First let me add my kudos to BFARD for a very, very nice project.
For reference to those interested in the unique cap-free crossover topology used in the Extrema Tony Gee of The Netherlands famous on the web among DIY speaker circles as the master mind behind Humble Homemade Hifi has a couple of designs posted using this topology.
http://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_The%20Monitor_copy.pdf
and
http://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_Paper%20HATT_copy.pdf
In his Paper HATT design he gives a good discussion of how the cap-free crossover works.
If you have read this entire thread you have seen it repeated that the Extrema "needs a lot of power". Looking at the schematic of this type of crossover one sees the resistors and inductors in parallel with the drivers. So to gain the benefit of not making the audio signal jump across the capacitors’ dielectric we instead dissipate some of the signal. And by ‘some’ I mean up to half! In his Paper Hatt Gee has on one parallel leg a 1.8 ohm resistor and the tweeter and woofer all in series, assuming the drivers are 4 ohm DCR call it 9.8 ohms DCR. Now the other parallel leg is an inductor with 0.07 ohms DCR and 7.83 ohm 10 watt resistor for a total of 8 ohms. So at DC the power is almost exactly split with half going thru the drivers to make sound and half thru the inductor and resistor to make heat. Of course we don’t listen at DC and as always the AC case is more complex, but still a significant percentage of the amp’s powers ends up heat in the resistors.
My guess is it was this lowering of efficiency that led both Sonus Faber and Gee to return to more conventional crossovers for their later designs. I tried this cap-free crossover topology in a design using Fostex woofer and horn tweeter and the result was a very transparent detailed sound.
For reference to those interested in the unique cap-free crossover topology used in the Extrema Tony Gee of The Netherlands famous on the web among DIY speaker circles as the master mind behind Humble Homemade Hifi has a couple of designs posted using this topology.
http://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_The%20Monitor_copy.pdf
and
http://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_Paper%20HATT_copy.pdf
In his Paper HATT design he gives a good discussion of how the cap-free crossover works.
If you have read this entire thread you have seen it repeated that the Extrema "needs a lot of power". Looking at the schematic of this type of crossover one sees the resistors and inductors in parallel with the drivers. So to gain the benefit of not making the audio signal jump across the capacitors’ dielectric we instead dissipate some of the signal. And by ‘some’ I mean up to half! In his Paper Hatt Gee has on one parallel leg a 1.8 ohm resistor and the tweeter and woofer all in series, assuming the drivers are 4 ohm DCR call it 9.8 ohms DCR. Now the other parallel leg is an inductor with 0.07 ohms DCR and 7.83 ohm 10 watt resistor for a total of 8 ohms. So at DC the power is almost exactly split with half going thru the drivers to make sound and half thru the inductor and resistor to make heat. Of course we don’t listen at DC and as always the AC case is more complex, but still a significant percentage of the amp’s powers ends up heat in the resistors.
My guess is it was this lowering of efficiency that led both Sonus Faber and Gee to return to more conventional crossovers for their later designs. I tried this cap-free crossover topology in a design using Fostex woofer and horn tweeter and the result was a very transparent detailed sound.
Tony Gee's "Monitor" xo was more in the topology of a series xo discussed in great detail in a number of threads here. John K. writes that a deficiency of the design is the woofer can interact with the tweeter; unlike a parallel network.
The top hat is indeed a SFE type design. My 'Intimates' also have this topology. The efficency is in the 84-85 dB @ 2.83 V range so the speakers need a minimum of 100 WPC to shine and they do indeed shine with SS drivers!
The top hat is indeed a SFE type design. My 'Intimates' also have this topology. The efficency is in the 84-85 dB @ 2.83 V range so the speakers need a minimum of 100 WPC to shine and they do indeed shine with SS drivers!
bfard - compliments, your speaker looks really good. Reviewing this and other threads suggest that there are actually not very many speakers out there
using this form factor. A lot of work
!
My pair (2011) is not a clone but loosely follow the form............
using this form factor. A lot of work
!My pair (2011) is not a clone but loosely follow the form............
An externally hosted image should be here but it was not working when we last tested it.
dan998 -
tweeter is
Madisound Speaker Store
and woofer is an Aurasound 8 inch also from same supplier, I see they are no longer listed, (was a closeout driver)
Xover 2nd LR @650
tweeter is
Madisound Speaker Store
and woofer is an Aurasound 8 inch also from same supplier, I see they are no longer listed, (was a closeout driver)
Xover 2nd LR @650
So, this project is the Extrema look (great job BTW) but not the Extrema xo topology?
My 'Intimates' have the Extrema xo topology but not the look. Introducing the "INTIMATES" (high WAF & quality sound) - Techtalk Speaker Building, Audio, Video, and Electronics Customer Discussion Forum From Parts-Express.com
Yes, they do need power. Power is cheap these days. So, for the price there is great sound from the combination of good quality drivers and simple xo.
