New Sigberg Audio development thread: The Sentinel - A music oriented reference subwoofer developed for the Manta system.

[Audionaut]

haven't shared the rear of the driver I think (for those geeky enough to be interested).

At the very least, the basket strongly reminds me of the Eminence LAB 15

Sentinel Prototype

 

[David_M]

I haven't shared the rear of the driver I think (for those geeky enough to be interested).

View attachment 541482


Next update will be the final dimensions of the cabinet, due to land next week.

Does the vendor provide distortion curves (vs frequency or SPL)? Or is it irrelevant (more or less) until the woofer is placed in a box, where the crossover and dynamics of an enclosed volume dictate the distortion performance?

 

[SigbergAudio]

Does the vendor provide distortion curves (vs frequency or SPL)? Or is it irrelevant (more or less) until the woofer is placed in a box, where the crossover and dynamics of an enclosed volume dictate the distortion performance?

Not sure if it's irrelevant, but the enclosure will quite heavily influence the result, so it makes more sense to make measurements of the finished product than the driver itself when it comes to distortion. But a driver manufacturer will typically produce frequency response measurements, and measurements that shows how the motor behaves in relation to excursion etc. That helps to understand how well it will work. And the standardized thiele-small parameters of course - which can then be used to simulate how the driver behaves in the box (though not including distortion).

 

[SigbergAudio]

Still preliminary but probably final measurements:

Height: 580mm (22.8 inches)
Depth: 580mm (22.8 inches)
Width: 490mm (19.3 inches)

 

[SigbergAudio]

Might be adjusted slightly to ensure effective production processes, but current design for bracing is pretty neat, clicks together like a 3D puzzle and ensures we have whole bracing pieces in all directions.

 

[SigbergAudio]

Tested to measure down to 5hz in the listening room, not a lot of roll-off.

 

[SigbergAudio]

Someone on our Facebook page commented on the SPL level being low on the previous measurement, so here is a bit louder. In-room about 2.5m from the subwoofer. Plenty of room gain here of course.

 

[David_M]

Very nice...

1. Why limit to 10 Hz?
2. Distortions at said SPLs?
3. How high (in Hz) does it go?

 

[SigbergAudio]

Very nice...

1. Why limit to 10 Hz?

Not exactly sure what you are asking here. Why the graph doesn't go lower than 10hz on the second graph? Because there's no limiter implemented yet, so I want to be a bit careful with my prototype drivers. New ones are months out still.

2. Distortions at said SPLs?

Distortion at low frequencies will depend on room gain as well, but with this particular room and test, THD was around 9% at 10-30hz, and 1.6% at 50hz.

3. How high (in Hz) does it go?

That is just a matter of configuration/tuning really. Measurement wise the drivers are completely clean up to 500hz and beyond. So not determined yet, but will likely start to roll it off around 300hz (similar to the 10D and Inkognito). We'll see.

 

[David_M]

Thanks for the answers... now on the limiter issue, is it common (or a requirement) for designers to implement these circuits in their subs? I thought the manufacturers of the drives ensured compliance down to almost DC. Or are you ensuring you are not exceeding the Xmnax limits of the drivers, though I thought they were guaranteed to be unexceedable (if that's a real word)?

 

[SigbergAudio]

Thanks for the answers... now on the limiter issue, is it common (or a requirement) for designers to implement these circuits in their subs? I thought the manufacturers of the drives ensured compliance down to almost DC. Or are you ensuring you are not exceeding the Xmnax limits of the drivers, though I thought they were guaranteed to be unexceedable (if that's a real word)?

No drivers (that I'm aware of) have inherent protection against exceeding xmax. So your assumption that they are unexceedable is wrong.

So you need to control / limit how much power they get. And the lower the frequency, the larger the excursion for the same amount of SPL. Otherwise the drivers can bottom out, and worst case be damaged or destroyed.

So in essence yes, most modern subs will have limiter circuits of some form.

 

[Vacceo]

I know these subwoofers are meant to be the Manta companions, but they´d not be out of place in a home theatre environment. Looking at graphs, these beauties would handle the infamous Edge of Tomorrow intro without breaking a sweat.

 

[SigbergAudio]

I know these subwoofers are meant to be the Manta companions, but they´d not be out of place in a home theatre environment. Looking at graphs, these beauties would handle the infamous Edge of Tomorrow intro without breaking a sweat.

An even larger (this is still relatively compact for a dual 15"), home theater oriented, ported subwoofer would still have higher capacity probably (and probably be cheaper) - but yes.

 

[Vacceo]

An even larger (this is still relatively compact for a dual 15"), home theater oriented, ported subwoofer would still have higher capacity probably (and probably be cheaper) - but yes.

While that is true for pure output, I can also see this project producing some of the best reproduction possible for tracks such as Prodigy´s Breathe. Techno would definitely shine with the Mantas and these subwoofers. Not that the Sarannas or the current SBS and the smaller subs wouldn´t, but these would produce some truly amazing kick on larger rooms.

 

[SigbergAudio]

While that is true for pure output, I can also see this project producing some of the best reproduction possible for tracks such as Prodigy´s Breathe.

Funny you should say that, I'm watching this as we speak.

Techno would definitely shine with the Mantas and these subwoofers. Not that the Sarannas or the current SBS and the smaller subs wouldn´t, but these would produce some truly amazing kick on larger rooms.

Fun fact; I was a wannabe DJ back in the late 90s early 2000s dragging my SL1200 turntables around playing techno and house in abandoned warehouses, so I'm pretty familiar with that scene, and all our systems are definitely tested on that type of music as well. There are many reasons I like to build stuff with decent dynamic capacity.

 

[Vacceo]

Funny you should say that, I'm watching this as we speak.

Fun fact; I was a wannabe DJ back in the late 90s early 2000s dragging my SL1200 turntables around playing techno and house in abandoned warehouses, so I'm pretty familiar with that scene, and all our systems are definitely tested on that type of music as well. There are many reasons I like to build stuff with decent dynamic capacity.

While I like Prodigy, given the choice to test your subwoofers, I´d go straight to some of your fellow countrymen: Red Harvest. Cold Dark Matter would probably sound absolutely monumental and I´m sure I´d find elements on them that I´d have never heard before.

 

[audiofooled]

Funny you should say that, I'm watching this as we speak.

Fun fact; I was a wannabe DJ back in the late 90s early 2000s dragging my SL1200 turntables around playing techno and house in abandoned warehouses, so I'm pretty familiar with that scene, and all our systems are definitely tested on that type of music as well. There are many reasons I like to build stuff with decent dynamic capacity.

I would recommend this, a bit different perspective, while you're at it.