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Using four bass guitar drivers to build a dual opposed subwoofer project

ppataki

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Even the title is unorthodox :)
I have recently built a dual opposed subwoofer (DOS) for my home office which was a hugely successful project for me. Once it was done I have taken it downstairs in my living room and started playing around with what I can do with two subs instead of just one...
The result was mind-blowing. I could bring my (room gain induced) -3dB point from 22Hz to 18Hz (or literally to 5Hz but I set Dirac to cut it at 18Hz to be more realistic, see below)

1724342918689.png


Step response got better too:

1724343179913.png


(note: I have not used Dirac Live Bass Control to optimize the two subs, I have done that manually and then Dirac 'saw' them fully integrated into my 4.0 sphere speakers. Later on I might try DLBC too but last time I tried it a few years ago it had a terrible sound...)

So in the light of the above I have decided that I will definitely need another subwoofer in my living room - so this project came to life!

Due to space and wife concerns I had to stick to 8" drivers only - I decided to go for four instead of two to increase cone surface area
I could have gone for the same model that I used in my home office sub project (Lavoce SSF082.00L 8-ohm drivers) but this time and I wanted to experiment with something more unorthodox and after a discussion in another thread here I have opted for bass guitar drivers, the Lavoce NBASS08-20.

I will be able to drive the four speakers with ~500W of power using a Sabaj A30A FDA
At 500W I will get 100.6dB SPL at 1 meter

1724344137074.png


Cone displacement shall be at 80% of the xmax so hopefully distortion will not be an issue

1724344180862.png


The (sealed) cabinet will look like this:

1724344329007.png


Another interesting experiment is the cabinet material - after my sphere projects I definitely wanted to use bamboo again
I turned to wizard IKEA again and chose this: https://www.ikea.com/us/en/p/laemplig-cutting-board-bamboo-00309829/ (I will need 5 of these to make the above cabinet)

Some photos about the drivers:

20240822_111544.jpg


20240822_111556.jpg


20240822_111613.jpg


These are my first neodymium magnet drivers ever; it is kind of funny how tiny and lightweight the neodymium magnet is (the whole speaker weighs only 1.2kg....)

I have tested them for motor noise and I am happy to confirm that they shall be fine - except for one of the four that has a manufacturing defect (more noise), I am sending that one back and ask for a replacement

Next update shall come in September, stay tuned!
 
Even the title is unorthodox :)
I have recently built a dual opposed subwoofer (DOS) for my home office which was a hugely successful project for me. Once it was done I have taken it downstairs in my living room and started playing around with what I can do with two subs instead of just one...
The result was mind-blowing. I could bring my (room gain induced) -3dB point from 22Hz to 18Hz (or literally to 5Hz but I set Dirac to cut it at 18Hz to be more realistic, see below)

View attachment 387973

Step response got better too:

View attachment 387976

(note: I have not used Dirac Live Bass Control to optimize the two subs, I have done that manually and then Dirac 'saw' them fully integrated into my 4.0 sphere speakers. Later on I might try DLBC too but last time I tried it a few years ago it had a terrible sound...)

So in the light of the above I have decided that I will definitely need another subwoofer in my living room - so this project came to life!

Due to space and wife concerns I had to stick to 8" drivers only - I decided to go for four instead of two to increase cone surface area
I could have gone for the same model that I used in my home office sub project (Lavoce SSF082.00L 8-ohm drivers) but this time and I wanted to experiment with something more unorthodox and after a discussion in another thread here I have opted for bass guitar drivers, the Lavoce NBASS08-20.

I will be able to drive the four speakers with ~500W of power using a Sabaj A30A FDA
At 500W I will get 100.6dB SPL at 1 meter

View attachment 387978

Cone displacement shall be at 80% of the xmax so hopefully distortion will not be an issue

View attachment 387979

The (sealed) cabinet will look like this:

View attachment 387980

Another interesting experiment is the cabinet material - after my sphere projects I definitely wanted to use bamboo again
I turned to wizard IKEA again and chose this: https://www.ikea.com/us/en/p/laemplig-cutting-board-bamboo-00309829/ (I will need 5 of these to make the above cabinet)

Some photos about the drivers:

View attachment 387983

View attachment 387984

View attachment 387985

These are my first neodymium magnet drivers ever; it is kind of funny how tiny and lightweight the neodymium magnet is (the whole speaker weighs only 1.2kg....)

