DIY Sealed Subwoofer
- Thread starter aeroash
- Start date
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Absolutely not! To achieve the same level of incompetence one has to build with his beverage of choice.
Here's a pro tip to build a great subwoofer, make sure you cover your drink while sanding.
Crown! I'll have to procure one.
Vineethkumar01
Well-Known Member
Here is the anechoic response of the Sub at the moment (along with impedance plots)
Compared to the previous measurements, the wiggles around 80Hz seems to be much benign.. This time the measurement was taken at a different location of the sub.
Tried to do a room mode identification simulation. Here is the result
So there does deem to be a room mode caused by the room height dimension exactly around the 80Hz region.
The impedance plot, even much more zoomed in doesn't indicate any 80Hz issues with the sub. So it seems like even the nearfield measurement is picking up the room mode contribution and thr sub is fine as such. The wiggles in impedance and frequency response around 260 Hz are anyway expected due to the box modes in thr sub contributed by the width and length dimensions of the sub being the same. Another contributer to that wiggle is probably the Surround resonance of the driver itself. But all that being outside thr passband of usage of this sub may not matter much anyway..
Compared to the previous measurements, the wiggles around 80Hz seems to be much benign.. This time the measurement was taken at a different location of the sub.
Tried to do a room mode identification simulation. Here is the result
So there does deem to be a room mode caused by the room height dimension exactly around the 80Hz region.
The impedance plot, even much more zoomed in doesn't indicate any 80Hz issues with the sub. So it seems like even the nearfield measurement is picking up the room mode contribution and thr sub is fine as such. The wiggles in impedance and frequency response around 260 Hz are anyway expected due to the box modes in thr sub contributed by the width and length dimensions of the sub being the same. Another contributer to that wiggle is probably the Surround resonance of the driver itself. But all that being outside thr passband of usage of this sub may not matter much anyway..
Polyfill stuffing to experiment. I kept stuffing in half a kilo increments and measuring until I achieved a smoother response. I ended up stuffing 3 kilos. @Vineethkumar01 will share the plot later. The sub appears to be sounding a tad softer than without the stuffing. I'm undecided if I like the sound with or without the stuffing. It's going to be a lengthy session of munching peanuts.
I have gated the polyfill at the driver niche with a mosquito net. This serves two purposes:
1) To keep the mosquitoes from getting into the stuffing, or, keep the mosquitoes already in the polyfill from escaping!
2) To keep the stuffing safely away from the driver.
I have gated the polyfill at the driver niche with a mosquito net. This serves two purposes:
1) To keep the mosquitoes from getting into the stuffing, or, keep the mosquitoes already in the polyfill from escaping!
2) To keep the stuffing safely away from the driver.
keith_correa
Well-Known Member
You will need to scallop the inner edges of the driver cutout on the baffle.
Vineethkumar01
Well-Known Member
In this case with a 15inch woofer, is it needed..?
There is a lot of area available for airflow already I think..
Vineethkumar01
Well-Known Member
Here is the frequency response and impedance measurement comparison before and after stuffing with 3kg polyfill
Important observations:
1) Lowering of tuning frequency: New impedance plot with stuffing shows that the current box tuning frequency is around 37Hz instead of around 41Hz earlier without stuffing. As a result the frequency response also slopes down more gradually now.
2) Supression of the 260 Hz box mode: Stuffing has sort of eliminated the box modes around 260 Hz which were there earlier.
3) Reduction in driver efficiency around tuning frequency: The impedance peak has become a low Q resonance instead of the higher Q peak without stuffing. Now more power will be needed to reach the same volume levels as before.
With a high order crossover (4th order) low pass filter around 80Hz, the 260Hz resonance may not be a problem though. And how it will all sound like will depend on the room and the location of the sub in it. The advantage of present box tuning is that one may be able to use the sub up to higher frequencies.
Ultimately it is up to one's personal preference which tuning will sound better..
So take time, evaluate and decide...
Important observations:
1) Lowering of tuning frequency: New impedance plot with stuffing shows that the current box tuning frequency is around 37Hz instead of around 41Hz earlier without stuffing. As a result the frequency response also slopes down more gradually now.
2) Supression of the 260 Hz box mode: Stuffing has sort of eliminated the box modes around 260 Hz which were there earlier.
3) Reduction in driver efficiency around tuning frequency: The impedance peak has become a low Q resonance instead of the higher Q peak without stuffing. Now more power will be needed to reach the same volume levels as before.
With a high order crossover (4th order) low pass filter around 80Hz, the 260Hz resonance may not be a problem though. And how it will all sound like will depend on the room and the location of the sub in it. The advantage of present box tuning is that one may be able to use the sub up to higher frequencies.
Ultimately it is up to one's personal preference which tuning will sound better..
So take time, evaluate and decide... It does appear sharp. But, any particular reason?
Decadent_Spectre
Well-Known Member
May have missed this but what driver is being used?
