I couldn't resist and hooked it up to my new amplifier (Loxjie A30). It's very obviously not an ideal test, as it's laying flat on my old hardwood floor with books and dumbbells on top of the baffle while the glue dries, but, I can tell already, without any EQ, that these can dig much lower than my old setup. I could, for the first time, feel the air pressure of sub 40Hz signals. I ran 20Hz through it and could feel the air exiting the bass reflex tube, very cool feeling!
There's some weird cancellation going on along the bass frequencies, around 60 and 80Hz mainly, based on ear test.
Tomorrow, they'll be placed properly, not heavily coupled to my very hollow floor, and I'll take measurements and do some EQ work. Exciting!
There's some weird cancellation going on along the bass frequencies, around 60 and 80Hz mainly, based on ear test.
Tomorrow, they'll be placed properly, not heavily coupled to my very hollow floor, and I'll take measurements and do some EQ work. Exciting!
When i brace the driver against the back (often) a much solider connection is used. ie either get it perfect or use something like venneer to create a firm, but not stress the basket
dave
Here's the measured response at 1.50 meters. Green line is without DSP and purple line is with DSP.
Of course, once the bass is boosted, the distorsion rockets.
The cabinets is audibly vibrating, particularly the rear panel. I suspect it's due to coupling the driver's magnet to it directly with measly foam in between. By clamping the cabinet as hard as possible with my hands, 99% of the artifacts due to vibrations are removed.
Also, for now, the driver is screwed directly to the XPS, which is very obviously less than ideal. And since the screws cannot really 'bite' that hard into the foam, there as to be some leakage and vibrating from the driver being passed to the front panel.
I tightened one of the screws while pressing hard on the driver and it already made an audible difference.
I'm going to see how I can make sure the drivers is correctly fastened to the baffle, perhaps by adding a dense cardboard ring between it and the baffle. Should give some additional bite for the screws and reduce vibrations.
Of course, once the bass is boosted, the distorsion rockets.
The cabinets is audibly vibrating, particularly the rear panel. I suspect it's due to coupling the driver's magnet to it directly with measly foam in between. By clamping the cabinet as hard as possible with my hands, 99% of the artifacts due to vibrations are removed.
Also, for now, the driver is screwed directly to the XPS, which is very obviously less than ideal. And since the screws cannot really 'bite' that hard into the foam, there as to be some leakage and vibrating from the driver being passed to the front panel.
I tightened one of the screws while pressing hard on the driver and it already made an audible difference.
I'm going to see how I can make sure the drivers is correctly fastened to the baffle, perhaps by adding a dense cardboard ring between it and the baffle. Should give some additional bite for the screws and reduce vibrations.
Alright. I unscrewed the driver and removed the brace that was touching the magnet. Most of the vibrations are completely gone and it sounds a looooot cleaner. Now, the only remaining vibration, although very slight, seem to in the 80-100Hz region. I'll see what can be done about this, but overall really really happy with how it sounds. It's big, warm-ish, but still detailed. I stuffed the port to try it sealed and I like it even more.
EDIT: I squashed the rest of the ringing emanating from the cabinet. Bass region is now as clean as can be, no weird vibrations. It is a little smeared and overwhelming, but I guess that's all that can be expected from a fullrange being pushed this low.
EDIT: I squashed the rest of the ringing emanating from the cabinet. Bass region is now as clean as can be, no weird vibrations. It is a little smeared and overwhelming, but I guess that's all that can be expected from a fullrange being pushed this low.
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(Now that I think of it, the smearing of the bass probably comes from the fact that the speaker is exciting room modes. Also, lots of it is transferred to the hardwood floor, which is hollow right below it, I'll have to look into how to decouple the speaker from the floor.)
If you use EQ you can make a smaller box and EQ the driver to your taste. Smaller box has less losses and is easier to build and carry.
That the driver will heat up more with EQ is a myth. As long as your amp has enough watts you can put your driver in a small box:
https://www.diyaudio.com/community/...how-off-my-new-18in-build.365764/post-6767025
Here you find some info on that claim.
Professional PA producers do the same - like RCF.
That the driver will heat up more with EQ is a myth. As long as your amp has enough watts you can put your driver in a small box:
https://www.diyaudio.com/community/...how-off-my-new-18in-build.365764/post-6767025
Here you find some info on that claim.
Professional PA producers do the same - like RCF.
Myth?
Assuming the same progamme material and average SPL, if you EQ the bottom end, you're putting more current through the VC so it will heat up more. As far as I know the laws of physics haven't changed in that regard. Whether it's a problem or not is another question -for typical home audio subwoofer applications, unlikely. With wideband drivers, with their smaller, low-mass coils? In some cases, perhaps. Depends on circumstance -driver design, coil former / pole-piece venting, basket restriction, how much EQ etc. That said, most drivers are rather more robust than is often believed -I regularly cross tweeters at very low frequencies, and thus far, I've yet to blow one that didn't have a fault already (although the filters usually aren't 'minimalist')
That is most definitely not a myth.
The power that is needed needs to come from either electrically or acoustically.
