Help for Crossover Designing for 3 way speaker

[CH2]

Hi all

Thanks for reading this thread. I am new and totally unexperience in speaker design. I have just been tasked by my friend to complete a set of uncompleted speaker. The spec of the speaker are as follow:

Tweeter: Focal tc120 tdx2, sealed enclosure, sensitivity=93.5db
Midrange: Focal 7k2, sealed enclosure, sensitivity=95.2db
Bass: Audax pr240m0, ported , volume= 70l, Q=0.7, sensitivity=95db.


The crossover has not been done and I have not a single clue about the how.

Can any of the Gurus, shed some light as to how I may start about doing the cross over?

For the design of the the bass unit, how can I tell if the speaker enclosure is ok for the driver?


Thanks alot for the help

 

[tbla]

http://www.linearx.com/index.htm

http://www.linearx.com/products/analyzers/LMS/LMS_01.htm

http://www.linearx.com/products/software/FilterShop/Fshop_01.htm

 

[CH2]

Wow, those software cost many times more than my friend speakers.

Now I know it pays to write software emulating speakers than building speakers.

Anyway, thanks alot tbla for the link.

Anyone has the software, to help me do a quick calculation?

 

[CH2]

Any hint as to how I should get started?

 

[tiroth]

www.speakerworkshop.com

Not easy to use, but free and invaluable.

 

[Timn8ter]

Another freebie.

http://www.pvconsultants.com/audio/crossover/pcdc.htm

And a primer.

http://members.aol.com/pjay99site/speakerhome.html

 

[claudio]

Hi,
first look at the woofer FR off axis, that shows an upper limit of 500-600 Hz to be crossed with the mid; then look at the midrange off axis FR, the 3000-4000 Hz range should be the limit to cross it with the tweeter.

Try a free software to model the crossover, or just do acoustic tests with various crossovers. Check here, for enclosure program:
http://home20.inet.tele.dk/kou/ubmodel.html

and here for crossover: http://www.pvconsultants.com/audio/crossover/pcdc.htm

Regards

Claudio

 

[sreten]

How can I properly put this ?

For the quality of the units involved your friend has set you an
impossible task, and IMO you would be well advised to refuse it.

For a start you need two PR240MO per speaker.

sreten.

 

[CH2]

Hi Tiroth, Timn8ster, claudio and sreten

Thanks alot for all the help. I really appreciate it

I know my friend will never get to complete the speaker without any assistance. And I feel it is such a waste for all those good components, to be rotting away. Thus my objective is to maximise the value of the parts. My humble aim is to make the crossover.

Hi sreten

Is the bass too small for the above speaker? Is it possible that I compensate it with seperate woofer? I guess it would be even harder to get a set of speaker and woofer to work together

Thanks again

 

[sreten]

Hi sreten

Is the bass too small for the above speaker? Is it possible that I compensate it with seperate woofer? I guess it would be even harder to get a set of speaker and woofer to work together

Thanks again

No its not that.

Due to baffle step you need 2 95dB units in parallel
to match the sensitivity of the mid and tweeter.

sreten.

 

[sreten]

No its not that.

Due to baffle step you need 2 95dB units in parallel
to match the sensitivity of the mid and tweeter.

sreten.

Just realised this is not strictly true.

If you can run the 7K2 low enough and include full
baffle step compensation on that driver you can use
just the one Audax bass unit.

Apparently the 7K2 is very similar to :

http://www.focal.tm.fr/gb/compo/midrange/7k6411.htm

If so going that low could be a problem passive crossover wise.

Its getting complicated .............

sreten.

 

[5th element]

Just realised this is not strictly true.

If you can run the 7K2 low enough and include full
baffle step compensation on that driver you can use
just the one Audax bass unit.

Apparently the 7K2 is very similar to :

http://www.focal.tm.fr/gb/compo/midrange/7k6411.htm

If so going that low could be a problem passive crossover wise.

Its getting complicated .............

sreten.

I was going to say a similar thing but you beat me to it

 

[Jimmy154]

The low passive x-over on a 3-way can be the worst part of an x-over, you need larger inductors. You should spend a lot of time trying to find a x-over for the 7K2 or 7K6411 and the 120 tdx2 or similar tweeter. There definately has to be a x-over for the 7K2, it would help to copy that to some extent, like the notch or zobel filter atleast if it needs one.

 

[CH2]

Hi sreten and 5th element

Sorry, I don't really understand much about full baffle step compensation. Does it matter if the cabinet is shaped like a avalon. Does it help with the baffle step?

Going low would be a problem for passive cross over.... by that do you mean that I should do a active crossover?

Thanks

 

[sreten]

Going active with a digital programmable crossover will make your life a lot easier.

Alternatively a passive c/o for mid treble and an active c/o
for bass/mid and overall EQ will still be a lot easier.

Look here for ideas under loudspeaker design :

http://sound.westhost.com/articles.htm

sreten.

 

[CH2]

Hi Jimmy, sreten

Any hint as to how to find the crossover? I have yet to start playing with the simulation software. I am thinking of starting of with a 2nd order cross over. what do you think?

I guess I would go active as a last stage alternative.

Cheers

 

[CH2]

Going active with a digital programmable crossover will make your life a lot easier.

Alternatively a passive c/o for mid treble and an active c/o
for bass/mid and overall EQ will still be a lot easier.

Look here for ideas under loudspeaker design :

http://sound.westhost.com/articles.htm

sreten.

Thanks for the link. Will start reading .....