Yes, they are.
It was just overall analysis. X4b is very nice two, if you assembly the driver with the motor pointing to smaller chamber it can give good cooling too.
Once the "model" gives good result, now it's just about optimization and fine tune for a given driver 🙂 The driver I used has Fs = 41Hz but I hadn't time to tune all boxes for the same exactly the frequency, my vocation was ending 🙁
Do you have the Hornresp records for these? The zip attachment only has frequency responses. I'm very keen to have a play with these, particularly the x5
Hello lexandredeyed,looks like I attached the wrong files previously, check the new attachments.
Hey guys, I have been messing with this manifold idea in hornresp and lordsansui's amazing CAD models and I like it a lot. It models really well and seems really easy to build.
I thought I would post what I want to build here, before getting the saw out.
I made it quite small, so I can fit a single on my cargo bike.
I chose B&C 15NDL76 driver, because it is not crazy expensive and very available in the EU. It also seems to model very nicely in this enclosure type.
I tuned it to work optimally in a stack of four.
I made the port straight, as I couldn't see the point in the flare, and a straight port makes construction easier.
The thing that concerns me the most right now, is the 15ms delay difference between the kick and the sub frequencies. Does anyone know if this is audible? Will it make things sound out of time?
The attached SPL charts are at 2.83v half space. Single cab and four cabs stacked.
Any thoughts? 🙂
Thanks for all the inspiration and information - Nesral
I thought I would post what I want to build here, before getting the saw out.
I made it quite small, so I can fit a single on my cargo bike.
I chose B&C 15NDL76 driver, because it is not crazy expensive and very available in the EU. It also seems to model very nicely in this enclosure type.
I tuned it to work optimally in a stack of four.
I made the port straight, as I couldn't see the point in the flare, and a straight port makes construction easier.
The thing that concerns me the most right now, is the 15ms delay difference between the kick and the sub frequencies. Does anyone know if this is audible? Will it make things sound out of time?
The attached SPL charts are at 2.83v half space. Single cab and four cabs stacked.
Any thoughts? 🙂
Thanks for all the inspiration and information - Nesral
Attachments
I'm running the system on battery power, outdoors, for extended periods of time, so efficiency is of upmost concern. I would like a deeper F3, but that would mean either bigger box, or less efficiency. Unless you have some magic cards up your sleeve?
I was thinking to play around with different port lengths in the prototype, to slightly alter the tuning.
It will be playing mostly trance music, so maybe deep bass is less of a concern?
I was thinking to play around with different port lengths in the prototype, to slightly alter the tuning.
It will be playing mostly trance music, so maybe deep bass is less of a concern?
The group delay around Fb (frequency of box tuning) is typical of a bass reflex enclosure.
It won't sound "out of time".
The offset horn reduces the rear chamber volume available for the bass reflex enclosure.
Using that volume for bass reflex and lowering the Fb, the F3 could be lowered at a similar efficiency, but with less output above 100Hz.
Well, electronic generes have much stuff below 50hz
This is what Google AI said
"The lowest frequency spectrum in trance electronica music is generally between 20 Hz and 60 Hz.
These are considered sub-bass frequencies, which are felt more than heard. They provide the foundation and "thump" that characterize the genre
However, it's important to note that this can vary depending on the specific subgenre of trance.
For example, some subgenres like psytrance or dark trance may incorporate even lower frequencies for a more intense and heavy sound."
Audiophile bass, yet a 4 string bass INSTRUMENT plays to 41hz.
Hello Nersal,
I'm happy the information are useful for you.
The port geometry other than tuning the frequency reinforcement you want can create problems such as noise. In general this happen at above specific SPL where the air moving inside the port starts to be turbulent, in English people refers to port chuffing. To mitigate that you can improve port geometry with rounded entry and rounded exit, Audiophiles do that with plastic accessories. For PA where in general the loundspeaker is fully made by wood, working with geometry is better.
There is a "new" compound model available on Hornresp called CH2, with this model you can model the port with 2 segments, allowing the entry and end to be big while the center can be narrow, like "venture effect", so keeping desired tuning frequency but improving air flow and reducing port noise. See Attachment #1
In general Hornresp emphasis the peaks and deeps for the simulation. From hornresp, go to group delay chart again and press "L" two times, hornresp will add some lines for you to better judge the group delay. See Attachment #2. If you plan to crossover between 300Hz and 400Hz it might be risky, In general for High Order loudspeaker people suggest to use 1 1/2 octaves of bandwidth.
If you tuned it to 51Hz, so, maybe it's safer to cross at 153Hz (51*2*1,5), maybe you can go until 200Hz depending from the slope you choose.
17ms delay at 51Hz isn't a problem and the auxiliary lines shows you.
