Coils n' caps and X and overs - DIY crossover for newbies

[Camillo]

Hi!

Asking about making coils yourself, some People warned about fire risks if not using proper tools. It is easy to buy them but... Its more fun to make them yourself i think!

I picked up some enameled wire about 16 awg at a flee market and tore down every transformer i could find and made some coils, ordered a cheap inductor-meter and never got the ohms under 0.7. Watching some Youtube some months later made me double check them with ampere-meter and calculated and with that measurement they all seemed fine under 0.4! (apparantly the cheap tool isnt that good and perhaps the Mh is a bit off also but it seemed okay with coils i knew the inductance off)

So to my questions, i just picked up some ordinary "home-cables" (english?). Heavy plastic or silicone insulated awg from 13-16. I know The size will be huge and that i probably need more length to get to the right inductance but i played around today and made a coil from 14/15 awg multistranded(?) heavy insulated wire. A piece big as my hand and weighted a lot with an inductance of 1mh and 0.45 ohms air core.

Is this neccesarily a bad coil, not to be used at all?

How much better is litz or enameled wire, just considering quality of a coil with less copper, closer together?


Another tip i got is to use capacitors from industrial lamps, fluoroscents with approx 8uf 250v, thoughts?

I run biamped and use active crossovers so this is more educational for me but.. Is this nasty crossover-making?

[Grant Bunter]

IMO, coils should only be made with enameled wire, not household wire. Sell the wire you find as scrap to fund "proper" inductors.
Values are crossover specific.

As far as using flouro caps, you realise you can't just throw any value cap in there right?
Values and type are crossover specific depending on purpose in the crossover...

[Camillo]

I see, i was just curious what the cons would be and it looks quite.. Different, and it would be fun in 20 years when someone opens a speaker and find more kgs of copper than needed

but i honestly would like to know how it behaves electronically when the insulation makes the wires so far from each other, compenssred with larger awg for DC-resistance when using, what i believe, longer wire. Hard to find many sources online so perhaps It's just stupid? And mostly because i have a lot of that wire to play around with..

As far as using flouro caps, you realise you can't just throw any value cap in there right?
Values and type are crossover specific depending on purpose in the crossover...

I know, i could have left the uF out in that question. I mostly wondered what kind of caps they were and.. Quality. The housing is big, i havent opened one and maybe there where things like "you need to take away part x from inside them... Or- You need to fill them with silicone so they dont rattle inside" , - or something like that.

[Grant Bunter]

...but i honestly would like to know how it behaves electronically when the insulation makes the wires so far from each other, compenssred with larger awg for DC-resistance when using, what i believe, longer wire. Hard to find many sources online so perhaps It's just stupid?

Inductors store energy in magnetic fields for a short period. The proximity of the turns or winds exponentially increase magnetic flux, making the inductor work better.
The thin enamel coating allows the turns to be as close together as possible, increasing flux.
Household wires have larger sheaths as you've mentioned, increasing the distance of the wire in the turns, which decreases magnetic flux. It is also to heavy in AWG and physical weight terms, and not required for power handling of the inductor.
The trick with inductors is to use the right type in the right spot

And mostly because i have a lot of that wire to play around with..

As I said before, sell it as scrap.

I know, i could have left the uF out in that question. I mostly wondered what kind of caps they were and.. Quality. The housing is big, i havent opened one and maybe there where things like "you need to take away part x from inside them... Or- You need to fill them with silicone so they dont rattle inside" , - or something like that.

The caps in flouro lighting form part of the ballast (a collection or combination of resistors, capacitors and inductors) to ignite the tube.
The function in the ballast of a capacitor, IIRC, is for power factor correction (so the meter can read the amount of power being used by the flouro).

You can purchase "audio" grade caps, but electrolytics and poly caps have their places in filters (as noted in all the plans) and are way cheaper. Since your source for caps from flouro's would be used units, best off just buying what you need new (funded by selling your scrap wire)...

[Camillo]

..... It is also to heavy in AWG and physical weight terms, and not required for power handling of the inductor.
The trick with inductors is to use the right type in the right spot.

Oh! So Even with enameled wire the awg can be too heavy? If I remember correctly, an air core coil with less than 0.5ohms DCR would be around 16 awg for the 1.8mH one would need for the hf-section in some of the plans i have, that is thicker than i've seen in most speakers i have opened though.

Also, i've read that DCR should be less than 5% of driver impedance (?). When connecting 8 ohms in series -16-, could one then - theretically- use higher DCR in a coil? 1 ohm? (I know it still says 0.5 in the plans, just curious, as an example)

I think of this thread as diy x-over from both new and scrap parts for both educational, second hand usage and budget questions, therefore i ask and thank you for the answers!

As above, i have what i need, i run bi-amped with active x-over. This is for educational purposes and future builds and experimenting. (Next up is a TallBoy i intend to give away as a gift, mostly to be used as a electric bass cab but i might sneak some mid/top end from stuff i have at home in it with on/off switches and then i might be cheap with the x-over parts for the owner to change later on if he wants)

[Grant Bunter]

Oh! So Even with enameled wire the awg can be too heavy?

Sure. That's why there is different recommendations in the plans for filters. No need to use a heavier AWG coil when you don't have to.

Also, i've read that DCR should be less than 5% of driver impedance (?). When connecting 8 ohms in series -16-, could one then - theretically- use higher DCR in a coil? 1 ohm? (I know it still says 0.5 in the plans, just curious, as an example)

You will notice the values of components changes based on impedance the filter is for.

Next up is a TallBoy i intend to give away as a gift, mostly to be used as a electric bass cab but i might sneak some mid/top end from stuff i have at home in it with on/off switches and then i might be cheap with the x-over parts for the owner to change later on if he wants

If you're going to gift it, build it with the components in the plans, or meet the specs of the components in the plans.
Filters are critical, use new parts.

It doesn't reflect well on the designer for the cab to fail or not perform as it should, when it was the builder who made the choices about what to put in it...

[Camillo]

Sure. That's why there is different recommendations in the plans for filters. No need to use a heavier AWG coil when you don't have to.

No need I understand, but is it bad to use heavier AWG? Low Q of the coil? I might order enameled wire and would it be bad to order a lot of, let's say, awg 13 to wind all the coils. 0.9 mH, 1.8mH, 2.2 mH and so on.

You will notice the values of components changes based on impedance the filter is for.

Yes, but does the DCR requirement theretically change, would a 2 ohm setup, that isnt in the plans, need lower DCR theretically?

If you're going to gift it, build it with the components in the plans, or meet the specs of the components in the plans.
Filters are critical, use new parts.

It doesn't reflect well on the designer for the cab to fail or not perform as it should, when it was the builder who made the choices about what to put in it...

So capacitors in filters should be changed Every second? Third? year?
IMO The designs are made for everyone, to choose to build them simple according to your own budget or with more expensive alternatives. This is for poor budget building, instead of iron core, homemade air core from scrap, coooould even be better but almost free aswell. Second hand caps might not even be old ones.

I get your point from building and thats how I built my OmniTops, but this thread, for me, is meant for projects that wouldnt be built otherwise. And educational

[Bill Fitzmaurice]

I used to wind my own coils, because there was no place to buy them. The last time I did so would have been around 1985. I've always used caps made for audio. There are some things where making your own makes sense, like speaker cabinets. Some don't, like coils, or using caps that aren't spec'd for audio usage.

[Camillo]

Ok. In 35 years i'd like to say that I made some coils myself then. Even though they were available.