Best Sub Cutoff Freqency

[chaikovski2002]

What is the best cutoff frequency for logitech Z-680's on audigy2zs to hear that awesome oomph?

 

[Chernobyl1]

The real oomph comes from the lowest frequencies which you will always get no matter what you set the frequency to.
The reason you can adjust the upper frequency limit is because the satellite speakers dont produce much if any bass.
The idea is to match the sub to the satellites as best you can by listening for upper bass notes that arent loud enough / are too loud.
If the upper bass is too loud, it can drown out the subtle lower bass tones.

The sound from the sub will change depending on where you place it.
Bass frequencies need to set up a standing wave to amplify them so they can be heard/felt better.
Sometimes the room itself or the space between your sub and the walls/furniture can cause excess resonance (a larger or more standing wave(s)) at frequencies that arent desirable.
Moving the sub around can help amplify the lower Bass.

Placing the sub close to a wall/corner/furniture will amplify high bass not the deep bass.
As you pull the sub away from the wall/corner/furniture, the higher bass will get quieter and the lower bass will get louder.
Try it with a few of your favourite tracks and see what position suits best.

I have found that raising the Sub a centimetre or 3 off the floor can help extend the bass lower, it depends a lot on the room and the subs position.
Some rooms are hard to setup a good standing wave in and as such need a more powerful sub.
ie wooden walled rooms.
This is unfortunate but can be helped by using a Graphic Equaliser in Windows to increase lower bass frequencies loudness.
If lucky you will have a volume control on the sub too. This can help a bit but can produce a boomy effect if turned too high as your sub is designed to produce higher bass as well to match the satellite speakers.

 

[OCZSpeedJunky]

I typically always put my subs with the "port", if it;s ported, or the "driver" in a sealed unit, facing a corner. With the corner setup, every wall surface the low frequencies reflect off of will add generally +3 decibals of sound. This usually increases the entire bass frequency, not just the higher end, but all of it. And raising the speaker off the floor will actually "tighten" the sound of the unit, but won't do much as far as the volume is concerned. As far as an actual "cutoff" frequncy, most systems with sat's are designed so the sub will handle anything from 80hz on down, so typically you want to set the sub between 40 to 80 hz. From 50 to 80 hz range, you will get alot more bass guitar, etc. blended in with the bass, I personally, set mine at 40 - 42hz to limit some of the over bearing bass guitar some audio recordings have. Only problem with this is that by setting it at say 42hz, that means all sound from 43hz to 80 hz is almost missing, as most sat's produce sound from 80hz on up too 20K hz. Try starting your cutoff frequency at 80hz, then bring it down till you find a happy medium that you like. I find that setting my sub at 42hz, I get good "ooomph" without a ton of muddy bass guitar. Try that and go from there. Also, make sure to use an EQ, this will help greatly for your lowend.
Incase I missed it, what are you using for a soundcard?? Wondering as some come with EQ's, and some don't. LMK and I'll check back later.

OCZ

 

[Chernobyl1]

lol, he only asked this
"What is the best cutoff frequency for logitech Z-680's on audigy2zs to hear that awesome oomph?"

 

[killernoodle]

I typically always put my subs with the "port", if it;s ported, or the "driver" in a sealed unit, facing a corner. With the corner setup, every wall surface the low frequencies reflect off of will add generally +3 decibals of sound. This usually increases the entire bass frequency, not just the higher end, but all of it. And raising the speaker off the floor will actually "tighten" the sound of the unit, but won't do much as far as the volume is concerned. As far as an actual "cutoff" frequncy, most systems with sat's are designed so the sub will handle anything from 80hz on down, so typically you want to set the sub between 40 to 80 hz. From 50 to 80 hz range, you will get alot more bass guitar, etc. blended in with the bass, I personally, set mine at 40 - 42hz to limit some of the over bearing bass guitar some audio recordings have. Only problem with this is that by setting it at say 42hz, that means all sound from 43hz to 80 hz is almost missing, as most sat's produce sound from 80hz on up too 20K hz. Try starting your cutoff frequency at 80hz, then bring it down till you find a happy medium that you like. I find that setting my sub at 42hz, I get good "ooomph" without a ton of muddy bass guitar. Try that and go from there. Also, make sure to use an EQ, this will help greatly for your lowend.
Incase I missed it, what are you using for a soundcard?? Wondering as some come with EQ's, and some don't. LMK and I'll check back later.

