Anyone prefer 100hz crossovers? - Page 2

Sounds like opinon stated as fact to me.


A sub low passed at 40 Hz shouldn't be thought of as "operating at 40 Hz". The purpose of the crossover is to keep it from not operating there!

Besides science isn't up for a vote, especially on an audiophile forum.

And your bias controlled listening tests demonstrating that are documented where?

Here's a possible scenario:

(1) You are repeatedly told by some unknown people on the web who got to you first, that subwoofers need to be crossed over to as low as possible to avoid problems with bass imaging or soundstage.

(2) You do some uncontrolled listening evaluations and your beliefs prejudice the outcome of the evaluations

(3) A new global truth has been cemented into your mind.

If perchance you ever go to a live chamber concert and listen, unless you are sitting close enough to the players to smell their cologne, the low bass if you could somehow separate it from the rest of the music, will sound like its coming from the center of the group, more of less. If you're in a large venue and are sitting in good seats (say row G or beyond) the music will strongly tend to sound like its coming from a blob in the middle of the stage.

Normally, tone pulses are not the same as pure tones. There are high frequency transients at the beginning and end of the tone, even if the tone burst appears to be smooth. These high frequency transients will probably allow you to localize the speakers they come from.

You're trying your best to not understand, I see. I specified 75Hz for the tone. Pure 75Hz. With pulse I mean a short duration of it followed by silence. Have you checked my location in the world? This is not my primary language, give me some leeway in wording please.
I have Master's degree in Computer Science & Engineering - I'm well aware of the frequency contents on an impluse.

On the other hand, we were talking about whether a bass system with a sharp (30dB) 80Hz cutoff should be stereocoupled or not. So it really doesn't matter if it's overtones from a pulse or from the music that makes them locatable. If they are locatable, then that makes a case for running them in stereo.

Even assuming no HF transients (everything Mr. Krueger wrote is true), sure, there would be a difference between that tone panned left vs. that tone in the whole sub setup: the tone panned left would be quieter, because there would be fewer cones reproducing it.

But "localization?" Don't be silly. Unless, of course, the tone set something near one of the subs rattling. Then you might "localize" on the rattle.

Who's being silly now, of course there is no level difference between a full signal in one side and two sides playing half the signal each. If anything different then you monofunction is a monononfuction.

Acoustic sum and electrical sum typically are not the same.  See the second post of a thread a started as it has references to that regard.

 

http://www.avsforum.com/t/1440078/bass-management-vs-full-range-speakers

Another thing to consider, if you listen to electronic music where the artists are phasing the bass slowly apart in left and right channels, will you be wanting to sum the signals to zero or will you be wanting your speakers to keep reproducing the material as intended?

The thread topic says 100Hz, so lets say it's done around 90Hz. Are you expecting perfect cancellation across all points in a room with that signal?

Which was exactly what I was typing at the same time as you did.

But you also specified that the tone be modulated.

I get that. It appears that you lack appropriate information about the effects of modulating a pure tone.


If you are so aware, why are you arguing with me?

I have a BS degree in control systems engineering and did almost all of my MS work (1 class shy) before circumstances pulled me out of school. That and about 40 years of experience. I aced Signals and Systems analysis and also did a PhD level class in Stochastic Linear Optimal control that was a heavy trip in more signals and systems analysis.

Actually, your lack of familiarity with English has you making a mess out of whatever you are trying to say in the sentence above.

Not at all. We drive subwoofers through crossovers and one of the purposes of a crossover is to keep high frequency sounds out of the subwoofer. If we do that well, then we can't locate the subwoofer by hearing under a very useful range of circumstances.

First, Please tell me where in the post to which I replied there was any mention of lowering the input signal with both stacks in play. You wrote "flipping a switch," which means that the same signal was going to both, only one time one side was turned off, and on the other time it was turned on.

Second, see post 36, supra. That's a valid point, and makes my above assertion merely likely rather than certain. It is possible at at 75Hz the new subs will actually act as sinks rather than sources. So a more accurate answer would be "you're hear a difference, because the absolute level will change, but that will be the only material difference if you are assuming that nothing rattles or buzzes."

As for your other point, any "phasing" cues you're going to get in a small room will be from higher-frequency components, not the subs. You may get more directional bass outdoors, but not in a small room. The nature of the music doesn't matter. The dimensions of the space are the relevant factor.

And lastly, I clicked on your signature link. You get props for using multiple subwoofers, but yours are very poorly deployed. There should be more variance in their placement, to better randomize room mode excitation.

So you are advocating running speakers full range and not taking the lower frequencies off them? Isn't that going against the common AVS forum consensus of using an AVR's bass management, setting speakers to small and an 80hz crossover (e.g) ?

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Edited by kiwi2 - 11/27/12 at 12:05pm

No.
Yes, same way as the LP part of the midrange crossover is to keep the high frequency sounds out of the midrange. You wouldn't ask that to be kept from being locatable would you?