Vineethkumar01
Well-Known Member
It is the SB acoustics Sb42fhcl75-6 15inch driver
keith_correa
Well-Known Member
Better airflow. Take a sanding drum to it and except at the area around the mounting screws, give it a good angle.
Decadent_Spectre
Well-Known Member
I think for the price a much better driver could be had...
It is a consumer driver and the xmax is low, there is no point. Should have bought a equivalent price 21" pro driver. Just my opinion of course.
Enjoy the sub.
Vineethkumar01
Well-Known Member
If it was me, i would have bought atleast an 18inch pro driver of suitable specifications and used it in the smallest possible box for the application and tuned it via DSP.
But for the OP, this is a first speaker/sub build. He wanted the least complexity of build and usage with low to modest SPL levels and the constraint of only using a 15inch driver. I think even though this driver is not the best available, it is a decent enough one that may suit his requirements. Hence this build..
Also the DIY journey has only started for him an I believe he has put his best efforts in this one.. Who knows, may be he will build a few 21inch subs in future..
Decadent_Spectre
Well-Known Member
If it was me, i would have bought atleast an 18inch pro driver of suitable specifications and used it in the smallest possible box for the application and tuned it via DSP.
But for the OP, this is a first speaker/sub build. He wanted the least complexity of build and usage with low to modest SPL levels and the constraint of only using a 15inch driver. I think even though this driver is not the best available, it is a decent enough one that may suit his requirements. Hence this build..
Who knows, may be he will build a few 21inch subs in future..
Building a sealed box is much the same, 15 or 21. The DSP can be omitted, yes a pro driver would have a higher FS but the measurements don't show a lot of extension. Paying around 40,000 for this driver seems very excessive to me, all I am saying is for the money a better driver could be had. Using it in too small a box brings its own problems, I think like with most things some middle ground is good unless space is at a premium. If I read the spec sheet correctly the xmax is about 11mm, that's just a touch more than the ubiquitous 2226H which is a woofer, not a sub. If SPL was not a concern I do wonder if some off the shelf woofer would have sufficed, if the point was a DIY build then for a first try its good. All the best.
Yelamanchili manohar
Well-Known Member
That is one awesome and beautiful looking build
Hearty congratulations, very well done
As an old git, let me point out for the benefit of younger DIY subwoofers builders, that it is absolutely necessary to get a combination of certain things really right to succeed at a sub woofer build.
Old monk should always be had with thumsup or coke, followed by a biryani.
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What driver, and internal volume, approximately? I could keep this info handy, just in case
The desire is strong to replace my two Rythmik 12" subs after what I have witnessed with this build. I tried one of the Rythmiks in the current room, and the 15" sub trumps it.Who knows, may be he will build a few 21inch subs in future..
I love the sub we built, It not only fits my requirement perfectly but has exceeded my expectation, so the mission is more than accomplished! thanks to you!
Here's how the sub measures at the MLP, with a little help from ARC to tame the peaks.
The sub has nicely settled in. The magical crossover point was found to be at 85hz.
If I were to describe the sound in one word, it would be PLUSH! It's soft room-filling bass, that's not overbearing nor offensive. The punch is just right. Soft sound is not to be confused with slow or flabby. The bass is tight, and fast and has a texture that is just "different", in a good way.
My listening levels usually don't cross 70db, but I have been enjoying this sub so much that I constantly find myself cranking the volume away, and it's still that same room-filling bass that thumps your chest gently, and in no way offensive even with the loudness. I'm amazed at how well it blends with the small bookshelves, and remain consistent at all volume levels.
Movie watching in my stereo setup has now taken a theatre-like feel. The whoosh of the arrows, the slam of the doors, the swish swashing of swords, and the thunderous footsteps of giants, are now an immersive experience. Dynamic visual scenes are not just eye candy anymore, they're properly felt and experienced.
Here's where they lay. The Lumina's mid-woofer is 4.5", for comparison.
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I can relate, when I introduced a basic Rythmik to my small Spendor set-up, the whole experience went up a notch. There was an acrimonious discussion on whether high level or low level connections were the best yada yada (some guru quit the forum in a huff based on my responses etc.) and what is audiophile and what is not, but nevertheless I have been enjoying the system tremendously since, and I wish you the same listening pleasure.
Cheers,
Sid
Cheers,
Sid
There are a few 'High' level connections to this beautiful build too.
My kind of bass.
And just to verify that the sub is in time with your bookshelves, listen to the track Beyond the Sea by Robbie Williams live at Albert Hall with a superb big band. Not the studio recorded album. I am talking about the live concert.
You should hear the rhythm and percussion sections playing perfectly in time at the start of the song.
Sooooo many speakers costing lacs and double figure lacs fail this simple simple test. And surprisingly most 3+ way speakers i have heard fail miserably. One kind of gritts and bears it for a few minutes and one then switches tracks or walks away knowing I will never ever put money on the product.
Try it out if you can.
Manek
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