OCZ

What kind of sub do you have? Isn't that basically like turning your sub off?

Set the sub to the highest frequency it will go, then adjust the crossover in your receiver. If you find the bass is too much, turn the gain down on the subwoofer. For god sakes, unless you already have huge friggin tower speakers with arrays of 8" drivers, dont turn your sub down to 40hz. You'll lose a huge chunk of your frequencies. As for the logitech speakers, you would probably be safe crossing them over at 120hz or so.

 

[phide]

With the corner setup, every wall surface the low frequencies reflect off of will add generally +3 decibals of sound.

I'm having trouble with this statement. Firstly, any reflection of a sound wave results in a loss of intensity (especially high frequencies) due to absorption of the surface (refer to absorption coefficients). I believe that a three decibel increase would entail that each surface becomes a 100% efficient transducer, which can never be the case. The sum of the room's resonances may add harmonic content, raising overall SPL at the listening position by some small degree (psychoacoustically reinforcing the fundamental), but each reflective surface certainly cannot reinforce the fundamental (harmonically or otherwise) by 3dB! By this logic, a room with four walls would reinforce low frequencies by 12dB, which is more than double the original loudness!

120Hz is the typical reference crossover point and is recommended. A good subwoofer will be neither boomy nor overpowering at this crossover point.

 

[tesfaye]

Setting the cuttoff frequency wouldn't help you get "awesome oomph". To get "awesome oomph" you need proper placement of your sub and the sub itself will need to be capable of delivering the punch that you are looking for. The fact that the sub plays loud doesn't mean it will ever be tight and punchy. Improperly placing the sub to boost the lower bass frequencies will just result in boomy bass that will obscure detail in the sound. Yeah the room might shake but you will be missing out on some of the music.

This topic has been rehashed time and time again on various A/V forums, so if you are really serious about getting the best sound out of your speakers then checkout AVS forums or Audio Asylum. You will find a TON of information on proper speaker placement techniques, calibration and proven theories. It's a good read, but be prepared to spend days getting the sound right.

 

[OCZSpeedJunky]

I'm having trouble with this statement. Firstly, any reflection of a sound wave results in a loss of intensity (especially high frequencies) due to absorption of the surface (refer to absorption coefficients). I believe that a three decibel increase would entail that each surface becomes a 100% efficient transducer, which can never be the case. The sum of the room's resonances may add harmonic content, raising overall SPL at the listening position by some small degree (psychoacoustically reinforcing the fundamental), but each reflective surface certainly cannot reinforce the fundamental (harmonically or otherwise) by 3dB! By this logic, a room with four walls would reinforce low frequencies by 12dB, which is more than double the original loudness!

120Hz is the typical reference crossover point and is recommended. A good subwoofer will be neither boomy nor overpowering at this crossover point.

First off, I see he's using the Audigy 2ZS soundcard, same one I am running, so he should have a EQ to use with the Creative Mediasource software. Be sure to use it Chai. Second, as far as placement near a corner, we are not talking about all for walls here. I am talking as within a "corner". And yes, if a sub is placed in the "corner" of a room, the walls or corner area that the lower end frequencies relfect off of WILL increase the sound by up too +3 decibels. It's a common thing most people who are familiar with using any type of sub knows. I could give you dozens of pages to read if you really want to debate it. For every wall in that general spot that the sub is sitting, you can gain as much as +3 decibels of sound from it. Keep in mind we are talking about the port(in a ported cabinet) or the driver(in a sealed cabinet) facing the wall or corner sitting maybe 12" from the wall or corner. Technically it doesn't change the frequency range in any way, all it does is give a slight decibel boost, nothing more. And yes, it will add more "boom" effect to the low frequency, but that is also very dependent on how a person has thier EQ set also.

