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Multi-Way Conventional loudspeakers with crossovers

What is "Paracross topology" xover?
What is "Paracross topology" xover?
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Old 30th November 2017, 06:41 PM   #11
andy2 is offline andy2  United States
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Quote:
Originally Posted by gpapag View Post
The slopes published for the Extrema don’t seem too different, yet see how simple the cross-over is. Their designer is very good in making cross-overs that match with the specific drivers.
Sonus Faber Extrema loudspeaker | Stereophile.com

George
There is a serious dip of around 10db (if I read the scale correctly) around 2 - 3KHz. My guess is the speakers will sound very "musical". But on the other hands, with simple xover, it may be what they are looking for.
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Old 30th November 2017, 06:47 PM   #12
andy2 is offline andy2  United States
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Originally Posted by gpapag View Post
Sonus Faber Guarneri Homage loudspeaker | Stereophile.com

George

>Edit: Scott, we've crossposted
I look through a lot of Stereophile speakers measurements and a lot of them have strange dips and peaks that I wouldn't let it go on my own diy projects at least to the best of my ability. I've seen some B&W speakers where the midrange is like 5db above the bass region. And some Dynaudio stuffs have some big peaks and dips that makes me rethink whether freq. response actually matters.
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Old 30th November 2017, 11:16 PM   #13
AllenB is online now AllenB  Australia
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Originally Posted by andy2 View Post
whether freq. response actually matters.
It does. Sonus used to cross their tweeters with a resistor and an inductor (they weren't the first). This approach is elegant but less versatile, and not well prioritised, but appealing to those who don't like capacitors. Less so to those who like a smooth response.

This speaker appears to have a notch below the tweeters passband. They claim their crossover is non-resonant, I don't know where to start with that but I'm dubious of using that wording to describe a first order slope (partial). Why do they do this? I speculate THD maybe, but sacrifices have been made to the response.. and why do they want to confuse us in the first place?

Last edited by AllenB; 30th November 2017 at 11:18 PM.
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Old 1st December 2017, 03:07 AM   #14
boswald is offline boswald  United States
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What is "Paracross topology" xover?
If you can't convince 'em, confuse 'em.
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Old 1st December 2017, 09:36 AM   #15
system7 is offline system7  United Kingdom
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I think it was the Red Queen in Alice in Wonderland who said that "When I use a word, it means exactly what I want it to mean"! I do this too. See, the word is not the thing. For instance if I use the word OAK TREE, it doesn't describe the Squirrels or the smell or the shade from the sun on a hot day.

Thus it is with "Paracross".

In fact it seems to refer to aperiodic or damped reflex bass here. It's not rocket science. You just stuff or damp the reflex port and it ends up nearer closed box with a bit more deep bass. Somewhere between 12dB closed box and 24dB reflex lies aperiodic 18dB "Paracross". And it does make the impedance flatter and more amp friendly.

Quote:
“Paracross topology”. The impedance at low frequencies is controlled for a clear and friendly amplifier performance.
• Lilium - Low frequency speaker Lilium - Loudspeaker cabinet design with tuned mass damper

6db filters are just audio hoey, IMO. In practise you always end up nearer 6-18dB/octave when you take mechanical rolloff into account. I have some screenshots of the SF Guarneri, built on Violin lines with stuff like lead and rubber damping on the cabinet at a silly price. Probably sounds OK with classical. Heavy-metal headbangers must take their chances. Seems a reasonable idea to damp coils with hotglue or tar. They are quite lively and resonant and microphonic, IMO.
Attached Images
File Type: jpg SF Guarneri Crossover.JPG (70.6 KB, 191 views)
File Type: jpg SF Guarneri Homage.JPG (18.1 KB, 188 views)
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Old 1st December 2017, 11:32 AM   #16
Scottmoose is offline Scottmoose  United Kingdom
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Originally Posted by system7 View Post
I think it was the Red Queen in Alice in Wonderland who said that "When I use a word, it means exactly what I want it to mean"! I do this too. See, the word is not the thing. For instance if I use the word OAK TREE, it doesn't describe the Squirrels or the smell or the shade from the sun on a hot day.

Thus it is with "Paracross".
True. Pure marketing. A necessary evil in this day & age unfortunately.

Quote:
In fact it seems to refer to aperiodic or damped reflex bass here.
Not as far as I can tell. All the references are related to the crossover rather than the box, & are probably referring to a notched 1st order or similar. Sonus have always described their mildly resistive vents as their 'stealth reflex port'.


Quote:
6db filters are just audio hoey, IMO.
I'm with you there Steve. A lot of compromises and precious few advantages.

Quote:
In practise you always end up nearer 6-18dB/octave when you take mechanical rolloff into account.
Ultimately true, but in fairness you can have 6dB/octave through the transition band, ultimately increasing to a higher order once the mechanical rolloff is factored in (or any stopband notches, additional filtering &c. for that matter). Depends on the flat BW of the driver on the baffle & the crossover frequency.
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Old 1st December 2017, 11:55 AM   #17
lisoformio is offline lisoformio  Italy
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Should be: Patent EP0485010A1 - A filtering device for high frequency loudspeakers - Google Patents
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Old 1st December 2017, 12:06 PM   #18
gpapag is offline gpapag  Greece
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What is "Paracross topology" xover?
Everyone (almost?) is inventive with marketing language. I find no reasoning to bash Sonus Faber.
I had auditioned their “Extrema” (the one with the B139 at the rear acting as a controlled passive radiator) and I have only positive words to say.

George
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Old 1st December 2017, 12:36 PM   #19
gpapag is offline gpapag  Greece
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What is "Paracross topology" xover?
Quote:
Originally Posted by lisoformio View Post
Should be:
Thanks Pietro.
They have patented the series resistor ("resistance greater or equal to 6-7 Ω") and the parallel inductance ("in the order of hundreds of µH") at the tweeter branch.

Why an inductor in parallel instead of a capacitor in series? Their reasoning:

"...the reactive component, which consists of the inductor, is placed parallel with the loudspeaker. This means that this component performs, with respect to the signal, a shunt or derivative function to an extent which decreases with the increase of the frequency and which therefore is close to zero when the signal is within the pass-band. Therefore, in the conventional case, the signal must cross the reactive component in order to feed the loudspeaker. On the contrary, in the device according to the present invention, this does not occur and the effect of the reactive component is to tend to cancel itself as the frequency of the signal tends to increase. In particular, this difference operates in favor of the quality of reproduction which is not limited by the quality of the reactive component being used."


George
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Old 1st December 2017, 12:57 PM   #20
AllenB is online now AllenB  Australia
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Originally Posted by gpapag View Post
is not limited by the quality of the reactive component being used.
So shunt components are irrelevant? This is how many DIYers used to talk, but a 'professional' appealing to a misconception, I'm not as sure. This is such an old view that reminds me of the automotive industry, which referred to the capacitor in an ignition system as a condenser until recent changes in technology.
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