Bass Management: A Controversy

[MDS]

Alright so what is the problem with setting subwoofer's x-over so it picks up were the mains left off without using the receiver or processors' x-over network? Does this make any audible difference? In case I caused some confusion here, I am sorry. This was my argument. Of coarse setting a sub's x-over to 40 hz when a hypotetical speaker starts rolling off around 60 hz.

As I tried to say before, it doesn't matter whether you use the sub's internal xover or the receiver's xover. A xover is a xover. I don't have knowledge of every single subwoofer available so there may be small differences in the slopes of the high pass and low pass slopes of a subwoofer xover, but receivers have standardized (for the most part) on 4th order low pass and 2nd order high pass. It's far more convenient to let the AVR do the xover in conjunction with other aspects of bass managment such as time alignment.

Note that if you have a THX certified receiver coupled with THX certified speakers, this is all a foregone conclusion as they will mate perfectly because all of the slopes will match.

 

[Seth=L]

Note that if you have a THX certified receiver coupled with THX certified speakers, this is all a foregone conclusion as they will mate perfectly because all of the slopes will match.

Their slopes will match, but does that mean it will sound good?

Well I guess this thread went off much more than it needed to, thank you for all your input guys.

 

[Nick250]

If speakers do have usefull output to a certain frequency, why not just use the x-over on the sub, so the sub can pick up exactly were the main speakers roll-off? I guess that is more my point, rather than cutting you main speakers off at 100hz.

You keep mentioning a 100Hz crossover. Unless you are running satalites, no one uses a 100Hz crossover.

Nick

 

[Nick250]

Oh, really? Fast subs are really called tweeters.

LOL, if I knew how to give you a green thingie, I would.

Nick

 

[no. 5]

if I knew how to give you a green thingie, I would.

the "scales of justice" next to the post number (I thimk )

 

[Sheep]

the "scales of justice" next to the post number (I thimk )

Correct.

Seth,

An 18inch driver can respond as fast as a tweeter with a Large magnet, stiff motor assembly, and powerful amp.

Also, boxes that resonate, or are poorly tuned can make the best driver sound like crap.

SheepStar

 

[Nick250]

Alright so what is the problem with setting subwoofer's x-over so it picks up were the mains left off without using the receiver or processors' x-over network?

There is nothing wrong with it, however the bass management in most receivers is usually more sophisticated than that of most subs and as a consequence provides for greater control of the bass.

Does this make any audible difference?

Given the choice of one or the other, I would pick the receivers bass management over that of most subs for reasons stated above.

 

[Nick250]

the "scales of justice" next to the post number (I thimk )

Thanks, found it.

 

[MACCA350]

Alright so what is the problem with setting subwoofer's x-over so it picks up were the mains left off without using the receiver or processors' x-over network? Does this make any audible difference? In case I caused some confusion here, I am sorry. This was my argument. Of coarse setting a sub's x-over to 40 hz when a hypotetical speaker starts rolling off around 60 hz.

Setting the receivers Xover where the mains roll off(or using 80Hz as a default) is what many people do. In using the receivers Xover and setting speakers to small actually cuts off the low frequencies from those speakers. This means that those speakers set to small are not being fed any signal below the Xover point and are not trying to reproduce those frequencies that they cannot adequately reproduce(this will not only alleviate the current draw on your receiver but also protect your speakers by not extending them past their capabilities).

Remember that movie and music tracks can and do contain bass to and below 5Hz(intentionally or not) and just because you can't hear/feel it from your mains doesn't mean they're not flopping around trying to reproduce it(unless they are have internal Xover to protect against this or you have your receivers Xover activated)

cheers

 

[Ampdog]

Since this has developed into quite an extensive discussion, perhaps the following also needs to be considered.

Regarding the "slowness" of stopping in its tracks of a (say) 15" driver compared to a smaller cone, one must remember that that has as much to do with cabinet parameters as cone mass. The amplitude of smaller cones are larger than with big cones, so the latter has less deceleration to do, offsetting higher mass (one does not mean exactly, just stating qualitively.)

I am also missing that any room with 2 bass radiators (mains) will have augmentation and cancellation somewhere - basic physics. The half-wavelength at 50 Hz is about 12 feet, and half that for 100 Hz; common enough distances in any living room. There is room-Q, which can make bass "linger" after the cone has stopped. There is the factor of group delay, etc. etc. - things that can never be made ideal at the same time, or then with the same set-up.

I must confess that I also have a problem with what exactly "slow bass" is. Cabinet design, room-Q? (Then it is even said that tube amplifiers have slower bass than semiconductor ones )

 

[Buckle-meister]

The 4 lines represent each speaker I use in my 2.2. setup below. 2 mains, 2 cornerload subs...

If I'm reading rightly, your subs are outputting up to approximately 1kHz!. That can't be right can it?

