Thanks 
Ok Allen, I am resurrecting this thread. I am using 2 dynaudio's 17W75 and a Vifa XT25TG30 tweeter in am MMT arrangement.
I did the crossover calculations for an mmt 2nd order @2500hz and come up with 0.36mh and 11uf cap on dynaudio's with a zoebel if 15uf and a 3.2 ohm resistor in parallel.
for the tweeter I have a 5.6uf cap and 0.7mh coil with 3 db of padding. does this sound like a good starting point?
Should I do baffle step calculations? make it a 2.5 way?
Thanks,
Jim
I did the crossover calculations for an mmt 2nd order @2500hz and come up with 0.36mh and 11uf cap on dynaudio's with a zoebel if 15uf and a 3.2 ohm resistor in parallel.
for the tweeter I have a 5.6uf cap and 0.7mh coil with 3 db of padding. does this sound like a good starting point?
Should I do baffle step calculations? make it a 2.5 way?
Thanks,
Jim
Hi jimbones. I'll trust you on the calculations for the time being. An MMT is a good opportunity to go 2.5 way. The fundamental process is relatively straightforward.
When designing the crossover, assume you have one woofer, your tweeter, and no baffle complications. For the other woofer you first need to calculate the centre frequency of the baffle step, which you can estimate based on the width of the cabinet. Calculate impedance compensation (zobel) for it and add an inductor. The size should be that which would cross it at the baffle step frequency.
When designing the crossover, assume you have one woofer, your tweeter, and no baffle complications. For the other woofer you first need to calculate the centre frequency of the baffle step, which you can estimate based on the width of the cabinet. Calculate impedance compensation (zobel) for it and add an inductor. The size should be that which would cross it at the baffle step frequency.
To treat the woofers separately, give them each their own zobel. Referring back to your first post today...double the resistance and halve the capacitance so they work with an 8 ohm driver, then make up four of them.
For the filter, double the inductance and halve the capacitance from what you posted so you can use it with the top woofer only.
The tweeter may need to come down a few more dB (and would even if you were making this into a standard two-way). An L-pad would be advisable at this point.
The lower woofer may want an inductor of around 3mH.
(I'm assuming by the way that you are wanting to move forward without making further measurements)
For the filter, double the inductance and halve the capacitance from what you posted so you can use it with the top woofer only.
The tweeter may need to come down a few more dB (and would even if you were making this into a standard two-way). An L-pad would be advisable at this point.
The lower woofer may want an inductor of around 3mH.
(I'm assuming by the way that you are wanting to move forward without making further measurements)
To treat the woofers separately, give them each their own zobel. Referring back to your first post today...double the resistance and halve the capacitance so they work with an 8 ohm driver, then make up four of them.
Agree I need 4 of them. I thought that these values are based on the dc resistance of each woofer so they would work for the 8 ohm driver?
For the filter, double the inductance and halve the capacitance from what you posted so you can use it with the top woofer only.
? are you referring to the LP @2500?
The tweeter may need to come down a few more dB (and would even if you were making this into a standard two-way). An L-pad would be advisable at this point.
Yes I intend to as I probably wouldn't get it right the first time
The lower woofer may want an inductor of around 3mH.
Yes for the BSC it works out to 3mj
(I'm assuming by the way that you are wanting to move forward without making further measurements)
I don't have any of my own measuring equipment. A buddy has some I will need to borrow. I remember reading about some freeware that you can download to your laptop and use a mic into the laptop for basic measurements??
I use HolmImpulse. It is accurate, it's free and it suits my needs. There are others worth looking at.
About the impedance correction, I see that you worked out the values for separate woofers in your second round, these will be fine.
About the impedance correction, I see that you worked out the values for separate woofers in your second round, these will be fine.
Yes. I also wanted to mention that the driver is rolling off near that point with some cone breakup artefacts. I'm not sure how much difference this will make or whether you would rather press on and see how it goes.
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