Example, if you place a sub in a small room say 8' x 8', set the sound as you typically would, the subs sound output will appear to be louder and a bit more boomy than it would be if say you did the same thing in a wide open yard. The accoustical effects of the low end soundwaves boucing of the wall and/or ceiling is what causes that extra loudness & boomy effect.

Take a car sub for example also. If you are running say 2 -12" subs with the proper amp in a ported box in your trunk, if you face the subs so they are firing forwards, towards the front of the car, the lowend frequencies will seem much softer and actually seems to require more power to get that extra "oomph" out ot them. Now, if you take the exact same setup in your trunk, and turn the box around so the subs are firing towards the rear of the car, you will get a much louder sound with alot more "oomph". But again, this a dependent on the users amplification hardware, and the way he sets the EQ/tone controls. That extra loudness/oomph is being created because before the frequencies reach you, they are being reflected off the rear of the inside of your trunk, before firing forward into the cars seating area.

Theoretically, what he could do is attampt to setup his PC sub the same way it is recommended to setup a home sub. Since it should produce the same result. Place the sub in the general position on the floor at the approximate location of where you are sitting when you are at you PC gaming/working, whatever. Then turn on your audio, be it music or whatever you want. With the sub/system running, move around(this would be the hard part with it being a PC sub 'cuz typically most people place them under the desk somewhere), but move around, crouched down to the left and right of your desk, and if possible maybe behind it. If you can, sit on the floor under your desk in a spot where you could place the sub, but keep moving around near your desk till you find a "sweet spot" where the bass frequencies from your sub sound good and you're happy with it. Bang, move your sub to the location you were in when it sounded best, and once you actually sit back at your desk, you will have that same sound you just found by placing the sub in your seating position and moving yourself around in the area of your desk.

Typically, when setting up a home theatre system, you do the same thing, place your sub near the couch or the chair, whatever you sit in while watching tv/movies or listening to music, and fire up your sub/system. And do the exact same thing, go stand next to the tv, at either end of the entertainment system if you have one, maybe if you can stand behind the couch, where ever you want, just check out the room to see where the sub frequencies sound best while the sub is sitting generally where you would be while watching a movie or whatever. When ya find that sweet spot where the lowend sounds good, place the sub right there, go take a seat where you normally would sit, and you will still have that sweet spot sound you found before.

But, like I said, this might be kinda difficult with the PC sub, just 'cuz alot of people will typically place it under the desk or in that area, so unless you feel like crouching under your desk, or behind it, it will be hard to hear where that sweet spot may be.

But as far as cutoff frequency, I don't know where you get your info, obviously somewhere much different, but most sub sattelite systems are setup so that the sub handles all frequencies below 80hz. If you run a sub at 120hz, it will sound very muddy and hollow. Most satellites are design to run from 120hz to 20K hz. I have never, ever seen a person in my life, be it home audio, car audio, PC, whatever, set a sub to handle frequencies from 120hz on down. That hurts the low frequencies the sub produces quite drastically. I only set my sub to take on frequencies from 42hz or so on down because I hate those certain songs that have ungodly overbearing bass guitar in them, and it's much easier to simply bring up a band on the EQ to add that slight bass guitar than it is to continually adjust the sub cutoff all the time.

As far as what I am currently running, my sub is a 8" with RMS power of 100w, and my satellites are 20w RMS each designed with a "ribbon transducer", not a typical driver, which also makes them bipole, firing sound to the front and the rear. The model is Monsoon Planar Media14, which obviously last I heard monsoon is no longer in the PC sound biz unfortunately. But the design of my satellites actually cover a very wide frequecny range than does a typical driver, so I am really not missing much by setting my sybs cutoof down at 42hz. I do still use my 10 or 12 band EQ that is with the soundcard, but I tend to use that more to "enforce" that "ooomph" he is talking about and looking for. But, as you more or less said, that "oomph" may or may not be obtainable with all subs, 'cuz it depends on the subs size, RMS rated power, frequency rating, several different things. So he may try and try all night long to get that enforced "oomph" out of the sub, and just never get it due to lack of power, or not a big enough driver. A lot of things can affect it.

