Sigberg Audio Manta (12" wideband cardioid active speakers) development thread

[SigbergAudio]

Is your solution somewhat similar to Seas KingRoy Kit or any fundamental differences besides the woofer size

I see how it would look similar on the surface, but I would say there are next to no similarities except the use of a coax and somewhat similar cabinet size (Kingroy is smaller).

This speaker is cardioid while KingRoy is a traditional sealed design.
This speaker is designed to play with a subwoofer while King is fullrange (so this is essentially 4-way as opposed to 3-way).
This speaker has a 12" midbass driver as opposed to a 10" bassdriver.

 

[SigbergAudio]

So a quick summary of this concept so far as we are approaching end of year:

This is now a dual cardioid system, where the four octaves from 100hz to 1600hz is covered by two individual cardioid systems and two drivers, instead of one. This means that instead of loosing efficiency, the system is roughly as effective as a traditional sealed system.

As the frequency range of a cardioid system increases, you'll get gradually increasing cancellation towards the front and reduced efficiency. This is avoided by setting up a cardioid system with a more narrow frequency band. Incidentally this merges well with our philosophy of having a dedicated driver in the important midbass range.

As far as I know there is no other dual cardioid speaker out there, so this is a pretty unique approach that gives the benefit of cardioid without loss of efficiency.

Results so far both from measurements and listening sessions are very positive. The plan going forward is to spend another couple of months tweaking the response of the speaker and ensure that the cabinet design has stabilized, and then build a prototype with production grade build and finish. I'm still debating whether to do anything fancy with the design or let the functional design and ports speak for itself and present it in a neutral satin black.

 

[thewas]

As far as I know there is no other dual cardioid speaker out there, so this is a pretty unique approach that gives the benefit of cardioid without loss of efficiency.

The 3-way Geithain models are also both acoustic cardioids in the woofers and mid drivers.

 

[SigbergAudio]

The 3-way Geithain models are also both acoustic cardioids in the woofers and mid drivers.

Are you sure? Which model specifically? They are marketed as "cardioid radiation characteristic in bass range". On one of the speakers they specified "cardioid radiation characteristics within the frequency range from 30 through 250 Hz".

The MANTA.1 combined cardioids have effect from ~80-1500hz.

 

[thewas]

Are you sure? Which model specifically? They are marketed as "cardioid radiation characteristic in bass range". On one of the speakers they specified "cardioid radiation characteristics within the frequency range from 30 through 250 Hz".

The MANTA.1 combined cardioids have effect from ~80-1500hz.

AFAIK all their non-2-way K (= cardiod) models, like 801, 901, 921, 944, the mid drivers are open to the back with just some special absorbent material to form a specific radiation pattern.

 

[SigbergAudio]

AFAIK all their non-2-way K (= cardiod) models, like 801, 901, 921, 944, the mid drivers are open to the back with just some special absorbent material to reduce the sound velocity and lead to a cardioid-like radiation pattern.

The midrange of the speakers like the 901 seem to just be mounted on a baffle in front of the bass driver? So in that case this is more like a dipole, but the way larger speaker is directly behind it, so not sure what kind of radiation pattern that results in. So basically a coaxial setup. I don't see how this is similar to the MANTA with two separate and actual cardioid loaded chambers.

Also as mentioned, they only market their speakers as being cardioid in the bassrange, surely they would mention it if something else was the case.

"Our reliable K-Technology is also used in the ME 901K1 and by the cardioid radiation characteristics within the frequency range from 30 through to 250 Hz the reflections on the back walls of listening rooms can be minimised.
(..)
The unit for the medium and high-frequency range is combined in a coaxial manner with our long-throw 16-inch bass system and is provided with a directivity index, which supplements in an excellent way that of the bass system."

I'm sure these are great speakers, but it's not the same concept.

 

[thewas]

The speakers like the 901 seem to just be mounted on a baffle in front of the bass driver? So in that case this is more like a dipole, but the way larger speaker is directly behind it, so not sure what kind of radiation pattern that results in. I don't see how this is similar with two separate and actual cardioid loaded chambers.

As said there is some absorber on the rear of the mid driver to avoid a dipole radiation. On the other hand with a large baffle like they use the mid driver range is above the bafflestep so radiation to the rear is reduced and an additional cardioid cancellation (which is used in the bass as the baffles are too small compared to the bass wavelengths) is not needed. With your more narrow baffle a cardioid may be useful at a higher frequency, would be interesting if you could show radiation pattern comparison both with the slots open and closed to see in which frequencies it makes a difference and how much.