The electric power that is needed is inversely proportional to the cabinet volume.
This can be very easily be modeled in your favorite simulation/modeling software.
Here is a example of the same woofer in a 4L cabinet vs 12liter cabinet, both with the same frequency response (corrected with EQ) and same SPL.
Yes they do, and one of the biggest tradeoffs, is max power vs cabinet size.
Especially at such high SPL's.
This is also why you want a speaker with a (very) high BL (often low Qt), plenty of permissible power and a well cooled motor in these cases.
Pardon,
Your curves have no axis labeling… looks like a huge step at just under 200 Hz. Way faster than baffle step would decline.
Have you got a leak in your box.
As to the driver brace, having done it hunddreds of times, your brace must have been poorly implemented as we get the opposite results, getting it just right is tricky.
dave
Your curves have no axis labeling… looks like a huge step at just under 200 Hz. Way faster than baffle step would decline.
Have you got a leak in your box.
As to the driver brace, having done it hunddreds of times, your brace must have been poorly implemented as we get the opposite results, getting it just right is tricky.
dave
@b-force
There is also amplitude statistics in music. In my example with 15 inch drivers you get more efficiency in the 50 to 150 hertz region.
Most music has no real deep bass lower than 50 hertz. So it electrical heat up depends upon the music played. I agree that 30 or 40 hertz could be more demanding than before.
But in PA systems sometimes they make a cut at 45 hertz then you stay there with a cooler running system. Big driver in a small(er) box.
There is also amplitude statistics in music. In my example with 15 inch drivers you get more efficiency in the 50 to 150 hertz region.
Most music has no real deep bass lower than 50 hertz. So it electrical heat up depends upon the music played. I agree that 30 or 40 hertz could be more demanding than before.
But in PA systems sometimes they make a cut at 45 hertz then you stay there with a cooler running system. Big driver in a small(er) box.
]
That is all relative, and totally not interesting for the question.
With the same music, in a smaller box with more EQ (aka some conditions) it still needs more power.
The only variable here is the acoustic volume and the EQ to compensate accordingly.
Since P=V²/Z (Z is impedance), electrical power MUST go up.
In this particular totally random example, we already have a factor 80/10 = 8 difference in power @ 50Hz.
I don't call that nothing, I call that extremely significant and enough to blow up a small amplifier when not taken care off.
@b-force
Your argument is not a true one i. e. "irrevelance".
If you can put the eq down in a certain bass region an make a cut below - you gain electrical power rating.
It all depends on the concrete design therefore nothing is random here. I will not argue further as all is said.
Your argument is not a true one i. e. "irrevelance".
If you can put the eq down in a certain bass region an make a cut below - you gain electrical power rating.
It all depends on the concrete design therefore nothing is random here. I will not argue further as all is said.
How stupid of me. Here's the curve with Var smoothing and proper labeling.
The response is somewhat wonky. I also EQ it with a very approximate house curve in REW, I'll need to work on it more tomorrow.
There's is definitely some weirdness in the 100 to 200Hz region. I squashed even more of the panel resonance since I made that measurement.
I checked for leaks and while I couldn't seem to find any by doing the 'wet lips trick' (made me look very stupid), the baffle seem to have come slightly undone in one place due to the glue not curing fast enough expect at the edges. I caulked it and it's now being pressed under weights. I'll leave it like this for a good day or so, as some of the glue points, while seemingly sturdy, actually haven't really cured yet. Which does help at all with panel resonances since the bond isn't perfect yet.
Well, I wasn't the one making a pretty bold statement about myths.
Sorry, but you can't just dump such claims without expecting responses to it.
We already went down from a bold statement to specifics.
Btw, with notching you don't "gain" any, as in a sense that all of a sudden you have more to spare somewhere else.
The problem with boosting is also the danger with clipping the signal and therefor the amplifier for example.
That's why as a very general rule of thumb, boosting more than about 4-5dB is not advisable, unless you really know what you're doing.
But as a general advice, sorry but saying that EQ doesn't effect power handling is just very bad advice without knowing the specifics. Or more rather very bad design practice.
It is most definitely NOT a myth.
On another note, in order to squash the panel resonances & vibrations for good, I was thinking of doing some constrained layer damping using either latex caulking or silicone to glue thin sheets of wood on the outer shell of the XPS cabinet.
It would make for a nice and clean finish, but I figured it could double down as an enhancement to the current state of the cabinet.
Does anyone care to weigh in? I found very little informations about this practice for speaker cabinets. I only saw @xrk971 use it in his Trynergy build.
It would make for a nice and clean finish, but I figured it could double down as an enhancement to the current state of the cabinet.
Does anyone care to weigh in? I found very little informations about this practice for speaker cabinets. I only saw @xrk971 use it in his Trynergy build.
Depends on what you're trying to do. You can't eliminate panel resonances (not physically possible) just move them to different frequencies. If you heavily brace a high rigidity cablnet, which will be raising panel Fs above the box operating BW, then add mass or constrained layers, the probability is that you'll just shift the panel modes back into the region where the most energy exists to excite them.