How crossover works? Q&A

[Downunderwonder]

Maths translates much easier than the English surrounding it.

 

[Szyszaczek]

Oh...

If we take impedance / frequency of chart is it's near impossible to match good crossover, unless its set as low, as it match linear on imp/freq graph. If I even do custom crossover at 4kHz it wont cross at 4khz cause at 4kHz impedance of 15" speaker will be diffrent - higher then 4Ohms. Bassicly it will set this crossover higher or lower due to rise od imedance in 15"??

So bassicly if guy who builds cabs uses same 4kHz or 5kHz to EVRY cab he make (210, 412, 215 etc) he makes the cross point random as hell!

 

[Passinwind]

Oh...

If we take impedance / frequency of chart is it's near impossible to match good crossover, unless its set as low, as it match linear on imp/freq graph. If I even do custom crossover at 4kHz it wont cross at 4khz cause at 4kHz impedance of 15" speaker will be diffrent - higher then 4Ohms. Bassicly it will set this crossover higher or lower due to rise od imedance in 15"??

So bassicly if guy who builds cabs uses same 4kHz or 5kHz to EVRY cab he make (210, 412, 215 etc) he makes the cross point random as hell!

So much for a simple and easy generic solution...Link Removed

 

[Szyszaczek]

1. So if I have 4kHz crossover set for 4Ohm LF speaker AND this speaker at 4kHz it's +/- 8Ohm the cross will be done at higher point or at lower?

2. And at 35Hz LF speaker has peak of 160 Ohm what happens there on cross?

Bassicly at bassic level of matching crossovers it can turn out good, bad or ugly

3. How high pass filter works? I mean How You connect it to the main circuit? Is it some another parrarel/series connection to the main LF speaker? Is it then HF another speaker in curcuit and changes Ohm of all build? (like giving 2,6Ohm setup? )

 

[alexclaber]

Read this: Link Removed

That'll get you started!

 

[Arjank]

Szyszaczek, designing a really good crossover takes a lot of experience and measuring equipment, but....
For a normal basscabinet, let's say a 210 (two 10" drivers + bullet tweeter) it's not all that complicated since these cabs (usually) aren't used for playing music so a bit of coloration isn't bad, a lot of bassplayers like (or got used to) the "hole" in the upper mids (between 3-5khz). With these off-the-shelf 210's the 10" drivers run fullrange (no LPF) and the tweeter has a HPF. Most of the time these HPF's are 12db/oct or 18db/oct (electrically). The HPF has two functions: protect the tweeter from getting fried and creating a "smooth" transition between tweeter and the woofers.
If you really want to dive into the world of designing crossovers I can tell you that it's a journey that will never end.....
Here are some links that may provide you some useful information:

Crossovers

Link Removed

DIY Loudspeaker Projects Troels Gravesen

Oh, keep in mind that "textbook" crossover designs don't work.
If you want to design a crossover start with doing some simulations in Boxsim, that's a software tool from Visaton. This tool has the complete Visaton driver library in it and an example. For starters you can load the example and change some of the component values to see what happens to the frequency response. Hope this helps you understanding crossovers (a bit).

 

[Szyszaczek]

IIf i take tweeter with High pass filter, do I just connect in parrallel to LF speakers circuit?

 

[Arjank]

IIf i take tweeter with High pass filter, do I just connect in parrallel to LF speakers circuit?

That's possible.
Remember that there are parallel crossover circuits and series crossover circuits....For the time being keep it to parallel crossover circuits, these are the most widely used crossover circuits and the most easy to design,

Here is an example of how to connect a tweeter + HPF to a woofer (without LPF).
Remember that you may need to swap the polarity of the tweeter so it's "in-phase" with the woofer.

 

[Szyszaczek]

Ok so bassicly with HPF when I play low all power goes to LF speaker and when I play high it goes to both speakers.

If i play low does 100% of power goes to woofer?
If i play high what is ratio of power distribution between woofer and HPF? 50%-50% for parrallel connection?

 

[Arjank]

Ok so bassicly with HPF when I play low all power goes to LF speaker and when I play high it goes to both speakers.

Sort of

If i play low does 100% of power goes to woofer?

Sort of but not exactly, the HPF does "absorb" a part of that energy so that the tweeter only gets a really small portion. A HPF (or LPF or BPF) increases the impedance in a specific frequency range.

If i play high what is ratio of power distribution between woofer and HPF? 50%-50% for parrallel connection?

This is frequency dependent, the impedance of a loudspeaker changes per frequency. And adding a HPF, LPF or BPF will also the impedance (per frequency)

 

[Szyszaczek]

Ok so bassicly HPF would be better in this situtation. This is 2 way system, no harm LF speakers would play whole band, and tweeter would only recieve its higher band above 4kHz or 5kHz. No need to worry about changing impedance of LF speaker then, no worry of havin gap between LF and HF.

 

[Arjank]

Yes

 

[Szyszaczek]

1. LF speaker with parallell HPF HF drive. How many % of power I will lose will playing low tones due to HPF - in compare to standalone LF drive?

 

[Arjank]

In this case it's neglectable.

To make use of all the power that's coming from your amp you would need to use an active crossover or dsp and have a separate amp for the tweeter.

 

[Szyszaczek]

Bass Guitar ----> Active crossover < -----> Bass Head ----> LF Cabinet
Bass Guitar ----> Active crossover <
Bass Guitar ----> Active crossover < -----> -20-50$ class D power amp ----> HF cabinet

Can it be some cheap class D amp?