Sigberg Audio MANTA dual cardioid active speaker development thread

[Sigberg Audio]

I gave a short interview to a Norwegian hifi magazine at the hifi show which has been uploaded now. It's in Norwegian, but it features some close-up video of the Manta which may be interesting. It starts at around 4:50 in this video:

 

[Sigberg Audio]

New renderings for a new revision of the stand based on feedback on various forums as well as the hifi show this weekend, where most people preferred the current retro stand. This new one is conceptually similar, but has the loudspeaker resting on a plate made of 5mm steel. This gives an illusion of the speaker resting on thin air, and with no visible edge below/around the speaker, while the rest of the stand retains that retro JBLish look.

 

[ryanosaur]

Looks good, Thorbjørn. Perhaps the only other item to consider may be a means of locking the Speaker to the Stand. Threaded inserts in the base of the speaker and matching holes in the stand for some small bolts or some such?
Just an idea... I've seen too many conversations of folk looking for ways to affix Speakers to more generic stands. Many purpose-built Stands for specific Speakers seem to offer that.

 

[Sigberg Audio]

Looks good, Thorbjørn. Perhaps the only other item to consider may be a means of locking the Speaker to the Stand. Threaded inserts in the base of the speaker and matching holes in the stand for some small bolts or some such?
Just an idea... I've seen too many conversations of folk looking for ways to affix Speakers to more generic stands. Many purpose-built Stands for specific Speakers seem to offer that.

Will look into that. The speaker is quite heavy and the stand has a 4 degree tilt, so it already rests quite securely towards the lip at the back of the stand. But will consider additional measures.

 

[TLS Guy]

New renderings for a new revision of the stand based on feedback on various forums as well as the hifi show this weekend, where most people preferred the current retro stand. This new one is conceptually similar, but has the loudspeaker resting on a plate made of 5mm steel. This gives an illusion of the speaker resting on thin air, and with no visible edge below/around the speaker, while the rest of the stand retains that retro JBLish look.

I think it looks very good. However, as you know, it goes against the grain with me not to use that volume and space below the speaker not to extend the bass.

Apart from some added expense I have a hard time seeing the point of putting speakers on stands. I know I'm not alone in this. Quality stands are not cheap either.

 

[Sigberg Audio]

I think it looks very good. However, as you know, it goes against the grain with me not to use that volume and space below the speaker not to extend the bass.

Apart from some added expense I have a hard time seeing the point of putting speakers on stands. I know I'm not alone in this. Quality stands are not cheap either.

As bookshelf speakers do exist, I suspect there may still be a market for it.

 

[Sigberg Audio]

The next revision of the cabinet is delayed further, I'm probably lucky if it arrives before xmas.. So until then I'll nudge the response of this further. Based on the sound at the recent hifi show I concluded that we may need a sliiight increase in the top end, especially given the fact that the listener is off-axis. Smoothed out the response between 1-2khz a bit as well when I was at it.

New (blue) and old response at 15 degrees off-axis (showing from 400hz with 1/12 smoothing as the measurement is done indoors):

New 15deg by itself:

 

[TLS Guy]

As bookshelf speakers do exist, I suspect there may still be a market for it.

I am absolutely sure there will be a market for them. It seems to me that if you had the option of a base that made the rig a true full range speaker, you would have a bigger market. I think this drive to active speakers will make an active modular approach, so to speak, a very attractive proposition. I think it is multiple boxes scattered about rooms that is a major resistance to sales. Those speakers need subs anyway, as the F3 is so high. So it then becomes how to do it, in a truly integrated manner with the highest acceptance factor as far as interior design issues are concerned.

 

[TLS Guy]

The next revision of the cabinet is delayed further, I'm probably lucky if it arrives before xmas.. So until then I'll nudge the response of this further. Based on the sound at the recent hifi show I concluded that we may need a sliiight increase in the top end, especially given the fact that the listener is off-axis. Smoothed out the response between 1-2khz a bit as well when I was at it.

New (blue) and old response at 15 degrees off-axis (showing from 400hz with 1/12 smoothing as the measurement is done indoors):

New 15deg by itself:

The next revision of the cabinet is delayed further, I'm probably lucky if it arrives before xmas.. So until then I'll nudge the response of this further. Based on the sound at the recent hifi show I concluded that we may need a sliiight increase in the top end, especially given the fact that the listener is off-axis. Smoothed out the response between 1-2khz a bit as well when I was at it.

New (blue) and old response at 15 degrees off-axis (showing from 400hz with 1/12 smoothing as the measurement is done indoors):

New 15deg by itself:

That was my experience, with my center coaxial design. I had a dip at 9K Hz. It was due to cancellation reflections from the main cone of the tweeter output.
Although it did not look that bad it did give the speaker just a slight dullness and impaired speech intelligibility.

I had used two of the same coaxial units, but only used the bass cone for the fill driver. So I designed a network for the other tweeter to fill in the gap. I think, probably, that they were separated in space that it helped. One thing I noted, was that the dip was maximal on axis and was less a problem as you moved off axis.

