If you think a Zobel is needed to sweeten the amplifier load use
( Ball-park figures )
2.2uF and 6R --> 8R resistor, the Zobel works at the upper end to flatten the impedance curve, to work out the crossover impedance follow the previous advice.
I make that to be 5.6R
Le (VC inductance) is probably no more than 0.15/0.5mH
For 3k I'd be using 4.7uF in series and 0.59mH in parallel ( you may want to use a standard value to keep cost as low as possible so a measured 0.56mH isn't that far off.
You may want to use a standard third order too.
That's 19uF in series, 0.22mH in parallel and then 6.3uF in series.
You could also try a non-standard 3rd order
4.7 series 0.59 in parallel and another 4.7uF in series
Regards
Ted
( Ball-park figures )
2.2uF and 6R --> 8R resistor, the Zobel works at the upper end to flatten the impedance curve, to work out the crossover impedance follow the previous advice.
I make that to be 5.6R
Le (VC inductance) is probably no more than 0.15/0.5mH
For 3k I'd be using 4.7uF in series and 0.59mH in parallel ( you may want to use a standard value to keep cost as low as possible so a measured 0.56mH isn't that far off.
You may want to use a standard third order too.
That's 19uF in series, 0.22mH in parallel and then 6.3uF in series.
You could also try a non-standard 3rd order
4.7 series 0.59 in parallel and another 4.7uF in series
Regards
Ted
Thanks Moondog!
I will use those values for the Vifa.
The other driver I'm unsure about is the Pyle PPA 15. I called tech support at Pyle and spoke with Frank, who says the DC voice coil impedance is 7.5 Ohms (which sounds strange to me) although he didnt have the voice coil inductance value. Any suggestions as to what componet values to use in the zobel for the Pyle? If so what impedance value will I have for the Pyle after the zobel?
Bill.
I will use those values for the Vifa.
The other driver I'm unsure about is the Pyle PPA 15. I called tech support at Pyle and spoke with Frank, who says the DC voice coil impedance is 7.5 Ohms (which sounds strange to me) although he didnt have the voice coil inductance value. Any suggestions as to what componet values to use in the zobel for the Pyle? If so what impedance value will I have for the Pyle after the zobel?
Bill.
I wouldn't worry about a Zobel on the .5 woofer ( the Pyle) you will be cutting that so low that a Zobel won't have any effect on the XO components.
7.5R sounds about right; without seeing the impedance curve that is.
The XO values for the midrange are probably going to have more effect of the overall sound ( read clarity ) you want to keep as much of the low bass as possible out of the midrange driver.
I think that the high pass section needs to use a second order, unfortunately that means rather large values of inductance.
You could try a first order bandpass to start with though.
When calculating the bandpass you need to do a little extra work on the XO for the bass and treble, you need to have no overlap; in fact because there may ( will be ) some interaction between components you need to make an allowance.
If you use 300 -->3000 for the midrange band pass, and you are using first order XO, use a 10% variance ; cut the woofer at 270/280Hz for example and bring in the tweeter at 3300Hz.
The wider the midrange bandpass the less of a problem this is, David Weems suggests using the inverse of the bandpass spread.
So 300 -- 3000 = 10 use 1/10 as the allowance.
The steeper the cross-over slopes the less this is a problem too.
You can make the bandpass smaller but personally I like to keep the midrange as wide as possible, if component values were not so large and the associated cost of the components also so high I would cross that Peerless driver in at 180Hz ( even though that is only 1 1/2 octaves above resonance )
Regards
Ted
7.5R sounds about right; without seeing the impedance curve that is.
The XO values for the midrange are probably going to have more effect of the overall sound ( read clarity ) you want to keep as much of the low bass as possible out of the midrange driver.
I think that the high pass section needs to use a second order, unfortunately that means rather large values of inductance.
You could try a first order bandpass to start with though.
When calculating the bandpass you need to do a little extra work on the XO for the bass and treble, you need to have no overlap; in fact because there may ( will be ) some interaction between components you need to make an allowance.
If you use 300 -->3000 for the midrange band pass, and you are using first order XO, use a 10% variance ; cut the woofer at 270/280Hz for example and bring in the tweeter at 3300Hz.
The wider the midrange bandpass the less of a problem this is, David Weems suggests using the inverse of the bandpass spread.
So 300 -- 3000 = 10 use 1/10 as the allowance.
The steeper the cross-over slopes the less this is a problem too.
You can make the bandpass smaller but personally I like to keep the midrange as wide as possible, if component values were not so large and the associated cost of the components also so high I would cross that Peerless driver in at 180Hz ( even though that is only 1 1/2 octaves above resonance )
Regards
Ted
I just read thru my post for a 3rd order XO and realized I had the placement of the caps reversed.
if using a standard 3rd order XO the smaller capacitor value is placed first in the circuit, then the parallel coil followed by the larger value cap.
I hope you hadn't gone ahead and built it already.
When building Zobels I try and glue them ( with silicon ) to the back of the driver itself
if using a standard 3rd order XO the smaller capacitor value is placed first in the circuit, then the parallel coil followed by the larger value cap.
I hope you hadn't gone ahead and built it already.
When building Zobels I try and glue them ( with silicon ) to the back of the driver itself
New thread.
I have now begun the process of designing a crossover network for my project. I am asking everyone to visit my new thread and make suggestions!
My new thread is at:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=146741
Thank you all, very much!
Bill.
I have now begun the process of designing a crossover network for my project. I am asking everyone to visit my new thread and make suggestions!
My new thread is at:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=146741
Thank you all, very much!
Bill.
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