New Sigberg Audio development thread: The Sentinel - A music oriented reference subwoofer

[sigbergaudio]

I have contemplated for a while to start this thread, but held off since it still early days - so this will bring you guys on board with the product development journey at the earliest stage so far (compared to the other development threads).

Quick background:
I've been thinking about a larger subwoofer for at least a couple of years, and at least since the Manta was launched back in 2023. To start to match the output of a pair of Mantas (not that anyone plays that loud), you need at least four of our current 10D subwoofers. I am very happy with our subwoofers, and there's no plan to build anything that compete with large, ported home theater subwoofers. That being said, I think there is room in the portfolio for a larger subwoofer than the current offerings.

Basic design targets / constraints:

• Not a hard constraint, but I would like to match the output of the Manta (122dB@1m) at least from 40hz and up. So roughly twice as powerful as the current 10D.
• It will be a sealed enclosure, as I would like to keep it relatively compact.
• Probably around 70 liters (~2.5 cubic feet) internal volume
• It will use high quality drivers and amplification just as our existing subwoofers.
• ~20hz in-room response as per our other subs.
• Will likely support stacking.
• It will be a premium, music oriented subwoofer. No target price at the moment.

Current status:
As mentioned this has been on the drawing board in many different iterations the last couple of years, but the last few months I've been actively looking into the technical aspects of building this.

Amplifier: We will likely have to move away from Hypex as I am missing some things I'd like to have in their current fusionamps, and I also need more power. At the same time I do not want to invest building a new plate amplifier from scratch. After extensive research I have found a recently developed 1000W DSP enabled subwoofer amplifier that will soon be available for OEM purchase that looks very promising. Hope to be able to share a picture soon.

Drivers: This has been a long and difficult journey (that might take us full circle, more about that a little later), inquiring both with Scan-Speak (which I currently use), Seas and also custom vendors. I have some quite interesting 12" prototypes (picture below) in the basement that have been developed specifically as potential drivers for this project. This driver will probably NOT be used for this project. A part of the reason is my perhaps silly decision to try to use European suppliers as far as possible. And from-scratch-custom subwoofer drivers quite quickly means China. So there's nothing inherently wrong with this driver (on the contrary), but it will probably not be a part of this project. I have some other promising alternatives, and I hope to conclude on driver choice soon.

Cabinet / enclosure:
For reasons (more later), this probably won't be a plain cube, so I am working with a designer to try to figure this out at the moment.

Product Name:
I have some ideas, but to be decided.

Protoypes:
None made yet that are close to what the end product will be.


...Sooo, a lot is up in the air still, but hopefully it will be a fun journey! I may not be able to answer many questions yet, but feel free to ask!

 

[Fledermaus]

Hi Thorbjørn,
Interesting - particularly since I have a similar project in mind, at my modest casual DIYer level.
Do you by any chance plan to use dual side-firing 12" ?

 

[kemmler3D]

Interesting concept with many details still up in the air... Am definitely interested in the (non cuboid?) shape point...?

 

[sigbergaudio]

Hi Thorbjørn,
Interesting - particularly since I have a similar project in mind, at my modest casual DIYer level.
Do you by any chance plan to use dual side-firing 12" ?

So you mean like a dual opposed 12", similar to the 10D but with 2x12"? That was the plan for a while, but I am exploring some alternative options at the moment.

 

[sigbergaudio]

Interesting concept with many details still up in the air... Am definitely interested in the (non cuboid?) shape point...?

Me too! I will share more about this relatively soon hopefully.

 

[dualazmak]

~20hz in-room response as per our other subs.

So, what would be declining SPL slope towards 16 Hz? I hope and assume it would be within -8 dB from 20 Hz.

I really like and love enjoying listening-to and feel-by-my-whole-body near 16 Hz organ sound and others in low/little distortion, as I repeatedly shared, for example as in my post #782 on my project thread as well as here #635 on the thread "BASS!", including spectrum data and YouTube links.

Reproduction and listening/hearing/feeling sensations to 16 Hz (organ) sound with my DSP-based multichannel multi-SP-driver multi-amplifier fully active stereo audio system having big-heavy active L&R sub-woofers: #782

A nice smooth-jazz album for bass (low Fq) and higher Fq tonality check and tuning: #635

Furthermore, I am very much looking forward to seeing your objective measurement data for "transient behavior = both of kick-up and fade-out pattern" of your planning new subwoofer in 16 Hz to 80 Hz zone by exciting with 8-wave and 3-wave rectangular sine tone burst signals, just like I shared mine in my post #495 on my project thread.

 

[sigbergaudio]

So, what would be declining SPL slope towards 16 Hz? I hope and assume it would be within -8 dB from 20 Hz.

I really like and love enjoying listening-to and feel-by-my-whole-body near 16 Hz organ sound and others in low/little distortion, as I repeatedly shared, for example as in my post #782 on my project thread as well as here #635 on the thread "BASS!", including spectrum data and YouTube links.

