Subwoofer connection to older tube amp

Sorry if this explanation is simplistic but I'm not sure where your confusion is.

Your power amp has two kinds of connections, both of them inputs. The first is the right and left inputs coming from the outputs of the preamp. Those are the RCA connectors on the back of the amp connected to RCA connectors on the back of the preamp. Those are line level - output from the preamp to input on the amp. There aren't any line-level outputs on the amp, only line-level inputs. The only output from the power amp is high-level, also called speaker-level.

The second kind of connectors on the amp are the speaker posts. Those are the speaker-level outputs that go - obviously - to your speakers.

The preamp can have a couple of kinds of outputs, the one kind every preamp has is a pair of line-level outputs controlled by the volume knob, like the ones going to your amp. You might also have another pair that aren't controlled by the volume knob, intended to go to a recording device and usually labeled "Tape out" or something like that. That's no use to you in this situation, even if you have them, since you want the signal going to the subwoofer to be controlled by the volume knob on the preamp.

So, you have two choices. First option is to use speaker cable to connect between the speaker terminals on your amp and the speaker-level inputs on the sub.

Second option is to split the output from the RCA connector outputs on the preamp using a 'splitter' as Steuspeed suggests and use two interconnects, one pair going from the splitter to the RCA inputs on the amp and the other pair going from the splitter to the line-level inputs on the subwoofer.

Some preamps have two sets of line-level outputs on the preamp but most don't. I'm assuming here that yours is one that doesn't.

The option I was recommending was option 1, the option Steuspeed was recommending was option 2. Either of them will work, which works better for you depends on your gear and what sounds best to you.

Sorry if this confuses things further. If it still doesn't make sense, please describe in some detail the connections you have on the back of your preamp.

Thanks again Sfar. My pre-amp is basically as you state. It has the main line level outputs(RCA) for the amp plus the RCA style tape output. So your saying that I can't use the "tape out", that I would have to split off the main out with one set of connectors going to the amp and the other to the sub?

I use a pretty high-end output cable between the amp and pre so I'd have to use a splitter thats a little better than Radio Shack quality to not diminish the connection to my amp.

I do want to use the amp in the sub since its 1000 watts and designed for it. If I just double the speaker wire connections off the amp- one set to main speakers and the other set to sub, it seems it would defeat the design of the sub and may overload the amp.

Right, you can't use the 'tape out' connections because they're not controlled by the volume control on the preamp, meaning the volume coming from the sub wouldn't change as you adjust the volume to your main speakers.

If you do want to split the preamp output you can use one of the devices Steuspeed recommended. He suggested one from Audioquest and there's another from Monster. Click here to see what the one from Monster looks like. Both it and the Audioquest version are solid connectors, no wire involved.

You shouldn't worry about using the speaker wire connection method, though. The subwoofer amp won't be pulling any substantial power from your main amp and won't overload it at all. That connection method is the one recommended by both REL and HSU, makers of some of the better subs out there. You should definitely do what you're most comfortable with, however, it's your gear.

So if I just go with the doubling of the wires off the same 8 ohm speaker output directly from the amp I'll be fine? That would be easiest and I wouldn't have to go out and buy more connectors.

Also, do I need to run left and right wires or just a single? Right now I'm using an A/V receiver that has the single RCA Sub output and its connected to the left input on the sub. Now I want to switch back to using my Audio Reserch gear. Do I need L&R or just go with one speaker wire off the ARC amp to say the left speaker sub input?