erik_squires How would you plug the speaker ports? There are two of them, each about 4 1/4" in diameter.
An old clean T-shirt will work. :) Just make sure you can pull them out. This will reduce the main bass, but also reduce cone excursion. Will let the subs work with less interference.
But the holes at 61, 77, and 99 Hz are too high for the subs to do much to.
Au contraire, mon ami!! Look at your sub's output. You have plenty of output at 80 Hz for sure. And here we get into, gee, if your crossover was working really well, you'd have a 4th order low pass at 80, 2nd high at 80, and you'd be able to get your two subs to provide overlapping coverage. Come on @audiokinesis, back me up here. :)
The peak at 36 Hz is easy to tame with the parametric equalizer in Roon. No real need for a miniDSP for that.
Yeah, I guess you could fix this peak with Roon, and it will sound good, but honestly it rubs me the wrong way. :) This may very well be snobbery on my part, but I like to equalize the individual components separately, then gently cozy them up to each other until they are spliced together as smoothly as a Han dynasty curved back chair. Using major global EQ often tells me I've messed something up in a speaker configuration. I recently did integrate my subwoofer with my speakers, but it seems I threw away most of the charts. Still, you may find this post I wrote useful. What you are doing is much of the same: https://speakermakersjourney.blogspot.com/2016/12/crossover-basics-driver-response.htmlBest, E |
You can make anti-modes, or dips controllable with bass traps like GIK Soffit traps, however as Duke would surely advocate, the point of the 2 subs is that the second sub should fill in the big dips, and it doesn't seem like it's happening. This usually requires non-symmetrical placement.
I suggest you plug your main speaker ports, and re-measure. See if that helps control the peak at ~38 Hz.
Not sure how REW works, but if you are using Roon what I normally do is rip my test signals to my music library, and play the test signals in Roon. This allows me to adjust the Roon PEQ’s accurately.
All of this however is made much harder due to not having a good crossover in place already. This feels like using gum and duct tape and I really think the miniDSP on your sub, plus plugging your mains is your way to glory. Everything else is merely better than before.
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Ahhh. Of course, an XLR to RCA adapter generally does the same thing, but it also unbalances the line.
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I'm not understanding, why not use the gain on the sub to attenuate the output?
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Hi OP, Really nice work on the main’s. Is this in a relatively narrow room? I ask from looking at the peak around 370 Hz. Consider bass traps in the corners behind the mains. GIK Soffit Traps are super nice, but also look at ATS Acoustics for even less expensive options. If I was a reactionary jerk I’d say something about @audiokinesis post, but since he’s being a super nice guy and 100% based in science I can’t. :0) Imo the close-miced curve of the Starke provides a lot of useful information. Which is why I was suggesting a single sub as a starting point, though honestly I did not think to do close mic’d, but at least we can see that this sub is in fact performing a lot better than the original plot. :) Now as we start adding complications like distance and 2 subs we'll better understand what is contributing to what. Best, E |
Hi 8th-note I have to take some issue with your statements, as I don't think they are in evidence yet:
2. You purchased two subwoofers which cost $350 each and weigh 40
lbs. to supplement the bass of a pair of full size, full range, highly
regarded $4500 speakers that reportedly compete with speakers costing 10
times their price.
I think you are far too focused on cost here. Admittedly, I'd have bought a Hsu or SVS, but integration is going to be a much more important step here than worrying about not spending enough money.
3. If the Moabs go anywhere near 20 hz you don't need subwoofers. If
pipe organ is your favorite type of music and you are missing the 16hz
notes then you could spend several thousand dollars on a sub that would
not only go that deep but was equipped with a high quality crossover
that included a very low cutoff point. Wilson makes a sub for $40,000
that accomplishes this purpose.
Woah, nope, totally disagree with this entire statement. Subs bring a lot more to the table than a spec. The ability to relocate them, to equalize them, and to limit the bass required by your main amp and speakers are big deals. Done perfectly, you bring a lot more power and dynamic range to the system than you would have otherwise, and reduction in distortion. Also, this is a giant PITA to do well, as this thread will attest to. 4. The subwoofers you bought are accentuating the frequencies that your
Moabs are already putting out. They are doing nothing constructive.
We have not seen evidence of this, yet. So far all we have see is the sub response, and that the sub is too loud. However, yes, the future of this system should be correctly integrating the sub with the main speakers. One step at a time. OP: I just noticed that your main speakers are ported. I am going to suggest you plug them before attempting to integrate with the subs. |
Hey OP,
Don’t be so upset about the Klipsch yet! See the dip around 28 Hz? This is a typical close mic measurement of a ported speaker. This is normal. Ideally you also close-mic the port, and sum the two together which is somewhat complicated math to do right. For more on this, see D’Appolito’s work, Testing Loudspeakers.
As you move the mic away from the sub, the rear port contributions will come into play, but so will the room. Unfortunately this is how we have to do it to get quasi-anechoic measurements of ported speakers.
Next, you are right, the Starke is pretty flat, but the crossover is not doing what normally you’d expect. The THX standard, which many try to match, is a 4th order low pass filter for the sub. This helps match with a main sealed speaker that has a 2nd order high pass applied. As Duke has previously noted (and looked through the messy data) this looks somewhere between a 1st and 2nd order low pass filter.
Instead of changing the crossover frequency, you are changing the slope, and in all cases you are left with a rather low Q factor for the filter. A bad thing, meaning the filter’s effects are visible almost down to 20 Hz no matter what the setting is.
