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Sigberg Audio: Building a "design" subwoofer that actually sounds good

sigbergaudio

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#1
@carlob mentioned that my subwoofers looked interesting and suggested I created a thread to share a bit more information, including of course objective measurements. I'll start out with a more subjective / informative post to share a bit about the product and concept, then I'll add an additional post with some measurements. I did a lot of measurements during prototyping and designing these subwoofers, but actually lost most of it due to a hardware failure, but I plan to do new measurements soon. Did some today for the 10" version (see next post), I currently don't have a 12" version set up here, but will get back to that.

The goal of this post isn't (just) to advertise for the subwoofers, but to share a bit about the thinking behind it and and be as open as possible about the process, hopefully it's interesting to some. I have product management / development background, and wanted to use startup / Lean / Agile principles when launching this, so everything has been done at a very small scale and quite quickly. I opted for "standard" but high quality components, but are looking into custom drivers etc now.

So what so special about this product?
I know a lot of you are all about massive subwoofers and maximum SPL, this is not what this product is about. The design goal was to build a subwoofer that could easily blend into modern interiors (as in high WAF / not having to sneak it past your significant other) while providing accurate sound reproduction and realistic sound pressure (defined as 105db peak at listening position) in a normal living room. This resulted in a subwoofer with an unusual form factor (very shallow enclosure), and support for wall mounting. As it sits very low on the floor it doesn't take up much visual space, and could even be hidden below couches or other furniture. The included damping feet uses an M8 mount, which means you could theoretically replace them with furniture feet and pretend it's a coffee table. It could also be wall mounted anywhere you please, either hidden behind something or visible. There are two versions, almost identical in size, but differes in drivers and amp. I chose high quality components (Hypex and Scan-Speak), and the cabinet was designed and prototyped over several months based on driver parameters, measurements (both response and vibration tests) as well as tight collaboration with one of the best cabinet builders in Norway, who have built hundreds of custom subwoofers and loudspeakers including horns, typically massive stuff for custom home theaters. It resulted in the following two models:

INKOGNITO 12:
  • 12" scan-speak driver (down-firing / towards wall)
  • Hypex FA501 (500W rms)
  • Sealed enclosure
  • 650x540x170mm (+30mm for feet/wall mount)
  • ground plane: 23-160hz
  • typical in-room: 18-160hz
INKOGNITO 10
  • 10" scan-speak driver (down-firing / towards wall)
  • Hypex FA251 (250W rms)
  • Sealed enclosure
  • 650x540x155mm (+30mm for feet/wall mount)
  • ground plane: 25-160hz
  • typical in-room: 20-160hz
They both sound very similar and have very similar frequency responses, but the 12" version has ~3dB higher max SPL.
They are currently available in flat white and flat black. The cabinets will be built in England by a company with loudspeaker and subwoofer cabinets for B&W, KEF, REL and Meridian (among others) under the belt, while the final assembly and testing is done in Norway.

Other design considerations:
I spent the majority of listening tests using music, as my accurate reproduction of music is very important to me. Not surprisingly, this means it also works well for movies, within it's SPL capabilities of course. It has three DSP settings, one that goes deep, one with somewhat less low end lift, and also more aggressive high pass filter, which will allow you to play ~3dB louder without significant distortion. The subwoofers also have active limiters which means you don't have to worry about the drivers crashing and burning. In practice it's almost impossible to bottom out any of the subwoofers in a normal living room situation with music, but movies with lots of low end content will of course challenge the low end capability when played very loud. The assumption was that most customers in the market for something like this rarely played at extremely loud levels, and would value accurate sound and the ability to have a subwoofer that blends in visually over maximum SPL.

Room coupling
A I guess not scientifically proved idea is that having the driver facing close to a wall or floor will reduce the room node problems for that specific plane. I don't have any other proof for this than measurements and listening tests and anecdotal evidence from testers (see below). But my impression is that the fact that both the driver is very close to the floor/wall, and the entire enclosure also is very shallow, somehow reduce issues with room nodes. I get less room interaction with this subwoofer than a regular sealed subwoofer at the same position. It also works very well half way up the wall (even less nodes triggered).