I have tested them for motor noise and I am happy to confirm that they shall be fine - except for one of the four that has a manufacturing defect (more noise), I am sending that one back and ask for a replacement

Next update shall come in September, stay tuned!
Is that driver response really as smooth as the graph suggests all the way up that high?
 
Is that driver response really as smooth as the graph suggests all the way up that high?
No, definitely not - that is just a simulation (which is otherwise pretty reliable where it matters: in the low end)

This is the official manufacturer-published response:
1724347939645.png

It shall be smooth till about 1000Hz
 
Is IKEA really the best / cheapest place to get bamboo boards?

Otherwise I think this looks like a really interesting project. Honestly would not have expected bass guitar drivers to have that much output down around 20hz.
 
Is IKEA really the best / cheapest place to get bamboo boards?
To be honest, I don't know
But I went to IKEA and checked these out - they really look like almost 100% bamboo (btw. officially they are 100% bamboo, not just the outer layers) and they are super-solid and super heavy
We shall see! :)
 
No, definitely not - that is just a simulation (which is otherwise pretty reliable where it matters: in the low end)

This is the official manufacturer-published response:
View attachment 387993
It shall be smooth till about 1000Hz
That’s still not bad for a subwoofer. I like shallow crossover filters so I’m usually as interested in the out of band response as I am the in-band response.
 
Not sure those drivers are right for a sub. The only bass cabs with 8" drivers are the small practice amps, most of which don't have much below 60hz. There usually built for durability and power handling, not distortion. That raw driver has a fc of 100hz how low can it go in a box?
 
Not sure those drivers are right for a sub. The only bass cabs with 8" drivers are the small practice amps, most of which don't have much below 60hz.
Well, if you have 4 of them, it helps a lot. They can take a bit of power as well, that helps also. But no, these are not drivers ideally suited for subwoofer duty. A closed sub only needs excursion and surface area. The others things are just details that dictate how efficient it is. In this case, not very efficient. Of concern may be that the driver needs to operate quite a bit below its fs. Not all drivers are very happy doing this.
 
Not sure those drivers are right for a sub. The only bass cabs with 8" drivers are the small practice amps, most of which don't have much below 60hz. There usually built for durability and power handling, not distortion. That raw driver has a fc of 100hz how low can it go in a box?
This driver has an Fs of 55Hz, the one I mentioned I tried before has an Fs of 52Hz and it measures like this in a cabinet
I agree it looks weird but we shall see - I will of course share the measurements once I get there
 
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There is a small update: today I have procured the cabinet materials (all from IKEA)

1000008961.jpg


On the right-hand side you can see 16.5 kg of bamboo and on the left-hand side you can see the future 'beauty' front and rear panels

I hope that we can start the build with my neighbor in the coming weeks
 
Consider buying another saw blade. Bamboo is really rough on tools
 
There is a small update: today I have procured the cabinet materials (all from IKEA)

View attachment 389436

On the right-hand side you can see 16.5 kg of bamboo and on the left-hand side you can see the future 'beauty' front and rear panels

I hope that we can start the build with my neighbor in the coming weeks
What are the front panels made of? (Pic on the left)
 
Finally some progress has been made :)
My neighbor who is the BCotW (Best Carpenter of the World) had some COVID hence the delay

20240917_190500.jpg


20240917_190517.jpg



Next steps will include finishing the inside, doing the paint job and mounting the drivers, cabling, terminal and the bottom spikes
Stay tuned!
 
A little bit more progress today:

20240918_200709.jpg


20240918_210355.jpg


Both the vibrodamping and the felt treatment are done

And a little knock-knock for fun:
I have built quite many speakers already but this sounds pretty remarkable (no bracing whatsoever yet!)
 
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