At any rate, placing the sub firing towards a corner will increase the decibel by about +3, I've done it for years, and seen it done plenty more. If ya want, I will get you plenty to read on this to explain the effect more. Of, if you live in the area, stop on over and I'll show you.

Anyway, Chai, be sure to properly get your sub positioned, and use the EQ that is with the Creative Mediasource software to control the frequencies. Also in the software, under you "speaker settings", you shoulfd have a "bass boost" tab, go in there and enable it, and try your boost set at either the +20 or +30 setting, see how that works.

Anyway, I'm done, I'm going to bed. I'll check tomorrow to see if you want some literature to read on subwoofer placement and whether or not placing a sub near a corner will make a difference.

Yap atcha then.

OCZ

 

[phide]

Shoot 'em over. Always interested in a bit of audio readins'.

It just seems that 3dB would be a highly exaggerated, attypical figure. The length of low frequency wavelengths wouldn't explain how propogation of the fundamental would be reinforced by such a large margin by a wall of studs of sheetrock. Even factoring in the contribution of the walls in the tramsmission of acoustical energy (in which low frequency waveforms tend to contribute a great deal), 3dB seems massive. Psychoacoustically, I could see a large increase due to whole-octave and sub-octave harmonics reinforcing the fundamental.

But, like I said, throw up some links or what have you to the literature and I'll read through them, for I am never one to turn down an education.

 

[OCZSpeedJunky]

Shoot 'em over. Always interested in a bit of audio readins'.

It just seems that 3dB would be a highly exaggerated, attypical figure. The length of low frequency wavelengths wouldn't explain how propogation of the fundamental would be reinforced by such a large margin by a wall of studs of sheetrock. Even factoring in the contribution of the walls in the tramsmission of acoustical energy (in which low frequency waveforms tend to contribute a great deal), 3dB seems massive. Psychoacoustically, I could see a large increase due to whole-octave and sub-octave harmonics reinforcing the fundamental.

But, like I said, throw up some links or what have you to the literature and I'll read through them, for I am never one to turn down an education.

No problem, I'll grab a few for ya later tonight. But don't get me wrong, I see your point. I had always thought the same exact way, "how the hell can placingthe sub in the corner or facing near the wall have an effect of possibly gaing as much as +3db", till I actually tried it, and it does actually give a slight decibel boost. Believe me, I was skeptical as hell too, thought people suggesting this were just plain whacked or bored lol. But it does help. Doesn't necessarly "change" the octave or frequency of the lowend sound waves, what it really does is just boost the decibels. There's tons of other crap we could sit and discuss too that will also effect the sound, but that would take awhile, lol. But at any rate, I'll either grab some info for ya later tonight, or this weekend when I have more free time. Either way, I'll get'm up for ya and whomever else to read. Later.

OCZ

 

[MetalDwarf]

the sub in the corner thing

its true it works Ive done this on many occasions

the general idea is that tweeters and high frequencies are very directional. they only go in the direction they are pointing. bass frequencies radiate all directions. so by placing the sub in the corner you are putting it in "quarter space" the same sound energy is bouncing off the floor and side walls reflecting back into the room. this gives the +3db boost. ofcourse walls will absorbe some sound, but much is still reflected. higher frequencies will be absorbed more so you get added "oomph" since bass sounds will not be absorbed as much.


one of the times i used this trick was when i worked as a sound tech on a cruise line. we were having a crew party and there wasent enough bass on the crew deck (small deck on the very front nose of the ship) so i draged out an old single 18" sub and amp. on the deck it didnt add too much. but on deck there was an empty pool dropping the sub into the corner of the pool created a HUGE boost in bass energy. so the one wussy 18" sub rattled the whole crew deck.

sound quality was ass but the DJs were terrible and apparently dont know that the big red clip light is a bad thing...

so to sum up. sub in corner = louder but worse sound quality

 

[Chernobyl1]

It wont necesarily give worse sound quality, it needs placing where it suits the room best.
A subwoofer relies on the fact that walls reflect sound to set up a standing wave between the sub and the wall.