So while I like the speaker curves overall, the built-in crossover is a coarse beast. Definitely get a miniDSP and leave the sub’s crossover "wide open." You’ll be able to not only execute a 4th order low pass filter at any Hz, but you’ll be able to clean up some of the anomalies and add millisecond level delay to the sub, allowing you to perfectly phase match with your mains.
Also, please note how much better this is than your original measurements. Now that you can see how well it does, you know what to shoot for. :)
Best,
E
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There is some great information here, but this thread REALLY has me wondering if I want to mess with subwoofers!
Cheeg, To be fair, it isn't the sub, it's the lowest octaves. There be dragons there. Sometimes you are lucky and they don't notice you, but if you are going to take them on, a sub is the best way to go. Having said that, for the single and dual sub use case I've stopped trying to advise anyone to integrate their subs, but rely on built in systems like JL Audio or automatic room correction. And like Duke, I think the depths are worth having. |
OP:
Nothing like measurements. They are a type of fact, and a lot better than opinions and theory. :)
E
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ONE possibility is that the subwoofer’s voice coil has very high inductance which results in significant peaking in the 40-50 Hz region, @audiokinesis I think your characterization, that this sub is rolling off far too soon is spot on, which is why I suggest removing confounds. :) |
Erik asked: "Then let me ask this question another way. Looking at the OP’s original data, have you ever seen 2 subs start out that poorly in a room?"
I’ve never measured two subs in a room. To my eyes, they should look a lot better than that, if configured well, but since I can't tell what is by design, and what is interference I think the OP would be well served by eliminating 1 major variable in his measurements. Plus, it’s fast, and cheap to do. |
Hi OP,
You may also find the people and forums at DIYaudio to be more helpful. The forums let you post images in your discussion, and lots of speaker builders in the multi-way and subwoofer discussions for you to lean on.
You may also like the forums in the Room EQ Wizard discussions.
Best,
E
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Hi OP
No, the measurements do not look like very good representations of crossover behavior when changing the crossover point. However, since there are two subs involved, I can’t tell what is going on.
I completely agree with Duke that 2 subs are better than one, but I think for the sake of your sanity, you should measure one first. :) See if that doesn’t work as you’d expect.
You know, you might want to try out XSim crossover simulator. It is free, and you can draw several ideal speakers, and use different crossovers on each, and plot their behavior.
Best,
E
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Duke,
@audiokinesis
Then let me ask this question another way. Looking at the OP’s original data, have you ever seen 2 subs start out that poorly in a room? :)
Best,
E
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Gah, can’t type today. Or any day. I wrote: However, it is clear to you, and other experts that 2 subs are better than 1. :) I meant to say: Duke, Toole and other experts agree that 2 subs are better than one, and I agree.
I’m just offering up a simple way to get to done from where the OP is, so I am suggesting to measure the single sub FR first. It can’t really be as awful as the first measurement was, can it ? Of course, a final 2 sub install should be equal or better than 1. |
I disagree with Erik’s assertion that "if you can’t integrate 1 sub, you can’t do 2. " As the number of intelligently-distributed subwoofers goes up, not only does the in-room response become smoother, but the specific location of any one sub becomes less critical.
Hi Duke, I don’t disagree that things get smoother, but if you don’t know what 1 sub will behave like, you have no idea of the second is making things better or worse. Attempting to set crossover points, and delays for both subs at the same time is a lot of work. Far easier to do after you’ve gauged the overall response of a single sub. The FR response of the OP using two subs was, I think you’d agree, pretty awful. Seeing a single sub’s FR would clarify much. However, it is clear to you, and other experts that 2 subs are better than 1. :) Best, E |
Kenjit,
We are all still waiting on you to post a blog post with details on anything you've bought, built or improved.
You are able to attack me only because I publish excessive details on what I've made.
Your only contributions to this forums have been random and self-contradictory theories with ZERO factual information.
Is this the week you believe in engineering, or the week you don't? Does that change hourly for you?
Best,
E
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erik_squires I can remeasure with one sub and set the crossover to its 200 Hz high point but I’m not sure the results will show much difference but you can never tell. Depending on the delay and the frequency, you can cause destructive interference. For sure, if you can’t integrate 1 sub, you can’t do 2. Measuring with one sub with the crossover wide open tells you what your sub is like alone. It’s an important baseline. For instance, if the FR looks like you posted, that’s pretty bad, and you are definitely going to have to do a lot of EQ. On the other hand, if it smooths out, and looks nice and flat-ish to 150Hz or so, you know you have a good starting point. Integrate your closest sub, so you know what is possible, then blend in your second so your result is as good, if not better than your first sub. If your overall FR with 1 sub still looks that bad, then you have other issues, and will need serious EQ. Putting in both subs and attempting to hammer the EQ into place though is madness. :) Trust me. :) |
It may help you to think of crossovers if your realize that the are not independent of the sub's own natural rolling off of higher frequencies.
The low pass filter in the sub ADDs to the natural low pass filter. To figure out what you are starting with, set the HP filter as high as you can and measure there.
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Finally, someone around here posts measurements. ;-)
Unfortunately, it's of 2 subs, so things are much more complicated. Turn one sub off and re-run your measurements.
And yes, miniDSP is a great alternative, which will add much needed EQ and very fine delay controls. :)
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