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Thanks Max, this sounds about right, but just because there is information, doesn't mean you have to reproduce it. From my personal experience, bellow 50hz is important for genres with deep melodic bass lines, such as hip-hop, dub and DnB, but in trance music I personally find it less important. As you point out it adds a deeper thud, which is very nice, but comes at a high cost. Sure it would be great to play 20hz at 140db outdoors, for those few songs that are mixed that low, but then I would need to buy a semi truck, and I can not afford 😢
Your posts however inspired me to make an attempt at hitting 40hz, without compromising too much, so I optimised the box for v-plating 4 cabs, this allowed me to make the horn smaller and the rear chamber bigger, without loosing SPL, then I also made the port a little smaller and as long as possible. I have attached the results compared to the previous. Displacement becomes a bigger problem (xmax 8mm) and port velocity also gets pretty spicy. I worry that this will get me less thump, due to lower efficiency and over excursion, and at the same time burn more battery power. I would love to hear your thoughts 🙂
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@LORDSANSUI Thanks for the very detailed reply. Much appreciated 🙂
I will start with a straight port, for ease of construction. If I experience problems with port noise in the prototype, I will consider a flare.
I'm glad to hear that delay isn't an issue. My mids play down to 100hz, but I would prefer to cross them much higher, to avoid excursion issues and let the bass bins take the kick duty.
I will start with a straight port, for ease of construction. If I experience problems with port noise in the prototype, I will consider a flare.
I'm glad to hear that delay isn't an issue. My mids play down to 100hz, but I would prefer to cross them much higher, to avoid excursion issues and let the bass bins take the kick duty.
Since you're chasing efficiency in a portable battery-powered rig for outdoor use, I'd be concerned about delivering the most above 60Hz.
Pursuing anything lower is wasting energy unless you can do it with impact... which will take a lot more than a single box on a bike!
Noone will miss that 10~20Hz when dancing on the street or in a park (and there's plenty of information in harmonics of basslines).
The nice peak at 100-150 in your previous design could be desirable too, giving some oomph to the kick and allowing you to cross higher too - so maybe revisit that. And give serious consideration to how often you could get four boxes together, since you might want to prioritise the single box deployment over designing around the four box stack.
Something interesting to note is a quote from Saturnus' post about the Boominator design
Whilst I don't have anywhere near the experience of some of the contributors on here, I can share insight that when putting speakers on bikes there is a world of compromises to consider that most will never encounter when speculating about a sub's output
Pursuing anything lower is wasting energy unless you can do it with impact... which will take a lot more than a single box on a bike!
Noone will miss that 10~20Hz when dancing on the street or in a park (and there's plenty of information in harmonics of basslines).
The nice peak at 100-150 in your previous design could be desirable too, giving some oomph to the kick and allowing you to cross higher too - so maybe revisit that. And give serious consideration to how often you could get four boxes together, since you might want to prioritise the single box deployment over designing around the four box stack.
Something interesting to note is a quote from Saturnus' post about the Boominator design
Whilst I don't have anywhere near the experience of some of the contributors on here, I can share insight that when putting speakers on bikes there is a world of compromises to consider that most will never encounter when speculating about a sub's output
If more bass is centered ~48Hz than 38Hz, the lower tuning will be more efficient.
The lower tuning results in a higher impedance in the same region of the lowest impedance at the 48Fb, so bass centered in that region will use less battery power and heat the voice coils less.
You might think about using the offset horn as the port exit to bring it to adequate size (which would drop particle velocity way down) without reducing the chamber volume.
Similar to one half the EAW SB1000Z, though you could skip it's parallel tube ports entirely.
The H3 section of a venturi "H3/H4" port could be bent around the back of the cabinet, the speaker positioned in the H4 section.
The 171mm deep B&C 15NDL76 occupies 3.5 dm³ (0.12 ft³) of air volume, putting it's magnet structure in the H4 section would be advantageous both from a cabinet volume and heat extraction perspective.
Art
This is one thing I really like about this design. the quarter wave of the horn resonates approximately 150hz (100hz when v-plated), to get that nice hard punch in the chest 🙂
Big fan 😍 Being from Denmark, my first build was of course a Boominator. They are everywhere here! Such a small box can power a surprisingly big party, and it has an f3 of 100hz.
Hey Art, thanks for your wisdom 🙂 I think I understand what you mean. I made a quick comparison in hornresp between a high and low tuned port (see attached images). It seems the low tune is slightly more efficient from 45-55hz, but the high tune is much more efficient from 55-80hz. I guess we determine overall efficiency by area under the curve? In that case the high tune wins?
So basically a tapped horn with a rear chamber? Similar to a Cubo? In that design I like that you can flip the driver around, to alter the tuning.
Another thought I had, was that I could tune it high, for high spl duty, and then just plug one of the four ports to tune it lower, when high spl and efficiency is not necessary.
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Hofmann's iron law: low, efficient, small, pick two.
Since you pick a small chamber, the lower tune only exceeds 10% efficiency from 50-60Hz, while the higher tune exceeds 10% efficiency 55-70Hz.
Similar to a Cubo, or the mid 1980s EV SH-1810L-ER, seems too much of the small box is given up to the offset horn, sacrificing low end for mid-bass efficiency.
You get to choose the efficiency ratio between the ranges.
It may be modeled like that, though what I described is an offset horn sharing the bass reflex port, making the volume occupied by the driver available to the bass reflex chamber.
The driver volume reduces the port's center volume, creating a "venturi port" in the slot/offset horn.
Art