Sigberg Audio MANTA dual cardioid active speaker development thread

Sigberg Audio

Sigberg Audio

Audioholic Intern
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Quick introduction: Sigberg Audio is a Norwegian loudspeaker company, our SBS.1 speaker was recently reviewed here on Audioholics. :) We've currently got three products: The SBS.1 active speakers and two different subwoofers. We've taken an extremely transparent approach to our development process, and have had development threads for all our products on both ASR as well as a Norwegian hifi forum. We now have a fourth product well under way, and already have threads about this as well on the aforementioned forums, but I thought it would be fun to do one here on Audioholics as well! (I humbly asked @shadyJ for permission :eek:)

Sooo, what are we working on now?

Our next project is the Sigberg Audio MANTA Dual Cardioid Active loudspeaker (gasping for breath). Before diving into the details, let's quickly compare it to our SBS.1 speaker, as there are several similarities. They're both designed to be played with subwoofers. Target -3dB roll-off point will be 90hz just like the SBS.1. They're also both very focused on having plenty of capacity in the critical midbass range, imo often neglected by other speakers. Finally, they both have (the same) coax driver for perfect imaging and soundstage, and uniform dispersion. :)

Our current SBS.1 active speaker can play more than loud enough for most purposes and rooms. It's precise, punchy and plays louder than any similar sized speaker without audible compression. But some want not just loud, but L O U D, and some have larger than average rooms. Thus, the MANTA will carry on the legacy of dynamics and effortless reproduction from the SBS.1 and supersize it. The midbass capacity is more than twice the SBS.1. We are talking a dedicated 12" driver for midbass (rolling off at 90hz). Similar to the SBS.1 5.5" midbass driver, this new 12" driver has a stiff suspension optimized for bass/midbass rather than subwoofer duty. And while we use the same coax as in the SBS.1, since it's now a 3-way design, its capacity is significantly increased as well. All these changes of course also translate to even lower distortion at both moderate and high playback levels.

What makes it even more special is that the MANTA have individual chambers for both drivers, and they both have acoustic ports, controlling directivity to a greater degree than a traditional speaker all the way down to 100hz:
  • Cardioid midrange: The dedicated midrange chamber is vented to reduce reflections from the side walls and the wall behind the speakers. The result is increased clarity and improved soundstage. To perfect the midrange, ports are cut out in the baffle on both sides of the coax driver to allow the midrange driver to "see" a more narrow baffle, resulting in ideal dispersion characteristics across the frequency range.
  • Cardioid bass: One would think you lost bass pressure by venting the cabinet, but when done right the very opposite is true. The MANTA achieves cardioid like performance down to 100hz, targeting the bass pressure towards the listener. This thight and consistent midbass experience is crucial for the rhythmic, dynamic nature of many music genres.

That was a quick intro to the build, we've already gone through a few iterations and now evolved into a pretty high quality prototype, happy to answer questions and share more details, and also build pictures from earlier prototypes, measurements etc - this is just the beginning to get the thread started! Hopefully this will prove interesting to the community! :D


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Steve81

Steve81

Audioholics Five-0
Looks like a sweet design after my own heart. A capable concentric mid/tweet and a high output woofer optimized to hand off to a dedicated subwoofer system? Yes please.
 
Sigberg Audio

Sigberg Audio

Audioholic Intern
Here's a quick dump of pictures of earlier prototypes and variants, showing the progression to where we're at today:

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ryanosaur

ryanosaur

Audioholic Warlord
Excellent, @Sigberg Audio !
What is happening that makes the baffle look like several different layers of MDF, please?
 
Sigberg Audio

Sigberg Audio

Audioholic Intern
Excellent, @Sigberg Audio !
What is happening that makes the baffle look like several different layers of MDF, please?
There are two layers. This is water resistant MDF, it looks a bit weird when you cut it. Note that this is a prototype, this is not the same material that the production cabinets are made of (not the same manufacturer).

The production cabinets are deep routing grade MDF which doesn't have the soft core of most typical MDF, and is somewhere between MDF and HDF in density. Exactly how the baffle will be constructed in the end hasn't been determined since there's a lot going on with the ports on the sides of the coax etc, but it will likely be dual layer, so similar to this one.
 
