Modify crossover frequencies for 3-way design

[snoopy33]

Dear all,

I'm re-using a crossover design that I know works for slightly different speaker units. The picture below is 3rd order 3 way and uses 800Hz,3000Hz for cutoffs. I need to move this to 700Hz and 5000Hz.

I did look at the online calculators but given they come out with capacitors along the likes of 1.7854uF etc they are unusable.

I will build all the inductors myself, so the mission is just to find the change in values.

PS) I'm not lazy, if anyone can point me to the correct algorithms I'll have a go converting myself, otherwise I'm happy to throw someone a few dollars to do it!

Cheers

Andrew, U.K

[gfiandy]

Hi, You are asking in the wrong place. Repost this in the multiway speaker forum and you will probably get some helpfull replies.

How do you know where you need to move it too? Normally crossovers are very interactive with the drive units you use them with. Generally you cant just shift the frequency and expect them to work as the phase and acoustic response of the drive unit affect the final result.

If you recalculate and the values are not available you will have to accept the compromise and use the nearest prefered value or create parallel / series combinations.

Regards,
Andrew

[Salas]

Moved.

[PeteMcK]

no calculator is going to give you preferred values, unless you extremely lucky... you have to do what gfiandy said, and parallel caps to get the values you need. e.g., your 1.7854 uf cap - I'd use a 1uf + a .82 uf, which is close enough - this isn't rocket science...

[wintermute]

The other thing you need to take into consideration is the impedance of the drivers. If the impedance curve's of the new drivers are different to the current drivers, then what you calculate will not necessarily match your new target. Additionally it looks like the woofers have an impedance compensation network on them, which may or may not have the desired effect on a pair of different woofers If the same impedance flattening can be obtained for the new drivers (with the existing compensation network) however then the calcs for the woofer coil at least should be fine.

Tony.