Development Thread: Sigberg Audio Saranna - active floorstander

[sigbergaudio]

​

I've started a few threads about our current products the last week, but this is where the fun is! This will be a development thread for our upcoming full range, active cardioid floorstander.

Current project name: "Saranna". The above is an early sketch of how it may look. Not obvious from the drawing but the back is more narrow than the baffle, so the side panels will likely be slightly curved in towards the back.

Sigberg Audio is currently known for loudspeaker systems consisting of monitors and subwoofers. There are two obvious segments of the market that we cannot reach with our current products:
1) Those who prefer floorstanders.
2) Those who do not want subwoofers.

The Saranna aims to address that.

Key Characteristics (subject to change)

• Huge soundstage, and rich, natural in-room sound (in line with other Sigberg Audio products)
• Full range (20-20,000hz) in-room response
• Cardioid midbass and midrange
• Ported enclosure (can be sealed by consumer for room tuning)
• As our other designs, placement close to the wall will be supported (but further out on the floor will work too).
• Simple presets (click a button on the back) for bass/placement adjustments, plus full 9 band EQ onboard for taming those room modes
• Dedicated preset for mating the speakers with our subwoofers; This presets introduces a high pass in the speakers, matching our subwoofers perfectly.

Preliminary specifications

• 3 channel, 600W amplifier per speaker
• Bass: Two 8" aluminium cone subbass drivers (fs:25hz)
• Midrange / Tweeter: 8" coax consisting of a midbass/midrange paper cone and 1.7" polymide compression driver
• Dimensions: 26x107x34cm (~10x42x13 inches)
• Expected frequency response (anechoic): 28-20,000hz +/-3dB
• Expected in-room extension: 20hz (-6dB)
• Cardioid dispersion from ~150hz and up

Some preliminary measurements (in-room) of prototypes:

In-room response at listening position with the speakers 10-15cm (4-6 inches) from the wall (left+right+avg):


10-200hz in-room (listening position, no subwoofer, no smoothing). Note that reference level is 75dB (avg of 300-5,000hz).
Relative to the reference level, in-room -3dB point is 22hz, and -6dB is 16hz:




Coax:



Bass driver:


More to follow!

 

[sigbergaudio]

The Saranna is a ported design, that with a combination of presets and opening or sealing the port will allow for different bass characteristics. This to accommodate for both tailoring the speaker to the room and individual taste. Exactly how this will work is still under development and subject to change, but currently it looks roughly like this.

Frequency on the x-axis, and in-room level/lift on the y-axis, where 0dB corresponds to the average level in the 500-5khz area:

 

[sigbergaudio]

New prototype iteration in the works, hope to have it done somewhat soonish. More to follow.

 

[sigbergaudio]

To share a bit more about the cabinet construction:

The current prototype has a separate cardioid loaded chamber for the coax with ports on the side similar to the Sigberg Audio MANTA.

The two bass drivers share a common enclosure with a single port. This chamber is relatively large, but quite well braced with braces both between the drivers and below the lower drivers (and above the upper driver the separation between the bass and coax chamber acts as a third brace). In addition to this the bass reflex port is part of the enclosure, going down behind the (again separate) chamber for the amplifier, adding two vertical braces.

The port itself is narrow, but as wide as the cabinet itself, exiting below the amplifier at the back of the cabinet. The port widens considerably at the exit to slow down the air flow and eliminate any port noise.

The current exterior cabinet design is relatively simple, but will likely be somewhat more elaborate down the road. The current plan is that the back will be more narrow than the baffle. So around the point of the final 1/3 of the side there will be an edge where the cabinet angles inwards towards the back. Whether the baffle itself will be slightly tilted back is undecided.

 

[sigbergaudio]

I have also done a rough quasi-anechoic measurement of the first prototype by splicing nearfield bass + 40cm nearfield of the speaker at 15deg measured indoors.

There's room disturbance/reflection around 150-200hz, and I did not splice in the output of the port directly, not sure how much of the port is picked up by this measurement, but it should be essentially flat to at least 25hz, so if I spliced in the port we'd also see the area from 60-25hz filled in.

Roughly eyeballing this and estimating the port response, I suspect we'll see a -6dB point somewhere around 21-23hz.

 

[Brucemck2]

Welcome to the forum. I’m a big fan of active speakers (and outboard subs).

 

[Ron Resnick]

Welcome to WBF, Sigberg!

This is a very interesting design. I think the midrange/treble co-axial driver is particularly interesting.

Why did you decide to place the midrange/treble driver on top of the two woffers rather than in the middle as a D'Appolito array?

What kind of amplification will be on-board the speaker? Class AB? Class D?

 

[sigbergaudio]

Welcome to WBF, Sigberg!

This is a very interesting design. I think the midrange/treble co-axial driver is particularly interesting.

Why did you decide to place the midrange/treble driver on top of the two woffers rather than in the middle as a D'Appolito array?

What kind of amplification will be on-board the speaker? Class AB? Class D?

Thank you!

With regards to MTM / D'Appolito; The main benefit of such an arrangement is theoretical vertical symmetry in the dispersion pattern (off-axis frequency response). This is already present in this design due to the coax driver, where both the midrange and the tweeter have the same center.

The D'Appolito design is also typically with a midrange above and below the tweeter, while the two drivers below in this design are essentially subwoofer drivers. The Saranna is expected to go flat to 20hz in-room (and the prototypes already does that).

On this particular speaker the coax could have between the two woofers, but then the tweeter would end up too low for a typical listening height. And since the woofers are crossed so low, it wouldn't have given any other benefit either.