Sigberg Audio

Sigberg Audio

Audioholic Intern
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The high power, high sensitivity (96dB) midbass driver. :cool:

Early tests of the Manta indicate 0,5% THD @ 96dB and max spl ~116dB.

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ryanosaur

ryanosaur

Audioholic Warlord
Would the Sica Drivers be considered Pro Drivers?
 
Sigberg Audio

Sigberg Audio

Audioholic Intern
Would the Sica Drivers be considered Pro Drivers?
The coax and the 5.5" midbass in the SBS.1 are designed for hifi / studio monitors, but it's obvious by the over engineering that these guys are well versed in the pro audio world. The 12" in the Manta on the other hand is a pro audio midbass woofer, and very well suited for the purpose. Very even frequency response, natural reproduction of for instance voices / vocals, quick and punchy with its low mass.

High sensitivity combined with almost unlimited power handling (rated at 1000w) makes it perfect for this slightly over the top build!
 
ryanosaur

ryanosaur

Audioholic Warlord
The coax and the 5.5" midbass in the SBS.1 are designed for hifi / studio monitors, but it's obvious by the over engineering that these guys are well versed in the pro audio world. The 12" in the Manta on the other hand is a pro audio midbass woofer, and very well suited for the purpose. Very even frequency response, natural reproduction of for instance voices / vocals, quick and punchy with its low mass.

High sensitivity combined with almost unlimited power handling (rated at 1000w) makes it perfect for this slightly over the top build!
I asked because there is a certain look to Drivers in the Pro Category that is not often shared by Drivers in the Consumer/Hi-Fi class (unless they are more budget oriented like some of the Dayton gear can be). The Sicas have that look to some extent, reminiscent of B&C, La Voce, Eminence, etc.

If I may ask, what are some other Drivers (by manufacturer) you looked at in the process of narrowing down the choice to Sica?
 
Sigberg Audio

Sigberg Audio

Audioholic Intern
I asked because there is a certain look to Drivers in the Pro Category that is not often shared by Drivers in the Consumer/Hi-Fi class (unless they are more budget oriented like some of the Dayton gear can be). The Sicas have that look to some extent, reminiscent of B&C, La Voce, Eminence, etc.

If I may ask, what are some other Drivers (by manufacturer) you looked at in the process of narrowing down the choice to Sica?
Yes, the double surround is pretty typical of pro drivers, I quite like that look personally, and it's a good configuration for midbass drivers.

I don't have the full list in my head, it's probably 18 months since we locked onto Sica. But the better known I guess is Seas, Scan-speak (which we already use for our Subwoofers, but they don't have a coax, but we looked at their woofers), BMS, SB Acoustics.. We wanted to do a coax, and there's not that many manufacturers that make good ones.
 
ryanosaur

ryanosaur

Audioholic Warlord
We wanted to do a coax, and there's not that many manufacturers that make good ones.
Indeed. I've seen so many measurements that leave me questioning why they are sought after for the problems they seem to have.
Is there any guidance you can share on what makes for a good Coax? Or was this particular Driver just a design that happened to work well? ;)
 
Sigberg Audio

Sigberg Audio

Audioholic Intern
Indeed. I've seen so many measurements that leave me questioning why they are sought after for the problems they seem to have.
Is there any guidance you can share on what makes for a good Coax? Or was this particular Driver just a design that happened to work well? ;)
Well, I doubt Sica just accidently made a good one :) But they apprently did a good job both shaping the small horn that the tweeter is situated in, the way it integrates with the midbass cone, as well as the way the transision to the surround / outer ring is done. The surround hardly sticks out beyond the cone at all, as opposed to some alternatives, so not contributing much in terms of diffractions / problems. The tweeter is also surprisingly powerful with low compression and distortion even at elevated levels. At 110dB you're still at between 1-1.5% THD depending on the frequency, which is pretty insane. Actually the midrange gives up before the tweeter.

