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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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Old 18th September 2016, 05:22 PM   #1
guidobullo is offline guidobullo  Italy
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Ciao.
Spero capirete che in Italia può capitare che gli articoli di elektor siano stampati con errori dovuti alla stupidità delle persone.
Comunque cerco la tabella 4 che viene nominata nell’articolo, la quale indubbiamente dovrebbe contenere le formule per il calcolo dei filtri, alle varie frequenze di taglio
Allego il file con il progetto di elektor, affinché sia chiaro cosa cerco.
Qualcuno ha la versione completa?
Grazie in anticipo a chi mi aiuterà
Amo LME49830.
Guido
Dimenticavo! FRD ci ha regalato degli ottimi programmi per il calcolo dei crossover, quello in cui si calcolava un quattro vie non riesco più a trovarlo qualcuno lo ha e me lo può dare? Era in formato. xls


Hello.
I hope you will understand that in Italy it can happen that the elektor items are printed with errors due to the stupidity of the people.
However I am seeking the table 4 that is mentioned in the article, which undoubtedly should contain the formulas for the calculation of the filters, the various cut-off frequencies
I attach the file with the project elektor, to make it clear what I'm looking.
Does anyone have the full version?
Thanks in advance to those who will help me
I love LME49830.
Guido’


I forgot! FRD has given us some good programs for the calculation of crossovers, one in which it was estimated a four-way I can not find someone has it and can give it to me? He was formed. xls Visualizza traduzione originale
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Old 18th September 2016, 05:27 PM   #2
guidobullo is offline guidobullo  Italy
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Default file

aggiungo il file
Attached Files
File Type: zip crossover.zip (944.2 KB, 193 views)
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Old 18th September 2016, 07:42 PM   #3
sreten is offline sreten  United Kingdom
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Hi,

The article is simply wrong. Active crossovers need to be not the target
function, but the target function minus the acoustic responses of the
drivers, so that you end up with the target function acoustic response.

rgds, sreten.
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Old 18th September 2016, 11:19 PM   #4
Struth is offline Struth  Canada
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Hi Guys

Personally I find it easiest to use the Sallen-Key filters with Riley-Linkwitz alignment. All this entails is adding the factor of root-2 into the star\dard equation, which means you are calculating a 6dB-down point for the crossover frequency.

The preferred alignments are 12dB/oct and 24dB/oct, with the latter preferred overall.

Low-pass is then two cascaded LP filters.
HP is two HP filters cascaded.
Middle bands are two LPs cascaded with two HPs to make a bandpass.

It is best to keep the crossover simple inasmuch as it just provides the crossover filtering desired. if you have a "problem" driver that needs an extra filter effect, add it to that band only and make this filter switchable so the crossover can be used with other drivers later.

It is of no value whatsoever for a DIY or purpose-built crossover to have variable frequencies. This just entails unnecessary expense and introduces opportunities for miswiring. It is good though to provide an output level for each band if you need to tweak the relative loudness of the drivers.

Bi-amping rules! It reduces system distortion by an order of magnitude.

A sub-sat system in the home provides much better movie sound than the artificial tone from a "home theatre" system AND provides far better music reproduction.

Have fun

Last edited by Struth; 18th September 2016 at 11:22 PM.
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Old 4th October 2016, 09:42 AM   #5
guidobullo is offline guidobullo  Italy
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grazie
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Old 4th October 2016, 10:00 AM   #6
AndrewT is offline AndrewT  Scotland
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I can't read that Italian article, but I think it is describing a subtractive filter arrangement.
I suggest you look at the simpler lowpass and high pass filters.
ESP has a couple of articles and a calculator for the LR filters.
Linkwitz Riley as described in the Linkwitz site is more comprehensive.
Sreten is correct that it's the total filter of electrical plus acoustic that needs to be your target. But Struth's very much simpler LR4 suggestion to get you started works quite well in some circumstances.

Use a good driver that performs well in it's passband and filter out the signals that make it misbehave and you will find that the steeper LR4 allows a good sound from good drivers very simply.
It's worth trying as a start. You may be happy with what you get.
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Old 4th October 2016, 10:46 AM   #7
consort_ee_um is offline consort_ee_um  United Kingdom
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More explanation here:
3-Way Active Crossover with Linearity Phase eng
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Old 4th October 2016, 11:34 AM   #8
billshurv is online now billshurv  United Kingdom
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Which is almost proof as to why EE's are often the worst people to design active crossovers!
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Old 4th October 2016, 01:35 PM   #9
JMFahey is offline JMFahey  Argentina
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Ciao Guido.

Well, I can read Italian, so will comment on the actual article

1) it´s an "Elektor Project", with all that implies
Not dissing them, quite the contrary, Elektor is THE DIY magazine, so at every issue, no matter what, they MUST offer at least a couple new , buildable projects, not an easy task every Month, every year.

And those must be "serious" projects, (not LED blinkers or LM386 amps), of good quality and fully developed and tested,including a proper PCB.
All that makes me admire them immensely because that´s a Herculean task

2) if anything, they tend to overcomplicate things, although in a way it´s understandable, I guess they want to stay ahead of the pack ........ which they usually do.

3) Guido !!!! : it´s a 1989 project !!!!!!
Doubt many will have it available here, but I know old Elektor editions have been scanned and are available as PDF on CD ROM so you might get the 1989 one, just search around .

4) recalculating everything will be a PITA and probably prone to errors BUT: the schematic and article provides values for 500 and 5000 Hz , other frequencies were provided for in the (lost?) table, BUT you can easily convert/transpose values to other frequencies by increasing/decreasing relevant cap values by a fixed factor.
Say, you want to move low/mid crossover, now 500Hz , to, say, 600 Hz, you decrease low band lowpass caps and midband highpass ones by a factor of 1.2 and you have the new ones.

Same with mid to high crossover.

Enjoy
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Last edited by JMFahey; 4th October 2016 at 01:41 PM.
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Old 4th October 2016, 03:49 PM   #10
guidobullo is offline guidobullo  Italy
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grazie a tutti
tankyou
guido
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