Did you get the Tube-01J?
I'm looking at getting one specifically for using it as a preamp for active duel subs that I have running through a Rolls SX95. I'm thinking I could set it up to use the gain switch as a simple bass boost toggle so I'm curious how it performs.
I'm not familiar with the SX95 so I looked it up.
I can't imagine that you actually need more gain for the signal going into your Rolls since it's designed to take normal line level signals. It has a level control. Are you running it turned up all the way and it's not loud enough?? If that's the case, a preamp is not the solution, IMO.
Also, the gain switch on that version of the FX is not a boost, it cuts the gain. It was added because many people found that the gain was too high with the regular version.
When subs are used for home theater they're mostly an effect. Great for explosions in action adventure movies.
When using a sub for music, the best results are obtained when it's effect is essentially subliminal. When music is playing you shouldn't be able to tell that it's turned on. But if it's on and you turn it off while music is playing you'll be able to tell that it's now gone.
The higher the crossover frequency, the easier it is to locate and tell that it's obviously on. So it's not just the volume of the sub that's important. It helps to use the lowest crossover point that works with your speakers.
The 80 hz point that you often see mentioned is really designed to work with surround sound home theater receivers, not amps designed for music listening. For music, it's a totally arbitrary reference point.
The Rolls seems like somewhat of a specialized device to me. Something that not many people would need. Most commercially produced powered subs would have no need for something like the SX95 because they typically have an adjustable low pass filter of their own.
It's apparently designed to be used with powered subs that don't have a built in low pass filter of their own. It provides a low pass filter which sends low frequencies to either one or a pair of subs and it has a "pass through" output that sends an unaltered, line level, output to the main amp. If you built your subs it's probably exactly what you need, though.
Since it's not an active crossover, your main amp is still receiving and amplifying the full frequency range coming from the source and sending it to your main speakers. So the lowest frequencies are being reproduced by both the subs and the mains.
You need an active crossover if you're trying to reproduce the lowest frequencies using the subs and only have the mains reproduce frequencies that are higher than what's being done by the subs.
An active crossover takes the full range signal from your source and sends different frequency ranges to different amp / speaker combinations. I bought one years ago. It's just a cheapie but it works fine. It can be setup as a 2-way or 3-way system.
I haven't looked at it closely, but there's a device called miniDSP which has all kinds of capabilities, including an active crossover. I believe it's adjusted using a smart phone app and it's pretty cheap as I recall. You might want to check it out if you're trying to limit the range of frequencies produced by the mains.
