Questions on driver selection and crossover filter


It's time to ask the experts!
This is my first post ever so please bear with me...

I'm planning to build surround speakers and have spent the
last month or two looking for suitable drivers for the purpose.
Not an easy task as reading specs is one thing but figuring out
if it will work quite another...
My thoughts so far are is to use two Seas drivers, mainly
because they seem to have good price/performance.

The CB17RCY/P(H571), which is a 6.5" woofer with paper cone
with the following specs:
Impedence: 8 Ohms
Voice Coil resistance: 5.7 Ohm
Voice coil inductance: 0.65 mH
Freq range: 40-4000 Hz
Free air resonance: 38 Hz
Sensitivity: 91 dB
Moving mass: 10 g
Vas: 34.9 liters
Oms: 1.31
Qes: 0.34
Qts: 0.27
The reasons for singleing this unit out is because of the
paper cone, highish sensitivity, low moving mass, and
fair(high) Qms. Anyone have any experience with this unit?

The tweeter I was thinking of to use is the Excel
T25FC-001 (E006), which has a sensitivity of 90 dB and can
be crossed at 2000 Hz (2000-25000Hz, free air resonance
of 750 Hz).

If these drivers were to be configured in a two way system my
questions would be:
1) Should a vented or sealed enclosure be used?
2) What's the recommended crossover frequency?
3) Which filer type to use?

My thoughts so far are to use a vented enclosure of 12 liters
(f3:60Hz, port diameter:2", port length:4.9") and a crossover
freqency of 2000 Hz. with a 18 dB butterworth filter for the
tweeter and a 6dB butterworth filer for the woofer.
But what values should the components have in order to electrically sum correctly in both phase and amplitude?
(HIGH + LOW = IN (see True Audios: An overview of
Crossovers - Part two (

I'm sorry for the bloated post.
Any help is much appreciated!


2007-12-13 9:48 pm
Hi! stappvargen
I will help you. I can see the graph respond for two drivers that you think to use it. I think it's the best performance driver. I see parameter . It's only use vented enclosure. And I try to simulate it by program. I get 9.5 lt for the woofer. When I check F3. It give me 70 Hz. I think it's not good. and i try again. I see 12 liters and F3 about 60 hz. I think 12 liters is good. low bass is not poor. For crossover point I think 2500-3000 hz. It's good performance. If you use 2000 hz I think the tweeter may be overdrive. It work hard and give distortion to you. the sound may be hard. and I think the 6-12 db crossover is good. It give you the music sound but it's not give you that it's crossover network sound. the end , Please you fine tune by yourself. I think that your ears are the best. The sound tools are lower than because you listen the music sound by your ears.:whazzat:
Thank you for your replies.
Sadly the project isn't finished. I got married and now have two beautiful children instead. But I do have the seas tweeters lying around, waiting for the right moment. I got Audx HM170Z18 woofers to go with them, but it was a while since I simulated any enclosures/filters. I have been thinking of going active, probably with a gainclone for each driver.