Tiniest 40hz Sub

Have you modelled or measured your listening room?
I would always start there as your room might have a notch at 40Hz for any suitable speaker position making it impossible for a small sub. Conversely it might have a peak there making it easy
No I haven't. The room is 3m wide, 5m long and has a slanting ceiling 2.4m tall on one side and 2.7m on the other. This will be on a corner stand against one long wall about 90cm off the ground and in a one box Bluetooth speaker type form factor
 
You can add parametric EQ, something like Fc 40Hz, Q 2.0 and +8dB while lowering the high-pass a bit. I wouldn't worry too much about modeling it exactly flat as the in-room response will throw things off anyway
Trying to get my head around this. How much amp power would be needed for a 10db boost at 30hz? The reason for asking is that I am trying to model a 23hz tuned box for testing what it will take for this OEM to play flat to 20hz. This results in a very long port, but this might be further folded beyond the simple capacity of the online ported box modeller. How is a foldback calculated for length?

Kittybass freq.jpg

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Kittybass xmax.jpg
 
The TS parameters though 😥.
Not sure about the Epique, if I remember correctly there are a few builds with passive radiators but around 12 liters link

About small subs, I built a Voxel Mini Sub (a Paul Carmody design) that has an F3 of around 35 hz in a 7 liters enclosure with a economical 5 inch driver (around 50 bucks from PE) and it rattled the windows of a small room with a cheap fosi audio amp link, it's laughably small when you have it in your hands but it does sound great
Eek! Are These things are pretty floppy if stretched to 35 hz in a ported box? Measured TS parameters suck compared to factory spec😥 I tried a T-tqwp and it was a bit ‘better’ than the BR for some reason
 

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The TS parameters though 😥.

Eek! Are These things are pretty floppy if stretched to 35 hz in a ported box? Measured TS parameters suck compared to factory spec😥 I tried a T-tqwp and it was a bit ‘better’ than the BR for some reason
Hi, with "floppy" you refer to cone movement and running out of xmax? Or you are talking about sound quality?

We have to be realistic about the limits of a medium quality 5 inch driver (is not a SEAS or anything like that) in a small ported enclosure

The idea was to give a few more hertz of bass to a small pair of speakers (Dali Spektor 2, with and F3 of around 50 hz) in a small room in a near field listening situation and it does that without any issue, will it rattle the whole neighborhood as some 4 x 18 inch setup of some guys around here? Absolutely not

Sounds very clean and way better that any cheap HT sub that you can buy for the cost of the driver + box + amp and it's a simple box so it's a very nice begginer proyect


Cheers
Alex
 
I think I used RoomSim, but it was a while ago. Try this: https://sourceforge.net/projects/roomsim/
Thanks for that,
Hi, with "floppy" you refer to cone movement and running out of xmax? Or you are talking about sound quality?

We have to be realistic about the limits of a medium quality 5 inch driver (is not a SEAS or anything like that) in a small ported enclosure

The idea was to give a few more hertz of bass to a small pair of speakers (Dali Spektor 2, with and F3 of around 50 hz) in a small room in a near field listening situation and it does that without any issue, will it rattle the whole neighborhood as some 4 x 18 inch setup of some guys around here? Absolutely not

Sounds very clean and way better that any cheap HT sub that you can buy for the cost of the driver + box + amp and it's a simple box so it's a very nice begginer proyect
I know this is addressed to someone else, but I would like to raise something regarding implications of such things re my project. I don't know enough to trust manufacturer specs, but do have the equipment to take readings. This is something I have to learn to do. The thing is that I am totally happy with my current setup but have the leisure and materials to peruse some fun and take up a silly target like 20-40hz out of an ice cream container

Mine is just a bite and see approach, so please just take in the spirit of fun DIY tinkering. I might actually get something out of this, if folks are interested in buying such cabs from me. It would be a nice support for a working retirement

