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How to connect subwoofers

Hello guys
I have a 2.0 stereo system, entry level high end, with Audio-gd R8 DAC, Audio-gd M1 preamp, Nord Acoustics Class D amp and Q Acoustics Concept 500 floorstanders.

I want to add a pair of subs, but before buying them I need figure out how I will be able to connect them to my system. 

There's seems to be two ways:

1. High level connection. The one I prefer for my room lay out, cables length and sound quality. 

This way I understand I have to connect the subs with speaker cables from the binding posts of the speakers, each sub connected to one speaker. 

I have different opiniones on this kind of connection from different dealers. Someones say the sub wont change the impedance, etc of the speakers and it wont affect the amp, but others say the opposite.

2. RCA connection. 

I only have one RCA output for each channel on the preamp, but I have two RCA inputs on each sub (right and left channel).

I understand I should use one single RCA cable for each sub, but that will mean that one RCA input on each sub will not be not connected and it will not get any signal. Could that harm the subs? 

Well I would appreciate your comments regarding your experience with subs as I guess most subs should behave similar, no matter the brand. Am I correct? 
plga
bstatmeister
537 posts
 
for the high level connection, I think you create a separate run of speaker cables going from the amp to the sub (not from the speaker to the sub). I think most high-end sub-woofer companies prefer this method since theoretically it keeps the "sound" of the amp through to the sub for better integration with the mains. REL sub-bass systems recommend this method as well as the guys at PS Audio. Those guys know their stuff, so I tend to listen when they have something to say.
However, is RCA really second class? not sure, but the proof is always in the pudding. Could always try both and go with what sounds the best to your ears.
As far as the connection from the preamp to the subs I think each channel goes to the left input on each of the subs
plga OP
184 posts
 
Thank you guys. 
One more question. 
My power amp has only 4 binding posts, 2 for each speaker channel, so taking a parallel pair of cables from the same binding post of the amp, isn't the same of just taking them from the speakers binding posts? 
mrdecibel
3,065 posts
 
No, it is not. Feed the subs the same way you feed the speakers. Example : Spades / bananas share a post on the amp.
paradisecom
337 posts
 
Using the high-level speaker connectors on the subs is fine. I don't see a problem connecting them to the speaker terminals, rather than the amp, if it's easier for you. The speaker level inputs on most subs are usually many thousands of ohms impedance, so your amp won't see any additional load. 

For the rca level inputs, you could install a simple set of y-cables from the preamp outs with one leg going to a subwoofer and the other the amplifier input. Connecting only 1 to a sub would be fine. 

What subs are they, anyway?
lalitk's avatar
lalitk
5,614 posts
 
Here is another recent discussion about integrating subs. 

https://forum.audiogon.com/discussions/best-way-to-integrate-subwoofers
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