I'm not crossing to subwoofer because it's not possible to locate, I'm crossing to bass modules to keep the bass load off the tops and to be able to place both tops and bass modules at the locations that are beneficial to each. Using stereo bass modules
I do not need to worry about them being possible to locate or not. Which was the point I originally tried to make, methinks.

But I think we agree but with a difference in how we put it.

I referred to the mono-switch on my crossover in particular. Sorry if that wasn't clear.
It looks like this for reference:


Yes? I don't care if an effect is very very tiny when being theoretical.

Miscommunication; I meant changing where the left and right tones were phase-wise in regards to eachother. say shifting them apart a degree per second in the test material, so they'd end up reversely phased a while later.

If they are the only position that makes the room still possible to have a family in, they are not poorly deployed. The room is quite kind so it works fine this way too. Don't you think 8 racing green boxes with 12" woofers in constitutes about the maximum you can ask in WAF?
( Besides, I have learned quite a lot over the last 8 years too. )
I have read the harman paper, so with a differently configured room and nothing else to take into consideration, I would have done differently. It will be slightly different in the theater, but unfortunately there's things like seating to consider there. Also there is a difference between ears and mics and where sound traps should be that leads to wanting the subwoofers upfront even if you can get a measured more even response with other kind of placements.

Now, why put that exception in? So if I was in a more intimate setting... i.e. a small room... say a chamber music session in your lounge... then the placement of the lower octaves is relevant?

I happen to be one of those people that prefer a "they are here" experience as opposed to a "you are there" experience. I like to feel the band has set itself up in my lounge and are performing in my very room if I was to close my eyes. I like the soundstage forward and wide wall to wall and with good localisation of the individual instruments/vocalists. I prefer this experience over a soundstage that extends back behind my speakers and behind the front wall of my room. That may sound like you are in the 10th row at a concert hall with a performance way up front... but I prefer to be more immersed and intimate.

So take a cello at close range for example. Would not the full range of octaves be emanating from the same location? How do you think it would sound in real life if you were only hearing the upper octaves from the cello itself, with the lower octaves being separated from it and coming from a different location in the room? Would not the imaging sound disjointed and more diffuse?

Yes, that is what I'm advocating, if one's mains are stout enough for it. If one has to run teeny-tiny baby mains, then one may have to filter them. See, e.g.here. Note that in that system I obtained that frequency response with a 120Hz highpass on the mains, and suffered no localization issues.

And I could care less about the "AVS consensus."

It's silly to talk about "phase" in the bass in small rooms. Consider the boundary dimensions, vs. the size of the wavelengths involved.

Hehe, fair enough.

Then you should have seen that my recommendation is subtly different from Welti and Devantier's. Rather than repeat myself, I'll just direct you to a larger explanation.

No.

Then we agree on the same thing. I have stated that I don't like my speakers having 80hz taken off them as I find the soundstage becomes less dynamic. I can live with 60hz and below being taken off them though. If you are running your speakers full range and are just being supplemented with subs, then you won't be experiencing the problem of your main speakers being deprived of the lower frequencies. So what exactly are you disagreeing with?

Will bookmark and read it another time, just an hour left to midnight here now, been working 2 hours on the theater and am a bit in pain.

But I'll leave you with a little measurement of my system and at least I am not very displeased with it given the number of things possible to improve in that room.



Upper curve is with my front speakers running fullrange, lower curve is with the subwoofers doing the full job below 80. Don't ask me to take any new measurements, the mic and software was just lent to me for a while.

Sounds like opinion stated as fact to me.

You run your speakers full range so you haven't turned your lower octaves in to mono. If you did you may notice the inferior imaging as well.

Do you have a full range freq plot of your room we can look at?

Here's one of my room with a 60hz crossover.... http://www.flickr.com/photos/55066546@N08/7761470438/sizes/o/in/photostream/

Geddes still does not do things the easy way according to your last link. That Geddes setup is impractical for most non-dedicated rooms in typical homes.

Just as a note, I can tell the difference in sound quality between a 120 Hz crossover and a 45 Hz crossover. The comparison is based on running mains and single subwoofer location in 2 channel mode and running the AVR crossover from 40 to 120 Hz while listening to music. It is easy to hear the difference in sound quality. Not locatability of bass, just a difference in spaciousness (for lack of a better word).

With multi-channel sound, low crossover points do make a difference (for R & L mains and R & L surrounds and single subwoofer)..

Hey, that looks like an accurate FR chart of a real room!

Thanks, looks pretty good.  Are you able to get it flatter with a higher crossover but just don't like the sound?

