Bass Management Basics – Settings Made Simple

[Audioholics]

Our latest article: "Bass Management (over)Simplified, Setting the Right Crossover, Size and Delay for Your Home Theater Speakers" is a guide designed to address the numerous questions we receive from new home theater owners who purchase a new system component and don’t quite understand the How’s and Why’s of bass management.

More advanced home theater folks may wish to peruse our more in-depth guides available on the site that give a more thorough explanation of this complex and often misunderstood topic.

For those of you just wanting to simplify the process of setting up a new receiver and understanding all of the hoopla about crossovers, Large and Small speakers, and delay settings... read on!

[Read the Article]

 

[Bobster]

Clint,

I enjoyed the article, but it brings me back to the question I've had for a long time...

My speakers frequency response is as follows:

Fronts: 30Hz - 22KHz
Rears: 45Hz - 22KHz
Center: 80Hz - 20Khz

I'm currently running them all as small with the crossover set to 80Hz. Is that the best fit? Or, should I bump the crossover to a higher (or lower) point?

In other words, is the center channel's relatively high dropoff point, which happens to fall at exactly the set crossover point; an issue that needs to be addressed by changing the setting?

My processer allows me to adjust the crossover in 10dB increments in a range of 40Hz to 120Hz.

Thanks!

 

[shokhead]

I'd play with 80 or 60.

 

[Bobster]

That's exactly my point. My center channel is rated down to 80Hz (+/-3dB).

From a bass management perspective, do I need to compensate for the center channel's frequency response by raising the processor's crossover to 90Hz or higher, or is it only important for the front channels?

Seems to me, if I have to compensate for the 80 Hz -3dB worst case for my center channel, my crossover should run at 90Hz or possibly 100Hz to provide some "legroom".

I'm currently running the crossover @ 80Hz but don't have a problem adjusting if it's the right thing to do.

"Things that make you go hmmmm"

 

[shokhead]

I wouldnt go more then 80 and try 60 and see how it is for awhile.

 

[Takeereasy]

Nice article, thanks. I need to get home and set my fronts to small!

 

[gene]

Unless your processor has independent crossover settings for channel pairs, and properly integrates the bass back into the sub, set the xover no lower than the 3dB point of the speakers in your system with the weakest bass response. In this case your center channel. Its imperative to get the bass integration between the center channel and sub correct as you will see in up and coming articles we are writing. Just b/c your main speakers are speced down to 30Hz doesn't mean they have a great deal of linearity down that low, especially when pushed hard. Most decent subs will handle that bass information better and you wont have to worry as much about path differences between multiple sources of bass and the listener. I am now a firm believe that in most cases all speakers should be set to small and the xover point of 80Hz is usually the best starting point!

 

[Bobster]

Hi Gene

Just b/c your main speakers are speced down to 30Hz doesn't mean they have a great deal of linearity down that low, especially when pushed hard.

So, does the linearity issue apply to any speaker's frequency response range? A 3dB point of 80Hz for this particular center channel speaker puts it's 3dB point right on the processor's 80Hz crossover.

To me, since my processor sets a single crossover frequency for all speakers, this implies that in the interest of sonic fidelity (and the center channel's linearity), that I might need to use a 90Hz crossover setting.

What's your opinion?

 

[galaxian]

Great article. I have one question though. I have set all my speakers to large in 6.1 setup. The reason being:

1. All of my speakers are running on power amps so my AVR is not being taxed by this setting.

2. My AVR has a sub setting called "max". What that means is that is frequency lower than crossover is sent both to large speakers and the sub.

3. I don't play at extremely loud levels (my reference is about 70 dB and I don't go substantially louder than that) and I have not heard any distortion yet from my rear center which is the weakest link with freq response at 70dB +/-3dB.

Is there still any reason for me to set my speakers to small, and if so should it be all of them (my mains has 39dB, rears 49dB and front center 60dB). A couple of things I have read to still set my speakers to small are:

1. Well if by some chance you were able to get your main speakers bass extension flat down to 20Hz, then adding the subwoofer on top of that would yield too much (up to 6dB) of bass output at the frequencies both are producing. Hence integration between the loudspeakers and subwoofer will be poor and the bass may be overpowering, sloppy and/or boomy. (From the article)

So from this I reckon if the bass does not sound boomy or overpowering this concern is not applicable to a setup.