When I conceived this plan, I was not optimistic it would be a satisfactory solution, but it works very well. The whole problem was corrected by this addition.

 

[Sigberg Audio]

I am absolutely sure there will be a market for them. It seems to me that if you had the option of a base that made the rig a true full range speaker, you would have a bigger market. I think this drive to active speakers will make an active modular approach, so to speak, a very attractive proposition. I think it is multiple boxes scattered about rooms that is a major resistance to sales. Those speakers need subs anyway, as the F3 is so high. So it then becomes how to do it, in a truly integrated manner with the highest acceptance factor as far as interior design issues are concerned.

But we do have such a base. The 10D subwoofer is exactly the same width, and we are experimenting with a foam wedge (pictures coming soon) that will give the speaker the appropriate 4 degree angle while situated on top of it. For those opting to use the stand, we also have the Inkognito subwoofers than can be easily hidden or integrated into the interior.

 

[TLS Guy]

But we do have such a base. The 10D subwoofer is exactly the same width, and we are experimenting with a foam wedge (pictures coming soon) that will give the speaker the appropriate 4 degree angle while situated on top of it. For those opting to use the stand, we also have the Inkognito subwoofers than can be easily hidden or integrated into the interior.

View attachment 57967

Well that is perfect. Well Done! In that case I doubt there will be much demand for stands, since those speakers without a sub will not impress because F3 is too high. In any event speakers and sub should be designed as a unit in my view. As the divide between speaker and sub IS a crossover and needs designing with as much care as any other.

 

[Sigberg Audio]

Well that is perfect. Well Done! In that case I doubt there will be much demand for stands, since those speakers without a sub will not impress because F3 is too high. In any event speakers and sub should be designed as a unit in my view. As the divide between speaker and sub IS a crossover and needs designing with as much care as any other.

No, they were never meant to play without a sub. But I'm sure some will buy with stands and place subs elsewhere. We'll see.

 

[Sigberg Audio]

Experimenting with foam wedges (originally made for tilting studio monitors) to get a 4 degree tilt on the Mantas when placed on top of the 10D subwoofers. This is just a test, but considering to custom make these so they fit perfectly. So with a bit of imagination you could imagine these foam wedges filling out to the front and being made in a darker color, I think it will look pretty decent.

You loose 5 centimeters (~2 inches) height compared to the stand, so this gives a tweeter height of 92cm (as opposed to 97cm). I guess we could create a filler foam plate to add the lost height too if need be.

 

[Sigberg Audio]

@TLS Guy and @ryanosaur - a bit of confusion here since I posted this originally in the wrong thread.

So this is a reply to your replies in the SBS thread (https://forums.audioholics.com/forums/threads/sigberg-audio-sbs-1-active-loudspeaker-review.125173/page-3#post-1575461) where I mistakenly posted the pics of the foam wedge thingy.

So, to be clear this is just experimentation at this stage, so I appreciate the feedback. Taller feet below the sub is of course an option, not sure if that would look great either. Some kind of base that the sub fits into might look better, but wont solve the issue of achieving the proper tilt unless the sub tilts with it, which I guess it could do, but you'd risk the speaker sliding off, so you still need something between the speaker and sub.

Also note that this will never be the main option, that would be the speaker stands, but are looking into possibly offering a solution for those who buys dual 10Ds and would like to place the speakers on top of them.

I think custom made wedges (probably not very thick ones) to get the tilt will probably look okay, but we''ll see.

 

[Sigberg Audio]

Experimenting with the integration between Manta and our subwoofers as well. This is an in-room measurements where two 10D subwoofers are connected via XLR through to each of the Mantas, so no external crossovers. The 10Ds roll off at 100hz (24db/octave), while the Mantas overlap quite a bit in the current configuration. -6dB in-room for the speakers is down at 40-50hz. The 75hz dip is due to the room.

So far it seems to both measure and sound great.

 

[TLS Guy]

Experimenting with the integration between Manta and our subwoofers as well. This is an in-room measurements where two 10D subwoofers are connected via XLR through to each of the Mantas, so no external crossovers. The 10Ds roll off at 100hz (24db/octave), while the Mantas overlap quite a bit in the current configuration. -6dB in-room for the speakers is down at 40-50hz. The 75hz dip is due to the room.

So far it seems to both measure and sound great.

I did not realize the speakers had to be tilted. I thought it was just because they were lower on the sub, than the stand.

Is there an odd order crossover involved in this? That is he only reason I can think of that would require a tilt if the tweeter is 36" above the floor.

What are those dips just above 130 and 180 Hz about? The 180 Hz dip is about an octave above crossover. There are admittedly fairly narrow Q. Put those dips, especially that 180 Hz dip, is well into a pretty crucial power band, where there is a lot of action in musical instruments, orchestra, organs, and even the lower ranges of the human voice especially baritones and Basso Profundos, and even contraltos. I can understand the 75 Hz dip, and that will not be audible, but the others might be. Those others are in a range where a speaker does not want to be at all "weak in the wind" so to speak. At least that is my experience.

 

[Sigberg Audio]

I did not realize the speakers had to be tilted. I thought it was just because they were lower on the sub, than the stand.

