I don't think the impedance curve is a problem. It just indicates a high tuning.
What does the response curve look like?
(I would not call those woofers "sub", by the way)
Because the high tuning makes them more "woofers" than "subwoofers", in my opinion. But that's just how I would call it.
The high tuning results in a peak at 75 Hz
Depends on ones needs, but it has been tried multiple times, that these lose a lot of perceived output when tuned low. I'd say that indeed ~50Hz is where it should be, under 50Hz tuning the loss is very significant. Tried 42Hz, and no, it was not that spicy anymore.
i'd look to make it go deeper with a more gradual rolloff rather than a peak at 80 even if it meant a larger box but that's just me...
if you want a compact kick why not a CUBO for 12's ?
if you want a compact kick why not a CUBO for 12's ?
Oh. Now after your post turk182 I get it. Yes, that seems like too high and kick woofer. Not a good plan for sub.
Historically, > 60 Hz/F-3 = sub bass, so based on this, technically missed it by a dB or so with 60-250 Hz bass, 250-2k mids, 2-6 kHz high mids, 6 k-up HF, though over time it's been condensed somewhat depending on whose book you used (>120 Hz for me, so well within being a 'sub') and nowadays THX apparently rules with (<) 14 Hz-300 Hz!, which is ~4.42 octaves, so really need multiple small, low Fs drivers and close coupling to the mids, deleting the traditional 'bass' speaker class altogether.
Because there's not much response below 60Hz? That particular "subwoofer" would struggle to reproduce the lowest note on a 4-string bass guitar.
The following solution would be a bit better, in a 30-litre enclosure:
Increasing the enclosure volume to 45 litres gives the following option:
Which after adding a 4th-order Linkwitz-Riley 80Hz low-pass filter and adjusting the enclosure tuning, we get a response function that is worthy of the label "subwoofer": 😉 🦾
I explain my reasons.
I have already done a failed test,
volume 35 liters, fb=41hz f3=41hz, in simulation it was perfect
but in reality applying 1000w I had a lot of unwanted vibrations and a hole of -10db at 80hz.
to make them sound decent I applied a high-pass at 45hz and created a filter 80hz +10db Q6.3
ps
This sub will be part of a 3 way system and must reach 300hz
I have already done a failed test,
volume 35 liters, fb=41hz f3=41hz, in simulation it was perfect
but in reality applying 1000w I had a lot of unwanted vibrations and a hole of -10db at 80hz.
to make them sound decent I applied a high-pass at 45hz and created a filter 80hz +10db Q6.3
ps
This sub will be part of a 3 way system and must reach 300hz
Consider that it is to be used in PA system or DJ set, it will not be used as a HT subwoofer.
Maybe it is better to look for a compromise and try a 60hz FB?
Maybe it is better to look for a compromise and try a 60hz FB?
I suspect that the sim was not good enough. Sims that use lumped-mass modeling (like the one above seems to do) do not show the impact of harmonic resonances on the overall response. They also tend to get the vent length required for Fb wrong once the volume of the vent approaches 10% of the net box volume. In summary, if your build used a large and long vent suggested by the program to hit an Fb of 41 Hz, it possible that the Fb was lower than expected and vent resonances impacted the response above Fb.
I'd bet you were actually seeing a room node, was the measurement done indoors? 80hz has a 1/2 wavelength of 7.2ft which means it's really easy to create a response null in the average room. And at 1000w input everything in the room will be vbrating. If you take that box outdoors away from structures I bet the measured response will look just like the model below 100hz.
The sound was good outdoor, but indoor it was a disaster. The problem is that I need this compact system for DJ sets in small venues, 40-80m2.
So, do you recommend me a fb50hz? Could it be a good compromise?
Subbass indoors is always a challenge, the room dimensions and the subs position in it determines where the LF nodes appear, no there is no escaping LF nodes indoors. The bigger the room the better.. the more it behaves like an outdoor space, so you should not have the problems you see in your home in spaces big enough for 100ppl or more. So I don't recommend intentionally limiting the LF extension of the sub because of this, aim for the widest bandwith you can get without impacting overall SPL capability, and do your best to get the bass where you want it in each venue. That means the sub/s may not always be co-located with the tops, or of they have to be then you live with the results that delivers.