 

[SigbergAudio]

With your more narrow baffle a cardioid may be useful at a higher frequency, would be interesting if you could show radiation pattern comparison both with the slots open and closed to see in which frequencies it makes a difference and how much.

Did that in post #25 (https://www.audiosciencereview.com/...ers-prototype-build-thread.28255/post-1008325)

The graphs in that post shows the difference between open and closed slots in the midrange chamber at 150 and 180 degrees.

 

[Valhalla]

If you want a true passive cardioid speaker using resistive ports, I can do the R&D job and come up with design details. Up to 16-17dB of cancelation is obtainable in ~100hz-600hz @ 180 degrees.
Good luck with the production BTW

 

[SigbergAudio]

If you want a true passive cardioid speaker using resistive ports, I can do the R&D job and come up with design details. Up to 16-17dB of cancelation is obtainable in ~100hz-600hz @ 180 degrees.
Good luck with the production BTW

Thank you, we're at 16-20dB from around 300-1,500hz now.

100-300hz is more like 6-10dB so that's not perfect yet, but better than a sealed cabinet. We're still working on that.

 

[SigbergAudio]

Here's a rough indication of current 0-180 (30 degree increments) based on imprecise outdoors measurements. Most of the humps and valleys here are due to reflections. ~10khz has a response peak that will be ironed out a bit in time. Focus at the moment is more on directivity than accurate response. Reasonably happy with the directivity match across the drivers too.

 

[SigbergAudio]

Not a whole lot have happened through the holidays, but I've rebuilt the DSP and crossover from scratch. The crossovers are now lower order, I've relieved the midrange driver a bit, and spent a little more time to get things right. In the previous round, the focus was on the cabinet and on the cardioid stuff, as I already knew the drivers were capable.

Here's an indoor measurements (from 400hz so you don't have to see so much room noise). Measured on-axis with the mic located/pointed between the coax and the 12" driver.

• On the woofer there's nothing but baffle step compensation, no correction of driver linearity.
• On the midrange there's nothing but baffle step compensation, no correction of driver linearity except supressing of breakup above 5500hz.
• Three correction points in the treble.

All crossovers are assymetric double 1.order. So a primary 1.order, and then a second 1.order filter significantly lower/higher in frequency to speed up the roll-off.

--
Thorbjørn
Sigberg Audio

 

[hege]

There's not many speakers I would be interested in upgrading from my 1237's, ignoring the larger models. This is one of the few that would be very interesting to hear on top of my subs.

 

[killdozzer]

This is quite fascinating. It looks to be a very successful design from you measurements. Do you find them lacking in any way? Are you completely satisfied?

 

[SigbergAudio]

This is quite fascinating. It looks to be a very successful design from you measurements. Do you find them lacking in any way? Are you completely satisfied?

Thank you! They are still under development (due to be released as a production speaker in Q3-Q4 2022 if all goes well), so they are not perfect yet, but getting there. The cabinet has been through a few iterations, starting to stabilize now. Need to do some more measurements outdoors to verify and test more, but it's -8C and snow here at the moment, so that part of the development is on pause.

The exact tune of crossovers and DSP will probably change too, but overall it sounds very good. I've tried to describe the sound a bit earlier in thread as well. But the soundstage, precision and imaging (depth/width) is probably among the best I've heard, some recordings sounds like they were recorded in surround. One of our core design principles to have a open and clear sound that doesn't become sharp and fatiguing, so it obviously has that as well (same coax driver as in our other speaker the SBS.1). Another prominent feature is of course the pure capacity, with a 12" midbass driver (f3 at 90hz). I can literally feel snare drums in my chest when playing loud on these speakers.

Anecdotally I've had a guy come by for a listening session who have 10,000USD Piega speakers, and another who just bought the B&W 803D4, they were both impressed by the sound.

 

[SigbergAudio]

Here's the response in the sweet spot in our test room these days. MANTA.1 + dual 10D subwoofers. Sounds quite promising.

 

[SigbergAudio]

The MANTA.1 prototype next to our SBS.1 speakers.

 

[diyhobby]

sigbergaudio I must say you have tremendous talent. Keep the hunt on. You are a rockstar.​

 

[diyhobby]

I would really buy your products just the customs and duties taxes in my country makes the price more than double

 

[SigbergAudio]

I would really buy your products just the customs and duties taxes in my country makes the price more than double

Actually, both shipping as well as the customs and duties taxes are included in the price you see on the website. Which country do you live in and what is your VAT rate?