Hello,
I'm using this site for rapid crossover simulation of two raw drivers : Speaker Crossover Calculators by V-Cap I like the possibiity to enter the impedance of the high pass and low pass for each driver.
I please have a question about these two impedance : should it be the impedance of each standalone at the precise cut-off frequency or the average Re (voice coil resistance) given in the datasheet... Or the lowest impedance point where the impedance curves meet each others in frequency ? I.E : the impedance at cut-off of the weakest Z of the two drivers cause this is what see first an amp!
Just for illustration : 2 bass driver, 2x 8 ohms with a Re of 7.8 ohms , chosen cut-off : 300 hz, here the impedance of the two // drivers measured raw is not half of the 7.8, i.e 3.9 ohms but 3.4 ohms.
The mid driver ha a Re of 7 ohms and at 300 hz the impedance curve is 6.5 ohms.
Sould I putt in the calculator at 300 hz : low pass : 3.4 ohms and high-pass:6.5 ohms or should I simply enter the average Re of each drivers given in the data sheet : 7.8/2 for the 2 bass : 3.9 ohms and 7 ohms for the high pass for the mid driver ? Or I enter the lowest impedance for the high and low pass cause electicaly this is where it goes : 3.4 ohms
The question is for passive XO but I ask for active crossover as well : has the exact impedance at Xo cut-off to be entered in the soft parameters as well or just the average Re of the drivers.
Many thanks.
I'm using this site for rapid crossover simulation of two raw drivers : Speaker Crossover Calculators by V-Cap I like the possibiity to enter the impedance of the high pass and low pass for each driver.
I please have a question about these two impedance : should it be the impedance of each standalone at the precise cut-off frequency or the average Re (voice coil resistance) given in the datasheet... Or the lowest impedance point where the impedance curves meet each others in frequency ? I.E : the impedance at cut-off of the weakest Z of the two drivers cause this is what see first an amp!
Just for illustration : 2 bass driver, 2x 8 ohms with a Re of 7.8 ohms , chosen cut-off : 300 hz, here the impedance of the two // drivers measured raw is not half of the 7.8, i.e 3.9 ohms but 3.4 ohms.
The mid driver ha a Re of 7 ohms and at 300 hz the impedance curve is 6.5 ohms.
Sould I putt in the calculator at 300 hz : low pass : 3.4 ohms and high-pass:6.5 ohms or should I simply enter the average Re of each drivers given in the data sheet : 7.8/2 for the 2 bass : 3.9 ohms and 7 ohms for the high pass for the mid driver ? Or I enter the lowest impedance for the high and low pass cause electicaly this is where it goes : 3.4 ohms
The question is for passive XO but I ask for active crossover as well : has the exact impedance at Xo cut-off to be entered in the soft parameters as well or just the average Re of the drivers.
Many thanks.
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I guess I'll be the first to answer: no.
Going to active crossover (esp with DSP) improves the driving of speakers in many ways (such as not having any elements between the amps and the drivers) and makes your question irrelevant.
With active crossover esp with DSP and sharp slopes (and which can be different for LP and HP... if that works better in your room you can reconsider XO point too.
B.
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With regard to passive crossovers, I find this 1st and 2nd order calculator useful because it generates frequency response plots (for both amplitude and power).
1st and 2nd Order Crossover Calculator and Response Simulator >> speakerwizard.co.uk
This calculator has the advantage of allowing you to view, graphically, the effect of small differences in impedance values and to judge the importance of such differences.
1st and 2nd Order Crossover Calculator and Response Simulator >> speakerwizard.co.uk
This calculator has the advantage of allowing you to view, graphically, the effect of small differences in impedance values and to judge the importance of such differences.
Thanks,
@ Bentoronto: It makes sense as of course each driver sees its own amp, but that was about the way such soft calcul the XO parameters ! I know nothing yet to the active filter so asked eventually if the exact Z of the driver was important as well for the DSP to apply the exact frequency whished, or if if it as as easy than entering the frequency cut off and tht's it. I know there is also a Q factor with active... but not put my fingers yet, planned next month...
But I'm very interested by the passive side of the question firstly cause data results might slightly differ if you use just a high pass filter with the bass and no coil for the low pass for instance : for instance some band pass or Karlson cabinets which has a mechanichal low pass but still of course an impedance related to a frequency for the driver... such softs seem to be precise enough, just I don't know exactly which impedance to enter : measured at XO / average Re of datasheet or nominal impedance... slighty change the capacitor and coil values.
@ Galu : that's a very nice, more versatile than the Vtec 🙂 ... I tried but it bugged on some result adding 100 uF more ! I like the possibility just to use a high pass without low pass !
@ Bentoronto: It makes sense as of course each driver sees its own amp, but that was about the way such soft calcul the XO parameters ! I know nothing yet to the active filter so asked eventually if the exact Z of the driver was important as well for the DSP to apply the exact frequency whished, or if if it as as easy than entering the frequency cut off and tht's it. I know there is also a Q factor with active... but not put my fingers yet, planned next month...
But I'm very interested by the passive side of the question firstly cause data results might slightly differ if you use just a high pass filter with the bass and no coil for the low pass for instance : for instance some band pass or Karlson cabinets which has a mechanichal low pass but still of course an impedance related to a frequency for the driver... such softs seem to be precise enough, just I don't know exactly which impedance to enter : measured at XO / average Re of datasheet or nominal impedance... slighty change the capacitor and coil values.
@ Galu : that's a very nice, more versatile than the Vtec 🙂 ... I tried but it bugged on some result adding 100 uF more ! I like the possibility just to use a high pass without low pass !
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Depending upon the filter topology and specific component values, you can see some big swings in the realized combined impedance. One draft of a three-way that I am working on saw an 8 ohm nominal woofer section combined with an 8 ohm midrange led to a 2.8 ohn load through a portion of the upper bass because of an excessive reliance on capacitance to hit my filter targets.
As a draft, it told me that I could get to what I wanted to achieve, but I needed an alternate path to get there. Since the phase match wasn't great either, except right at Fc, I knew that I needed more work anyway.
I'd offer the same advice for you. Any rapid XO calculator is likely to give you the textbook crossover filter values. Unless you get Lotto-winning lucky, the textbook filters are not going to be the final draft. So, people combine two four ohm nominal drivers all the time. Alternatively, with some aggressive filtering, two 8 ohm nominal drivers might yield an undesirable outcome once you start adjusting the signal feeding the drivers.
DSP takes these issues out of the equation, but for analog, the realized filter matters a lot.
Thank you,
I have also some soft from J Bagby (rip) or Vituix or Xsim, but it's more on how to use it : what Z (first before tunning) should I enter of the 3 first (average Re, Z at XO, or nominal Z) ?
I have also some soft from J Bagby (rip) or Vituix or Xsim, but it's more on how to use it : what Z (first before tunning) should I enter of the 3 first (average Re, Z at XO, or nominal Z) ?
