Crossover suggestions?

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3 way system. 41 litre enclosure for the woofer. 1 litre enclosure for the mid. Sealed. Using old boxes - solid walnut sides (I think its walnut) and MDF front and back.
Woofer - Vifa PL26WR09-08
Mid - Audax AM100Z0
Tweeter - Visaton G25ND
Specs are attached

Another couple of things. Current speakers have 1/2 " recessed front baffle. Should this be changed. I could laminate MDF into the recess.
 

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Warning, N008 advice:

I might fill the recess with felt or some sort of open celled foam and then cover with grille cloth for pretty.

As for crossovers, I really like active because if you can get enough amp channels the electronics become very cheap. and thus experimentation becomes cheap. It will cost me less than ten dollars to change the crossover frequency, or to compensate for baffle step, or to extend bass response. I like that flexibility. I would say that limiting the amp's duty range frees it up to sound better as wel...

good luck!
 
Thanks for advise on recess. I am using these boxes until summer when I can build some new ones outside (as soon as the snow melts - wife would kill me for building them in her new basement).
As for crossovers - I do have a friend who rebuilt his Mirage OM8 crossovers and gave me his old ones. They may work or not. He works for an electronics store so building new passive crossovers will not be a cost problem. Just looking for suggestions on what type of crossover to build.
 
first crossover design

Here is my attempt at designing a crossover for the drivers above. Any comments would be greatly appreciated.
 

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It’s difficult to decide without having modeled driver curves-phases. It looks a good start. I believe the upper cross freq. will be at about 2K which is perhaps too low for the tweeter – 3K would be better. Phase should probably look ok, and impedance would look relatively smooth as well.
Regards,
Thalis
 
I did a quick model of these drivers. It’s not precise: The real boxes and baffles are evidently not modeled. Drivers are modeled in the same vertical plane, mid acoustical center 1cm behind the tweeter and woofer 2,5 cm behind. Midrange is modeled in a big closed enclosure (>6 litter), Woofer’s model doesn’t matter significantly for these crossover points. I also decreased a little some cone breakups since they will get somewhat smoothed in a real enclosure.
SPL magnitude of the circuitry looks like this:

An externally hosted image should be here but it was not working when we last tested it.


Imp magnitude:

An externally hosted image should be here but it was not working when we last tested it.


If woofer and tweeter are positively connected and the mid inverted, SPl mag will look like this:

An externally hosted image should be here but it was not working when we last tested it.


I changed a little some values in your circuitry:

An externally hosted image should be here but it was not working when we last tested it.


I worked things out for some baffle correction, making some assumptions regarding your baffle according to the volume you stated. So, in the next frequency responses you should consider that beyond 400-500 Hz the real loudspeaker output will be less, hopefully at about the same order with the rest frequencies (if baffle step, woofers placement and room gain come into the equation together).
So, here is the SPL mag:

An externally hosted image should be here but it was not working when we last tested it.


And impedance will be like this:

An externally hosted image should be here but it was not working when we last tested it.


I also worked a slightly different circuitry, adding 2 values:

An externally hosted image should be here but it was not working when we last tested it.


With these you get this SPL response

An externally hosted image should be here but it was not working when we last tested it.


and this impedance curve

An externally hosted image should be here but it was not working when we last tested it.


Normaly, these two are a good starting point. In reality you shouldn’t get considerably different responses. Nevertheless you should work your enclosures, measure your drivers in them, and then some improvements could be made.
Regards,
Thalis
 
Sorry for newbie response

What does the 1% on schematics mean - is this tolerance?
Also you state that the mid was modelled in a 6L enclosure. I have a 1L (or 1.25L) bullet shaped enclosure from SEAS.

As stated before I am going to drop in the drivers in old 41L boxes and build a new enclosures this summer. Does the mid enclosure need to be this big.

All in all - do you suggest I build crossover according to your second proposal.
 
Forget the 1% tolerance - tolerance is used in this program for some sort of analysis – I just chose the 1% figure in the end because without any tolerance all values are written with two decimal zeros which are some times distracting.
I didn’t see your note about the 1litter enclosure, so I modeled the mid in a big one. There will be no phase differences in the crossover point with this change, only a minor magnitude difference in the 100-300 Hz region were the mid contributes a little only – in any case it is not significant. 1 litter is a very small place for the mid to play really good though and you should place a lot of stuffing inside.
I think that the second proposal should be fine, but I also suggest you get some basic measurement software and a basic mic to perform some measurements with these drivers in their box. It is possible that frequency curves given by the manufacturers (especially for the tweeter) are not precise and that my assumptions are not perfect and this could possibly end up with magnitude differences and phase dif. as well.
Regards,
Thalis
 
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