Ways to connect subwoofer?


I have a Velodyne Minivee powered subwoofer I'd like to add to my stereo. It consists of a Benchmark DAC2 and a pair of Nuforce Ref 9 V2 SE amplifiers powering Focal Micro Utopia Be speakers.

The subwoofer has RCA inputs with high pass RCA outputs. The Nuforce amplifiers have both RCA and XLR inputs. The DAC2 has RCA and XLR outputs.

My question is whether I should use the high pass outputs of the subwoofer or wire the subwoofer in parallel with the amps? The Focal speakers are good to 50Hz, but the sub only has 80Hz high pass. Will running the speakers full range with the sub muddy the sound?

There are three ways to wire it up:

1. XLR to amps and RCA to sub from DAC2.
2. RCA to sub, high pass RCA to amps.

I'm not sure if this way will work but...
3. XLR to amplfiers, RCA out of amp (parallel with Pin 2 on XLR) to subwoofer.

Option three just makes it easier to manage the wiring, but I'm not sure if adding another load to the hot side of the XLR signal will cause issues with the DAC2 output driver.
gherrera1
Probably the easiest way would be to run a cheap pair of speakers cables from the binding posts on your speakers to the binding posts on the sub. Its a very common way to connect a sub.
I'd go with option #1. I had the same sub and ran it that way with a Bel Canto Pre3. It worked fine.
"1. XLR to amps and RCA to sub from DAC2."

That should work, but will the DAC let you run both Balanced and SE outputs at the same time?
Thanks for the replies. I'm leaning towards option one, however, an 80Hz high pass seems a tad bit high.

I've read quite a few posts about running the sub in parallel with the main speakers full range, but the NuForce amps are balanced; i.e. the negative terminal isn't at ground potential. This eliminates using the high level inputs.

The Benchmark DAC2 has both XLR and RCA outputs that can be used simultaneously.
I've read quite a few posts about running the sub in parallel with the main speakers full range, but the NuForce amps are balanced; i.e. the negative terminal isn't at ground potential. This eliminates using the high level inputs.
There are most likely some ways around that. One way that works in many systems, although in a few cases (depending on the internal grounding configurations of the amp and the sub) it could conceivably result in a loud hum, is to connect the negative high level wire from the sub to the chassis of the DAC2, by putting it under a chassis screw. (I suspect that it would only be necessary to do that for the negative input terminal of one of the two input channels the sub provides, as its two negative input terminals are probably connected directly together within the sub. Also, I'll mention that I would have said to connect to the chassis of the amp, rather than the DAC2, if you were using a stereo amp rather than monoblocks). Each of the two positive high level wires from the sub would of course be connected to the + output of the amp for the corresponding channel.

Another approach, that should almost certainly work well, would be to purchase an RCA plug, perhaps at Radio Shack, and solder the negative high level wire from the sub to its ground sleeve connection, leaving the center pin of the plug unconnected. Then insert that plug into an unused RCA output connector of the DAC2 (an unused input connector will most likely work well also), thereby establishing a connection between the negative wire from the sub and the system's circuit/signal ground. (I would have said to insert the RCA plug into the unused RCA input connector of the amp if you were using a stereo amp rather than monoblocks). The positive wires from the sub would of course be connected to the amps in the same manner as for the previous approach.

Regards,
-- Al
I would use #2. Regardless of the stated spec of your speakers, they will be much happier not seeing frequencies below 80 Hz. Actually, unless Velodyne has changed things, their high pass filter is first order, so the main speakers will still get a hefty signal below 80 Hz.

Just for reference... Richard Vandersteen recommends a high pass filter even on his Model 3.
Al, never occurred to me to wire it up this way. It should work just fine, but I think I'll try the easy way first and use RCA's all around.

Bob, funny you mention Vandersteen because I'd been looking at their passive crossovers due to the length of RCA cables I have available. I think I may be able to move the sub closer to the preamp and amps to use the built in crossover.
I'm not a fan of passive crossovers due to the source and load interaction on the filter characteristics. Just about the only 2-channel active bass management controller left on the market is this one from Hsu Research: http://www.hsuresearch.com/products/high-end-crossover.html

Hsu also has a simpler high pass filter only product.
Thanks for the links Bob.

I think this weekend I'll be able to get everything connected. I'll try it with and without the sub and try different configurations as well...