Super noob question - sub woofer hookups

[Trajan]

Years ago, for reasons I still don't understand, my dad bought a very powerful sub woofer. I just ended up with it this afternoon and -- since I know virtually nothing about audio systems -- was hoping I could get a little help hooking it up!

It's a self powered/integrated amp model, a Definitive Technology "Powerfield SuperCube II" if that means anything. I'm hooking it up, sans amplifier (I hope) to my widescreen TV which runs on integrated stereo speaks.

The back of the subwoofer has a few inputs I wanted to ask about.

* LFE In: this is what I'd use if I had my own amp, I think?
* High Level In/Out (+/-): this is what I'd use if I were using speaker cable/wire type connectors?
* Low Level In/Out (R/L): this is what I'm going to actually use... is that right?

There's also a "T/8A/250W" jack which I'm smart enough to know is for electrical and which I can ignore in favor of the built in 120v connection. Then there's a Subwoofer Level knob which I gather is the equivalent of volume control.

The last tricky part though is that there are three other knobs:
* Variable Low Pass Crossover
* Variable Phase Alignment
* Variable High Pass Crossover

I have a general sense that crossover is important to me because I don't have my own amp and therefore the setting does matter in my set up, and I read I should set crossover at around 80 (the knobs range from 40 to 150). I didn't know there were two types of crossover, though, and I have no idea what variable phase alignment is.

I'd be grateful for any 101 type help on configuring this. I get the sense I accidentally ended up with a really high end subwoofer that is going to be wasted on a non-audiophile, and if that's true, I'm sorry for it!

 

[s44]

Low pass = cuts off what's above
High pass = cuts off what's below

The idea is that you put the source (full-frequency) into the low-level in, use the low-pass to set where the subwoofer starts using the signal, and have the high-pass to your main speaker setup attenuate around the same point so the sub and speakers don't double up too much.

However, with the TV I'm guessing you'll be connecting the sub (the low-level in, as you've guessed) to the TV audio out (or headphone out). This should work if that output is variable by TV volume -- otherwise, ick. Since the TV speakers don't go very low, set the low pass as high as possible (lower it a bit if you get too many localized voices coming from the subwoofer or such). Since you're not using the sub's outputs at all, the high pass shouldn't matter.

Set the phase at zero, but if you don't seem to get much bass from that location, flip it to 180. Adjust the sub level to taste -- you could buy a sound pressure meter to equalize things, but I'd just save the money to a future cheap AVR fund.

PS -- the Supercube II isn't a super-audiophile thing, but it is a neat attempt at a "small sub" design. 8" driver with a pair of 8" passive radiators... Testing shows a -3db point of 27hz which is pretty good.

 

[JSt0rm]

you can also get a useful spl meter on the iphone if you own one.

 

[calvie]

You are using TV speakers and wants to add a powerful sub?
Its never going to sound right even if you are able to do so. best way to do this is with a receiver and a pair of bookshelf to go along with your nice sub.

 

[electroju]

LFE is Low Frequency from a low signal and not high level like speakers.

Do not need to set the low pass crossover at 80 Hz. This is just a dumb requirement. Sure it is requirement from THX stating that 80 Hz is good starting point. IMHO, it is dumb requirement to integrate a subwoofer with speakers.

The easiest way to integrate a subwoofer with two speakers is to send a stereo pink noise. Pink noise is an average level of all frequencies. Pink noise helps to have near flat level of all frequencies. You can either generate pink noise with a computer or with a device. To use a computer you can use WinAMP, Audacity, or any other program that generates special effects. Set the length of the pink noise to about 30 minutes. After you generate a pink noise file and you connect the computer audio output to the TV audio input, do the following steps.

1) Set TV volume to good level to hear the pink noise.
2) Assuming the subwoofer is hooked up to the TV, set the volume to 0, set phase to 0 degrees, and set low pass crossover to its highest.
3) Increase the volume of the subwoofer until is about the same loudness of the TV speakers.
4) Adjust the crossover to its lowest setting since you already know the baseline of the highest. This will give the lowest baseline.
5) Increase the crossover until the subwoofer just about matches with the TV speakers.
6) Fine tune the subwoofer by adjusting the crossover and volume of it. Use a audio content that has a lot of bass.

This gives you a rough way to integrate a subwoofer with two speakers. Just make sure that the TV audio output is set to variable instead of fixed. The subwoofer should be about 5 feet from the speakers if the crossover is set near 150 hertz.

Passive radiators are drone speakers. They look like speakers, but they are not speakers. They are missing two components that make a speaker driver. These components are a voice coil and a magnet. Passive radiators are port substitutes in bass reflex system. A passive radiator advantage over ports is the ability to tune low in a small box. Tunning low gives the speaker driver or woofer to be in more control at high power output and handle low frequencies. The speed or the response times of a passive radiator type of system is slow at 60 milliseconds and higher. A sealed or acoustic suspension is around 15 milliseconds or faster. For passive radiator designs do not lay the side that has passive radiators flat on the floor because you will damage the passive radiator.