Sub crossed over at 120?

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Jazzaudio

Re: Sub crossed over at 120?
« Reply #20 on: 30 Jan 2018, 02:33 pm »
Thanks jMelvin...that copy is much easier to look at!!

rollo

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Re: Sub crossed over at 120?
« Reply #21 on: 30 Jan 2018, 06:07 pm »
  When doing adjustments play piano recordings. The piano has the lowest and highest notes.


charles

macdane

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Re: Sub crossed over at 120?
« Reply #22 on: 31 Jan 2018, 12:03 am »
Here's a interesting way of looking at the chart. It lists the kick drum's range (fundamentals and harmonics) as 50hz-8khz.  If you take the midpoint of that range and follow it down to the subjective descriptions near the bottom of the chart, you'll end up between the subjective "fullness/mud" and "whack" and "tinny" sounds.  Many of the frequency ranges contain both positive and negative subjective narratives. Which description actually applies depends on how the instrument should actually sound (by design or tuning), or ones personal preference.  The midpoint range of the kick drum actually falls in the subjective "honk" sound...but since the kick isn't a brass or a woodwind instrument this may not apply  But that midpoint includes the "fullness/mud" subjective range, but does not include the "whack" or "tinny" ranges.

Hmm. This has got me thinking about stuff I haven't thought about in years. Prior to buying the Omegas I have now (the Super 3S model) I've used Fried speakers for as long as I can remember, and for a while was having regular conversations with him about this stuff. He always tended to cross the woofer over at about 100Hz and I've taken that for granted for so long that it's kinda cool to have this thread pop up and get me thinking about it again.

Bud had a few rules about this woofer-to-midrange crossover that are worth mentioning in light of this conversation and the diagram that's been posted:

1. Get it as far below 650Hz (where most musical energy resides) as practical;
2. Drivers should be capable of performing well two octaves from the crossover point; and
3. Gentle slopes (I believe around 6dB/octave) are inherently more phase-linear.

Those rules — in conjunction with his ears and the drivers he had access to) led him to choose ~100Hz as the crossover point, almost always. Anecdotally, Bud talked a lot about evaluating a speaker by ear, and using very familiar instruments like the piano or the human voice as a guide. Everyone knows what those things should sound like, he argued, and a listener is instantly aware when something is "off" about the reproduction even if we can't pinpoint what's wrong.

Now look at that chart, specifically the junction between fundamentals and harmonics for the various instruments. With just four exceptions (snare, tuba, contrabassoon & piccolo) a 100Hz crossover is at least two octaves removed from that junction point for the other instruments and also corresponds to the lower limit for human voice. I don't think that's a coincidence. So there might be an argument there for avoiding a higher crossover point. Mightn't there?

RDavidson

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Re: Sub crossed over at 120?
« Reply #23 on: 31 Jan 2018, 01:37 am »
There could be an argument there, but everyone's systems and rooms are different....and the difference between 100hz and 120hz is not huge, but also not necessarily trivial. It really depends on a case by case basis. The important take-away is that bass integration can be rather complex, moreso with main speakers that have limited bass range. Challenging, but not impossible.

macdane

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Re: Sub crossed over at 120?
« Reply #24 on: 31 Jan 2018, 06:14 am »
There could be an argument there, but everyone's systems and rooms are different....and the difference between 100hz and 120hz is not huge, but also not necessarily trivial. It really depends on a case by case basis. The important take-away is that bass integration can be rather complex, moreso with main speakers that have limited bass range. Challenging, but not impossible.

You're right, of course. With this thread as the impetus, I've actually been thinking about it from a point of view opposite that of the OP. I guess guf isn't clear about whether he started at 120 and turned it up, or started at some lower point and turned it up to 120 ... did he say and I just missed it? Anyway, he got me thinking about where I set the subs to kick in. By default I set mine around 100Hz, which my subs are completely comfortable with, and then just fiddle with the level until it sounds right on a variety of music. Not very scientific, but I trust my ears to tell me what they like.

After this thread popped up, I got thinking about *why* I was at 100Hz. My Omegas operate full-range, after all (which really isn't FULL range but easing into the 40s, giving more than an octave of overlap). I started lowering the crossover point and found that right around 70Hz (with a slight nudge up in volume) kept the deep bass but cleared up a slight thickness that I hadn't realized was there. Under the right circumstances, nudging in the opposite direction can also work.

roscoe65

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Re: Sub crossed over at 120?
« Reply #25 on: 31 Jan 2018, 01:01 pm »
You're right, of course. With this thread as the impetus, I've actually been thinking about it from a point of view opposite that of the OP. I guess guf isn't clear about whether he started at 120 and turned it up, or started at some lower point and turned it up to 120 ... did he say and I just missed it? Anyway, he got me thinking about where I set the subs to kick in. By default I set mine around 100Hz, which my subs are completely comfortable with, and then just fiddle with the level until it sounds right on a variety of music. Not very scientific, but I trust my ears to tell me what they like.

After this thread popped up, I got thinking about *why* I was at 100Hz. My Omegas operate full-range, after all (which really isn't FULL range but easing into the 40s, giving more than an octave of overlap). I started lowering the crossover point and found that right around 70Hz (with a slight nudge up in volume) kept the deep bass but cleared up a slight thickness that I hadn't realized was there. Under the right circumstances, nudging in the opposite direction can also work.

One point to keep in mind is that in almost all cases the crossover "point" is not a point at all, but a point at which high and low pass elements are both 3dB down.  The slopes to get to this point may be so shallow as to start two or three octaves above or below the crossover point.

When running my own Omega's full range, they act a bit like a sealed box, falling off gently beginning about 200hz or so.  Depending on where they are positioned in the room, I have to adjust the subwoofer crossover point to blend in.  With my subwoofers, I can adjust output level, phase, crossover frequency and slope.  I've found the natural asymmetrical slope (6dB HP, 12dB LP) helps fill in the bottom while preserving the illusion that deep bass is coming from the mains.

An advantage of this method is the the bass gain can be adjusted independently of the gain for the mains, allowing me to simply turn the bass up or down (or off) depending on need.

macdane

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Re: Sub crossed over at 120?
« Reply #26 on: 31 Jan 2018, 01:30 pm »
With my subwoofers, I can adjust output level, phase, crossover frequency and slope.  I've found the natural asymmetrical slope (6dB HP, 12dB LP) helps fill in the bottom while preserving the illusion that deep bass is coming from the mains.

Interesting. What crossover do you use? The crossovers in my little Dayton APA-150 amps aren't that flexible, but then I didn't expect them to sound good enough to keep this long! Speaking of "preserving the illusion," for a couple days last week I had my Fried subs and satellites and a pair of Fried Studio IVs — along with my Omegas — in my tiny (roughly 10x11) listening room. At one point I caught my wife sitting in there listening to the music and I asked her if she could tell which speakers were playing. The correct answer was the Omegas along with the subs in the background, but I liked her response: "Aren't all of them playing?"




mrvco

Re: Sub crossed over at 120?
« Reply #27 on: 13 Mar 2018, 11:41 pm »
I tried a few different high pass filters between my pre-amp / DAC and amp to remove some of the low frequencies and let my deepOmega8 carry more of the load.  I could never get it sounding right, but I only have a single deepOmega8.  At the db levels I listen at, letting my Omegas run full-range seems to work best for me.  I don't recall what my deepOmega8 is crossed over at, but it's at or a bit lower than 100Hz.  Setting the cross-over to ~120Hz always sounded a bit too flabby in my room.