In the current prototype there's a 5.5" coax with a traditional silk dome in the middle, so in that prototype the crossovers are at 250hz and 2500hz.

In the upcoming prototype (depicted in the illustration in the first post), there will be an 8" coax with a high capacity compression driver in the middle. So the new crossover configuration will likely be 200hz and 1600hz. Pictures of that will follow as soon as it is built.

The amplification is Class D from Hypex.

 

[Ron Resnick]

Thank you very much for the detailed answers!

 

[sigbergaudio]

New driver soon arriving.

 

[sigbergaudio]

New drivers have finally arrived and one speaker is complete. Will be a few days before the second one is done and speakers have been tuned enough to get a first impression. The 8" coax with the naked horn sure looks brutal though! More will follow!

 

[sigbergaudio]

New prototypes are up and running with some rough initial tuning. The cabinet and port design got some adjustments too. Among other things the cabinet is 2cm deeper.

I think it would be fair to call this a fullrange floorstander at least. The coax looks promising too. This was measured at ~1m distance in-room.



Will share some listening impressions of the new coax after I've spent some more time with it.

 

[sigbergaudio]

Currently playing flat to 21.5hz, and -6dB at 18hz when measured at the listening position.

 

[sigbergaudio]

There has been some controversy over the looks of the coax driver with the naked horn on a Norwegian forum, I suspect it will be a love/hate thing. At least it is recognizable.

I think it looks pretty cool, and it also have a radial phase plug hidden in the centre hole that is pretty nifty looking. Not so easy to see on pictures, but looks cool in real life.





Laptop permanently connected these days to be able to quickly do small adjustments by ear as I listen through familiar material. And, yes will of course measure along the way too. Typical process is to alternate between listening and measuring, doing adjustments during both.

 

[sigbergaudio]

A few more measurements, note that they're all rough indoor measurements for now.


Testing different crossovers today, currently testing one of the lowest I can practically use with these drivers, at 130hz - to get the cardioid as low as possible.

Crossover between bass drivers and coax:


Current 0-30-60-90 degrees off-axis (300-20,000hz):

 

[sigbergaudio]

Time to share some subjective impressions of the sound of the second prototype with the new 8" coax with compression driver

The overall tonal balance and sound signature is now not too far from Manta with subwoofers. These speakers love rhytmic and complex music like rock / hard rock, and putting on something like Volbeat or Rammstein sounds full, rich and clean rather than thin, messy and chaotic (as with way too many speakers). The bass is tight and deep and the midbass present and punchy. Guitars and rock vocals are in your face, raspy and tough without being harsh.

The compression driver is impressive too, with clear, open sound and no dynamic compression whatsoever no matter how loud you play. I had a slight fear that it would be harsh or unrefined, not the case at all. Pretty confident the new coax driver is worthy of being mounted in a Sigberg Audio speaker.

A track like the Space Oddity cover by Passenger rewards you with a three dimensional soundstage, crisp guitar, clean bass notes, tight percussion and beautiful vocals floating in the air between the speakers. Put on Lost Without You by Freya Ridings, and you get confirmation that female vocals sound excellent too, and the larger than life piano production is just that: Larger than life.

The bass drivers are the same as before, but the bass port has been redesigned and tuned slightly differently. Current port tuning is 27-28hz. Put on some elektronika and the bass, well, I have a 10D subwoofer connected to this system, let's just say I've had to get up and check that it was turned off more than once. The bass drivers are currently crossed over at ~140hz (subject to change) with the coax rolling off relatively hard to minimize excursion.


And another photo (note that this is still obviously a very rough prototype with regards to fit and finish)

 

[sigbergaudio]

These little buggers were introduced in the signal path yesterday. A passive crossover component!

 

[sigbergaudio]

The resistor in the picture above (a low inductance MOX resistor from Jantzen Audio) has been introduced in series with the tweeter, as the compression driver has very high sensitivity. This increases the impedance as seen by the amplifier, and lowers the sensitivity by 5dB, making it a better match to the other drivers from a gain perspective.

This could have been done digitally, but by doing it this way the inherent noise level and hiss is reduced, and the sound level of "pops" or other noises from on/off on the amplifier or connected preamps/sources will also be reduced.

Beyond that, the introduction of the resistor and the increased impedance will change the phase relation between current and voltage, affecting the way the driver distorts (theoretically in a good way). Finally, the impedance curve is such that you will get slightly higher attentuation in the lower frequencies (as is typical with tweeters), so in this way you get a natural gain/extension of the highest frequencies.

 

[bjofred]

Any idea of pricing yet? Noen ide om salgspris ennå?

 

[sigbergaudio]

Any idea of pricing yet? Noen ide om salgspris ennå?

Hi. I got the same question on another forum just the other day, so let me just paste that answer:

That is a very difficult question for a couple of reasons. First of all it is still early days, so the complexity of actual commercial production is hard to predict.

The second is that prices of everything surrounding production like raw materials and logistics have increased pretty signifcantly the last few years. And since the release date of the speakers is likely 12-24 months in the future, it's simply impossible to have the full picture of cost, since it will have changed before the speakers are available. Since not all components are sourced locally, things like currency exchange rates also affect the final cost.

A guesstimate is an export price somewhere around 15,000USD / 14,000EUR + import taxes and VAT (almost nothing in the US, but up to 20-25% in some European countries) with the current exchange rates.

Fluctuations in currency and changes in the global economy (affecting logistics etc) could swing that guess probably up to 20% either way. I also haven't made up my mind about how fancy the cabinet will end up, so that could affect the final price too.

That's a ballpark at least. Full disclaimer that for unknown reasons this may end up being completely wrong.