For people that design Crossovers! Impedance question.

[chasw98]

I am curious as to what are some tricks, techniques, methods, etc. to designing a crossover and then finding out it has a nominal 2 ohm impedance. How would you get the impedance up into a higher range? I have a mid driver with a 5.8 ohm DC resistance and a tweeter with a nominal 3.5 ohm DC resistance. After constructing a 'classic' 2nd order electrical xover at 2,000 Hz the impedance chart goes a little too low, I believe.



Ignore anything below 250 Hz because I did not measure that. This is a generic question. The crossover is just an inductor in series and capacitor in parallel for the mid and the reverse for the hi. I really hope there is a simple answer and I have just been dumb and overlooked it. Thanks.

Chuck

[Dennis H]

I'm a rookie with LspCAD but I think the optimizer has a tab to not let the impedance go below X ohms.

[chrisn]

Did you pad the tweeter down at all?

I'm but a mere novice, so heed others advice before mine. Impedance phase looks weird (to me).

good luck

[chasw98]

Did you pad the tweeter down at all?

I'm but a mere novice, so heed others advice before mine. Impedance phase looks weird (to me).

good luck

I have tried it padded (resistor series, then parallel) and unpadded. I am but a mere novice also. That is why I am asking fro help. It might even be as simple as the polarity of the driver. I don't know.

[chrisn]

Could you post what drivers you are using and the crossover values? Did you use an impedance jig to measure? If so, is it calibrated (with the speakers disconnected) and the resistor value correct? I use arta for impedance measurments and that is the procedure I use.

What effect did padding the tweeter have on the impedance curve?

[Curt C]

Did you measure just the tweeter and its network separately? You may just have a 4 ohm tweeter. Generally, tweeters require attenuation to match up with the rest of the drivers, and a couple of ohms in series will get you back on the good side of 4 ohms.

I'd need to see more information to make any further determination.

C

[Amphiprion]

Need schematic...

[chasw98]

Here is all the data:
Hi FR



Hi Imp



Mid Fr



Mid Imp



Xover Fr



Xover Imp



Xover Schema

[chasw98]

Did you measure just the tweeter and its network separately? You may just have a 4 ohm tweeter. Generally, tweeters require attenuation to match up with the rest of the drivers, and a couple of ohms in series will get you back on the good side of 4 ohms.

I'd need to see more information to make any further determination.

C

Thank you Curt! Getting rid of the pad (R1, R2) and putting a 3 ohm resistor in series at the beginning of the hi portion has raised the impedance above 5 ohms (on paper at least).