Crossover in 2.1 set up

[droht]

I've been setting my sub to cross at 80Hz in my 2.1 system. At that point the music is completely seemless. Is there a magic # for crossover where you expect to notice that sound is coming from sub? I can't easily test because I do not have bass management in this set up. I am thinking about picking up some smaller speakers that only go down to 110 or so, but I am hesitant because of this question. Current speakers go down to at least 70 I think. Any thoughts would be appreciated!

Thanks.

[dweekie]

It will vary a bit based on a few factors (your ears, crossover settings), although 80hz seems to be the often quoted number. How about a 2.2 setup. Then it shouldn't matter as much :whoopie:

[droht]

It will vary a bit based on a few factors (your ears, crossover settings), although 80hz seems to be the often quoted number. How about a 2.2 setup. Then it shouldn't matter as much :whoopie:

You're killing me man, but you knew that already...:yes:

Space is definitely at a premium, and sub placement is fairly limited. This is my office. I had sub under my desk, but that didn't work. It is now right next to my chair, which is fine. Don't have lots of other options though. Someone needs to make a nice 10 incher with a built in file drawer. I'd could drop one of those on either side of my desk and be set. If only I was a DIYer...

[dvenardos]

I wouldn't think that would be too difficult, just build the file drawer glue it to the top of the sub and finish as one unit.

Space is definitely at a premium, and sub placement is fairly limited. This is my office. I had sub under my desk, but that didn't work. It is now right next to my chair, which is fine. Don't have lots of other options though. Someone needs to make a nice 10 incher with a built in file drawer. I'd could drop one of those on either side of my desk and be set. If only I was a DIYer...

[Jethro]

just make sure to use acoustic glue :rock:

[mojave]

This file drawer looks easy enough. :D

[gonk]

80Hz is the THX standard. That was the basis for design of THX-certified speakers and subwoofers. As such, it's pretty commonly used.

Do you know what the rated -3dB point is for your speakers? If you want to set a crossover specifically for your system, this is probably the first thing you need. If the -3dB point is 70Hz, you should probably stay with 80Hz as a crossover or even go a bit higher (maybe 100Hz). If the -3dB point is something like 40Hz, then you could move to a 60Hz crossover. One approach I've heard before is to take the -3dB point for the speaker and set the crossover one octave higher (which would mean doubling the -3dB point, or using an 80Hz crossover for a speaker with a -3dB point of 40Hz). I've often used a less conservative approach and stepped up at least 10 or 15Hz to establish a lower limit for my crossover point, then tweaked from there to get the sound I like best.

[Chane M&C]

Something I don't personally understand with regards to these types of discussions...

It seems to me that you can go through this exercise using a little bit of math use the following considerations:

- high pass crossover point
- high pass crossover slope
- low pass crossover point
- low pass crossover slope
- room gain

or

you can say that whatever the math says, all that matters is what I hear. In which case, you use your ears to determine the best settings.

In most discussions that include the "little bit of math", people always talk about crossover points but rarely talk about crossover slope. I would think that a speaker being -6db at 80hz is far different than a speaker being -24db at 80hz.

What gives?

One other point - does anyone know if crossover alignment is applicable to electronic crossovers? It seems that for passive crossovers, a 2nd order butterworth is different than a 2nd order Linkwitz-Riley. I think one results in flat response at the crossover point whereas the other results in a "bump" at the crossover point (assuming no room gain or any other external factors).

[dweekie]

Something I don't personally understand with regards to these types of discussions...

It seems to me that you can go through this exercise using a little bit of math use the following considerations:

- high pass crossover point
- high pass crossover slope
- low pass crossover point
- low pass crossover slope
- room gain

or

you can say that whatever the math says, all that matters is what I hear. In which case, you use your ears to determine the best settings.

In most discussions that include the "little bit of math", people always talk about crossover points but rarely talk about crossover slope. I would think that a speaker being -6db at 80hz is far different than a speaker being -24db at 80hz.

What gives?

One other point - does anyone know if crossover alignment is applicable to electronic crossovers? It seems that for passive crossovers, a 2nd order butterworth is different than a 2nd order Linkwitz-Riley. I think one results in flat response at the crossover point whereas the other results in a "bump" at the crossover point (assuming no room gain or any other external factors).

I think you are touching on something a bit more complicated than the usual methods to add a subwoofer to bookshelves. Many use the natural rolloff of the speakers and the built in crossover slope of the subwoofer amp. Another option is to use a receiver that has built in slopes that are fixed for both high and low pass. Adjustability of slopes never really applies in these cases, so simply using your ears works out well.