In rooms of that size, room acoustic modes are clearly going to influence the sound at whatever listening position you may choose. An Fb ≥ 50Hz is hardly conducive to moderately faithfully reproducing a wide range of musical genres. The DJ will be plagued with an anemic bass response on many tracks, and they will be unhappy with the results when the clientele are also not getting into the (missing) groove. What I'd suggest, as a bare minimum, is to try and get your low-frequency response extended out to a −3dB point of no higher than 40Hz; that would be a good compromise. Of course, with the driver you have chosen, that will mean trading off some upper-frequency response by attenuating it with a shelf filter, or similar, and then upping the gain on the amplifier.
Here is a possible design for a 30-litre ported enclosure, where the volume of the 2x 7cm vents is just under 10% of the enclosure volume. For this enclosure, Fb = 44Hz, and when a 4th-order 300Hz Linkwitz–Riley low-pass filter is applied we get quite a good low-frequency response, with just a modicum of ripple in the passband. The −3dB point is a low 41.8Hz, so the bass enclosure is going to be relatively capable.
If we increase the enclosure volume to 40 litres, and change the port tuning to Fb = 43 Hz, we get the result below. This is for 4x 5.1cm vents, whose total volume is just under 7% of the enclosure volume. When a 4th-order 300Hz Linkwitz–Riley low-pass filter is applied we again get a good low-frequency response, with around ±0.5dB of ripple in the passband. The −3dB point is now at 40.0Hz, so the bass enclosure is a little bit more capable than the previous design.
If it is desired, the addition of a modest +1.5dB of PEQ at 80Hz with Q=1.0 can be used to flatten the small dip between 50Hz and 100Hz. This should help to add quite noticeably to the perception of a "punchy" sound.
With all of the above designs, we note that with around 80W re 8 ohms of input power, the driver excursion is well under the maximum excursion capability. However, owing to the small enclosure sizes, the peak vent air velocity is just starting to exceed the warning threshold around the 40Hz mark.
If we opt for a 30-litre closed-box enclosure, then we can achieve the following result when using a 2nd-order high-pass peaking filter (42Hz and Q=1.90) and some PEQ. Here the driver displacement is maxed out at 42Hz with 100W re 8 ohms of input power.
If we increase the enclosure volume to 40 litres, and change the port tuning to Fb = 43 Hz, we get the result below. This is for 4x 5.1cm vents, whose total volume is just under 7% of the enclosure volume. When a 4th-order 300Hz Linkwitz–Riley low-pass filter is applied we again get a good low-frequency response, with around ±0.5dB of ripple in the passband. The −3dB point is now at 40.0Hz, so the bass enclosure is a little bit more capable than the previous design.
If it is desired, the addition of a modest +1.5dB of PEQ at 80Hz with Q=1.0 can be used to flatten the small dip between 50Hz and 100Hz. This should help to add quite noticeably to the perception of a "punchy" sound.
With all of the above designs, we note that with around 80W re 8 ohms of input power, the driver excursion is well under the maximum excursion capability. However, owing to the small enclosure sizes, the peak vent air velocity is just starting to exceed the warning threshold around the 40Hz mark.
If we opt for a 30-litre closed-box enclosure, then we can achieve the following result when using a 2nd-order high-pass peaking filter (42Hz and Q=1.90) and some PEQ. Here the driver displacement is maxed out at 42Hz with 100W re 8 ohms of input power.
Last edited:
Many thanks for the advice, final result: VB=31 liters, FB=43hz, 2 vents 75x350mm, high pass filter 40hz 48db butt, crossover 400hz 24db LR, filter 80hz +2db q10, I can still improve but already like this the sound is amazing in a room of 80m2, applied power 1100watt rms powersoft