Sounds at the same frequency as the standing wave and near the frequency will get a nice boost, as will double, quadruple the frequency of the standing wave, each reducing its added gain by half. Of course, only those frequencies emitted by the sub will matter.

By placing the sub equidistant from both walls in the corner, the frequencies around 1 standing wave frequency will be boosted a lot but if you place the sub at different distances from both walls, you can give a broader spread of bass frequencies that get boosted by creating 2 standing waves.
The closer to the wall the sub is, the higher the frequency of the standing wave.
By the same tune, the further away the sub is from the wall, the lower the frequency of the standing wave.

Pulling the sub too far from the wall will drop bass off dramatically as the standing wave frequency will go below the response of the sub.
By moving the sub back towards the wall a little, you will find the distance you need to boost the lowest frequencies.
As most subs arent square with the cone in the centre, this measurement could well be slightly different for each side of the sub so each will need its own test.


An earlier poster mentioned a very good way of getting near the optimal position for your sub by first placing the sub where you intend to sit.
Walk round the room and see where the bass gives the most satisfying sound.
You should notice some quite dramatic differences in the feel and sound of the bass as you walk around.
Once you have found the best sounding spot, put your sub there, adjust to get optimal results.

If you arent satisfied with the bass anywhere, try placing the sub in a different place where you can also sit and repeat the above.

 

[Fryguy8]

80 is the THX standard, and it should probably be lower than this.

 

[OCZSpeedJunky]

Here ya go. Here are 4 very good guides/articles discussing subwoofer placement, the effect of corner/wall placement, and the proper cutoff frequency. You will find all the information you'll ever need here to back up what I was saying. Enjoy.

http://www.guidetohometheater.com/howto/805bass/index.html

http://www.sonicdesign.se/subplace.html

http://www.audiodesignlabs.com/product_5.html

http://www.audioholics.com/techtips/setup/loudspeakers/subwooferplacementguide.php

 

[OCZSpeedJunky]

And thanks for slightly backing up what I was saying also there MetalDwarf & FryGuy. Atleast someone knows what the heck I'm trying to expain lol

 

[ironforge]

Here is the quick version.

Move the sub around until you find where it sounds "loudest". Then play some music, etc and just adjust the crossover until it sounds good. I wouldn't break out the calculus book for what you are trying to do.

 

[OCZSpeedJunky]

Here is the quick version.

Move the sub around until you find where it sounds "loudest". Then play some music, etc and just adjust the crossover until it sounds good. I wouldn't break out the calculus book for what you are trying to do.

What the hell do ya think I already explained a couple posts above. Jeez...read ppl...lol

 

[texuspete00]

Alright dude. Claps to you already!



Honestly though thanks for the links.

 

[Omegaslast]

did you guys read his post!?

he has z680s

the amp has a 120hz crossover built into it

they will always sound boomy even if he places the damn sub on an anti gravity platform

 

[OCZSpeedJunky]

Alright dude. Claps to you already!



Honestly though thanks for the links.

Bite me TXPete lol..j/k And hey, np. I spend plenty of time reading up on crap, so I have plenty of links for info lol. Gotta kill bordem somehow.

And as far as his Z680's, if they already have a built in active 120hz x'over, he should still be able, if he drops the cutoff frequency in his Audigy software, be able to still drop the frequency via the software below 80hz. Naturally ALL sub/satellite setups have a built-in x'over in them, typically 80 - 120hz, some rare few may even have an adjustable one ranging from 50-120hz, but if he still sets his cutoff in the software to 80hz or a little below, he will be fine. Normally, the sub takes anything from 80hz down, and the sats from 80hz on up, the only reason they set the sub x'over at 120hz is to overlap the frequency range so the satellites don't appear to be missing any midrange frequency. At any rate, he'll still be good dropping it with the soundcards software, I have mine set just fine. But even with adjusting the cutoff with his soundcard, what is really going to make a difference too is getting his EQ set properly. He can play with the x'over and cutoff frequency all day if he wants, but it won't do what he wants if he doesn't have the EQ set good. Plain and simple. He just needs to take the time to do alot of tweaking and testing to get it where he wants it.

