My son and his friend have been pranking me with bassreflexboxes for my birthday.
Since I hate helmholtz like I hate root-canal work, I had to take a gruesome revenge on them.
With the help of Hornresp I tried to get as many functional pieces of PVC pipes into one box as possible, and a symmetrical loaded 8th order band pass box was definitely the way to go.
Thanks to David McBeans excellent program Hornresp, designing the 8th order BP was a pleasant stroll in the park.
Spl and phase.
THD.
Groupdelay.
Lots of PVC pipes.
The measured response does not match the simulation very well, but I don´t have reliable data on the driver and I know the volumes of the chambers is off by a few liters. It is close enough for me to view this as a success.
I did not expect much performance from one cheap car audio driver and 6 pieces of PVC pipe, but I am blown away by the performance.
It is clean, powerful and loud, way beyond my expectations. Port-noise becomes noticeable at about the same time as the whole house rattles and buzzes violently. The steep acoustic bandpass filtering really lowers distortion from the driver.
This is an extremely surprising level of performance from a 60 dollar subwoofer-build.
GAS BEAT124 | GAS | Billjud | Brl.se
A very cheap bass driver. Surprising performance once you filter out all the distortion with steep acoustic band pass filters.
Lots of fun. It is quite large, but if you have the room for it it seems to be a very nice home theater sub with a very physical and tactile bass reproduction.
My "gruesome revenge" turned into a surprisingly nice budget subwoofer.
Cheers,
Johannes
A very cheap bass driver. Surprising performance once you filter out all the distortion with steep acoustic band pass filters.
Lots of fun. It is quite large, but if you have the room for it it seems to be a very nice home theater sub with a very physical and tactile bass reproduction.
My "gruesome revenge" turned into a surprisingly nice budget subwoofer.
Cheers,
Johannes
- extremely cool project and a fine build !!!! 😀 - will have to look for woofers to fit your build - that's a nice size
- AH - the MCM DVC 12 used by Marshall Leach fits nicely
- AH - the MCM DVC 12 used by Marshall Leach fits nicely
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Could you make it for a 8” or dual 6” drivers?
Are you going to post the diy plans for the box? Really cool build
Also what’s the size of the tubes and how long are they?
I guess I asking about plans for this box and maybe I can reduce the size to use smaller drivers.
Thanks for showing us your unique build
Are you going to post the diy plans for the box? Really cool build
Also what’s the size of the tubes and how long are they?
I guess I asking about plans for this box and maybe I can reduce the size to use smaller drivers.
Thanks for showing us your unique build
It's a high-order bandpass alignment. I'd strongly recommend simulating in Hornresp before trying to re-size and drop random drivers in there. Doing that guarantees you'll get performance that's equally as random.
The software is free - all you need is time.
That's a cool build, Johannes!
Now I want to try something similar myself.
Chris
Looks like a B0$3 dumbed down version of the unique looking 8th order Karlson K15, which is too when limited to 2-2.5 octaves like yours, though of course harder to build. 😉
Then again, with minor mods could mimic its 'look'.
😀GM
MCM's old but good spec DVC woofer (used by the great - late Marshall Leach whose work which helps fuel hornresp) looks decent as a drop in. For a new build, a 6th order series BP would be easier to tune. I think series 6th are easier to tune than parallel vent 6th BP. For a given bulk I remember a series BP could use equal volume chambers while parallel ran 2:1 ratio. (the Karlson ran 2:1 except for the klam which were 1:1) 20yr ago I had a 10" Madisound DVC in a BP6A - probably ~ 35 liter per chamber and it graphed -3dB @ 28Hz/110Hz.
that MCM DVC 12 is s good driver - imagine its xmax is around 5mm but would have to search the internet. Newark doesn't seem to post its specs.
that MCM DVC 12 is s good driver - imagine its xmax is around 5mm but would have to search the internet. Newark doesn't seem to post its specs.
Have any of you seen the muse model18 sub? It’s a 6th order bandpass box. It’s very large at something like 26”x26”x26 and 155lbs. I have one here in my house and really don’t use it much. Something wrong with the amp. When I turn it off it makes some very nasty pops and crackle sound
Is the muse anything like what you guys are talking about?
