Bass amp as home theater sub

[Grumbanumba5]

I have a 15" 120 watt Crate Bass amp. I want to use it as a subwoofer for my home theater system as well as a bass amp. I have an audio receiver with a "preout" subwoofer out jack and I got a 1/4 in to rca cable and there is a serious buzz. why is this? is there any way to prevent the buzz and have it work for both home system and bass amp(not at the same time obviously). any help would be appreciated, thanks.
-Eric

[87PRS]

how do you have the bass amp connected to the system? If you are using a line out to a sub out ....its not going to work...unbalanced cabling can cause a buzz too, your problem can stem from several problems...ie ohms mismatch, line out-line in mismatch, wattage mismatch...I've tried using live gear hooked up to a stereo system, sometimes it just won't work. Good luck & welcome to the audio forums!

[sabianq]

I have a 15" 120 watt Crate Bass amp. I want to use it as a subwoofer for my home theater system as well as a bass amp. I have an audio receiver with a "preout" subwoofer out jack and I got a 1/4 in to rca cable and there is a serious buzz. why is this? is there any way to prevent the buzz and have it work for both home system and bass amp(not at the same time obviously). any help would be appreciated, thanks.
-Eric

the instrument amplifier uses a line input called instrument level which is different than your output from your stereo which is consumer line level, you need to isolate the signal and re-amp it to suite your needs.
in other words,
you need to re adjust the level of your consumer line signal to match the impedance and dbu of the amplifier.
you need to also isolate the signal using a transformer, a passive DI box
http://www.jamtank.com/images/dibox2.jpg
might help you do what your looking to do but there may be some issues, you should borrow one and try it.

Also radio shack sells an audio line isolator that might help your situation. they are cheap
http://members.dodo.net.au/~cavelandelec/caveland/electronic/built/mp3/isolator-lrg.jpg

some reading here might help shed some light on what you are trying to accomplish.
http://www.electronics-tutorials.com/basics/impedance.htm


but in general, read up on reamping
http://en.wikipedia.org/wiki/Re-amp

here is a solution that I bet would work fine for you.


http://www.reamp.com/

[ecc83]

Sure, if you can sort out your connection problems, use it as a sub, but.

Bass Git speakers are primarily designed for surviveability not very low Fs. Typically a 15" 300Watter will have a cone resonance of 35-40Hz the enclosure will push this up a bit so you will be lucky to get a system resonance below 44-55Hz. The consequence of this is that it will be hard to get really low CLEAN low frequencies. Another problem is that even bass guitar speakers have a fair output in the 2-4kHz range and the filter slope in your amp might not be steep enough to keep this range out.

In short, yes, you will get a lot more "bass" but it will not be the smooth, bowel churning 'wooomph' you get from a really good Hi-Fi sub. If you want to recreate the sort of sound kids have in their Subarus', go ahead!

Dave.

[TimmyP1955]

All of the bass cabs I've tested have their hottest spots at about 160Hz and 65Hz. Below 65 they trail off pretty quickly. Mediocre for bass, lousy for home theater.

[ecc83]

It is perfectly possible to operate a speaker below the system resonance(known as stiffness controlled as opposed to mass controlled operation) a famous example is the Bose multi drive unit box. But it needs some pretty urgent filter slopes and prodigious amounts of power.

Adequate though it is for gigging I am sure, the Crate is about 10dB shy of the sort of juice needed for serious 30hZ window rattling.

Dave