advise on 2/3 way network

kdlsrinu

Member
2005-08-17 10:51 am
dear friends i am having jvc make1" tweeter(8 ohms) and 5" mid(8ohms) and 5" woofer(6 ohms) of 2 sets each.please suggest me a crossover network of resulted impedence 8 ohms or morefor each set. my intention is to use them as surround speakers.either 2way or 3 way is ok. but network should be simple.because in india getting parts is some what difficult.
please suggest.
 
The simplist I could suggest for 3 way and keeping reasonably close to 8 ohms (although the bass driver is still 6 ohms) is:-

Connect 4.7uF capacitor in series with tweeter for 6kHz filter (8 ohms).

Connect 47uF capacitor in series with 0.2mH inductor in series with midrange 6kHz filter and 600Hz filter (8 ohms) respectively.

Connect 1.5mH inductor in series with woofer for 600Hz filter (6 ohms).

If you can't find bi-polar capacitors where you live, you can use two standard type electrolytic capacitors "back to back" (negative connected to negative) to make your own.
Use two 10uF to replace 4.7uF, and use two 100uF to replace 47uF.

If you simplify it further, the impedance will drop below 8 ohms in the higher frequencies, but it can be made simpler.

Hope this helps.
 
If you need any more help with the crossover, if you can't get hold of the parts required for example, e mail me and I can provide you with alteratives using different components.
You might find that the inductors are hard to find there. If so, I can give you guidance on how to make them yourself with what you have available or a design using capacitors only.

Good luck:smash:
 

kdlsrinu

Member
2005-08-17 10:51 am
reply with thanks

good mornig bobhayes,
i am really surprising for this kind of positive response. i am going to buy those inductors and capacitors in a nearest town on tomorrw, i dont know whetherr i will find it or not.
if i didnt got it then i will request u for altarnative.
thanks alot again
srinivas:D
 
OK, you are going to have to get your hands on some Enamelled copper wire (winding wire).
This looks like normal bare copper wire, BUT it has a transparent plastic coating on it. Normal copper wire is no good for this purpose as it will short circuit and be useless.
Enamelled wire comes in a veriety of thicknesses (gauge) and you will want something like 16 or 18 gauge wire for your inductors.
It is usually available at electronics stores, but if you know of any local companies that make transformers, you might get some for free!
The thicker the wire, the better (within reason) but you'll need more of it, the thicker it is.
I would use 16 or 18 gauge as you will need less.
If you get 18 gauge wire, you will need about 40 metres for each speaker (80 metres in total).
Post again to inform me of the wire, if you can get hold of it, and I will advise on the making of the inductors.
If you want to know more, you can get all this information here:-
www.colomar.com/Shavano/inductor_info.html

Good luck hunting!




:) :)
 
OK, assuming you're going to use the 18 gauge wire, now you need to make some 'formers' which will hold the wire in the shape of a coil.
These formers need to be shaped a bit like a car wheel rim without the tyre on, but can't be made from metal.

The idea here is to make a central ring of the appropriate dimensions, and then place a larger disc on each side to hold the wire turns onto the ring.

For your 0.2mH inductor, you will need a tube of around 42mm in diameter and only 10mm wide.
Plastic plumbing pipe is good for this, but you can use cardboard if it is supported in the centre of the ring somehow, or even use a solid wooden dowel.

Now glue a disc 75mm diameter cut from of thin plywood, or stiff plastic, to each side of the ring to make up the 'spool'. You can drill a hole through the centre of both discs and put a plastic nut and bolt through to hold them in place, if you can get them, or you could use a metal nut and bolt but it must be removed later if you use metal.

This is so that the discs are well attached to the ring, as the copper wire will force the sides apart as you wind it.

Now you need to carefully punch or drill a little hole through one side disc, right up against the OUTSIDE of the centre ring to feed the wire through.

Feed a few centimetres of wire through the hole, to connect later to your speakers and wind 57 turns of wire onto the spool, as neat and close together as possible, going back and forth across the ring.

When there are 57 turns of wire on the spool, leave a few extra centimetres of wire to connect and cut the wire. Be careful that the coil of wire does not spring loose by securing the wire in a little cut or hole in one of the spool sides.

That's one of the 0.2mH inductors complete. Make another one!

You will need to scratch the plastic coating from the wire ends to solder the wire.

The 1.5mH inductors are made in the same manner, except your centre ring needs to be 62mm in diameter, and 16mm wide, and the side discs should be about 100mm diameter.
For these, you will need 128 turns of 18 gauge wire.

The hardest part of this is making a good rigid spool, as they will fall apart if they aren't strong enough. If your spools are good, the rest is simple.

Good luck

:smash: :smash::smash: