Need Help Powering my subwoofer

[mcsoccerdude]

Hello!

I need help. I have very little experience setting up sound equipment. My wife and I just bought a new house and one of the rooms came with a surround sound system. I believe it is an NHT system from the 90's. It is a 5.1 system. I have gotten the 5 speakers working by buying a Yamaha Av Receiver (RX-V371). This is when I relized the sub is a passive sub (didn't know what that was before), but I believe it needs an amp? The model of the sub is NHT SW2P. (Impedance 8 Ohms).

My question is how to get this sub woofer working. ON the back of my Yamaha Ave Receiver is one output spot for the subwoofer. And on my subwoofter (SW2p), it only has (2) speaker wire things (red and black). I need to buy an Amp correct? Also what type of amp / specs should I be looking for. And how do I connect this to my receiver? (doing a google search it appears the original Amp would have been a MA-1A)

On a side note, does anyone know if this sound system is good relative to the systems out there now? just curious?

I am hoping this is a very simple answer. I really appreciate your time and help.

[sanlyn]

I'm afraid you're not giving enough info about your NHT's. They made a bunch of different models in the 90's. One way to "empower" a passive woofer is to buy and install an in-case amp known as a "plate amplifier" designed for subwoofers. This means you'd have to modify the subwoofer enclosure. You can buy plate amplifiers from outfits like PartsExpress , or you can buy an outboard subwoofer amp in an external enclosure (more expensive). Warning: some of the plate amps you find being sold are really cheap, and really horrible. PartsExpress and others also sell the parts you'd need to build your own subwoofer or enclosure from scratch or from a kit - but it's easier to find a small ready-made powered subwoofer (you can get decent ones as small as 6.5" that will do the trick. Movie soundtracks don't have bass that great to begin with). You could also find a cheap or used integrated amp to accept the receiver's bass output, but that's not the best idea: you'd likely encounter feedback and/or other problems using a full-scale amp.

[Hoser Rob]

As sanlyn mentioned you can buy dedicated sub amps. They have a line level input you plug your receiver into. They're mono. And, very importantly, they have built in low pass filtering. You shouldn't use full range signals with a sub.

NHT have always made good speakers. Speaker technology is actually pretty mature. If it was good 20 or 25 years ago, and it's in good shape, it's still good.

[MOVIEGEEK]

As was mentioned a powered sub is best but you can get your old sub working by using zone 2(A/B switch) on the amp, just hook it up as you would a normal speaker and set the A/B switch to both zones. This is assuming the sub has a built-in low-pass crossover with a variable frequency knob on the back, if it doesn't then just buy a new sub.

EDIT: just looked at the specs for your sub and it doesn't have a low pass filter, if you are handy you could cut out the back and mount a plate-amp:
http://www.parts-express.com/cat/subwoofer-plate-amplifiers/332

[mcsoccerdude]

Thanks for all the input!

I am still a little lost. Again, I really do not know what I am doing. Is the Plate ampliflier my only option? Or will I be able to buy an "out" amp (dedicated sub amp???)

I am not very handy, so I want to stay away from modifying the existing sub. Someone mentioned to me that this would work for it??
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-812

Do you think this amp would work/ what am I looking for in an Amp to work for this. Also will I then plug my two speaker wires from the sub into the L output spots? Then will I need to have some type of audio cord to go from my receiver to the input on the amp? (so a 1 to 2 connection)?

Sorry if this all is very basic, I really do not know what I am doing. I am just trying to get this to work for relatively inexpensive. I do not want to simply abandon the sub if it is good and would not cost much to get working.

Thank you again for your time and help!

[MOVIEGEEK]

That amp above will work fine and can sit on top of your sub, you can use line level output from your Yamaha. Select mono and bridge the output to your sub, set the low pass filter to 60-80Hz.

[mcsoccerdude]

Great! Thank you for the response. That makes sense.

I am trying to find the cheapest amp that will do the trick to get the sub working.

would this work ??? http://www.amazon.com/AudioSource-AMP-100-Stereo-Power-Amplifier/dp/B00026BQJ6/ref=sr_...ower+Amplifier

Or is there another amp you would suggest?

Thanks again.

[Hoser Rob]

The amp from parts express makes more sense to me.

You need to filter the highs from the sub. Subs nowadays are powered with a filter built in. A/v receivers assume that and don't filter the sub output. The amp in the link from amazon will only give you a full range signal. Not good for a sub.

Also, running a cheap stereo power amp in bridged mode isn't a good idea if your speaker impedance goes under 8 ohms at all.