Question about bass boost option on sound card

[J87X]

Could bass boost on my audigy 2 zs damage my swan m10s in any way? Also what should the cutoff frequency be set to? Should it be set to 42hz since that's as low as the m10s can go?

thanks

edit: Another thing, I noticed in the specs (http://www.swanspeaker.com/product/htm/view.asp?id=373) that the frequency range of the amplifier is only 100Hz-20kHz. Does this mean the sub will never go to 42hz?

[Redshirt #24]

The specs aren't written clearly (which isn't that unusual), but the subwoofer should go down to 42Hz just fine while the speakers appear to bottom out at 100Hz. So to answer your previous question: if you actually can set a cutoff frequency,you want it somewhere around the lower frequency range for the main speakers (thus 100Hz).

[skyline889]

Well first off I highly doubt the M10s can actually go down to 42hz. Many floorstanders don't even go down to 42hz, I assume the measurements are taken at something like +/- 10DB which makes the number irrelevant. Second off, unless you're blasting these speakers out to ear-bleeding levels, the bass boost feature will not damage your speakers. Finally, despite the fact that bass boost will in all likelihood not damage your speakers, I would strongly suggest against it. It'll completely distort audio and defeats the purpose of going with a better speaker system. If you wanted loud, distorted bass, you could have just gone with a set from Logitech. If you really want more low end impact use your EQ, you'll get better results.

[ourfpshero]

just try it and see if u like it. make sure the main volume on the sound card is less than 50% so no distortion is introduced. x-fis do this, and audigys might too. i keep my x-fi at 40% volume and can use bass boost no problem(to headphones anyway, speakers get overwhelmed)

[Nenu]

Its not the most straight forward topic and can be explained in easier terms with less detail.
I'll take the middle ground here and explain it a bit.

If you push your speakers hard (loud / bassy) and they are well matched in power handling to the amp ...
If the speakers can reach 42Hz (+/- 3dB), it may be better not to feed lower frequencies to them as they will still dissipate some lower frequency power (heat) in the voice coils which can be enough to turn a working speaker into an damaged speaker.
The oils that help cool the voice coils can literally cook and the speaker becomes crap even if the coil isnt burnt out.
It takes a while to elevate the coil temps enough to burn the oil so the effect isnt immediate which means you can get away with some very large instantaneous power peaks if the cone doesnt rip first !

Also the wasted power is provided by the amp which has a maximum power handling that you do not want to exceed or it will definitely distort the sound. (its more complicated than that but that will do for now)
You can kill a 250W speaker with a distorting 100W amp, so careful not to allow wasted power use and not to distort.
Pushing too much power into a speaker can make the speaker hit its end stops, either damaging the speaker cone or overheating the voice coil as no movement converts all remaining energy fed to it directly into heat!

fyi:
Distortion itself is a killer as it can cause more cone movement and produce more heat in the speaker coils and amp.
Less distortion can adversely allow a speaker to handle higher power than it is rated for.
Unless you have well chosen equipment and use it sensibly, you take a risk exceeding the power rating of a speaker.


Speakers respond to frequencies and as such they have a reactance (a form of resistance) which varies depending on the frequency.
Thus at lower frequency (below the rated F. response) they may have a higher effective resistance which some people will tell you means that the power cannot be dissipated in the speaker coil.
It helps stop the power being dissipated in the coil but doesnt stop all of it by any means as when you turn the volume up you can see the speaker respond to much lower frequencies.

This is where the soundcards bass re-direction comes in.
If enabled, this will roll off the bass (from the set frequency) so not as much is fed to your main speakers and is instead fed to the subwoofer connection.
If you are using the subwoofer/LFE channel, it is wise to use bass redirection if you love extremely high sound pressure levels.

NOTE:
Using bass boost makes the above problems harder to handle so you need to take more care when boosting bass.


Now to explain it from the other end by relating how I have set up my kit.
I'm using a 180W/ch amp with 250W main speakers and 150W centre/surrounds and 2 subs (+ LFE sofa shaker).
All my 5 main speakers get the full range of frequencies, the only cutoffs are provided by the crossovers in the speakers themselves which do not limit the lower frequencies to the bass speakers.
This can be dangerous for some speakers if driven hard for a long time and indeed at times I wonder if I am going to kill my centre speaker as the cone moves too much. My risk.
It is dangerous for the speaker so why do I do it?
For sound quality :)

I am using analogue out from my Auzentech Prelude as it sounds better so there are no amplifier DSP circuits to limit what frequencies go to each speaker.
Unfortunately the Prelude doesnt have the ability to limit frequencies fed to my centre speaker either unless I enable bass redirection to LFE which I cannot do as I am not using the LFE channel.
My LFE channel is turned off so LFE is fed to all speakers instead.
I have set it up like this because I want my front speakers to produce a lot of the bass (they are a quality bass speaker) and also my subwoofers take a direct feed from the front speaker live terminals instead of the LFE channel.
This sounds much much nicer as the sub and speakers get the same tonal and harmonic response from the main amp and the sound merges/integrates better between them.
The main amp doesnt drive the subs though, they have their own amps and convert the live speaker output to line level themselves and also control their own frequency response which I use to match them to the front speakers.

So my front speakers are powerful enough to handle the LFE effects being fed to them but my centre isnt.
If it dies I will replace it with one that has higher power handling.
(my rear surrounds get less power as they are nearer the sofa so arent pushed as hard)
Its worth noting that I do not push the amp so hard that it distorts and I have a fan drawing heat out of it so giving it a bit more breathing room when pushed hard for a long time.


I hope that helps :)
Please excuse any errors (but please do correct them), I can only read it all so many times!

[djoye]

Just to clear something up for you:

Lowpass filter = cutting off frequencies above XXHz
I'm guessing you're using the bass re-direct setting on the Audigy, that setting is to block higher frequencies from getting to the sub, I usually don't go any lower than 80Hz.

Highpass filter = cutting off the frequencies below XXHz
This is what you would apply to a speaker to block out lower frequencies (bass). You would use a high-pass filter to keep loudspeakers from becoming overpowered by bass.

Also, if those Swans plug in to the sound card using just the front speaker output (single 1/8" jack) then likely everything is handled in a single amplifier in the Swans; the Swans themselves filter the high and low frequencies appropriately. The bass re-direct option on the Sound Blaster cards then wouldn't do anything and I'd recommend leaving it turned off so the full range of audio is sent to the front speakers so the amplifier in the Swans can sort that out.

[skyline889]

Nenu, this is true if you're blasting audio however at normal listening levels, this level of distortion will not adversely affect any of the components to the point of noticeable degradation. I wouldn't do it because bass boost to me has always sounded like crap however, unless he's really pushing his speakers, they aren't going to be physically damaged at this level.

[Nenu]

Nenu, this is true if you're blasting audio however at normal listening levels, this level of distortion will not adversely affect any of the components to the point of noticeable degradation. I wouldn't do it because bass boost to me has always sounded like crap however, unless he's really pushing his speakers, they aren't going to be physically damaged at this level.

Agreed, if not pushing the speakers hard there is no problem.

[Nenu]

...
edit: Another thing, I noticed in the specs (http://www.swanspeaker.com/product/htm/view.asp?id=373) that the frequency range of the amplifier is only 100Hz-20kHz. Does this mean the sub will never go to 42hz?

That must be a misprint.