OCZ

 

[azulcorvette]

First off, with small satilites, you must have a 120 Hz cutoff point otherwise you'll have a lack of sound from the 120 Hz down to where ever you put the cutoff at.

As for the most optimal cutoff, the THX standard likes it at 80 Hz, which is what I run it at when I use bookshelves or floorstanding speakers and my subwoofer.

If you have large front speakers, then you can put your cutoff lower, but if you have "small" front speakers (smaller than 5" woofers) then you better have it at 120 Hz. If you have a 6.5 inch woofer then you could probably go down to 80 Hz like me.

But to answer this thread, follow what the others say and put it at 120 Hz until you get better speakers. You'll always get an annoying boomy noise when you put the cutoff high at 120 Hz.

 

[Team Obi Juan]

Yep, software crossover is not needed when there's one in the amp on the sub anyway. Put your crossover as low as it'll go and let the speaker system do the rest.

 

[OCZSpeedJunky]

Well, however he wants to set it, either way will be fine. Mater of personal preference and what his taste is in sound. At any rate, No point in debating this for weeks on end. Some prefer 120hz, some prefer 80hz and even the Lucas Films THX standard is 80hz, so, you decide which is better. Personally, to me and how I like things set, be it my PC, home audio, car audio, or Prefessional equiptment, 80hz is always the starting point, and setting the cutoff at 120hz creates an incredible amount of muddy, flat bass. But, that's just my preference. Maybe some people just need to be better educated in audio. But, it all boils down to preference. Later.

OCZ

 

[Omegaslast]

well it doesnt matter anyways because the Z680s crossover CANNOT BE SET LOWER than 120hz

 

[phide]

well it doesnt matter anyways because the Z680s crossover CANNOT BE SET LOWER than 120hz

 

[Chernobyl1]

The Windows bass settings have no control over the subwoofers cutoff frequency.
Use the windows settings to fine tune once the sub is setup.

 

[Team Obi Juan]

http://img224.imageshack.us/img224/3499/cutoffjk0.jpg

Dude, tweak it all you want in that little Creative console... the crossover is physically set up not to go below 120hz on the actual amp. Amp crossover is higher in the chain of command than the signal sent to it. Whatever the signal, it's not going below 120... you CAN make it cut off HIGHER than 120.

 

[azulcorvette]

Dude, tweak it all you want in that little Creative console... the crossover is physically set up not to go below 120hz on the actual amp. Amp crossover is higher in the chain of command than the signal sent to it. Whatever the signal, it's not going below 120... you CAN make it cut off HIGHER than 120.

Point is leave it at 120. Don't put it any higher than 120, and if you put it any lower then you will be lacking sound. Just get better speakers if you want something other than a 120 Hz crossover.

 

[Omegaslast]

phide isnt the OP, hes just someone that doesnt know what "built in crossover" means when it comes to subwoofers..

 

[OCZSpeedJunky]

Dude, tweak it all you want in that little Creative console... the crossover is physically set up not to go below 120hz on the actual amp. Amp crossover is higher in the chain of command than the signal sent to it. Whatever the signal, it's not going below 120... you CAN make it cut off HIGHER than 120.

You may want to rethink this post. My sub has a built in Active 200hz crossover, and yes, using software, I have the cutoff set much lower than that. I can see exactly how you are looking at this, so you may want to think about your comment, and possibly do a bit more reading. Just some advice. Also, whether the system has an active or passive crossover will make a difference.

OCZ

 

[phide]

phide isnt the OP, hes just someone that doesnt know what "built in crossover" means when it comes to subwoofers..

Please. Consider the audio chain, consider the fact that I've used the Logitech Z-680s along with an Audigy 2ZS previously, and then reconsider your opinions of me.

There is a hint I can give you, as you may find it necessary: the crossover acts on the input.

