2. amps-preamps
  3. 1260293112

how to include the subwoofer?

I have power amps (Kharma MP150s) that only have balanced inputs.

I have a preamp (Nagra PL-L) that only has selectable outputs (balanced or single ended), and only one set of balanced outputs. It does have a pair of unblanced.

I have speakers (Wilson Benesch Curve) that go down to about 35 Hz.

I have a subwoofer (Velodyne DD12) that I would like to use to round out the bottom octave and help with some room nodes.

What is the best compromise:

> to use the pair of unbalanced outputs on the preamp and use RCA-->XLR adapters at the amp end, and regular RCA cables to the subwoofer;

> to use XLR y-cables out of the preamp balanced outputs

> use an electronic crossover that has both balanced inputs and both balanced and unbalanced inputs (expensive solution, but offers added capability of not running the speakers full range).

None of these seem very good to me. Any other thoughts? As always your insights are most apprecited
dgaylin
martykl
3,578 posts
 
I'd go with your last choice - separate x-over. If the high pass filter in your DD12 is the same as the one in my Velodyne SMS-1 controller - and I believe that it is - it ain't great. It subjects the main signal path to A/D/A processing and has a fixed turnover and slope. By contrast the low pass is incredibly flexible and IMO the A/D/A is much less objectionable way down there in the deep bass.

I use an NHT x-2 x-over to feed my SMS. It works like a charm, is inaudible (to my ear) AND it's inexpensive, to boot.

BTW, even though your main speakers have decent bass extension, you should experiment with crossing over at 80, 100, and 120 hz. This will allow the DRC in your sub to do its thing. I suspect you will be amazed by the improvement in sound.

Good Luck.

Marty
martykl
3,578 posts
 
I recommended experimenting with higher x-over frequencies because my experience with room issues has usually revealed the most audible problems lie between 50hz and 150hz, especially 80ish to 120ish . These are pretty common and usually very, very audible.

I use bass busters which are pretty effective at knocking out the hump between 80hz and 120hz in my current room. I cross at app. 75hz and the DRC in the SMS-1 does the rest. Without bassbusters, I'd start at 120hz to judge the effects of the DRC, then directly compare the sound to a much lower, audiophile approved x-over point. You may be surprised.

Note: if you use bass busters (or similar treatments), you can probably safely cross as low as 70hz - 80hz and get most of the benefit of DRC in the DD subwoofer. If you cross any lower, the DRC won't get a crack at the worst nasties in the room.

Marty
dgaylin OP
255 posts
 
Marty -- yes thanks, your thoughts are very similar to mine. And in fact, with my previous pre-amp, I used the Velodyne exaclty as you noted -- by setting the crossover higher and having it reinforce the speakers output below 100 hz, I got better bass, and was able to use the parametric eq in the sub to smooth out the bass response. My problem is that the Nagra is a wonderful piece but for it's lack of output options. I've been pretty happy running the speakers full range, and the SMS unit built into the Velodyne confirms that, properly tweaked, I've got a nice flat response (except for one null at about 165 hz that I can't do anything about). So the crossover, while interesting, is largely a glorified output doubler. I am not convinced the NHT unit will be inaudible (based on some inquiries I've made in this respect) in my system, but it's not all that expensive an experiment to try.
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