Subwoofer connection to older tube amp

That's great, congratulations. Now you can take your time adjusting the output, crossover and phase settings to get it to sound best with your system. You'll probably find that what works really well for one recording isn't ideal for another and it takes some going back and forth to find the setup that's the best compromise.

As explained to me by the main tech at HSU, the builder of my sub, the second set of speaker cables going to your sub from the main speaker terminals aren't drawing any appreciable power, they're just picking up frequency and amplitude information to be amplified by the amp in the sub. He said the gauge of the cables going to the sub doesn't even need to be the same as your main speaker cables since they're carrying very little power.

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.

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.

Davidrb - Yes, it will work fine with a tube amp. I used that setup for a couple of years with and AES/Cary Superamp. The amp has five-way binding posts and I used spade connectors on the cables to the speakers and bananas plugged into the same binding posts for the cables to the sub.

According to the tech at HSU I talked with there is no reason to use the same gauge cable for the sub since all it is carrying to the sub is the frequency and amplitude information which the sub then amplifies on its own. He said, essentially, that using larger grade cable was a waste of money.

I used Canare 48s, I think, which was overkill, but I had bought a bulk lot of it from Markertek for another project and had it lying around. I've also used cables made from Cat5 network wiring, also because I had a spool of it, and it worked fine.

Jamesk58 - It would be a good idea for you to ask this question in a new post since the only ones who are seeing it now are those who answered your original question about the sub hookup.