Are all subwoofers powered?

[jimmy w]

I've looked at photos on-line of the backs of several AVRs and they don't have speaker connections for subs. Just line outs for subs. Is this standard practice? If so, why? AVRs do everything else!

Thanks in advance for any insight, JW

 

[Cygnus]

This is because powered subwoofers are better then non-powered, hence AVR's only have that one option. If you don't have a powered sub though, I'd think that you could buy an amp for it.

 

[Doug917]

I would have to disagree, a powered sub is no better than a passive (non-powered). I have 2 passive SVS subs and this allows me to run the RCA out from the receiver to an external amplifier and gives me much more control. Some passive subs are better and some powered subs are better. The main reason manufacturers of AV receivers do not include an amplification channel for a sub is because it is the most demanding channel. The low frequencies the subs produce require more power than the rest of the channels. You will rarely see a powered sub with an internal amp less than 100W and more often see internal amps with much higher power ratings in subs. Receivers commonly have less than 100W per channel.

 

[8118]

if you are looking at those sub come with HTIB, most of them are passive. those sub are lousy.

But if you are talking about separate sub, most sub are powered. only few are passive. just like doug says, some powered are better and some passive are better... many factors influnce the performance.. amp, size, design, crossover, bass extension.......

 

[mtrycrafts]

I've looked at photos on-line of the backs of several AVRs and they don't have speaker connections for subs. Just line outs for subs. Is this standard practice? If so, why? AVRs do everything else!

Thanks in advance for any insight, JW

No, not all subs are powered. But even if they are not you would need an external amp as subs like power. It needs lots to get loud and low. And you need it loud to hear it as your ear is less sensitive to the low frequencies then the mid bands.
So, receivers offer sub out.

 

[jimmy w]

Thanks!

So, for the sake of this discussion, if a receiver has (7) 100 watt amps, how much power would a sub need or an external amp need to keep up? Generally speaking, without regard to speaker efficiency, etc. Say 2X , 3X?

JW

 

[markw]

As much as possible.

So, for the sake of this discussion, if a receiver has (7) 100 watt amps, how much power would a sub need or an external amp need to keep up?

The more power a sub can handle, the cleaner iwt will sound. And, with subs it's more a matter of quality as opposed to mere watts.

 

[Cygnus]

I would have to disagree, a powered sub is no better than a passive (non-powered). I have 2 passive SVS subs and this allows me to run the RCA out from the receiver to an external amplifier and gives me much more control.

Actually, now that I think of it, that makes alot of sense. Sorry if I mislead you, Jimmy.

 

[benolium]

Where to begin?

This is because powered subwoofers are better then non-powered, hence AVR's only have that one option. If you don't have a powered sub though, I'd think that you could buy an amp for it.

I have a passive sub with 2 10" woofers. I would like to add an external amp to it. I am thinking abou getting on of the Axiom systems. If I can make this sub work, I would like to save some money. Where do I begin. What is the termanology of the amp that I am looking for. Thanks-newbie

 

[jaxvon]

Is that an old car subwoofer?

Anyway, a good quality PA amp will work just fine, though you may have to adjust your wiring to make sure the impedance isn't too low. Something like a QSC RMX-850 would work great. It puts out 830W at 4 Ohms, so it should give you plenty of power. Just make sure that you're presenting a 4 ohm load to the amp.

 

[WmAx]

Is that an old car subwoofer?

Anyway, a good quality PA amp will work just fine, though you may have to adjust your wiring to make sure the impedance isn't too low. Something like a QSC RMX-850 would work great. It puts out 830W at 4 Ohms, so it should give you plenty of power. Just make sure that you're presenting a 4 ohm load to the amp.

Another option: a used Adcom 555 off of ebay can be had for reasonable price($300-$350), and is stabile down to at least 2.8 ohms nominal[I once used it for home theatre on subwoofers that measured 2.8 ohms nominal and it performed flawlessly even at high SPLs for long periods]. It has no fans, so it is silent. The amp is rated at 200x2 @ 8 ohms and 325x2 @ 4 ohms. It can also be bridged. In 3rd party reviews, the amplifier typically tested about 25% higher power than the rated numbers.

-Chris

 

[Buckeyefan 1]

No, not all subs are powered. But even if they are not you would need an external amp as subs like power. It needs lots to get loud and low. And you need it loud to hear it as your ear is less sensitive to the low frequencies then the mid bands.
So, receivers offer sub out.

Nah, my 10" Design Acoustic plays loud and low off an old Yamaha 2 channel 40 watt receiver. It depends on the passive sub.

 

[brian32672]

Yes all subwoofers are powered. JK.
Well all except Bucks....
Don't mind me, its the alcohol. (I know, lay off the sauceyyyyy)(But its Friday night, well actually Sat. morning)

 

[benolium]

It's a sub for a home audio system. I have it wired to the Yamaha 636 fronts to handle the bass. The major problem is. When playing movies the sound has to be turned way up on the receiver to get any bass, since it is passive, and has no adjustments. The brand is by Video Acoustics. It has each one sub facing west, and one south. There are the opposing sides that would facilitate an amp. Thanks for the advice. Steely Dan kicks ***! The box set rules.