 

[OCZSpeedJunky]

Please. Consider the audio chain, consider the fact that I've used the Logitech Z-680s along with an Audigy 2ZS previously, and then reconsider your opinions of me.

There is a hint I can give you, as you may find it necessary: the crossover acts on the input.

Precisely. And depending on whether it is an Active or a Passive crossover, also plays a role in how it works within the system setup. I am thinking that what alot of these people are believing, is that once that 120hz crossover is put in that sub, then that is where that frequency is set in stone to stay at, which isn't true. An Active crossover is going to have totally different characteristics than a Passive one, which is another thing I don't think any of them understand. Some of these people just need to educate themselves a bit more before they use thier brains to make an ignorant post. As I'm sure you know, anyone with a decent amount of audio knowledge, should know how a crossover actually completely works within the system. And how an Active one will work compared to a Passive one. At any rate, I got things to go do. We'll see what the next uneducated post is I guess. Later.

OCZ

P.S. And just so ya don't take this post wrong, nothing is directed towards you, just at a couple other people who seem to not understand how things actually work.

 

[Team Obi Juan]

You may want to rethink this post. My sub has a built in Active 200hz crossover, and yes, using software, I have the cutoff set much lower than that. I can see exactly how you are looking at this, so you may want to think about your comment, and possibly do a bit more reading. Just some advice. Also, whether the system has an active or passive crossover will make a difference.

OCZ

Do explain. I'm not being a smartass at all, I legitimately want to know.

If the amp that's built into the speaker system is a passive crossover, you can manipulate your software to effectively bypass that "hardware" crossover?

But if it's an active crossover, it can't be bypassed?

Do I have that backwards?

 

[Fryguy8]

If you have a 200hz lowpass crossover, and you set a 100hz lowpass crossover, except for some minimally effected frequency response differences in the 200+ range, you have the same thing as a 100hz crossover.

It's not "bypassing" the crossover.

 

[Omegaslast]

If you have a 200hz lowpass crossover, and you set a 100hz lowpass crossover, except for some minimally effected frequency response differences in the 200+ range, you have the same thing as a 100hz crossover.

It's not "bypassing" the crossover.

please put it into the terms of a z680 setup

you set the crossover at 100hz on an audigy 2, so the audigy 2 is sending out 100hz to the sub and 100+hz to the speakers. What stops the z680s amp saying "yeah i see your 100hz, but it doesnt matter, im sending everything below 120hz to my sub, and everything above that to my speakers"

 

[Chernobyl1]

You are feeding discrete channels to the amplifier, the amplifier doesnt mix the channels together (unless you are using a pseudo surround mode), it amplifies the signals and sends them to the speakers.

The crossover for the Z680's sub will reject frequencies above its cutoff (120Hz in this case).
The satellites wont respond (at volume) to frequencies below the cones lowest operating frequency which is likely to be somewhere around 100Hz. They may also have a high pass filter to prevent frequencies below around 120Hz getting to the cones. Either way, the effect is the same.
You wont know exactly what they will respond to until you test them.

If you set the Audigy crossover so the sub gets 100Hz and below , the satellites will need to be able to respond to frequencies from 100Hz up or there will be a hole in the sound.
Try and see what sound you prefer.

 

[Omegaslast]

You are feeding discrete channels to the amplifier, the amplifier doesnt mix the channels together (unless you are using a pseudo surround mode), it amplifies the signals and sends them to the speakers.

The crossover for the Z680's sub will reject frequencies above its cutoff (120Hz in this case).
The satellites wont respond (at volume) to frequencies below the cones lowest operating frequency which is likely to be somewhere around 100Hz. They may also have a high pass filter to prevent frequencies below around 120Hz getting to the cones. Either way, the effect is the same.
You wont know exactly what they will respond to until you test them.

