Getting a sub for my Nad 7155
- Thread starter Audio_Nub
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- nad sub woofer
Here is my advice for what it's worth:
1. You definitely need a powered sub, not passive. Virtually all powered subs will have crossover/level controls, many will have phase switches or controls.
2. Since your NAD does not have a subwoofer output (which is not a concern at all), a powered sub could be connected in one of two ways: a) Line-level inputs; b) Speaker-level inputs;
3. Popular opinion is that line-level is better because the signal sent to the sub bypasses the receiver's amp section, which could add coloration/distortion. To connect via line level to your NAD, you would put an RCA splitter cable on the "pre-out" of the NAD (removing the jumper first), then loop one side back into the NAD "main in" (replicating the jumper) and connect the other to the powered sub's line level left and right inputs. Because you ONLY have left/right outputs on the NAD (rather than a summed mono signal that a receiver with a sub output would have), you should only consider subs that include both left AND right (stereo) line-level RCA inputs, not a sub that only has a mono/LFE RCA input.
4. My experience and others, but certainly not the "popular" opinion, is that for 2-channel music, driving the sub with speaker-level outputs sounds better than line-level. Although there is more "stuff" in the signal chain using speaker-level (and having "more stuff" is generally bad), the goal of the sub is to be a seamless extension of the mains and (in my experience and others' minority opinion) that seamless extension is better realized having both the mains and sub see the same signal directly from the amp (both see whatever "coloration" there is from the amp). Speaker-level as a preference for 2-channel is a minority opinion, but most people who insist line-level is better openly admit they have never tried speaker-level. To connect the powered Sub to the NAD via speaker-level: you would run speaker wires from the NAD to the Sub's speaker-level inputs, then connect the Sub's speaker-level outputs to your speakers. Some powered subs only have speaker-level inputs and no outputs, in which case you connect the sub "in parallel" to the sub and speakers.
5. To have the most flexibility on connection type, get a sub that has both left/right RCA inputs and speaker-level inputs. Again, do not choose a sub that only has a mono line-level input.
6. There are no absolute rules in what constitutes the "best" sub for music, but all things being equal, sealed subs are generally be better for music only. Ported subs are more efficient and go deeper, but are more prone to group delay which can make it difficult or impossible for the sub output to align with the mains in an "all analog" system like your NAD. You don't need the deep powerful bass for music that you do for theater, so there is generally no need for a ported sub. This doesn't mean individual ported subs can't be great for music, but generally sealed are more likely to be better.
7. When I was looking for a small sub for a 2-channel system, the sealed Sunfire HRS was what I ended up with. The HRS has less power and deep extension than the more expensive Sunfire True Subwoofers that were available at the same time, but the HRS are more musical and have more than enough extension for music. If you are looking for a tiny sub for music, the HRS is still a very good choice. There are many others of course, hopefully you will get specific suggestions on sub brands and models for music.
1. You definitely need a powered sub, not passive. Virtually all powered subs will have crossover/level controls, many will have phase switches or controls.
2. Since your NAD does not have a subwoofer output (which is not a concern at all), a powered sub could be connected in one of two ways: a) Line-level inputs; b) Speaker-level inputs;
3. Popular opinion is that line-level is better because the signal sent to the sub bypasses the receiver's amp section, which could add coloration/distortion. To connect via line level to your NAD, you would put an RCA splitter cable on the "pre-out" of the NAD (removing the jumper first), then loop one side back into the NAD "main in" (replicating the jumper) and connect the other to the powered sub's line level left and right inputs. Because you ONLY have left/right outputs on the NAD (rather than a summed mono signal that a receiver with a sub output would have), you should only consider subs that include both left AND right (stereo) line-level RCA inputs, not a sub that only has a mono/LFE RCA input.
4. My experience and others, but certainly not the "popular" opinion, is that for 2-channel music, driving the sub with speaker-level outputs sounds better than line-level. Although there is more "stuff" in the signal chain using speaker-level (and having "more stuff" is generally bad), the goal of the sub is to be a seamless extension of the mains and (in my experience and others' minority opinion) that seamless extension is better realized having both the mains and sub see the same signal directly from the amp (both see whatever "coloration" there is from the amp). Speaker-level as a preference for 2-channel is a minority opinion, but most people who insist line-level is better openly admit they have never tried speaker-level. To connect the powered Sub to the NAD via speaker-level: you would run speaker wires from the NAD to the Sub's speaker-level inputs, then connect the Sub's speaker-level outputs to your speakers. Some powered subs only have speaker-level inputs and no outputs, in which case you connect the sub "in parallel" to the sub and speakers.
5. To have the most flexibility on connection type, get a sub that has both left/right RCA inputs and speaker-level inputs. Again, do not choose a sub that only has a mono line-level input.
6. There are no absolute rules in what constitutes the "best" sub for music, but all things being equal, sealed subs are generally be better for music only. Ported subs are more efficient and go deeper, but are more prone to group delay which can make it difficult or impossible for the sub output to align with the mains in an "all analog" system like your NAD. You don't need the deep powerful bass for music that you do for theater, so there is generally no need for a ported sub. This doesn't mean individual ported subs can't be great for music, but generally sealed are more likely to be better.
7. When I was looking for a small sub for a 2-channel system, the sealed Sunfire HRS was what I ended up with. The HRS has less power and deep extension than the more expensive Sunfire True Subwoofers that were available at the same time, but the HRS are more musical and have more than enough extension for music. If you are looking for a tiny sub for music, the HRS is still a very good choice. There are many others of course, hopefully you will get specific suggestions on sub brands and models for music.
Wow, thank you for that very informative reply! I may try some of this out in the future as my setup evolves, and I’m sure that anyone else seeking the same answers as I will find your post (as well as all previous posters’ contributions) very helpful.
As it stands, i got a line level, ported sub (lol). I can hear that it is not as tight as it could be, but man is it worlds better than not having one at all! Also looking at the hrs series, that was unfortunately a bit outside my budget. Maybe next year!
So now i have 2 klipsch r15m speakers, and 2 yamaha ns-6490 speakers with the klipsch r100sw sub all set up with a splitter and in line 70 hz crossover high pass going to the main in. All together it sounds great! Was a bit muddy at first but i flipped the phase switch and its way better now. The yamahas seem to have some funny passive crossover wiring that makes them kinda squeaky now with the high pass on, will eventually replace them.
All in all, very happy with the experience as well as the sound i’m getting now. Many thanks again to everyone here, I’d be lost without you!