What can I say, it's just a damn good driver. I had the SBS.1 at Seas to do the measurements in their Klippel (those guys are the best by the way), they were somewhat miffed I wasn't using Seas of course, but I think even they are pretty impressed with this coax, though they'll never admit it. :D
 
TLS Guy

TLS Guy

Seriously, I have no life.
Well, I doubt Sica just accidently made a good one :) But they apprently did a good job both shaping the small horn that the tweeter is situated in, the way it integrates with the midbass cone, as well as the way the transision to the surround / outer ring is done. The surround hardly sticks out beyond the cone at all, as opposed to some alternatives, so not contributing much in terms of diffractions / problems. The tweeter is also surprisingly powerful with low compression and distortion even at elevated levels. At 110dB you're still at between 1-1.5% THD depending on the frequency, which is pretty insane. Actually the midrange gives up before the tweeter.

What can I say, it's just a damn good driver. I had the SBS.1 at Seas to do the measurements in their Klippel (those guys are the best by the way), they were somewhat miffed I wasn't using Seas of course, but I think even they are pretty impressed with this coax, though they'll never admit it. :D
What I don't understand in this design, is how you are summing the rear cone output with the front. The output from the rear of the cone is obviously out of phase with the front.

Just so members know what we are talking about, below is the radiation patter of a driver on a flat baffle, so a di-pole.



So there are nulls at the sides. The frequency of the cancellation will be lower the greater the width of the baffle. But obviously, what you are trying to do, is to make it seem as if the baffle is narrow, and control the forward response.

However, I don't understand how your design controls the inevitable cancellations between the forward radiation and the radiation from the rear via the openings.

It seems to me that unless the rear radiation is somehow reversed to be in phase with the front radiation, then the off axis polar response will be very lumpy.

I did consider this problem around fifty years ago and solved it. It was for a system I designed for a large venue where bands and music groups performed and was for sound reinforcement.

This was an active horn system. The bass sections used back loaded 15 JBL drivers in a bass horns the size of a small kiosks, with three foot horn mouths.

The top end was a two line sources of eight Jordan Watts drivers, these were mounted in the back box. There were throats down either side, and a short exponential flare either side. This solved the reflection problem, as the width of the back box was only the width of the drivers. The horn design, inverted the rear radiation, and the flare gave just the radiation pattern I wanted.

The system sounded absolutely marvelous, and reinforced bands and vocals beautifully. Because the system was so linear there was excellent forward gain from the mics.

One evening we had a really good Bohemian band up from ND. I was in Canada then. They sounded just wonderful. I made a stereo recording of the live mix, but sent mono to the two speaker stacks, built in either side of the stage.

The evening was so good, I issued an LP of the live mix, which in the upper Midwest became a really good seller.

I think something similar might give just the response and effect you are looking for.

Changing the subject. I had not heard of those SICA drivers previously. I see they are Italian. They seem to make a huge range of drivers, with parameters from low Q high FS to higher Q but still quite high FS. Many of the specs are usually seen in PA type pro drivers. I have not had nearly enough time yet to digest that "motherload".

They claim MC Audiotech of Florida as their US agents. But MC Audiotech, make no mention of being involved in any way with SICA or their drivers.

I do not see a source of those drivers in the US, but may be you can enlighten me further on that last point, and probably the other as well.
 
ryanosaur

ryanosaur

Audioholic Warlord
@TLS Guy , you need to look into the Dutch and Dutch 8C and similar concepts of passive cardioid design.

I am far from expert on this, but as I recall, the D&D 8C is generally very highly regarded for what it achieved. As best I can say, it is using that backwave energy as a passive "waveguide" or perhaps "beamforming" tool.

Here is a link to Erin's review and associated thread on ASR:
 
TLS Guy

TLS Guy

Seriously, I have no life.
@TLS Guy , you need to look into the Dutch and Dutch 8C and similar concepts of passive cardioid design.

I am far from expert on this, but as I recall, the D&D 8C is generally very highly regarded for what it achieved. As best I can say, it is using that backwave energy as a passive "waveguide" or perhaps "beamforming" tool.

Here is a link to Erin's review and associated thread on ASR:
That DD speaker just has side opening, which will be out of phase with the driver. So essentially that is the reverse of a cardioid microphone. The Sigberg speaker however has openings on the side and front. However my approach added the rear output in phase to the front output, as well as giving controlled directivity. However I acknowledge you can't do that in a bookshelf speaker.
 