 

JPC, you helped me along in my other thread about electrical vs acoustic sum so you probably know what I'm going to say but...I heard "more spaciousness" like you mentioned with a lower crossover too.  But my thought now is that is because of gaining too much bass (electrical sum) with a higher crossover which requires reducing the sub level.  And some may be the differing freq response of the two settings.  It is just really hard to separate out what I'm actually hearing.

Yes.

Bass seems like it just comes from dead centre of the room rather than from anywhere in the soundstage itself the higher I set the crossover.

Right so the question is should it sound that way. I lot of searching I did seemed to point to mixing bass equally in both channels for 2 channel music so in theory it should image to dead center. Some recommended doing this as high as 150hz. I'm starting to think some of this so called spaciousness with lower crossovers is simply the frequency response and phase or time alignment between 2 channels not being exactly the same in one's room. Where as electrical summing to a sub yields the perfect image to center. And along with this perfect summing comes a boost in output so the sub level needs to be reduced slightly. I'd be curious in your comments if you tested that theory....try a higher crossover and reduce your sub level a couple DB. It worked well for me.


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Your ellipses hide an awful lot of context for one thing. Including a system I mentioned low-passes the mains at 120Hz! And it imaged better than my reference system (identical Tannoy System 12 DMT II based mains, in low-diffraction closed boxes), frankly. Those little KEF 3005 eggs are the best-imaging speakers I've heard at any price. They have other flaws, mostly related to their scant volume displacement, but they throw a spectacular image on recordings with great imaging. All adding the subs did was add some meat to the image, and seemingly improve the system's "timing."

But the point is that there is no magic lowpass for the subs, or highpass for the mains (if any), beyond the general rule that it's usually better to have as many sources at as many different points in the room as possible in the modal region.

Still, there is only the best performance one can get in a given room with a given set of equipment. If one has small mains, highpass them. If one has stouter mains, the more sources playing in the modal region, the better. I don't know of a better way to do it than fiddling and measuring, short of hacking into Harman's network and using their SFM program with your data, or employing Keith Yates to run models for you.

And if one's equipment doesn't include multiple subwoofers around the room, any result is probably going to be a poor compromise anyway, so multiple subwoofers is the first step.

Nonsense. For one thing, see here.

That's three subs, and a 120Hz highpass on the mains. (Because they were tiny.)

Funny, but I'm managed to apply his placement and setup methods in now eight systems in seven different multipurpose living rooms since 2005 or so, four of which my own, and three of which had no subwoofers visible at all, and two of which only had the corner sub visible. The successor system to the "modest multisub" setup linked-to above, for example, had the corner sub (Aurasound NS12 in 65L closed box) hidden inside an Ikea HOL double-sized chest, which was padded with fleece on top to give the cats a perch from which to look out the window; a Gallo MPS-150 hidden against the wall inside a cheap "floating table" from West Elm; and a sub (Aurasound NS10 in 15L closed box) up high hidden behind a basket-front inside one of those cube shelf things.

Yes, it requires some thought and often some custom cabinetry to stealthily integrate a multisub system into a multipurpose room. But it's hardly "impractical."

Well, a single sub system is going to be compromised no matter what, so a lower crossover probably is better. Then at least you have two sources to smooth things out a little in the modal region, rather than just one. And the sub adds extra ULF under that. Perhaps, depending on the quality of the sub, relieving it of midbass duties makes its flaws less obvious, too. Something with a cheap driver with no shorting rings is going to be a lot worse than, say, an underhung-motor Aurasound driver with a copper sleeve on the pole and smooth response up to 800Hz or so along with a long throw. Or even a value current-production sub like the SVS SB12-NSD, which is really pretty amazing (nicely built and finished cabinet, big NRTL safety approved amp, Peerless XXLS woofer, all for $600 or so).
Edited by DS-21 - 11/27/12 at 7:04pm

Each time I have tried a different setup or crossover point, I have remeasured the room's FR to see what is going on and to adjust the volume going to the subs in order to make sure the response is reasonably flat down to at least 25 or 20hz.

I will try again though in the next few days with a higher crossover and make sure things are optimised for that higher crossover. I don't mind experimenting as it costs nothing and you only gain to benefit if you like the new setup. Will let you know how it goes.

Just trying to be factual. ;-)

It turns out that I've recorded thousands of groups in dozens of different venues, and I sometimes am close enough to smell the cologne and know what live music sound like there, and lots of elsewheres.

Much more likely. It's totally unlikely in what most people think are the best seats in large venues, which BTW isn't the first row!

You can't smell the cologne in the tenth row, and the experience is much like the rest of the room - very diffuse imaging.

What's close? I often have the freedom to walk around the venue during rehearsals, and if I want to I can get close enough to the cellist to tickle her, ;-)

That's totally unrealistic for any reasonable seat in the room. There are two major variables and one is the ear's lack of precise directional response at low frequencies, and the other is the fact that low frequency sound tends to diffuse thoughout the room and the sound field at low frequencies says more about the room than the source.