2. The sub might have phase issues with the sub. From page 8 of the SVS PCUltra sub:

Phase. Think of bass waves as conflicting or enhancing each other, depending on the timing of their arrival at your listening location (either together, or not). Since some of your room’s bass might come from main, center and/or surround speakers, as well as your sub, getting these bass waves to arrive in a complementary, enhancing fashion is the difficult job of the phase knob. Essentially, this control varies the timing of the bass waves coming from the sub. The effect of bass cancellation will vary by volume and frequency in your room, and no one setting is likely to ever be “perfect”. One technique to optimize phase is to find a nice “bassy” loop (such as the menu of “Godzilla”) measuring its bass response at various SPL peaks. As the loop runs, vary the phase knob. Where you see the most response on a given bass passage is the phase setting providing the least bass cancellation in your room (for the frequencies of the demo loop you chose). Adjusting phase is mostly a concern in dual sub configurations or systems with “Large” mains.

Nice suggestion but my current sub has no phase knob or control. The only thing it has for phase is normal or reverse which I have absolutely no idea about what it is

Can anyone think of any other reason or problem with setting speakers to large?

cheers,

galaxian

 

[shokhead]

99 out of 100 will tell you to set them all to small unless your front mains are bass capable. I had to look high and low to see how low was meant by bass capable. I figured 30Hz or so. Nope,it was 20 so being that its 20,i can see why 99 out of 100 set them to small as there's very few with that kinda bass capable speakers. Having said that,if you watch very few DVD's and when you do you play it low and mostly listen to 2 channel music and not loud,set them to lg but whatever you do,play around and listen. Imo,a sub is meant to be played loud,at least 95-100db,but thats me.

 

[MDS]

Even if your mains are capable of playing pretty low, there is still a good reason to set them to Small.

The bass frequencies take the most power to reproduce correctly. Setting the speakers to Small relieves your amplifier of the duty of amplifying all of those low frequencies and puts the burden on the sub which is designed to do just that. So your mains won't have to work as hard and you may get increased clarity in the mid and high range and a higher overall SPL out of the whole system.

But...try it and see which you prefer.

 

[kaos]

this article is exactly what i needed!

but i'm still not too sure about what to set the crossover to.

all 6 of my speakers go equally low to 55hz so what should i set the sub to? right now i've got it at 80 but if it sounds better and is the right thing to do at 70 or 60 then i'll certainly adjust it.

also, how loud should my subwoofer be in comparison to the speakers? when using the spl meter should i treat it as a speaker and get it as close as possible to matching the rest of the system in volume or do i want it to be a few decibels higher? it would seem like it's a personal preference issue but any advice?

 

[howie85]

Where to go from here?

I am wondering now about my possible future upgrades. I have been drooling over the Axiom mt80i since first reading the reviews here, but after learning more on bass managment im wondering if i should be looking at a speaker system that has approximately the same -3db hz rating. It could be said that having large towers up front that can play to 35hz and then smaller surrounds that cant go past 60 or 80hz would be a waste of speaker potential for someone who likes HT more than music or even mulitchannel music for that matter. If setting the crossover for the sub so you can get the most of your speakers at say 40hz for the fronts would be over driving the surrounds and 80hz for the rears would be wasting the potential of the front towers. I guess having different settings for the fronts and rears would solve that or smaller fronts or larger rears. Are there any AV units on the market that have the ability to set the bass managment differently for different speakers? Im just thinking out loud here that it could be money saved on getting speakers closer matched or a Pre Pro that can handle different size speakers as I mentioned before. Money saved on book shelf vs towers could be put into a higher quality sub? Or is this not as critical as it seems to be when trying get a seemless transition between sub and system?