Sigberg Audio

Sigberg Audio

Audioholic Intern
They claim MC Audiotech of Florida as their US agents. But MC Audiotech, make no mention of being involved in any way with SICA or their drivers.

I do not see a source of those drivers in the US, but may be you can enlighten me further on that last point, and probably the other as well.
To answer the easy part first, we're not based in the US (but Norway), so I am afraid I don't know anything about Sica distribution in the U.S.
 
Sigberg Audio

Sigberg Audio

Audioholic Intern
What I don't understand in this design, is how you are summing the rear cone output with the front. The output from the rear of the cone is obviously out of phase with the front.

Just so members know what we are talking about, below is the radiation patter of a driver on a flat baffle, so a di-pole.



So there are nulls at the sides. The frequency of the cancellation will be lower the greater the width of the baffle. But obviously, what you are trying to do, is to make it seem as if the baffle is narrow, and control the forward response.

However, I don't understand how your design controls the inevitable cancellations between the forward radiation and the radiation from the rear via the openings.

It seems to me that unless the rear radiation is somehow reversed to be in phase with the front radiation, then the off axis polar response will be very lumpy.

I did consider this problem around fifty years ago and solved it. It was for a system I designed for a large venue where bands and music groups performed and was for sound reinforcement.

This was an active horn system. The bass sections used back loaded 15 JBL drivers in a bass horns the size of a small kiosks, with three foot horn mouths.

The top end was a two line sources of eight Jordan Watts drivers, these were mounted in the back box. There were throats down either side, and a short exponential flare either side. This solved the reflection problem, as the width of the back box was only the width of the drivers. The horn design, inverted the rear radiation, and the flare gave just the radiation pattern I wanted.

The system sounded absolutely marvelous, and reinforced bands and vocals beautifully. Because the system was so linear there was excellent forward gain from the mics.
Sounds like an impressive system!

Okay, I will try to explain and also share measurements of what is happening, without necessarily sharing exactly how this is done.

Firstly, the ports on the front and the ports on the side have different purposes. The ports in the front baffle is as you say an attempt to "trick" the coax into seeing a more narrow baffle, to get a more even off-axis response. And it works. Here is measurements of the speaker with a closed front baffle (which sounded good already):
1651990269517.png


And here with the ports on each side of the coax:
1651990299423.png


Notice how the "lumping" at around 800-2000hz is reduced. For the record these are in-door measurements which is why they are somewhat untidy, but the point is the difference in responses.



Secondly, you have the ports on the side, which partially cancel out the sound to the sides and the rear. The most obvious way to show the effect is to compare the energy level at 180 degrees on the Manta compared to a traditional enclosure, namely our own SBS.1:

Here is on-axis vs 180 degrees for the SBS.1 (traditional enclosure):
1651990509057.png


And here is on-axis vs 180 degrees for the Manta (previous prototype iteration, the new one has yet to be measured):
1651990542588.png


Notice how the energy level is significantly reduced (actually more than 50% on average) all the way from the bottom octaves and throughout the entire audio band. The difference in how the speaker interacts with the room is almost hard to explain. Everything comes forward, you get more sense of room (depth/width) and details are easier to discern and "spread out" in 3D space. Some recordings almost sound like you're listening to a surround system. Again, hard to explain without sounding like a commercial or something I just made up.

Reduced energy towards the rear of the cabinet also reduces the cancelation of midbass frequencies due to the back wall (SBIR effects), so you get noticeably better punch in the midbass as well.

This was measured on a Klippel system with both speakers and mic fixed in place and the speaker automatically rotated, so there's no trickery of moving the speaker further away or anything involved. :)
 
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Sigberg Audio

Sigberg Audio

Audioholic Intern
Obviously early days and lots of work left, but here's preliminary on-axis + 30 degrees off-axis with the new enclosures (that arrived this week). :)

(0,5m in door measurement)

1652004333214.png
 
Steve81

Steve81

Audioholics Five-0
Are there active and passive versions planned, or is this an active only project?
 
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