Bookshelf Speakers, Subwoofers and Crossovers

I have been thinking about this for a bit now since I no longer have the Parasound Halo P5 in my system with its active crossovers (which I only used the crossover for movies). And thinking about it a bit more just now, I think I might have just answered my own question…

My system is strictly 2-ch, with 98.9% of the time for music only. The other 1.1% is when the family gets together to watch the occasional movie on the weekends.

I stand in the same corner as Paul, in allowing the mains to play full range, then adding in stereo subs to fill-in the natural roll-off of the mains. In this case, it’s a pair of Sonus faber Venere 1.5’s and a pair of JL Audio e110 subwoofers.

I’m running the balanced outputs from the GCD to the two bridged NuPrime STA 9 amps, the single ended outputs to the JL subs, which are then Y’ed into both L/R inputs on the subs. This is where I think I answered my own question…

My amps have both SE and balanced inputs, and I can switch between them on the rear panel. The subs low level outputs actually get crossed over at whatever crossover point I have them set at. So why can’t I run the system as is right now for music, then for movies, run interconnects from the sub outputs to the SE input on the amps, flip the input switch from balanced to SE and get the crossed over signal from the subs to the amps, thus protecting the mains from that nasty deep movie bass?

I believe this would work just fine, but thought I would ask first. I think this would be a win/win situation as I do NOT want to run a SE signal to the mains all the time, nor do I want them going through the subs’ crossovers all the time, probably as an inferior signal vs balanced straight out of the GCD. With music, I care about the purity and quality of the sound. With movies, I only really care about protecting my mains.

Does this all make sense to you guys? LOL

the question on the amplifier inputs is best posed to the amplifier manufacturer. Some switches kill the input, others do not.

Secondly, the Y connector you are using on each of your subs is not necessary. If you are only running one channel to each of your subs, the Y connector is just dividing the signal in half, which the subwoofer then combines into a mono signal to drive the subwoofer.

You can probably run the RCA cables to the subs, and just turn on the subs when you want them. If you set it up correctly, you will enjoy your subs with music just as much as with videos.

You can also do Paul’s favorite method, and feed your subwoofers a speaker (high level) signal from the amplifiers, and turn them on when you want them.

You will get the best sound out of your GCD with only the XLR cables connected.


I agree on the sub inputs. On most if not all JL subs use the left channel input as the mono input (one sub for side) so take out the y-connectors. As to the other question if you want to go through the wire swapping for the “rare” movie night then it should work.

I don’t think the Y-adapters matter as far as what I’m talking about. According to the JL manual, you can run a signal into either the left or right input as the sub sums both internally anyway. And if I recall correctly, I get slightly more gain out of the subs with the Y-adapters installed with the same given input level.

@hlg3 - Not sure where you’re going with “just turn the subs on when you want them”. My subs are continuously on no matter if I’m listening to music or watching something on TV.

It isn’t a question if I will enjoy my subs with music and movies. It’s a question of added protection for my mains when watching bass intense movies, hence feeding my amps the filtered output signal from the subs’ outputs to the SE inputs of the amps.

With music, I would be feeding the amps via the balanced inputs directly from the GCD as I am now.

Again, the amps have a small toggle switch on the rear panel to choose between balanced and SE input.

I can understand wanting to limit the bass frequencies going to your small bookshelf speakers. I used to have to do that also.

Using the Y connectors is just adding another set of connectors, which causes loss of signal quality. If the level control on your subs is not maxed out without the y connector then you are fine. If your level control is maxed out, and you still need the y connector to get more gain, that is a sign of too smalll a sub(s) for your room.

If you want to go through your subs to get to your amp, you are splitting the signal with the y connector, you are essentially sending half the voltage to your amp. You should not try to use another y connector to send the signal to your amp. Y connectors should never be used to sum a pair of signals, only to split them.

Also, as noted in another thread, by using both outputs on you GCD, you are essentially unbalancing the XLR outputs of you GCD.

hlg3. Is that true of all preamps with dual rca and xlr outputs that it unbalances the xlr output ? Never was aware of that. I run xlr outputs on an Oppo 105d directly to my amps and the rca’s to my subs also. Wonder if I have turned the xlr into an unbalanced signal also ? Thanks.

drumnman2, it is true of any output where the balanced and single ended outputs are not isolated. By connecting both, you are adding load to one side of the output, therefore unbalancing it. It will not always be noticeable. It is easy to test, just unplug the RCA connectors from the back of your OPPO.

If you can hear it, you can then explore a different way to connect your subs.