D'appolito crossover help!

[HenrikW]

Hi,

I'm hoping to get some input/help. I'm trying to construct a crossover for a D'appolitto construction, this is what I've got so far:

Tweeter: (@ 4500Hz and up)
(XT25 filter: Sens 91,1 dB)
Seriel capasitor:
L1 6,25uF

Parallel Coil:
C1 0.2mH


Network 1:

+
---L1-----+--+
| |
C1 XT25
- | |
-----------+--+


Bas/Mr: (@2250Hz)
(2xTC14 in parrallel, each has it's own filter: Sens 87dB)

B/MR filter 1:
Serial capasitor:
L2 12,5 uF

Parallel coil:
C2 0,4mH

+
---C2----+---+
| |
L2 TC14
- | |
----------+---+


B/MR filter 2:
Serial capasitor:
L3 12,5 uF

Parallel spole:
C3 0,4mH

+
---C3----+---+
| |
L3 TC14
- | |
----------+---+


Please feel free to give me som feedback

Btw. in a normal "1 XT 25 tweeter and 1 TC14 bass/mr" i would have to lower the tweeter about 4dB, but since i'm using 2 TC14 I guess they will boost the output by 6dB, therefore no Attenuation Circuit.

[HenrikW]

*Bump*

Not any comments at all? I really could use some help here.

[Shaun]

Hi Henrik

I don't know enough about those drivers to judge if what you're doing is right.

However, current best practise is to work off acoustic measurements of the setup as it stands. Your approach will get you in the ballpark, perhaps. Measurements will show if there is an SPL mismatch between the tweeter and mid/bass drivers. You'll also be able to see how much baffle step compensation to dial in, and the diffractive effect of the driver layout and baffle dimensions.

I suggest using Speaker Workshop (measurement mic required), which is free, or the tools available at The FRD Consortium (do search). Your approach to designing your loudspeaker is really the hard way to do it. It can be done, and has been done in the past, but these days it does not make sense, considering how cheap a home measurement and simulation system is currently.

Consider that for a true D'Appolito alignment, which has requirements over and above the driver configuration, not only must the roll-off rate be correct, but the relative acoustic offset also has to be compensated for. This is difficult to do without measurements.

Good luck.

[HenrikW]

Shaun, thank you wery much! I will certanly use Speaker Workshop. I now see that I have started the wrong way, must build a box first

/henrik