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Development thread: High-end dual opposing 10" subwoofer: Sigberg Audio 10D

A couple of quick pics of the white version too. The original plan was white grilles, but now I'm not so sure. The black grille makes it look smaller / more narrow when seen from the front like in the second picture, which I guess is a good thing.


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Just out of curiosity, what is the reason for having the 9 holes drilled through the box in picture #3 immediately above? I can't quite tell what I am looking at.
 
You haven’t considered to bolt the drivers together as this Elac sub?

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Just out of curiosity, what is the reason for having the 9 holes drilled through the box in picture #3 immediately above? I can't quite tell what I am looking at.

It's one of the internal bracing walls (the one closest to the front panel). The reason it has holes is so that the the space on the other side of it will still be part of the internal volume of the subwoofer, and the more holes, the less of the volume is lost due to the bracing wall. Behind it we can see dampening foam.
 
You haven’t considered to bolt the drivers together as this Elac sub?

No, not sure exactly how that will benefit things. I guess the entire structure would be even more rigid, but it's already plenty rigid, and due to the dual opposing design there are next to no vibrations. Do you have a link to this subwoofer so I can read what their reasoning is?
 
From mechanical point the reason would be that the inertial reaction forces of the 2 woofers cancel each other out directly via the stiffer chassis structure and not via the usually less stiff detour patch through the enclosure, that depends of course also on the stiffness of the enclosure and how much the differences are measurable and even more audible, which is another story...
 
From mechanical point the reason would be that the inertial reaction forces of the 2 woofers cancel each other out directly via the stiffer chassis structure and not via the usually less stiff detour patch through the enclosure, that depends of course also on the stiffness of the enclosure and how much the differences are measurable and even more audible, which is another story...

We try to focus on things that has an effect. For instance, we did quite extensive vibration measurements on our current Subwoofer series (the slim Inkognito subwoofers), as we wanted to keep the weight down (it supports wall mounting). We found that good bracing was way more important than the thickness of the cabinet. And due to the fact that it is so slim, four of the six walls actually are very rigid to begin with since they are very short in one direction. In other words the panels are typically much smaller than on a regular subwoofer. So we could use relatively thin walls (16mm) while still maintaining a very rigid chassis.

The 10D is more traditional in form (a cube), but there there are cross bracing inside, and double baffle walls, and decoupling and dampening feet. Which means there are very little vibration to speak of here as well, even if it wasn't a dual opposing assign (which it is). I agree that the concept you refer to would probably reduce the vibration in the cabinet itself even more, but given the low level of vibrations to begin with, I question whether it would be anywhere near audible, at least in our design.
 
We found that good bracing was way more important than the thickness of the cabinet.
That is true and known also from other similar tests. On the other hand directly connecting the woofer magnets with for example metal rod doesn't weigh almost anything and gives thus an almost free improvment from vibration point of view.
 
That is true and known also from other similar tests. On the other hand directly connecting the woofer magnets with for example metal rod doesn't weigh almost anything and gives thus an almost free improvment from vibration point of view.

It's perhaps almost free from a weight perspective, but it's not free from a construction and design/development perspective. :) As a small manufacturer with limited R&D budget, our design approach is to do the basics very well (many don't) without doing too much "innovative" and expensive solutions with limited benefit.
 
our design approach is to do the basics very well (many don't)
Hope you will send your subwoofers and loudspeakers to some reviewer with very thorough measurements (like for example Erin) to see how well you do them. :)
 
Hope you will send your subwoofers and loudspeakers to some reviewer with very thorough measurements (like for example Erin) to see how well you do them. :)

It's under consideration, especially the speakers. The problem with subwoofer measurements/reviews as carried out by Erin and Amir is that it's typically based on CEA2010, which focus almost entirely on maximum output, often weighted against cost - as a result of subwoofers being used mainly for home cinema where maximum low end output is more important than size and visuals, and even sound quality.

Our subwoofers focus on size / ease of placement combined with high sound quality, with focus on music systems rather than home cinema systems. If you want maximum SPL per dollar with no other considerations, our subwoofers are obviously the wrong choice. :)

That being said we will still share the typical measurements you would get from such a review, so it will be available. Some have been shared in this thread already, will make new measurements of the pre production models. Since the cabinets are now relatively small, the low end extension will likely be somewhat less than the prototype.

Happy for @hardisj to share his thinking / approach on testing something like this (a 3500USD subwoofer that has other design goals than maximum SPL).
 
as a result of subwoofers being used mainly for home cinema where maximum low end output is more important than size and visuals, and even sound quality.
The problem is how do you define "better sound quality" and also show it via measurements on subwoofers. Personally I would like to see at least some HD, IMD and GD measurements except the usual FR ones, maybe @hardisj who has more experience with subs can his experiences there. Also I have no problems if you do all those measurements yourself as long as you do and show them (I trust also measurement of companies that give a serious impression and we have many experienced people here who probably smell if something looks too good to be true).
 
Some initial in-room response, running dual 10D (so two subwoofers) in our test room. We pushed the size of the cabinet down quite a lot, and due to those pesky laws of physics we fully expected the low end extension to take a hit. Working from a music first approach as well as favoring small form factor, this is a reasonable tradeoff.

We're nowhere near finished dialing in yet, but current in-room shows -3dB at ~24hz, and -6dB at ~20hz depending on what you pick as your reference point. The peak at 70hz is a room node.

The sound I guess is best described as tight and punchy, which is how we like it. :)


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Ground plane measurement (outside) carried out today. No smoothing.

25-200hz +/-3dB
21-250hz +/-6dB

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It looks really nice. Too bad you're all the way in Europe. International shipping and customs duties are way too expensive.

Not too far away if you are in Norway, there's a big bunch following these guys over here in Norway too, I perceive Sigberg Audio as being one of the most open, transparent and communicative in this business. There are no secrets, full openness on the design, what are the building blocks of the products, they search for input from the market during the design stage, they are very open to consumer requirements .... the list goes on and on :)

I already purchased 4 subwoofers before I heard of Sigberg Audio ...
 
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Been outside and finetuned the limiter today. So below we can see one curve that is essentially maximum output with the current configuration (red curve, @1m outdoors), and one where the limiter hasn't kicked in. So as you can see you can play up to 100dB and get the specified frequency response, and then continue up to 110-112dB, but will then get a gradually falling response below 40hz.

Also worth noting is how flat the response is within the frequency range where we find most music, roughly +/-1dB from 30-200hz.

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I didn't call it a day after the measurements yesterday because frankly it was somewhat less than expected. So I kept pushing the limiter up until the amplifier went into protection and shutdown, and then dialed it back a bit (you won't know the limit until you cross it).

This gained us an additional 2-3dB in the top end (red was the measurements posted yesterday). Again, the lowest graphs is the highest you can play without the limiter kicking in, so getting the specified frequency response. We're now at 106dB, with the -6dB point at around 23hz (100dB), so this is nearly 6dB higher than the previous measurement before low-end compression starts kicking in.

Maximum continuous output in a sweep is now more than 114dB.

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Also updated our CEA2010 table with the 10D results:
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