How low should a subwoofer go?

[Grand Dizzy]

WARNING: Stupid newbie question!

I've been looking into speakers and thinking about getting one of the Canton packages, but I was a bit surprised that the subwoofers only go down to 33Hz (25Hz for the more expensive package).

I've read that the normal human ear can hear as low as 16Hz. And I've just checked the documentation for my cheap computer speakers, and the subwoofer on them goes down to 25Hz (several semitones below the Canton subwoofer).

How come a cheap £40 computer speaker set can do 25Hz, yet a £480 home cinema system subwoofer is only doing 33Hz? Yet the Canton system is supposed to be really good.

How can this be when it doesn't produce any of the lower sounds audible by the human ear?

I'm confused; please can someone explain?

[davehk]

possibly because Canton quote the -3dB point, and the computre speaker makers quote the -18dB point (without telling you)

Don't forget: their are lies, d*mned lies, statistics ... and then we come to specifications.

[bob1]

The frequency response of subwoofers can easily be made to measure just about anything ,its more likely that the computer sub response is been made to seem better than it really is ,if everybody measured the response to the same standard it would be easier for the buyer.
The 33hz for the canton is probably more realistic ,it will go lower than that but at a reduced output.

[Ian J]

Originally Posted by Grand Dizzy

How come a cheap £40 computer speaker set can do 25Hz, yet a £480 home cinema system subwoofer is only doing 33Hz? Yet the Canton system is supposed to be really good.

Without delving deep into the spin put on figures presented by various marketing departments I think that you may be confusing depth with quality as it is a relatively simple and cheap matter to reproduce deep distorted notes and I would suggest that most of the sound coming from your computer subwoofer is distortion.

[Grand Dizzy]

Thanks everyone, especially Ian, for clearing that up perfectly!

From what I gather, it's a bit like having a cheap camera with a high resolution sensor — megapixels don't mean a thing if the camera takes poor quality photos!

[Nick_UK]

The wavelengths of low frequency waves are so long (a 50Hz tone has a wave length of 22.6 feet) that you will see (or rather, hear) lots of cancellation effects as the sound bounces off the walls. Unless your room is very big, of course ! That's why bass notes always sound better in the open air. My friend fas a pair of Kef bass cabinets, and they only sound good if you put them at the foot of the stairs, and listen at the top.

By the way, a 20Hz tone has a wave length of 56.5 feet !

[Londondecca]

A very minor point. I am not so sure the average ear can hear 16Hz but we can perceive frequencies much lower than this.

There is also the question of how much information is contained in most music/av sources other than sub-harmonics, say below 40Hz

[eviljohn2]

There is also the question of how much information is contained in most music/av sources other than sub-harmonics, say below 40Hz

What's a sub-harmonic?

[Thunder]

In answer to the original question, In my opinion a sub should ideally be able to reproduce a 20hz signal to reference levels in most rooms its placed

[Nick_UK]

That is a very vague answer, since cancellation (and addition) effects can cause huge variations in perceived levels at locations only inches apart within the room.

[Nick_UK]

Originally Posted by Londondecca

A very minor point. I am not so sure the average ear can hear 16Hz but we can perceive frequencies much lower than this.

Too true..... the resonant frequency of the stomach is around 7 to 9 Hz, any high levels of sound at these frequencies will be perceived by stomach churning and maybe even vomiting

[Grand Dizzy]

Fascinating stuff! Thanks everyone!

Nick, I've been looking for you! (Tried PMing you but couldn't.) I had a couple of questions to ask you about the Yamaha RXV640RDS (you recommended it to me ages ago). If you get the chance, could you please take a look at the thread I posted in the "Integrated Amplifiers & Receivers" forum?

[Thunder]

Originally Posted by Nick_UK

That is a very vague answer, since cancellation (and addition) effects can cause huge variations in perceived levels at locations only inches apart within the room.

The subwoofer should when placed in the optimum position (after some experimentation with a RTA) and after EQ to achieve the flatest possible response, in most rooms be able to reproduce a 20hz signal accurately.

[Ian J]

Originally Posted by Thunder

In answer to the original question, In my opinion a sub should ideally be able to reproduce a 20hz signal to reference levels in most rooms its placed

A true sub bass speaker should reproduce those type of low frequencies but the term subwoofer has now acquired a slightly different meaning as it now seems to refer to the bass part of the signal not handled by the satellite in a sub / sat setup

[Thunder]

Originally Posted by Ian J

A true sub bass speaker should reproduce those type of low frequencies but the term subwoofer has now acquired a slightly different meaning as it now seems to refer to the bass part of the signal not handled by the satellite in a sub / sat setup

Agreed Ian. there are plenty of products out there now that are called "sub-woofers" which in my opinion certainly ain't