 

[Buckle-meister]

Gene, would you say that it's almost irrelevant whether or not one's speakers are full range because even if they are, it'd still be advantageous to use subs from the point of view of minimising negative room effects by utilising the greater freedom of placement a sub has over other speakers?

 

[Sleestack]

If I'm reading rightly, your subs are outputting up to approximately 1kHz!. That can't be right can it?

Yes, they are TACT W210 cornerload subs and aren't really subs per se. They are designed to be crossed over as high as 800Hz, although I cross them around 200-300Hz.

 

[gene]

Alright so what is the problem with setting subwoofer's x-over so it picks up were the mains left off without using the receiver or processors' x-over network? Does this make any audible difference? In case I caused some confusion here, I am sorry. This was my argument. Of coarse setting a sub's x-over to 40 hz when a hypotetical speaker starts rolling off around 60 hz.

That's the problem. Most people set the xover of the sub too low and then boost the heck out of it to get a better blend in the transition region. You then have too much bass below the xover point and it sounds boomy or slow. In the case where the speakers play down to 60Hz, I would set the xover to 80Hz and call it a day. There are some cases where setting the mains to large can also be beneficial. You have to use a RTA to determine this and measure across the listening area, not just one seat.

Don't forget many processors will truncate the LFE channel if you set the xover below 80Hz.

 

[Sleestack]

Gene, would you say that it's almost irrelevant whether or not one's speakers are full range because even if they are, it'd still be advantageous to use subs from the point of view of minimising negative room effects by utilising the greater freedom of placement a sub has over other speakers?

I think that is generally true, but I don't think the crossover for the mains have to be 80Hz, especially in a room corrected system. My setup definitely sounds better with a 50Hz crossover. I always set my LFE crossover at 80Hz.

 

[Dolby CP-200]

Hello

In an ideal world of professional commercial cinemas some of the THX cinemas use a huge array of fronts that are designed with motion picture soundtrack format in mind.

It’s a PA affair where all the fronts use 15” bass mid that will kick slam into your chest all with the high end is delivered via 4ft square horns to cover the auditorium with equal coverage.

The home does have a few problems that most don’t really cotton onto, one all the fronts must be matching! Size is an issue if you’re room size can’t accommodate PA cinema size motion picture loudspeakers. The user is ether forced to make slight compromises in the loudspeakers size.

The fronts should reproduce lows from 20Hz up to 20 KHz but, how many can hear that high up in the frequency range not many!

Ideally the fronts should be set to large as well as the surrounds only really small loudspeakers that can’t handle the large setting should be set to small. But there is a catch that I’ve twigged onto.

Sending the lows from all the other channels to the sub bass where it is blended with the LFE.1 sounds dreadful! And it rather limits the whole fun of experimentation.

More subs, doesn’t necessarily mean louder nor, lower it does give the user more headroom for the films soundtrack to reproduce without effort or very little strain.

Anyway, I guess some just don’t know what home cinema means after been misinterpreted with so much misleading information over the years and suddenly someone starts going barking mad. Mate if you saw how it is done in the cinema you might change you’re tune!

I’ll give a little bit of cinema advice piece at a time.

 

[gene]

Gene, would you say that it's almost irrelevant whether or not one's speakers are full range because even if they are, it'd still be advantageous to use subs from the point of view of minimising negative room effects by utilising the greater freedom of placement a sub has over other speakers?

Yes in small listening spaces, multiple subs and bass management are essential if you desire even bass response across the whole listening area. If you have active equalization, you can set the mains to large if they are capable and eq the whole system for smooth bass response but its difficult.

Mate if you saw how it is done in the cinema you might change you’re tune!

Home theaters vs Movie theaters are two different animals and are NOT to be treated as the same. Small listening spaces require multiple sub distribution and bass management to deal with standing waves and room modal/nodal issues. If one things setting all speakers to small and dumping the bass to a sub or two sounds awful, then they didn't do a good job setting the system up.

I am using 4 subs in my setup, 2 of them are within 5-6 feet of the listening area yet you would never know it if blind folded in the room.

 

[Sleestack]

Yes in small listening spaces, multiple subs and bass management are essential if you desire even bass response across the whole listening area. If you have active equalization, you can set the mains to large if they are capable and eq the whole system for smooth bass response but its difficult.

Not so difficult when you have the right tools to work with. I"ll try to post corrected measurments later:

 

[Dolby CP-200]

Hmm, what computer sound model are you using there friend?

Is it a free download version?

 

[Sleestack]

Hmm, what computer sound model are you using there friend?

Is it a free download version?

No, it is the software that comes with the TACT TCS MKII. You can read all the measurements in your room, draw target curves and route signals however you want. Then you can take a corrected measurement. Earlier in this thread, I posted uncorrected and corrected measurements in my 2.2. setup. The audible impact on a multichannel setup is even greater b/c of the increased difficulty in properly balancing more speakers.