from my wife! -- that uses the Purifi Eigentakt class-D amplifier module, or a modified version thereof. As I understand it, and that's not so far at all, I should not hook up a subwoofer using the speaker-level outputs because of something in the design of the circuit. (Or something.)

I'm wanting to get a pair of subs that I'd place inside my speakers -- KEF LS50s -- and had been thinking of a pair of SVS SB-1000s, as they are about the right size and price. I was planning to use the SVS wireless adaptor, until I learned about latency. So, finally, to my question:

My preamp, a Wyred 4 Sound STP-SE, is connected to the NAD with a run of balanced interconnects. (The amp is between the speakers, with the rest of the equipment on a side wall.) Am I assuming correctly that I'd need to run balanced to the subs, too? If so, can anyone recommend a pair of modestly priced, modestly sized subs with XLR inputs? (The W4S has another set of balanced outs, so that's not a problem.)

Finally, could I run single-ended from the pre to the subs, or would that be a problem because I'm running balanced to the power amp? I understand that there'd be the possibility of noise, but I'm not certain if there's some other reason why it would not be wise to run balanced to the power amp and single-ended to the subs. If that would be OK, it would obviously open up many, many more possibilities for subs, as my searching so far has found few with XLR inputs that aren't giants.

Thanks very much for any help you good folk can provide on this.

-- Howard
hodu
mikelavigne
2,156 posts
 
Audiogon is a decent place to ask subwoofer questions. certainly plenty of subwoofer users here. but if you want to get deeper into choices and alternatives the AVS Subwoofer forum is a much more robust and serious forum about subwoofers. you will get much more attention and information there on this subject.

https://www.avsforum.com/forums/subwoofers-bass-and-transducers.113/
millercarbon's avatar
millercarbon
12,531 posts
 
You can run the subs unbalanced RCA no problem. You can also run the off the speaker outs on the power amps, but in this case you will need a Line Out Converter to drop the voltage down from speaker level to line level. Sub interconnects do not need to be high quality. Which way you do it will have as much to do with how much you want to spend and how you want it to look. In terms of performance there will be no difference.  

What will make a difference is where you put the subs. They do not need to go between the speakers. In fact they will work a lot better with one in each corner, but each one a different distance from the corner. This alone will be far greater a difference than anything you can do in hooking them up. Do a search for Distributed Bass Array. 
mike_in_nc
1,124 posts
 
+1 to everything from @millercarbon on this question.
  • Speaker-level input is an unnecessary complication.
  • Unbalanced runs typically are fine for a sub.
  • With subs, positioning is critical. Asymmetry will help give smoother response.


hodu OP
313 posts
 
Here's what's got me nervous about using the speaker outputs:

The C 298 manual says the following:

  • The blue terminals must never be connected to ground (earth).

  • Never connect the blue terminals together or to any common ground

    device.

  • Do not connect the output of this amplifier to any headphone adapter,

    speaker switch or any device that uses common ground for left and right channels.


    I'm nobody's electrical engineer -- far from it -- but doing a bit of reading around has made me worry about the wisdom of trying to hook up a sub off the speaker outputs of this amp that's employing some newfangled technology that I can barely pronounce, let alone understand. I'd really hate to blow up my nice gift after just, like, two weeks.


    And I've been liking the way it sounds, too!


    -- Howard



millercarbon's avatar
millercarbon
12,531 posts
 
The blue. Well that clears it up. Without pronouncing or understanding the newfangled technology, can you type the letters?
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