It’s the one on the bottom, the top is a SVS 12” ported model. A very old sub
Is the muse anything like what you guys are talking about?
It’s the one on the bottom, the top is a SVS 12” ported model. A very old sub
I guess the woofer is somewhat entombed (?) - but that provides good protection against UV. at age 68+ don't know why I even worry about foam surround longevity 😱
Not me.
6th order has one less chamber than 8th order, but otherwise should be functionally the same.
GM
The outer dimensions of the box is 95 cm X 49 X 60,4 cm.
The chambers are 36 cm + 15,4 cm + 36 cm. The walls are a mixture of 19 and 22 mm particle board.
The PVC pipes are 110 mm outer diameter and 3 mm wall thickness.
It was an extreme low budget build. We built it as a joke, but the joke turned out to be on us. It was meant to be an example of how not to build, but it ended up being much nicer then we anticipated.
Cheers,
Johannes
The chambers are 36 cm + 15,4 cm + 36 cm. The walls are a mixture of 19 and 22 mm particle board.
The PVC pipes are 110 mm outer diameter and 3 mm wall thickness.
It was an extreme low budget build. We built it as a joke, but the joke turned out to be on us. It was meant to be an example of how not to build, but it ended up being much nicer then we anticipated.
Cheers,
Johannes
If one took the $38 MCM DVC 12 and made a two (equal volume) chamber BP6 - it might look like so vs your 8th order
https://i.imgur.com/DmWkqJH.jpg
https://i.imgur.com/DmWkqJH.jpg
The fun thing with the 8th Order BP is that you can mix Helmholtz and Quarter Wave as you wish.
Here is strange hybridization between QW and Helmholtz, where the first and last section is Quarter Wave and Chamber 2 is Helmholtz.
It makes it easier to design and build, since Chamber 2 is much more flexible in its layout then if it where a straight pipe QW section.
It is a ROAR but with a Helmholtz coupling the driver to the large front resonator in the midbass.
Here is a crude sketch of what I had in mind.
It is not to scale in any way. It is just a crude simple sketch to show how to combine Helmholtz with quarter wave in a 8th order BP.
Improved filtering of transducer direct sound due to chamber 2 and porting function, improved timing between HH (chamber 2) and QW segment (chamber 1) due to resonance buildup delay in the port, improved end aperture QW segment (chamber 3) efficiency due to a less disrupted base surface (chamber 2 ported baffle).
Spontaneous thoughts while being severely sleep depraved due to a 3 months old son and the worst heatwave seen in Sweden in over 200 years...
Spontaneous thoughts while being severely sleep depraved due to a 3 months old son and the worst heatwave seen in Sweden in over 200 years...
Is he ill or ? Don't get much in the way of international weather, so wasn't aware of the heatwave; guess the local weather folks didn't see much 'newsworthy' in temps we live with much of the year.
GM
it's north of us, but thanks for asking, it has been (and is) pretty bad when viewed on a Swedish scale, I have lived in Maastricht and it could get pretty evil there in the summers but you sort of expect it to be, our homes are built for a far colder climate on average, they are designed to keep heat in which does not exactly help matters in these conditions.
Sorry for the OT but sleeping is sort of a luxury under "normal conditions" with a 3 month old, but for the last three months or so that this blasted heat has prevailed the luxury has transformed into high connoisseur territory... 🙂
...and just to prove Maxwell's law* late last night we got an emergency issued SMS telling us to close all windows and kill the ventilation due to the close proximity of a fire in a factory, talk about the the perfect set of circumstances...
*/ Maxwell's law is a extrapolation on the well known Murphys law, which if simplified stated that the most likely outcome of any given scenario is always the most annoying one, Maxwell's law extrapolates on this and correctly states that "Murphy was an optimist".
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@GM - on an international scale our "heatwave" would not even register, thats the hard facts of things, we are just simply not accustomed to these temperates (35C / 95 F) for that long, thats all, just a bit of good old fashioned Swedish complaining happening here.
But enough about that, let's hear more about these horrendous porting adventures 🙂
But enough about that, let's hear more about these horrendous porting adventures 🙂