Is there an odd order crossover involved in this? That is he only reason I can think of that would require a tilt if the tweeter is 36" above the floor.

What are those dips just above 130 and 180 Hz about? The 180 Hz dip is about an octave above crossover. There are admittedly fairly narrow Q. Put those dips, especially that 180 Hz dip, is well into a pretty crucial power band, where there is a lot of action in musical instruments, orchestra, organs, and even the lower ranges of the human voice especially baritones and Basso Profundos, and even contraltos. I can understand the 75 Hz dip, and that will not be audible, but the others might be. Those others are in a range where a speaker does not want to be at all "weak in the wind" so to speak. At least that is my experience.

The tilt is to be able to send a bit more high frequency energy into the room without having it sent directly at the listener, as well as getting a more even vertical dispersion / similar frequency response for people sitting as opposed to standing in the room. Remember that these speakers are designed to be parallell with the wall (not angled towards the listener), so we need some extra energy in the high-end to get a good response off-axis. In summary this gives the most even response at the listening position as well the best and most favorable compromise with regards to response / dispersion patterns wherever you may be in the room. It's basically tonally similar anywhere in front of the speaker, until you actually pass by on the side of the speaker (so more than 90 degrees if possible in your room), where you get an interesting effect of rapid midbass roll-off due to the cardioid pattern.


With regards to dips: As mentioned these are in-room responses (listening position), so all dips are room related. The anechoic response is +/-2dB across the range, and that the deviation is even that much is mostly due to by design lift in the low end, and by design recessed response in the 2-4khz area.

Here's nearfield 15deg off-axis 400-20,000hz (below that you'd see the room affect the response as this isn't measured in an anechoic chamber) - it's basically +/-1dB except 2-4khz (on purpose), and would be the same in the bass in an anechoic chamber.

 

[TLS Guy]

The tilt is to be able to send a bit more high frequency energy into the room without having it sent directly at the listener, as well as getting a more even vertical dispersion / similar frequency response for people sitting as opposed to standing in the room. Remember that these speakers are designed to be parallell with the wall (not angled towards the listener), so we need some extra energy in the high-end to get a good response off-axis. In summary this gives the most even response at the listening position as well the best and most favorable compromise with regards to response / dispersion patterns wherever you may be in the room. It's basically tonally similar anywhere in front of the speaker, until you actually pass by on the side of the speaker (so more than 90 degrees if possible in your room), where you get an interesting effect of rapid midbass roll-off due to the cardioid pattern.


With regards to dips: As mentioned these are in-room responses (listening position), so all dips are room related. The anechoic response is +/-2dB across the range, and that the deviation is even that much is mostly due to by design lift in the low end, and by design recessed response in the 2-4khz area.

Here's nearfield 15deg off-axis 400-20,000hz (below that you'd see the room affect the response as this isn't measured in an anechoic chamber) - it's basically +/-1dB except 2-4khz (on purpose), and would be the same in the bass in an anechoic chamber.
View attachment 58070

I can see the problem if the speakers are flat to the wall and you need to get more HF in the room.

I doubt those dips I was referring to are the garden variety room effects. I suspect they are cancellations from reflections from the back wall, despite the cardioid design.

I have seen those sort of effects from back wall reflections before, and had a problem dealing with them in my in wall system. What ever the cause, that is a problem in need of a solution in my view.

 

[Sigberg Audio]

I can see the problem if the speakers are flat to the wall and you need to get more HF in the room.

I doubt those dips I was referring to are the garden variety room effects. I suspect they are cancellations from reflections from the back wall, despite the cardioid design.

I have seen those sort of effects from back wall reflections before, and had a problem dealing with them in my in wall system. What ever the cause, that is a problem in need of a solution in my view.

Isn't cancellations from reflections from the back wall garden variety room effects? I've never seen a room without it. In a typical room and setup 100-200hz looks far worse than the posted graph. To be clear this also zero smoothing.

 

[TLS Guy]

Isn't cancellations from reflections from the back wall garden variety room effects? I've never seen a room without it. In a typical room and setup 100-200hz looks far worse than the posted graph. To be clear this also zero smoothing.

I can't argue with what you say, but the wall behind the speaker is obviously part of the room. However if you are going to design a speaker to be used near a boundary, then it requires adjustments in design to minimize it. So lets look at that 180 Hz dip, the one that concerns me the most. So to get cancellation, then the reflection has to be antiphase to the output. So for that dip, the antiphase half wavelength is slightly over 2 ft.

I have encountered this. First in my center speaker. So the upper fill driver is equalized in the active crossover to take care of it. That speaker is a through wall design.

The next time was my in wall design. That was much tougher dealing with the reflections off the wall and TV screen. I got the left and right sorted, but the in wall center still has some issues, I think because of the usual three way center with the bass drivers side to side, and the tweeter above the mid between the two. These speakers are passive, and it is much easier to deal with these type of issues in an active design.

One of the huge advantages of DIY, is to be able to customize designs to the architectural considerations.

So yes, I believe it is a room effect, but still one that needs correction if the intent is to have an against wall design.