Anyway, back to the test box. It doesn't gel with me to make something without a clear purpose, plus there are size implications to 4L with 23hz port. External folding results in a cab size that is similar to 8L with 23hz internal port. 8L models with higher SPL numbers and F3 of 20hz. This is about 10L external and due to port length results in some awkward boxes. So I have decided to give the awkward size a purpose. A 2.1 soundbar with full spectrum at near field. I have given it a generous 3L of extra volume for any built in satellite speakers and amps. The DS18 3.5" FR and DS18 ZR6.2D are the closest off the shelf fit drivers for this cab. I'll have some very similar subwoofers with extended upper range, but I have use for all of them

Post up some width dimensions that you folks would like me to play with in CAD
 
Hi, with "floppy" you refer to cone movement and running out of xmax? Or you are talking about sound quality?

We have to be realistic about the limits of a medium quality 5 inch driver (is not a SEAS or anything like that) in a small ported enclosure

The idea was to give a few more hertz of bass to a small pair of speakers (Dali Spektor 2, with and F3 of around 50 hz) in a small room in a near field listening situation and it does that without any issue, will it rattle the whole neighborhood as some 4 x 18 inch setup of some guys around here? Absolutely not

Sounds very clean and way better that any cheap HT sub that you can buy for the cost of the driver + box + amp and it's a simple box so it's a very nice begginer proyect


Cheers
Alex
I tried the same driver in these 2 boxes with the ~same Fb. The ‘bass reflex’ setup sounded strange when driven hard. Upon further investigation the dats v3 revealed the TS parameters where conpletely different than the manufacturer specs. (High Fs/high qts) .
 

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pon further investigation the dats v3 revealed the TS parameters where conpletely different than the manufacturer specs

Is that one of the drivers that I can try in my project? Regarding the specs, surely you wouldn't have been the first person to have used the model. I am surprised that an issue like that hasn't been picked up on already and reported back to the brand! I am sure that they would check for consistency if reported. The DS18 FR that I referred to earlier in the thread has the overview of a completely different speaker up on their site
 
I tried the same driver in these 2 boxes with the ~same Fb. The ‘bass reflex’ setup sounded strange when driven hard. Upon further investigation the dats v3 revealed the TS parameters where conpletely different than the manufacturer specs. (High Fs/high qts) .
Mine sounded nice and clean, maybe I got lucky and mine was closer to spec (or close to what Paul used for the design), but again, I did not drive it very hard, just to medium volume, and I think that the tuning of the enclosure (in the Voxel case) does not help the driver at higher volumes and that is one drawback of the design

If you want to drive it hard, go with a higher tuning or better / bigger driver and bigger box
 
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Thanks man, I tried to get some tang bands including this initially but the shipping from US is crazy unaffordable. They are not in contention for me

Is the voxel 7L net or does that include driver displacement and port volume? What is the external volume of the voxel? I think we can better that
 
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I listen to loud bass heavy dub reggae and have to say that I must have been around speakers with good ports as I have never had to remark on port noise. Even on dub with synth bass. It will be interesting to see if the 23hz port is noisy at these small volumes

One thing that I have noticed is that at such small scale, little linear changes have a large effect on volume, so shared space for electronics is a bad idea. A dedicated compartment locks the box in. Being a soundbar format, it is resembling a two segment TL at the moment

Kittybar001.jpg
 
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These are fun/interesting and after 3xFb it goes dead until 5 x Fb (you can draw it all to scale in mm to see the resonance freqs, in phase freqs and cancelations
 

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I have come up with this, does it make any sense? 998mm wide x 240mm deep x 120mm tall. Tuned to 20hz and fit for drivers from 3" to 6.5". Cab accommodates 2x 3.5" FR drivers per side. This is a distraction from my goals of a tiny 40hz sub though. Once I have this soundbar Cad model sorted, I'll get back to the 40hz one

Kittybar 20hz 001.jpg