Customer feedback
I've been running a test pilot program for a few months now where people could borrow a subwoofer (or even two) for free, in return for giving me feedback on the product. The general feedback is that they sound very accurate and precise with very good low end extension. A very consistent feedback is also that they integrate very well and easily with the main speakers, feeling like a natural extension of the speakers. Just the other day the 12" subwoofer was tested in a Norwegian hifi magazine receiving 5/5 stars, again commenting specifically on ease of integration. Conclusion: "The sound of Sigberg Audio Inkognito 12 is deep, powerful and impressively controlled - and it's never been easier to integrate a subwoofer with your main speakers." - Scandinavias largest hifi magazine currently has a subwoofer for testing as well, due out in September.

Check out https://www.instagram.com/sigbergaudio/ for pictures and also some behind the scenes / build picture, showing internal bracings etc.

avstivninger2.jpg

svart-large.jpg

vegg-1.jpg


Next post: Measurements.
 
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sigbergaudio

sigbergaudio

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Thread Starter #2
sigberg10-ute.jpg

Inkognito10-inroom.jpg

sigberg12-ute.jpg

inkognito12-inroom.jpg


Above is groundplane/in-room frequency response for both speakers.

Due to some unfortunate data loss this summer I lost a lot of the measurements done during development (REW saved measurements locally and my cloud backup somehow wasn't setup to save that area, and then my laptop died..), but I did some quick compression test and CEA2010 testing of the 10" version today (all 12"s I have is either in disassembly or out on load through my test pilot program, but will get to that later).

cea2010-inkognito10.png

Measurements was done at 1m, so calculated the 2m since that seems to be the norm. This was done outside, so room gain will of course give a better result in the low end in a living room situation. The results is pretty much as expected within my design goals with these subwoofers.


inkognito10-compressiontest.jpg

In the loudest measurement in the compression test above the distortion below 25hz was a bit high, so I didn't push it further. As the CEA2010 test shows, it can go louder in higher frequencies. Note that this is the smallest of the two subwoofers. The larger one has 12" instead of 10" and double the amplifier power.
 

bigjacko

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#3
Interesting subwoofer with shallow box! Does placing the subwoofer down firing create issues on the compliance of subwoofer? Like does it make subwoofer's compliance loose or asymmetry?
 
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sigbergaudio

sigbergaudio

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Thread Starter #4
Interesting subwoofer with shallow box! Does placing the subwoofer down firing create issues on the compliance of subwoofer? Like does it make subwoofer's compliance loose or asymmetry?
Not sure I understand exactly what you mean, but the driver itself doesn't suffer from being upside down if that's what you're asking. It also does not negatively affect the frequency response if that was the question. :) Based on our testing there are no negative effects.

Would also like to point out that despite the box being shallow, the drivers are full size. Over 6kg each, and they're literally wedged against the back wall to make them fit. :)
 

bigjacko

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#5
Not sure I understand exactly what you mean, but the driver itself doesn't suffer from being upside down if that's what you're asking. It also does not negatively affect the frequency response if that was the question. :) Based on our testing there are no negative effects.

Would also like to point out that despite the box being shallow, the drivers are full size. Over 6kg each, and they're literally wedged against the back wall to make them fit. :)
Thanks for answering. I mean does the spider web that holds the driver get lose because gravity pulls it down when it is facing up or down? Or maybe gravity pulls it down even facing front? Also does it create distortion or something? Those are my main concerns, I have no experience in up or down firing orientation but curious to know would there be any problem or not.
 

carlob

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#7
The only issue I see for wall mounting is that with a subwoofer (or more) you never know what the optimal position is. You make a subwoofer crawl and end up where it measures best, it would be great if you could put it everywhere so you could prepare cable ducts etc.
 

carlob

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#8
Another thing that I hate of subwoofers is cabling, you got to have cables around and I hate seeing them.
 
