Please help with the crossover

[eitanwaks]

Hi,
although I haven't even begun building the enclosure I would like to design my crossover. I have the following two components:
1. Morel MW 267
2. Morel supreme 110

their specifications are as follows:
MW267:
nominal power handling - 180W
transient power 10ms - 1000 W
nominal impedance - 8 ohms
sensitivity 1W/1m - 89 dB
frequency response - 20 to 3000 Hz
resonant frequency - 30 Hz

supreme 110:
nominal power handling - 220 W/12 dB
nominal power handling@crossover 2200 Hz - 120 W/6 dB
transient power 10ms - 1000 W
nominal impedance - 8 ohms
sensitivity 1W/1m - 91.5 dB
frequency response - 1400 to 22,000 Hz
resonant responds - 680 Hz plusminus 10%

I haven't yet measured the drivers that I have personally. These justifications were taken from the manufacturer's web site.

Where do you propose I placed the crossover? I was thinking that around 2000 or maybe 2200 Hz.

What order crossover should I use? From what I've read up till now it is preferable to use a first order.

Thank you very much for your help,
Eitan Waks

[johngalt47]

Eitan,
Rabbitz has a very good description of how to do that design. You can read it in the wiki. Also, Vance Dikason covers it in his Loudspeaker Cookbook. Alternatively you could use software like LspCAD.

[eitanwaks]

johngalt47,
thank you for the suggestions. I own a copy of Loudspeaker Cookbook however, I haven't yet got to the point of reading the crossover section. What I would like to ask is if there are any suggestions. The resources that you mentioned are great for formulating the crossover once you have figured out what you want is to be, that is, what frequency is preferred? Which order crossover is preferred? Etc.

what I would like to do is build upon the experience of others.

Thank you for your input,
Eitan Waks

[ScottG]

It doesn't matter how good the software is if you don't know the freq. response of the driver. Seek measurement software first..

These are the free ones:
http://www.audua.com/
http://www.fesb.hr/~mateljan/arta/index.htm

There are a lot of free box and crossover modeling programs available..
Here is the FRD's stuff:
http://www.pvconsultants.com/audio/frdgroup.htm

Common "pay" software:

I believe that LspCad has measurement software in addition to its crossover and box modeling. SoundEasy does as well - and in general is considered easier to use.

Note that you'll need to assemble a "jig" with any of these for proper measurments. (though some of the costlier software/hardware packages already include this.. like CLIO - including the microphone and preamplifier.)

http://mysite.verizon.net/tammie_eri...jig2/jig2.html

Finally you'll need a mic and possibly a mic amp with built-in compensation.. OR your software will need to be able to compensate for the mic and soundcard mic-out.

http://www.linkwitzlab.com/sys_test.htm#Mic
or
http://www.highefficiencyloudspeaker...amplifier.html

As for the basic design.. the thing I'd be most concerned with on a two-driver loudspeaker is Baffle Step compensation. (search for this). (..also consider midbass driver relative to the floor for "floor-bounce").

As to the basic crossover topology for these drivers.. IF you don't need a great deal of power handeling then I'd suggest a 4th order LR for the midbass and a 1st order for the tweeter (with a summed acoustic/electrical cross-point some where around 1.4 kHz). In addition to the power handeling problem of the tweeter with this design.. distortion will also be higher because the tweeter will extend lower in freq. than normal. There are however several benefits to this design.. and I feel that with these drivers the benifits will outweigh the detriments.

[alfa147]

you can try bassbox x-over design.

[johngalt47]

Eitan,
If you will read Rabbitz' article, he will show you the general process of how to arrive at a workable crossover point.

[eitanwaks]

ScottG,
thank you so much for your input. It really set me on the right path. I have one more question however, do I designed crossover after I've built the enclosure? I'm asking this because how can I otherwise get proper measurements from my drivers. I mean, if I measure the drivers not in their final enclosure and build a crossover upon that data won't it be flawed.

[ScottG]

Originally posted by eitanwaks
ScottG,
thank you so much for your input. It really set me on the right path. I have one more question however, do I designed crossover after I've built the enclosure? I'm asking this because how can I otherwise get proper measurements from my drivers. I mean, if I measure the drivers not in their final enclosure and build a crossover upon that data won't it be flawed.

Your welcome!

Yes, your quite right about that.. however most modeling progams have theoretical modeling to compensate for your enclosure (and their starting to get pretty accurate).

I'd do it like this (if possible):

1. Model
2. Build a cheap mock-up box based on model
3. Measure drivers seperatly on mock-up box
4. See if projection is accurate, if so build crossover, if not alter crossover as model program advises based on measurements
5. Measure again with crossover, make adjustments if neccesary (..and it always is neccesary).
6. Build real box
7. Measure with corrected crossover
8. Make adjustements to crossover if neccesary
9. Make crossover with premium components (being prepaired make further adjustements to it).