Crossover question - pre build crossovers?

[CasperH]

Hi guys and girls

I'm working on my first project and have come to the speaker build ( going great ) - but have come to a dead stop.

Crossover!

As I have 10 thumbs and I'm not really happy about beginning to build a crossover from scratch - too much can go wrong when I'm doing it.

People are really good at showing why 2 and 3 way pre-build crossovers are crap, and I get it.

But if we look at a simple straight forward oneway crossover, what can go wrong?

https://www.soundimports.eu/en/dayton-audio-6000-lpf-4.html

Can they be used ?
Can you just wire them in series so they will split for bass, mid and tweeter?

My logic says

Crossover 1 splits the signal 2 ways
Crossover 2 takes signal from the first crossover and splits it 2 ways

Crossover1: bass
Crossover 2: Signal to mid and to tweeter

Or is my logic failing me yet again ?

 

[AllenB]

They can work, they just won't be very accurate.

 

[Ugg10]

If you can tell us what speaker drivers you are planning on using there may be a design for the box and crossover out there ready to go that you can copy/use. Or better still if you don't have the drivers yet, pick an already done design that suits your needs and build it, probably the best way if it is your first build and you have no measurement gear. There are literally hundreds of DIY speakers with enough information on the drivers/box/crossover so finding one that suits your listening habits/budget/room is highly likely, you can always customise the design somewhat so long as the baffle/position of drivers/and volumes stay the same.

 

[YSDR]

What can go wrong? Check for example the 4Ohm, 500Hz low-pass filter: 40mH inductor + 2.6uF capacitor, need to say more? I hope they just replaced the units in the table. It needs to look more like this: 2.6mH inductor + 40uF capacitor.

They are not much better than other pre-built multi-way crossovers. Without measurements, you just shoots in the dark.

 

[giralfino]

People are really good at showing why 2 and 3 way pre-build crossovers are crap, and I get it.

I'm sorry if this sounds rude, but you don't get it. Off-the-shelf crossovers work only in those conditions:
1) the impedance at the crossover frequency is equal to the impedance for which the crossover is designed,
2) the frequency response of the driver is flat for a very extended range near the crossover frequency,
3) the speaker is an infinite wall (or similar) so you can neglect the baffle step effect,
4) you need at least provide appropriate l-pads for the mid and tweeter.

In general when you use an off-the-shelf crossover, your crossover points won't be where you think they are, crossover point for LP and HP filters will be different and thus drivers summing won't be correct, and bass will be thin as it will be 4-6dB lower than the midrange and highs.

In general for a 3-way speaker, you need a LP filter at crossover point 1 for the bass, a HP filter at crossover point 1 and a LP filter at crossover point 2 for the midrange, and a HP filter at crossover point 2 for the tweeter.

Ralf

 

[Old bones]

Due to the limitations mentioned above, and many other responses on various forums, I have come to the conclusion that "off the peg" crossover boards have no useful function if you're looking for decent performance from your speakers.

 

[Lojzek]

You have to be careful not to completely dismiss pre-built crossover filters. They can potentially be a good value purchase if you know what those parts exactly are and you need them anyway. Right now at PE, a 500 Hz LPF-4 crossover sells for $16.98 with pcb, and parts bought separately would be more expensive.

The mix-up with values from the table is basically a decimal point error.

edit: let us do a small experiment what would have a prebuilt filter work like if we knew the driver and cabinet measures.

Casper, care to provide those design details?

 

[PeteMcK]

add a Zobel across your driver and the off-the-shelf xover will work better