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sigbergaudio

sigbergaudio

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Thread Starter #9
Thanks for answering. I mean does the spider web that holds the driver get lose because gravity pulls it down when it is facing up or down? Or maybe gravity pulls it down even facing front? Also does it create distortion or something? Those are my main concerns, I have no experience in up or down firing orientation but curious to know would there be any problem or not.
No, that is not a problem. There are many commercially available downfiring subs, so that's not a new concept in itself.
 
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sigbergaudio

sigbergaudio

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Thread Starter #10
The only issue I see for wall mounting is that with a subwoofer (or more) you never know what the optimal position is. You make a subwoofer crawl and end up where it measures best, it would be great if you could put it everywhere so you could prepare cable ducts etc.
Yes it's a bit more difficult to "test" a wall position, but in a living room situation many are limited in available spaces anyway, so people end up putting it where they can. One advantage with wall mounting capability is that you may be able to fit two subwoofers, one on the floor and one on the wall. Then you not only get subwoofers different places in the room, but also with different elevation. This would further help evening out the frequency response. Personally I have one nearfield on the floor next to the couch, and another on the wall behind the TV (the TV is on a TV/audio-furniture, not wall mounted), that works very well!
 
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carlob

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#11
Personally I have one nearfield on the floor next to the couch, and another on the wall behind the TV (the TV is on a TV/audio-furniture, not wall mounted), that works very well!
Have you measured that setup? I actually have two ugly svs sb2000 pro which are ok but I was hoping for better measurements (I have only the front wall available, can't put them around)
 
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sigbergaudio

sigbergaudio

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Thread Starter #12
Have you measured that setup? I actually have two ugly svs sb2000 pro which are ok but I was hoping for better measurements (I have only the front wall available, can't put them around)
sigberg-10-10.jpg


Here's one, both subwoofers in this measurement are the 10" versions. One on the floor to the side of the listening position, and one on the wall between the main speakers. I have a null in this room at around 22-23hz as you can see. So the response from the subs extending quite smoothly below 20hz, but that null messes up the graph a bit (not really audible).

This setup sounds very tight and punchy.
 

Hemi-Demon

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#13
Wow that looks amazing. Would you mind posting more pics here, as I can't see them on instagram for some reason.
 
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sigbergaudio

sigbergaudio

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Thread Starter #14
Wow that looks amazing. Would you mind posting more pics here, as I can't see them on instagram for some reason.
Thanks. There are some pictures on the website as well. But here are a few more. Under a sofa, living room, two in a dedicated cinea, one of them shows the back and the wall mount (included) as well. It's one part that attaches to the subwoofer, and then two wall mounts that the subwoofer then slides into. Then some random pics. :)

D6C93BC4-E035-485B-99CD-7A87EF978DDA.JPG

rubiconlcr.jpg

dobbelsubihjemmekino.jpg


forside2.jpg
IMG_2896.jpg
vegg-2.jpg
 
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sigbergaudio

sigbergaudio

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Thread Starter #16
Pricing and availability plans for the US?
Currently we only have a direct sales model, and with the current margins there's not really room for a distributor model - and there are no plans for the introduction of distributors either. Hard to tell right now if that will change.

Purchases are however open world-wide as we speak. Rough USD prices (exchange rate will vary):

Inkognito 10 (so the 10" version): ~2270USD + shipping and import tax/customs.
Inkognito 12 (so the 12" version): ~2650USD + shipping and import tax/customs.

Shipping to Europe: flat fee of ~115USD
Shipping to the rest of the world (so including USA): flat fee of ~170USD

So 2240USD for 10" and 2790USD for the 12" including US shipping then. Import taxes/VAT is on you.
 

Duke

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#20
Very nice, sigbergaudio! I think your tucks-under-furniture form factor fills a niche (literally as well as figuratively). Especially since you aren't compromising along the way.
 
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