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MultiWay Conventional loudspeakers with crossovers 

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5th November 2013, 02:47 PM  #1 
diyAudio Member
Join Date: Nov 2013

crossover calculators and impedence
Hello all !
So I've been fooling around with online crossover calculators and got wondering.... For say a twoway speaker it asks for the impedance of each driver in order to do the calculations. So my question is if I am adding resistors to each driver to make each one a 16 ohm load should I be entering in the original impedance (sans resistors) of each driver into the calculator or the impedance after adding resistors ? Values change so drastically when you add resistance to the mix ! 
5th November 2013, 03:04 PM  #2 
diyAudio Member
Join Date: Apr 2007

A resistor dissipates energy, it doesn't convert it into acoustical energy well, speakers are rather inefficient too !
However, the answer is a nono. The online calculators might be of some utility for high pass only, as woofers are rather unpredictable.. 
5th November 2013, 08:14 PM  #3 
diyAudio Member
Join Date: Nov 2013

I am actually looking to run a fullrange driver with a tweeter to top off the top end. So the tweeter is a 6 ohm. The impedance curve show by seas shows that it stays between 68 ohms in the frequency range I would be using it for. So I am looking at using it from about 10 kHz up. So I've put a 10 ohm resistor on it to make around 16 ohms. The fullrange is a 4 ohm with a 12 ohm on it.

5th November 2013, 09:09 PM  #4 
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Location: Sunny Tustin, SoCal

I think you need to back up a notch or three. It sounds like you're trying to use resistors to make your drivers 16 ohms to match the output of a tube amplifier this is not a good method. Crossovers are fairly complex, and the impedance in the passband isn't the only issue.
Can you be very specific about what you're using and how?
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5th November 2013, 11:16 PM  #5 
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Join Date: Nov 2013

I am making both drivers 16 ohm to make an 8 ohm load when run in parallel. I am using just cap for the tweeter, It's not for my tube amp.

6th November 2013, 12:34 AM  #6 
diyAudio Member
Join Date: Oct 2008

OK, are you also to be running these in parallel physically? Ie, will they be in the same cabinet, or beside each other or something else?

6th November 2013, 04:31 AM  #7 
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Join Date: Apr 2007

You don't put any resistor in line with a woofer at least not more than 11.5Ω in some ( sealed enclosure ) case  and the capacitor decouples the tweeter
from the amplifier. Look at any design whatever it may be fullrange + tweeter or woofermidtw...the resistors in series alone play a different role. 
6th November 2013, 08:53 AM  #8  
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Join Date: Feb 2009

Quote:
Adding a series resistor to a woofer is basically a nono because you are wasting energy without a real benefit. If your amp cannot drive a 4 Ohm driver then change driver or amp. Mixing a 4 Ohm woofer to a 6 Ohm tweeter doesn't pose any problem. Another problem I see is running the fullrange without a low pass filter. You'll have lobing problems in the treble. Ralf 

6th November 2013, 11:05 AM  #9 
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Join Date: Nov 2013

So what I am using is a Seas FU10RB 4 ohm fullrange with just an 12 ohm resistor run in parallel with a Seas 27TBCD DXT tweeter 6 ohm with a 10 ohm resistor and a capacitor. (I do have a pair of Seas FU10RB in 8 ohm available if needed). I am not worried about a lowpass filter as of yet as my amp will let me control it.I would just like to start with a simple first order crossover and expand along the way. I am looking to learn along the way and expand as a go. I do see many coaxial speakers with just a capacitor on the tweeter and they seem to work okay for what they are. The drivers I have are in a sealed box currently and I could modify to port them if needed. Basically what I am looking for is a 6 ohm load or higher as the amp says 68 ohms.

6th November 2013, 11:07 AM  #10  
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