Connecting a subwoofer to my 2-channel preamp without losing balance control

[tcrossma]

I'm trying to integrate a sub into my 2-channel system to see how it sounds, and i'm not sure the best way to go about it.

I have an Adcom pre that has 2 sets of unbalanced outputs and 1 set of balanced outputs. Currently I'm using one set of the unbalanced outputs going to my amp and the second set and balanced are free.

My subwoofer has a single RCA input, so my first thought was to use the second set of outputs and using a y-adapter connect it to my sub. I have some sort of Rat Shack cable lying around that has 2 RCA's on one end and 1 RCA on the other, which seemed like it'd fit the bill. When I hook it up the sub functions as it should, but my speakers operate in mono mode, which I'm assuming is because the sub cable is jumpering the left and right channels together. If I unplug one of the cables from the preamp then everything functions as it should, however then I'm potentially missing bass information from one channel.

So I guess I have two questions:

1. What's the best way to integrate a sub into my setup

2. Is my current cable the cause of the problem and will I be able to use a Y adapter to make this work, or will it always jumper the 2 channels together and cause the main output to be mono? Do I need some sort of active electronic solution for this?

Thanks

[Ern Dog]

The same thing happened when I hooked up my sub to my tube preamp using a Y adapter. Like you, I removed the Y adapter and I'm finding that operating my sub in mono works great.

[tcrossma]

The problem is that if low frequency information is sent to the channel that is not connected that information will not be sent to the sub and will be lost. So ideally I'd like to get both the L and R data to the sub somehow.

[Gaara]

Sounds like you have the right idea to hook it up, a Edcor S2M should fix the issue.

[tcrossma]

Thanks Gaara. I'm not sure what that is yet, but I'll research it.

[10-SE]

Do not try to "sum" left and right channels with a Y adapter. Y adapters should split signals, not sum them. You need added resistance. see http://www.rane.com/note109.html

Eventhough more often bass is mixed equally on both channels and almost never missing on the left channel, some engineers can get a little creative. So the of potential missing some low frequency info from an absent right channel, although rare, is a legitimate concern.

You should use a stereo-to-mono converter instead of a Y adapter
http://audioplex.com/llsc1.htm

Or if your sub has speaker level inputs, you can use those. But it means sending the low frequencies through the main speaker outputs of your amp. Tapping into these signals for a sub will not change the impedance (load) your amp sees with the main speakers, so it will not smoke your amp. But it will require you to send low frequencies on to your main speakers which may be less than ideal if your main speakers are small. Even if your main speakers are small, you can still get away with it by turning bass down at the amp/preamp, and turning gain up on your sub.

I'd chose the first option of summing your spare unbalanced outs. You still have the other option of using speaker level signals if your sub takes them.