crossovers visaton

[terteliu]

I've accidentally discovered that, on the visaton official site, there is the construction plan and the crossover for every "speaker - 2,3 way" that can be bought from the market.

My problem is that in the crossover scheme I do not recognise any of the bessel, butterwroth, linkwitz-riley functions, for exemple :

Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories

I want to make this construction, and they say that the crossover has the cut-off frequency at 200 hz and at 3000 hz.
Using the known crossover calculators based on the mentioned functions, the values revealed for capacitors and inductors, have nothing to do with those from their crossovers.

Can you help me to discover who's equations do they use in here?

[terteliu]

the interesting thing is that they use inductors with lower inductance, so cutting down from 12 mH to 4 mH, means much cheaper inductors and much more space

[PeteMcK]

If they're using the woofer to add some BSC, a smaller inductor would be used

[giralfino]

That has been said many times on this forum, one more won't harm.
Using crossover calculators (and the same apply to off-the-shelf crossovers), can often lead to bad speakers. This is true because the drivers are not a pure resistive load with constant resistance.
See what a well known diyer has to say: Troels Gravesen - Crossovers

Another problem is that novices tend to think in term of electrical slopes, but what really is important is the acoustical slope, and that depends also on the driver natural behavior (rollover), and the effect on the baffle. For the low pass on a mid it can also depend on the cabinet volume and tuning.

It is possible to design a crossover without measuring yourself the drivers, but you have to have at least a measure of the driver in a KNOWN condition (infinite baffle or other condition), and using appropriate software calculate the effect of YOUR baffle and cabinet.
See for example this link: FRD Consortium tools guide

Ralf

PS I know nothing on this Visaton design, I'm only speaking in general terms.

[Arty]

thing is..
any off the shelf Xover will 100% for sure will not do whats written on it.
Unless You use resistors instead of speakers.

If you manage to mesure the impedance curve of the speakers, then it is far better to do Your own crossover.

That infomration alone is not enough for the "professional" making, YET still is lightyears ahed of any off the shelf xover.

To mesure the impedance curve You only need winisd, and a multimeter.
Impedance correction network then can be estimated and verifyd.
Then You can do a simple test -when You have the speakers in the box You want to build- You may relay on Your ears, or use a microphone capsule (electret type, simple to DIY one, in most cases its quite linear in the tipical xover regions) and find a suitable Xover point.

Nowthen, to answer Your main question, the component values are depending on_
-aligment of filter
-order of the filter
-crossover freqvency
-the load impedance

Even if You take an 8 ohm woofer, the impedance will never be exact 8 ohms.
There is absolute no clue telling what impedance load was that xover designed for.

From the above "quick and dirty" xover design procedure You can see for Your self, that the xover component values are highly depending on the load.
Just as mutch as they depend on choosen xover point.

[terteliu]

Originally Posted by giralfino

Another problem is that novices tend to think in term of electrical slopes, but what really is important is the acoustical slope, and that depends also on the driver natural behavior

This is exactly what I've done. I have a degree in electronics, but what I know is only teoretical with no practice, and anyway, it's far away from the knowledge about corssover.

I've read today about baffle but I still do not understand how they should be calculated so that the lower frequences wouldn't feel like -6 db, and the highwr frequences like +6db. If you have a gould material, please send it.

Originally Posted by giralfino

PS I know nothing on this Visaton design, I'm only speaking in general terms.

They have everything on their site, the wood pieces and what dimensions, and the electrical scheme of the crossover, but they do not explayn how the circuit it's broken into what with their definite function, like this is zobel, this is the lpad etc.
So, I want to make the mentioned box, but insead of 2 W100S 8 Ohm, I want to use 1 w130s 8 Ohm, just because I already have this driver, and also the woofer and the tweeter, bought a year ago. So in order to adjust the circuit I need to understand it, because using a different driver on the mid frequences, and only one not two, I am sure that copy paste the circuit is bad from start.

[giralfino]

They have everything on their site, the wood pieces and what dimensions, and the electrical scheme of the crossover, but they do not explayn how the circuit it's broken into what with their definite function, like this is zobel, this is the lpad etc.
So, I want to make the mentioned box, but insead of 2 W100S 8 Ohm, I want to use 1 w130s 8 Ohm, just because I already have this driver, and also the woofer and the tweeter, bought a year ago. So in order to adjust the circuit I need to understand it, because using a different driver on the mid frequences, and only one not two, I am sure that copy paste the circuit is bad from start.

The link I gave you explain how to use a measure done for example on an infinite baffle, and predict what will be the measure on your baffle/enclosure. After that you need to import that simulation on a crossover simulation software (I use Passive Crossover Designer, also from the FRD Consortium).
You have the measures of the drivers done by Visaton, you should try to replicate this speaker frequency response: VOX 200 LIGHT Frequency Response
If your simulation is good, you could also try your mod.
Try also to learn from some well known diyer (Zaph Audio, Troels Gravesen).

Ralf

[terteliu]

I've lost almost 10 hours but now I understant a little more after studying FRD Consortium tools guide.

And after playing with passive crossover designer I understand what function have those components on the crossover, and i'm quite happy.
Having the amplitude and the impedance spectrum imported into frd and zma, and then into passive crossover designer I could easily see what was going on.

Problem solved
Thank you