 

[shokhead]

I am wondering now about my possible future upgrades. I have been drooling over the Axiom mt80i since first reading the reviews here, but after learning more on bass managment im wondering if i should be looking at a speaker system that has approximately the same -3db hz rating. It could be said that having large towers up front that can play to 35hz and then smaller surrounds that cant go past 60 or 80hz would be a waste of speaker potential for someone who likes HT more than music or even mulitchannel music for that matter. If setting the crossover for the sub so you can get the most of your speakers at say 40hz for the fronts would be over driving the surrounds and 80hz for the rears would be wasting the potential of the front towers. I guess having different settings for the fronts and rears would solve that or smaller fronts or larger rears. Are there any AV units on the market that have the ability to set the bass managment differently for different speakers? Im just thinking out loud here that it could be money saved on getting speakers closer matched or a Pre Pro that can handle different size speakers as I mentioned before. Money saved on book shelf vs towers could be put into a higher quality sub? Or is this not as critical as it seems to be when trying get a seemless transition between sub and system?

Me,i'd go with the M22ti's for front mains and surrounds and get a killer sub. Set your speakers you have now to small,belive me,and play with you x over at 60 and 80.

 

[shokhead]

this article is exactly what i needed!

but i'm still not too sure about what to set the crossover to.

all 6 of my speakers go equally low to 55hz so what should i set the sub to? right now i've got it at 80 but if it sounds better and is the right thing to do at 70 or 60 then i'll certainly adjust it.

also, how loud should my subwoofer be in comparison to the speakers? when using the spl meter should i treat it as a speaker and get it as close as possible to matching the rest of the system in volume or do i want it to be a few decibels higher? it would seem like it's a personal preference issue but any advice?

If your using the LFE,dont worry about the sub,set the x over at the reciever. Try 60 and 80 and it shouldnt be so loud that you notice where the bass is coming from but you might start at +10db more then your mains. I like bass.

 

[gene]

but after learning more on bass managment im wondering if i should be looking at a speaker system that has approximately the same -3db hz rating.

Please don't dismiss the importance of a good floorstander speakers just b/c you are likely to cross them over. There is still significant bass energy below the crossover point so the speaker is still contributing to the overall response. In addition the M80's have much more dynamic range than the M22's, larger soundstage, and more piston area = less distortion. I would still consider the M80's if you have the space. They will blend well with a good sub if you set them up correctly.

 

[shokhead]

80's better be nice at 1200 bucks.Ouch!

 

[howie85]

Axiom

I was just on the phone with the Axiom folks and I was asking about their subs. I currently run 2 velodyne cht 150 15" subs and they tell me that the ep 600 will play as loud or louder than both of my current subs and deeper and more accurately. HMMM??!!! I think I feel the itch...

80's better be nice at 1200 bucks.Ouch!

My point exactly would the money be better spent on the sub or

In addition the M80's have much more dynamic range than the M22's, larger soundstage, and more piston area = less distortion.

is the dollor to how much better/cleaner/louder ratio worth it.

I would still consider the M80's if you have the space.

Is there a standard on how much space any particular speaker needs? My room is 24x14 and im running 7.1. I have to admit it would be nice to have some more space but it is not really cramped. I can say that i could probably use some acoustic material for sure. I currently have what I consider some pretty decent equipment as far as speakers go. Polk rt55i front bookshelf Polk Cs 1000p Center and 4x FX1000i surrounds. My Velodynes are the first slated to be replaced at this point. This room is planned to be remodeled and extended so it will probably end up more like 26x24 at that point I is where floorstanders would really be a benefit ?

 

[shokhead]

For me,i'd rather spend less on good bookshelfs and stands which would be less then towers and the money you save,get a killer sub as your using with either one,towers or bookshelf and they will both be set to small. I think you could get 6 of the M22ti's for the same price as the m80 towers. Now of course if money isnt the problem,the towers would be great.

 

[Takeereasy]

Hi guys, I may be a bit late but I have a quick question. I have a Sony STRDE-1075 receiver and as long as I am running all my speakers as small I can adjust the crossovers for all my speakers to different settings. I have my Center crossed at 80 hz and my fronts and surrounds crossed at 70hz, while my rear surround is crossed at 100hz. This is my first Receiver and I wanted to upgrade it soon. Can't the receivers you guys are using do the same thing, or are you stuck with one cross over setting for all your speakers? I have been looking at a Denon 2105 and similar, but I find this bass management problem a bit worrisome.
Thanks