Configuring a passive or active crossover requires knowledge of the points you brought up, and I don't think many people choose to spend the extra time and money into setting up anything complicated. It also seems to depend on what frequency range you are referring to. I think you won't find too much discussion on the various types of crossovers utilized for subwoofer integration since it's usually fixed in most systems, whereas talk of the crossovers in loudspeakers are heavily oriented towards slopes since the effects are greater. The interaction between a tweeter and midwoofer is absolutely critical, while the subwoofer crossover seems to work okay with generic profiles that you find in receivers and subwoofers. Well, that's what my ears tell me anyway.

[Chane M&C]

I think you are touching on something a bit more complicated than the usual methods to add a subwoofer to bookshelves. Many use the natural rolloff of the speakers and the built in crossover slope of the subwoofer amp. Another option is to use a receiver that has built in slopes that are fixed for both high and low pass. Adjustability of slopes never really applies in these cases, so simply using your ears works out well.

Configuring a passive or active crossover requires knowledge of the points you brought up, and I don't think many people choose to spend the extra time and money into setting up anything complicated. It also seems to depend on what frequency range you are referring to. I think you won't find too much discussion on the various types of crossovers utilized for subwoofer integration since it's usually fixed in most systems, whereas talk of the crossovers in loudspeakers are heavily oriented towards slopes since the effects are greater. The interaction between a tweeter and midwoofer is absolutely critical, while the subwoofer crossover seems to work okay with generic profiles that you find in receivers and subwoofers. Well, that's what my ears tell me anyway.

I totally get that people don't need anything complex to integrate subs to a set of bookshelf speakers. And in fact, I personally prefer less complexity also.

I guess what I was getting at is that using your ears to fine tune your system is perfectly fine. In this case, what difference does it make whether the dial points to 80 or 120? And what would be the point of comparing numbers when everyone's ears and preferences are different, let alone the components they are using?

It's just that I find it weird to talk about crossover frequencies (even for just subs) without at least raising the point about the crossover slope. They seem like they go hand and hand. Take the same subwoofer change the crossover slope on it without touching the crossover frequency - the sub sounds completely different.

[droht]

The reason I am asking about #s is that I am thinking about buying a pair of speakers that only go down to ~ 110, as I said in the original post. I'm more than happy to tune by ear, but I'd rather avoid the purchase if the result is localized bass.

[Chane M&C]

The reason I am asking about #s is that I am thinking about buying a pair of speakers that only go down to ~ 110, as I said in the original post. I'm more than happy to tune by ear, but I'd rather avoid the purchase if the result is localized bass.

I personally am not the person to give "advice" on this, I am sure there are many who could steer you better..

One thing that is not clear is, how did you determine that the new speakers will only go down to ~110 hz? Is that the tuning frequency of the box or something?

[gonk]

(I'm avoiding work - got to pull together documentation for a building energy model...)

He's likely reading the manufacturer's specifications, which will provide a frequency response. If it said something like 110Hz-20,000Hz +/-3dB, then the speakers would need to be paired with a sub and the bass management would need to cross the speakers over to the sub at above 110Hz.

[m-fine]

The reason I am asking about #s is that I am thinking about buying a pair of speakers that only go down to ~ 110, as I said in the original post. I'm more than happy to tune by ear, but I'd rather avoid the purchase if the result is localized bass.

If the sub is up front, between the mains and relatively equidistant to the listening spot, I would expect you would not notice localization with the XO set at 110 to 120 hz. If the sub is not near the mains or at a different angle, I would at least be concerned about it, but it depends on a number of factors so it is impossible for anyone to really answer for your situation.

Also, when you say the speakers go down to 110 hz, at what SPL is that? It is not unusual for the -3 db point to creep up with volume levels as a small driver simply runs out of displacement. That is one of the reasons for the rule of thumb to put the XO a full octave above the -3db point when you have both a HP and a LP such as on a receiver with an LFE out. If you want to push the volume up, you may find you are getting a mid bass hole and then you will want to up the XO to fill it in, but that could put you too high where you can localize or above where your sub is capable of performing well. I can not imagine you being happy with a XO at 220 in most situations.

[droht]

I'm considering the Aperion Intimus 4Bs. They do have the whole risk free trial thing, so I can try them out. I just want to skip the hassle if the bass will obviously be an issue. Doesn't sound like that is the case, so they are probably worth trying. Thanks for the feedback.

Mfg specs:
Frequency Response (+/- 3dB) 120-20,000 Hz
(+/- 6dB) 100-22,000 Hz
Impedance 8 Ohms
Sensitivity 84 dB
Recommended Power 50-150 watts
Amplifier Power
Tweeter 1" Audiophile-grade Silk-Dome Tweeter
Midrange
Woofer 4" Woven-Fiberglass Composite Woofer
Driver Configuration 2-Way
Enclosure Type 3/4" HDF, sealed
Dimensions 8.75" H x 5.33" W x 5.5" D
Weight 6.5 lbs