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An adventure with 8th order BP
An adventure with 8th order BP
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Old 29th July 2018, 06:57 AM   #1
Circlomanen is offline Circlomanen  Sweden
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Default An adventure with 8th order BP

8thorderBPHornresp.JPG

8thorderBP-vsHornresp.JPG

6portar.jpg

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.
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Old 29th July 2018, 07:10 AM   #2
Circlomanen is offline Circlomanen  Sweden
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phase8thOrder.jpg

Spl and phase.

THD8thOrder.jpg

THD.

8thOrderBP-GD.jpg

Groupdelay.

merrör.jpg

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.
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Old 29th July 2018, 07:20 AM   #3
Circlomanen is offline Circlomanen  Sweden
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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.


påplats.jpg

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
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Old 29th July 2018, 08:12 AM   #4
freddi is offline freddi  United States
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An adventure with 8th order BP
- 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

Last edited by freddi; 29th July 2018 at 08:25 AM.
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Old 29th July 2018, 05:17 PM   #5
carlthess40 is offline carlthess40  United States
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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
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Old 29th July 2018, 05:20 PM   #6
chris661 is offline chris661  United Kingdom
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Quote:
Originally Posted by carlthess40 View Post
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
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
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Old 29th July 2018, 05:46 PM   #7
GM is offline GM  United States
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Quote:
Originally Posted by Circlomanen View Post
Lots of PVC pipes.

This is an extremely surprising level of performance from a 60 dollar subwoofer-build.
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
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Old 29th July 2018, 06:00 PM   #8
freddi is offline freddi  United States
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An adventure with 8th order BP
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.


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Old 29th July 2018, 06:11 PM   #9
carlthess40 is offline carlthess40  United States
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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

IMG_1529.JPGIMG_0744.JPG
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Old 29th July 2018, 06:14 PM   #10
freddi is offline freddi  United States
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An adventure with 8th order BP
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
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