first go at 3 way crossover- comments please :)

[lufbramatt]

hi
after a lot of fiddling around on speaker workshop, ive come up with this theoretical crossover for my current project, using scanspeak 8555-01 woofers (virtually given away to me, wouldnt have paid full price for them!), seas mca15rcy midranges and seas 27tbfcg tweeters.
I used the frd consortium tools to simulate the effects of the cabinet and the baffle on the response of the drivers, which gave me a good idea of how things are affected once the drivers are mounted in a cabinet.
Although i have had a go with the speaker workshop measuring facilities to generate frequency responce data for the drivers, im still not sure how much i trust my results, i ive used figures off the web.
Heres the frequency responce and impedance charts for the crossover, if the drivers are connected with opposite polarity i get nice big nulls at the crossover points.
Any comments would be most welcome, especially about the peak in the bass driver at about 3.5khz and what i should do about it.
Ive listened to the bass drivers in various size enclosures and the bass certainly doesnt sound as rolled off as it looks in the charts, so I think itll be ok once its in a room.

[lufbramatt]

and the network:

[Paul W]

Bass appears to be the largest question, but if it's good in-room, so be it. If not, I think you'll need to give up some sensitivity and rebalance level for the other two drivers. The 3.5k woofer peak is probably cone breakup. Try a series RLC trap directly across the driver terminals to notch the resonance.

The mid is showing a little interference with the tweeter...you might try rolling off the top end of the mid with a little steeper slope. (I'm working on my second project with the same MCA15 mid and the 27TDFC tweeter.)
Paul

[tinitus]

try 47uf in midrange instead of 33uf and adjust it with a resistor in
series with the 47uf
make the 1mH in midrange smaller and make the paralel 3uf bigger(with a resistor in series)

and make the crossover so that you can make changes easy

tweeter may be too loud

[tinitus]

mistake sorry, NO resistor in series with 47uf(33uf)

[lufbramatt]

thanks, some good ideas. ive never really designed a crossover from scratch beofre so good to get some pointers from more experienced minds.

Ill try them out later on

[opp]

It seems to me that the midrange is working in a fairly narrow band (roughly 2 octaves). I have read somewhere that the xo frequencies in a 3 way system should be as far a part as possible to reduce interaction between the to xo circuits. Personally I would prefer most of the important midrange to be handled by one driver.

[rabbitz]

You are better off sticking with crossover points on a 3-way that have a ratio of (xo frequency high) / (xo frequency low) = 10. This will give a good 3.4 octaves for the mid.

Example of this is the woofer to 300Hz, mid 300Hz - 3000Hz, tweeter from 3000Hz.

Good luck with the 3-way and have fun with it.