Reproduction and listening/hearing/feeling sensations to 16 Hz (organ) sound with my DSP-based multichannel multi-SP-driver multi-amplifier fully active stereo audio system having big-heavy active L&R sub-woofers: #782

A nice smooth-jazz album for bass (low Fq) and higher Fq tonality check and tuning: #635

Furthermore, I am very much looking forward to seeing your objective measurement data for "transient behavior = both of kick-up and fade-out pattern" of your planning new subwoofer in 16 Hz to 80 Hz zone by exciting with 8-wave and 3-wave rectangular sine tone burst signals, just like I shared mine in my post #495 on my project thread.

It varies with the room and placement. With our current subs I've seen some have almost flat down to 12-14hz, others start to fall off as early as 25hz. On average most go to 18-20hz before any significant roll-off.

 

[sigbergaudio]

This will likely be the amplifier.

 

[sigbergaudio]

Working name:

 

[sigbergaudio]

And an actual picture of the amp:

 

[Audionaut]

• It will be a sealed enclosure, as I would like to keep it relatively compact.
• Probably around 70 liters (~2.5 cubic feet) internal volume
• It will use high quality drivers

Hello Thorbjørn,
70 liters enclosed is a tight specification.
I would look for drivers among my usual suspects in the PA sector.
BMS would probably be my first choice, followed by the best drivers from Sica, Beyma, RCF, B&C, Precision Devices and Faital.
2 x 15 inches in an impulse-compensated arrangement, if one is to keep up with the Manta to some extent.
In China, if you're looking for custom-made products, you can check out A&D Audio; their carbon woofers are very good.

 

[Sokel]

If the amp is of enough quality and very low noise, why not extend it to mid-bass crossing frequencies (it would have to do straight to 1kHz so useful under 500Hz) and give the people who try to do pseudo-3 ways out of 2-ways+subs a meaningful way to do it?

 

[Matt_Holland]

Got to be at least dual 15” drivers surely or a single 18”?

I say that because if you really want to match the Manta it should be for big room setups where such SPLs are appropriate. The 10D works for many customers because of its size and smaller rooms give enough boundary gain to match the Manta. But in big rooms you always need big drivers. I think a pair of single big subs is preferable to the option to stack because it offers much better value for money.

 

[sigbergaudio]

Hello Thorbjørn,
70 liters enclosed is a tight specification.
I would look for drivers among my usual suspects in the PA sector.
BMS would probably be my first choice, followed by the best drivers from Sica, Beyma, RCF, B&C, Precision Devices and Faital.
2 x 15 inches in an impulse-compensated arrangement, if one is to keep up with the Manta to some extent.
In China, if you're looking for custom-made products, you can check out A&D Audio; their carbon woofers are very good.

I am pretty close to making a decision on drivers, but only 90% decided.

It doesn't have to be exactly 70 liters, but say 65-80 is the target. And yes, I think I've been through all the usual suspects from all of these manufacturers the last few months. Was not familiar with A&D Audio, will have a look at those, thank you!

 

[Keith_W]

Hi Thorbjorn, I would have preferred a terrifying Nordic God as the name of your subwoofer. Jormungandr? Surtr? Fenrir? You know, celebrate your heritage and all that

Can I ask what is the difference between a "music oriented" subwoofer and a "HT oriented" sub?

 

[sigbergaudio]

If the amp is of enough quality and very low noise, why not extend it to mid-bass crossing frequencies (it would have to do straight to 1kHz so useful under 500Hz) and give the people who try to do pseudo-3 ways out of 2-ways+subs a meaningful way to do it?

Sure. Our current subwoofers can be crossed as high as 300hz, this will likely be the case for this new one as well.

The driver currently used in our 10D sub is pretty tidy up to 1000-1500hz. The 12" in the Inkognito has similar performance. Being used to this + focusing on music and good performance in the upper bass is one of the reasons it's difficult to find new drivers, as this is not necessarily the case for most subwoofer drivers.

 

[sigbergaudio]

Hi Thorbjorn, I would have preferred a terrifying Nordic God as the name of your subwoofer. You know, celebrate your heritage and all that

Can I ask what is the difference between a "music oriented" subwoofer and a "HT oriented" sub?

One of the things is what I just mentioned above, performance at higher frequencies, and overall linearity. I have seen many drivers with similar xmax / Max SPL performance as the ones I use, but that have much higher distortion at moderate levels. This is one of the problems with the CEA2010 protocol often used to evaluate subwoofers, it only really tells you how the driver/subwoofer behaves at its limit.

And a HT oriented sub would typically be larger and ported (less focused on being compact and fitting into a normal living room).

 

[kharan]

I think some high end HT builders, like Matt Poes, prefer closed subs because their phase response makes it easier for multisub handling algorithms like Dirac and Trinnov, I'm not entirely sure how true this is.

 

[Keith_W]

If the subwoofer goes up to 300Hz, doesn't that limit where you can place the subwoofer? Effectively they can only be placed on either side of the speaker.

Agree with you about sealed vs. ported.

 

[Audionaut]

If the subwoofer goes up to 300Hz, doesn't that limit where you can place the subwoofer? Effectively they can only be placed on either side of the speaker.

I assume this is an optional feature for stereo operation, for example, and that you can probably set the crossover frequency up to 50Hz. Either in 10 or 5 Hz increments or continuously variable.
Closed subwoofers have a better impulse response and are easier to integrate acoustically into the room.