If you set the Audigy crossover so the sub gets 100Hz and below , the satellites will need to be able to respond to frequencies from 100Hz up or there will be a hole in the sound.
Try and see what sound you prefer.

i understand gaps in sound, and im willing to bet the z680s satellites dont quite reach down to 100hz without dropping off an outrageous amount of decibels...

but lets say they reached well down to 80hz or something

you set the crossover on the audigy 2 to 100hz, im pretty sure that high pass filter will not *allow* the 100hz-120hz to even go to the satellites, so you basically have that entire range missing.

which brings up the point, sure you can send 100hz and below signals to the sub and "bypass" the built in crossover, but you still arent covering 100-120hz, which means you gotta leave it at 120hz anyways.

 

[phide]

One thing to keep in mind when you're discussing cutoffs is that they aren't brick walls. In fact, "cutoff" is a bit of a misnomer, because what is actually occuring is "rolloff" (in our case, a high pass filter). The typical rolloff is second order, which means that rolloff is 12dB per octave, unless it's adjustable. So, with the filter set at 120Hz, 120Hz will be -3dB, 240Hz will be -15dB and 480Hz will be -27dB. -3dB at 120Hz is important, as the summing of two signals at identical voltages will cause a signal gain of 3dB. So, there are no hard "gaps" in the output, only bands of varying amplitude.

I would peg the Z-680 satellites at somewhere around 85-90Hz at -3dB, which isn't horrid. I still wouldn't advise that anyone actually dick around with the bass cutoff in the drivers, but it can be done, with varying degrees of results.

 

[Chernobyl1]

One thing to keep in mind when you're discussing cutoffs is that they aren't brick walls. In fact, "cutoff" is a bit of a misnomer, because what is actually occuring is "rolloff" (in our case, a high pass filter). The typical rolloff is second order, which means that rolloff is 12dB per octave, unless it's adjustable. So, with the filter set at 120Hz, 120Hz will be -3dB, 240Hz will be -15dB and 480Hz will be -27dB. -3dB at 120Hz is important, as the summing of two signals at identical voltages will cause a signal gain of 3dB. So, there are no hard "gaps" in the output, only bands of varying amplitude.

I would peg the Z-680 satellites at somewhere around 85-90Hz at -3dB, which isn't horrid. I still wouldn't advise that anyone actually dick around with the bass cutoff in the drivers, but it can be done, with varying degrees of results.

Dont worry I'm fully aware of this, I was trying to keep some technical detail out.
I tried to stress in the following quote from my earlier post that speaker response after the cutoff frequency is largely diminished:
"The satellites wont respond (at volume) to frequencies below the cones lowest operating frequency..."

Which filter type(s) have you assumed is in use?
Without seeing the circuit(s) for the crossover(s) its not possible from here to determine the type of the filter nor the order of the filter.
You have assumed the satellite speaker specification reports the cutoffs as -3dB points, this is not always the case. Many manufacturers specify -6dB (or other) points to make it look like the speaker has an extended response.

There is no way we can know what the response of the satellites will be, given that we dont know the speakers -3dB point, the filters zero attentuation point, the filters -3dB point, the type of filter in use and the order of the filter.
We also know nothing of the Low Pass filter used on the sub other than its cutoff is specified as 120Hz. Is this its -3dB point or something else?
Again we dont know the sub speakers -3dB high cutoff, the filters zero attenuation point, the filters -3dB point, the type of filter and the order of the filter.

This is why I suggested he try to see how low the satellites can respond without leaving a hole in the sound

 

[Chernobyl1]

i understand gaps in sound, and im willing to bet the z680s satellites dont quite reach down to 100hz without dropping off an outrageous amount of decibels...

but lets say they reached well down to 80hz or something

you set the crossover on the audigy 2 to 100hz, im pretty sure that high pass filter will not *allow* the 100hz-120hz to even go to the satellites, so you basically have that entire range missing.

which brings up the point, sure you can send 100hz and below signals to the sub and "bypass" the built in crossover, but you still arent covering 100-120hz, which means you gotta leave it at 120hz anyways.

My point was meant for the OP really.
It is unknown what the low response of the satellites will be, so its also unknown if settings the subs cutoff to 100Hz will cause a gap in the sound.
The OP needs to try and see.