Sonus Faber Extrema

Blackmorec

Well-Known Member
Feb 1, 2019
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Of course, apologies for my over long post. Just one summary point before I go silent: current limited amplifiers like the Devialets and the Halcros will definitely not work very well with the Extremas (which are very hungry for current).
The Extrema has a sensitivity of 88dB/W/M, so at 1m distance, 1 watt will produce an SPL of 88dB

Now, lets apply some very simple math to get to a realistic listening position and volume

If we sit 4m (13ft) away from the speaker, we‘ll need 4W for the same 88dB (double the power for doubling of distance)

If we now start to crank up the volume we get the following (For each doubling of input power to the speaker, there will be a 3 dB increase in output)
88dB 4W
91dB 8W
94dB 16W
97db 32W
101db 64W
104dB 128W

Given the Extrema spec calls for a maximum 200W amplifier input, the most you‘re going to get out of them at 4m is about 105dB. If you need more for a larger room or a more distant listening position, then you’ve bought the wrong speaker and you need something that is more sensitive and can handle larger input currents.
Take a look at the Halcro and Devialet specs. 1000w into 6 ohms and 500W into 4 ohms Both have thermal cut-off protection But if you were driving your Extremas flat-out, you’d be using between 12.5% or 25% of either amplifier’s output capability. The reason the cut-off is thermal is that it limits SUSTAINED output rather than instantaneous. But, depending on the mains supply you are using, if its a regular household mains supply based on the typical 1.5mm2 cabling over quite some distance, with lots of questionable junctions then, you will potentially get some voltage drops at high volume (high current demand) which will clearly manifest through a drop in sound quality. If you want to get the most from these speakers you do need to make sure you’re providing the instantaneous current capability they need.
The reason high current amplifiers are recommended for the Extrema are:
1. They’re quite inefficient at 88dB/W/M
2. They need a largish room to operate at their best (plenty of space between them and well away from walls)
3. For a small 2-way speaker they produce great dynamics when the amplifier has sufficient instant current capability and plenty of headroom.
4. They are capable of handling high power transients.
So what you need is an amplifier with around 200W preferably with a mains supply that can respond to the amplifiers’ instantaneous power demands.
 

Raker24

Member
Jul 28, 2020
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The Extremas were also unique in the sense that they did not have any capacitors (supposedly, I never checked myself) in the crossover. Sonus Faber called this "Sine Cap", or "Without Capacitor" in English. The tweeter was protected by a large resistor (although I managed to blow one tweeter in Doha in 1995, playing way too loud with the very first BAT VK5 tube preamp and the Adyton Cordis 3B power amplifier). I am not a technical expert like Blackmorec, so I may be wrong, but it is possible that this unique crossover configuration contributes to the "power hunger" of the Extremas.
 

Blackmorec

Well-Known Member
Feb 1, 2019
424
584
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The Extremas were also unique in the sense that they did not have any capacitors (supposedly, I never checked myself) in the crossover. Sonus Faber called this "Sine Cap", or "Without Capacitor" in English. The tweeter was protected by a large resistor (although I managed to blow one tweeter in Doha in 1995, playing way too loud with the very first BAT VK5 tube preamp and the Adyton Cordis 3B power amplifier). I am not a technical expert like Blackmorec, so I may be wrong, but it is possible that this unique crossover configuration contributes to the "power hunger" of the Extremas.
Hi Raker24,
Yes, thanks to the tweeter’s extra-wide bandwidth and power handling capacity, SF could implement a very gentle 6dB/Octave filter using a parallel inductor rather than the more usual in-line capacitor. A resistor is required to provide the necessary source impedance for the inductor and will of course dissipate a small amount of power over the speakers’ entire frequency range. The heat sink was there to ensure that the resistor remained cool. I checked mine a few times after some ‘head banging sessions‘ but it was never even particularly warm.
As far as electronics go I certainly wouldn’t describe myself as a technical expert, more a well-read lay person who‘s spent 45 years trying to get his hi-fi to sound good :)
 

LL21

Well-Known Member
Dec 26, 2010
12,510
1,098
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Great few posts (#61-63)...and ones to remember for any of us who might have a desire to pick up one history's great speakers...
 
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RDSChicago

Well-Known Member
Nov 13, 2013
108
71
258
Have they arrived?
Yes! They’re here but I need to do some listening. I’ve been out of town and will report back with some critiques. They do make quite a presence on the stands! They’re huge!!
 

DLS

Well-Known Member
Jan 12, 2013
25
27
355
New York
Huge they are, but they will disappear when setup right. So you were able to get proper stands made - that's great! I'm very curious how the Aleph's will drive them, even though they are lowered powered, the quality of that power is superb.
 
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RDSChicago

Well-Known Member
Nov 13, 2013
108
71
258
The Extremas are simply incredible. Full, rich and dynamic. I can’t stop listening to them. I’m playing all genres and not finding faults. The Aleph 0’s and my 120 watt 845 tube monoblocks seem to drive them with ample authority.. Based on the recommendations in this thread I’d love to try them with a mega-powered solid state amp. If anyone In the Chicago area wants to loan me one, please let me know!
 
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Gregm

Active Member
Mar 14, 2019
123
79
35
France
The Extrema has a sensitivity of 88dB/W/M, so at 1m distance, 1 watt will produce an SPL of 88dB

Now, lets apply some very simple math to get to a realistic listening position and volume

If we sit 4m (13ft) away from the speaker, we‘ll need 4W for the same 88dB (double the power for doubling of distance)

If we now start to crank up the volume we get the following (For each doubling of input power to the speaker, there will be a 3 dB increase in output)
88dB 4W
91dB 8W
94dB 16W
97db 32W
101db 64W
104dB 128W

Given the Extrema spec calls for a maximum 200W amplifier input, the most you‘re going to get out of them at 4m is about 105dB. If you need more for a larger room or a more distant listening position, then you’ve bought the wrong speaker and you need something that is more sensitive and can handle larger input currents.
Take a look at the Halcro and Devialet specs. 1000w into 6 ohms and 500W into 4 ohms Both have thermal cut-off protection But if you were driving your Extremas flat-out, you’d be using between 12.5% or 25% of either amplifier’s output capability. The reason the cut-off is thermal is that it limits SUSTAINED output rather than instantaneous. But, depending on the mains supply you are using, if its a regular household mains supply based on the typical 1.5mm2 cabling over quite some distance, with lots of questionable junctions then, you will potentially get some voltage drops at high volume (high current demand) which will clearly manifest through a drop in sound quality. If you want to get the most from these speakers you do need to make sure you’re providing the instantaneous current capability they need.
The reason high current amplifiers are recommended for the Extrema are:
1. They’re quite inefficient at 88dB/W/M
2. They need a largish room to operate at their best (plenty of space between them and well away from walls)
3. For a small 2-way speaker they produce great dynamics when the amplifier has sufficient instant current capability and plenty of headroom.
4. They are capable of handling high power transients.
So what you need is an amplifier with around 200W preferably with a mains supply that can respond to the amplifiers’ instantaneous power demands.
At 4m away, I think the Extremas are even less sensitive! We lose 6dB with every doubling of distance (OK that's a textbook value), so at 4 ms we would lose around 12 dB. In other words, only about 76dB will reach the listener at 4 metres (88-12). The 200W max input (is that peak or sustained, I wonder) the Extremas will output ~98dB SPL at the listening position. At 128W they will do 97dB.
On papaer, anything less than a 250+W amp will not cut it. Interestingly, my Kraft did cut it when I tried these at home for a while -- but then, I don;t listen too loud.
 
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