Crossover construction techniques

[wiredmonkey]

Hi,

I've been *slowly* putting together a couple of bookshelf speakers and was wondering if anyone could give me some advice regarding the physical construction of crossovers.

Due to the size of the caps and inductors I'm thinking its better to secure them on a more solid surface than a PCB and wire them up point to point. Is this the general way it is done?

Thanks in advance

[mightydub]

I built a pcb and used hot glue to secure the coils after soldering them. Or you can use zip ties through the board.

Also remember to orient the coils to minimize coupling between them.

[mightydub]

Here's an example pcb layout. It mounts on the binding posts - physical mounting and electrical connection all in one.

[tinitus]

Would help to see how your schematic is done

I always draw my schematic logically like this

And I find the best way to layout the components is exactly the way its done in schematic

On a piece of wood is fine

Use solidcore copperwire fore all "lines", mounted at the ends either through small wood "blocks" or solder terminals

I dont twist leads but just solder them together, very carefully

Fore mounting components I use polyurethane foam glue

If one driver(tweeter) needs to be reversed, I prefer to do it at output of filter, others do it at driver terminals

[wiredmonkey]

Thanks for the ideas and help!

Just wondering, why don't people mount the crossovers in an external enclosure and run seperate leads to each driver. Wouldnt that be a much more ideal scenario? Is it just plain practicality that prevents this or am i missing something?

[SY]

I did that with the last set of dynamic speakers that I designed. It makes circuit changes much easier and eliminates any possibility of microphonics from loosely wound coils or caps. It does, though, mean lots of wires coming out of the back of the speaker cabinets.

[wlowes]

I just finished my first crossover, and I must say that I am very happy with my results.

The original xover was mounted on a piece of fibre board inside the speaker cabinet.

I built my replacement with high quality parts mounted on a 1 inch thick piece of oak plank. The parts were secured with a glue gun to the wood. I drilled holes into the wood and ancored the capacitors and resistor leads with hot glue and or epoxy into the wood. Then I wired it point to point with unshielded solid silver and copper wires. The crossover boards sit on the floor behind the speakers, and are wired to the drivers via separate solid wires. They sit on a sheet of bubble wrap to further insulate them from vibration.

I took an unconventional approach with the caps and used NOS BlackGate AC as opposed to the conventional wisdom of exotic film caps. 2 reasons. The BG AC had been listed in many posts as being as good as all but the best Mundorf Silver/Gold in Oil versions, and they are a fraction the price. Also the rest of my System is Black Gate equipped, and it just seemed kind of cool to have a tribute to the Black Gate legend. I used MILS resistors. The BG's do take a while to burn in. Right at first the improvement was dramatic. My system was already pretty well defined with a fully 3d sound stage and no apparrent speakers in the presentation. The new xover immediately moved mids and highs to clear and clean presentation. The last of symbols sounding more like polywrap being crunched was replaced by shimmering brass. I ran it for about 100 hours. It is now unbelievably opened up and cyristal clear. The sound stage is hudge and 3d airy. Voices are human and pianos are pianos. As I write this I'm listening to a guitar that is spooky real. Cello solo's are alive and vibrant.

I guess my message in all this is I listened to advice on the DIY forums and it worked for me. The advice was:
Put the xover outside the box.
Hard wire and solder everything. Strong physical connection / crimp first and a little solder to keep it that way.
Solid core wire everywhere in the signal path.
I like copper and pure silver. I use small guage 28awg for the high frequency and much larger copper for the lower registers.
Check out the capcitor shoot out pages and choose high value within your budget and expect them to take a while to reach their potential.
As with everything, keep vibration to a minimum.

Hope this helps.

[Ron E]

My last set I free-wired each section, tucked/bent them into a small package and velcroed them to a cabinet wall, separated a bit.

[wiredmonkey]

Thanks everyone just the advice I needed I've actually headed down the path of a shielded enclosure which was surplus from work and figure because the crossover point is at a pretty common point for a two way (3kHz) I could use it to do preliminary testing on new designs.

Thanks again!

[tinitus]

Originally posted by wiredmonkey

headed down the path of a shielded enclosure

Thanks again!

Iron is a big nono, but even aluminium affects the coils

Take a look here, and study very carefully, it is priceless information

http://www.troelsgravesen.dk/coils.htm