What does "apassive subwoofer" mean? (1 Viewer)

[Brian W.]

I'm considering buying the Kenwood HB-405. It seems to come quite highly recomended, both here and in the customer comments on the Circuit City web site, and I don't have the money for individual components or the patience to learn about them.

But that "passive subwoofer" or "non-powered subwoofer" does seem to be a minor complaint -- a few even recommended the comparably priced Sony HTDDW740 for that reason. Can someone enlighten me on what this phrase means?

Edit: This probably sould have gone in the Home Theater Basics forum, so feel free to move it.

 

[John Garcia]

"apassive" is not a word. A PASSIVE sub is one that does not have it's own amplification built in, this means the burdon of heavy bass is put on the reciever while it is trying to drive all the other speakers, reducing the total available amplification for all.

I personally cannot stand Circuit City, and I would strongly recommend you simply give a budget here and ask for recommendations for a system in that price range. You might be surprised at what you can get.

 

[Brian W.]

Ha! That was a cut-and-paste from a comment where the "a" and "passive" were run together. Told you I don't know anything about sound systems.

Thanks for the explanation. You'll be pleased to know I'm wasn't planning to buy at Circuit City anyway. I was just looking at their customer product reviews, which seemed to be excellent for this item. Several people in another thread here said they felt the Kenwood was the best home theater in a box for the money (under $300), hence my interest in it.

 

[derek]

According to Kenwood's site...the HB-504 does have a powered sub with separate 100 watt amp. If you do have a passive sub and the receiver has a sub preout you could drive it with an old stereo receiver or amplifier.

 

[John Garcia]

If you do have a passive sub and the receiver has a sub preout you could drive it with an old stereo receiver or amplifier.

I agree with this completely and a system not having a preamp out for the sub is a big minus in my book too.

 

[Brian W.]

double posting

 

[Brian W.]

Thank you for your advice. You're talking to a complete novice, though. I don't even have a stereo in my house -- I listen to music through headphones or in the car.
Can you explain the effect of a passive sub versus a powered sub on what I will HEAR? I've been searching the web looking for something that will explain this, but all I find are explanations in operational terms. Will there be a drop in overall volume when there are deep notes in the sountrack, or will it just not get as loud as it would with a powered sub, or what?
Or maybe you can direct me to a resource that will explain these things. "Home Theater for Dummies" or something. Thanks again for your help.

 

[Chris Tsutsui]

I didn't think it was possible for one to have 600 posts and not have a stereo or HT. Your patience is very admirable.
I guess they should perhaps rename passive as non-powered.
The benefits of a non-powered sub is that you can choose your amplifier however you feel. Just because it's passive doesn't mean it's bad at all, I have a decent sounding 15" tempest that's passive. I then have to wire an amp to it in order to drive it.
There are also passive SVS subwoofers, only they just wouldn't call them that for marketing reasons.
Most receivers don't exceed 100 watts unless you jump into spending $1000 or more. But then again 100 watts can be plenty for a passive sub if the driver has decent sensitivity. With self powered HT subs, they are almost always powered with an amp over 100 watts to deliver more power and bass.

 

[Brian W.]

Sigh. Thanks for trying, Chris, but I have no idea what a driver is, I have no idea what an SVS subwoofer is, I don't understand half of what you just said.

you can choose your amplifier however you feel

And this means...what?

 

[John Garcia]

SVS = Very nice subwoofers! (See link at top of page) or SVS.
A "driver" is the actual speaker in the subwoofer.
Sensitivity is related to the amount of sound (SPL - sound pressure level) a driver can generate, normally measured with 1 watt of power at a distance of 1 meter.
Essentially, the only difference between a passive sub and a powered sub, is that the amplification is not included with a passive sub. What Chris is saying, is this allows you to choose whatever amp and amount of power you like to drive the sub with. Amps have varying quality, and choosing a quality one to do the job will have an effect on the performance of the sub, since low frequencies and large drivers tend to draw the most current.
A non-powered sub can be powered by your receiver, by using the speaker level input (regular wires to the speaker terminals on the receiver), then to the main speakers. With this method, the sub handles the crossover of high and low frequencies between itself and the other speakers connected to it. The disadvantage to this method is the receiver now has to handle amplifying the low frequencies as well as the highs, which puts a more significant strain on the internal amplifier.