My 'Intimates' have the Extrema xo topology but not the look. Introducing the "INTIMATES" (high WAF & quality sound) - Techtalk Speaker Building, Audio, Video, and Electronics Customer Discussion Forum From Parts-Express.com
Yes, they do need power. Power is cheap these days. So, for the price there is great sound from the combination of good quality drivers and simple xo.
Fgroen: Unbelievable work. I salute thee ...
I have a question which has been rolling around it my head ever since I saw the aulos with the heil tweeter suspended in front of the woofer fitted @ a 45 degree angle and a curved tri oval style body for the woofer cabinet - I'd start out with a pine tree trunk and machine that down. I wanted to ask you if you picked MDF for any particular reason - it probably is less interveneing auditory wise I think.
Thanks.
Srinath.
I have a question which has been rolling around it my head ever since I saw the aulos with the heil tweeter suspended in front of the woofer fitted @ a 45 degree angle and a curved tri oval style body for the woofer cabinet - I'd start out with a pine tree trunk and machine that down. I wanted to ask you if you picked MDF for any particular reason - it probably is less interveneing auditory wise I think.
Thanks.
Srinath.
I've been looking forward to doing this post. Rubbing my hands in glee, in fact. If I tread on some people's dreams, sorry. Here goes...The Sonus Faber Extrema has the STOOPIDIST crossover I have ever see. It burns half your amplifier power on a ridiculous resistor/inductor tweeter section. They call it "CAPACITORLESS", but I call it "BRAINLESS".
The circuit is along these lines:
An externally hosted image should be here but it was not working when we last tested it.
Now you might think there is some audio voodoo magic in there, or at least be confused enough to give them the benefit of the doubt. But there isn't.
This circuit works exactly the same, without burning all your bass power in a resistor:
An externally hosted image should be here but it was not working when we last tested it.
That is why Sonus have dropped this topology. It is plain daft. The speaker sounds good because it has good drive units and cabinet, the crossover was an embarrassing mistake. More graphs here if you want to follow it up:
http://www.diyaudio.com/forums/multi-way/206843-sreten-speakerman-go-series-xos-57.html#post3047689
The SFE had an efficiency of 88 dB, mostly thru the use of 4 ohm drivers which were probably quite efficient themselves. So, I suspect the 'power hungry' SFE's were't so bad after all.
Without know the intimate details of the drivers used in the SFE you can't say for sure how 'bad' the xo design was. Many audiophiles today still seek used SFE's.
Sonus Faber Extrema
I my case with the 'Intimates' I didn't have the budget or luxury of having custome made drivers with high sens. and low ohms to accomplish similar results.
Without know the intimate details of the drivers used in the SFE you can't say for sure how 'bad' the xo design was. Many audiophiles today still seek used SFE's.
Sonus Faber Extrema
I my case with the 'Intimates' I didn't have the budget or luxury of having custome made drivers with high sens. and low ohms to accomplish similar results.
I've been scratching my head over the AR-SXO crossover for months. This Sonus one seems to be along the same simplistic lines. John Kreskovsky is of the "older and wiser" opinion these days that series crossovers have no particular magic.
That's a bit sad, but in the case of the Sonus Faber Sine-Cap crossover, it is provably a very poor design. The capacitor equivalent appears to work identically, without the silly power consumption and need to protect the tweeter with a big bypass capacitor. Who better to test it but you?
You are then left merely with the tendency of these low order crossovers to fry the tweeter or at least drive it into distortion, and let breakup from the midbass unit through. They never are 6dB per octave in practise either. I was seeing something like 16dB per octave here.
FWIW, there is a very fine 2nd order design lurking in the Sonus Faber. Almost ruler flat.
That's a bit sad, but in the case of the Sonus Faber Sine-Cap crossover, it is provably a very poor design. The capacitor equivalent appears to work identically, without the silly power consumption and need to protect the tweeter with a big bypass capacitor. Who better to test it but you?
You are then left merely with the tendency of these low order crossovers to fry the tweeter or at least drive it into distortion, and let breakup from the midbass unit through. They never are 6dB per octave in practise either. I was seeing something like 16dB per octave here.
FWIW, there is a very fine 2nd order design lurking in the Sonus Faber. Almost ruler flat.
I think it's time you tore youself from your computer for awhile and built a pair of Intimates. Then, YOU could measure and experiment with series, SFE or parallel xo's yourself and deal with the real world for a change.
I really don't care if they are precisely 6 or 7 or 8 or 16 dB/octave as long as they sound good. Just a reminder relative to your distortion comments, I named the speakers the Intimates because they should not be played loud (95+ dB) for extended periods for risk of tweeter distortion and/or damage. That's stated clearly at my PETT link.
Cheers,
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We might be digressing a bit here. No doubt that first order has some nice qualities, but some weaknesses too. I can understand you are a bit cross about this, but the testable assertion I am making is that the capacitor circuit will work as well sonically, and better on power. Now if you'll excuse me, I must sign out. I have to remove a tank from my bass crossover which reduces cone breakup one way, and then increase the rolloff capacitor a tidge which does it another. You see, I do build stuff and listen to it.
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