final crossover schematic

tdemont · 12th January 2005, 08:11 PM

have decided on a simple high and lo-pass passive crossover and L-pad attenuator design (for the tweeter), I have looked on the internet for a wiring diagram that includes all three linked together and can't find one. How do they link up?

Do I connect the positive and negative parts of the two crossovers together at the binding post and add the L-pad closest to the tweeter?

Also, if a resister is rated at 12 watts rms and it is 20 ohm or 1 ohm, how many watts can it handle from the amp before blowing?

tdemont · 13th January 2005, 06:15 PM

A hip diagram is attached. Please help, all I need is a nod if it is correct.

tdemont · 13th January 2005, 06:15 PM

I used the tools recommended else where on this site
(http://www.carstereo.com/help/Articles.cfm?id=55#second)

to get the capacitor, resistor, and inductor types. Did I choose wisely?

Bill Fitzpatrick · 13th January 2005, 06:48 PM

That's the correct way to wire it.

I take issue with the attenuation resistors. No degree of attenuation results in those values.

Also, since this is a textbook crossover which cannot take into account the response curves of the drivers, it will only approximate correctness. A zobel across the woofer will help.

tdemont · 13th January 2005, 07:14 PM

I know a zoebal requires measurement of inductance and DC resistance of the woofer, but I lack the equipment.

I think I picked a pretty common driver, is their a site that lists that information? Or is their some way to infer it from the impedance graph?

As far as the resistors go, I used the tool at http://www.carstereo.com/help/Articles.cfm?id=55#second and entered in 2 decibels, a figure slightly higher than the sensitivity difference between the speakers. Those are the values it gave me. (driver impedence = 4 ohms, desired attenuation = 2db gave me resistor recommendations which I rounded to the nearest available resistor at speaker city .822 to 1 and 15.44 to 15 ohms. Is that the wrong tool to use?

what resistors would you recommend for a 1.5db difference in tweeter and woofer sensitivity?

Thanks again.

Bill Fitzpatrick · 13th January 2005, 10:16 PM

Sorry, my mistake. The 2 resistor values are correct but they are reversed.

As to the parameters on the woofer, see:

http://www.d-s-t.com/vifa/data/mg14sk09-08d.htm

tdemont · 13th January 2005, 10:25 PM

Redid calculations. Think attenuator is better now. R1=1.5 OHM, R2=6.0 OHM

tdemont · 14th January 2005, 01:08 AM

Using the link you gave me, I found the stats for the FOUR ohm model, I then plugged those (DC resistance 3 Ohms, Voice coil inductance [H] 0.00045)
into the Zoebel circuit calculator (http://www.carstereo.com/help/Articles.cfm?id=55#second) ,
and I get a design using a 3.75 ohm resistor and a 50mF capacitor!
I can't even find 50mF capacitors on speaker city. They only go up to 20!

Bill Fitzpatrick · 14th January 2005, 03:05 AM

They have it. You're looking for an electrolytic. It's $1.75.

tdemont · 14th January 2005, 03:52 AM

You could almost charge for it... thanks again.

12th January 2005, 08:11 PM	#1
tdemont diyAudio Member Join Date: Jan 2005 Location: Arizona	final crossover schematic have decided on a simple high and lo-pass passive crossover and L-pad attenuator design (for the tweeter), I have looked on the internet for a wiring diagram that includes all three linked together and can't find one. How do they link up? Do I connect the positive and negative parts of the two crossovers together at the binding post and add the L-pad closest to the tweeter? Also, if a resister is rated at 12 watts rms and it is 20 ohm or 1 ohm, how many watts can it handle from the amp before blowing?

13th January 2005, 06:15 PM	#3
tdemont diyAudio Member Join Date: Jan 2005 Location: Arizona	Also... sorry to be such noob, but... I used the tools recommended else where on this site (http://www.carstereo.com/help/Articles.cfm?id=55#second) to get the capacitor, resistor, and inductor types. Did I choose wisely?

13th January 2005, 07:14 PM	#5
tdemont diyAudio Member Join Date: Jan 2005 Location: Arizona	Thanks. and about attenuation... I know a zoebal requires measurement of inductance and DC resistance of the woofer, but I lack the equipment. I think I picked a pretty common driver, is their a site that lists that information? Or is their some way to infer it from the impedance graph? As far as the resistors go, I used the tool at http://www.carstereo.com/help/Articles.cfm?id=55#second and entered in 2 decibels, a figure slightly higher than the sensitivity difference between the speakers. Those are the values it gave me. (driver impedence = 4 ohms, desired attenuation = 2db gave me resistor recommendations which I rounded to the nearest available resistor at speaker city .822 to 1 and 15.44 to 15 ohms. Is that the wrong tool to use? what resistors would you recommend for a 1.5db difference in tweeter and woofer sensitivity? Thanks again.

13th January 2005, 10:25 PM	#7
tdemont diyAudio Member Join Date: Jan 2005 Location: Arizona	I think I found issue. Redid calculations. Think attenuator is better now. R1=1.5 OHM, R2=6.0 OHM

14th January 2005, 01:08 AM	#8
tdemont diyAudio Member Join Date: Jan 2005 Location: Arizona	Thanks again. 50 mf capacitor? Using the link you gave me, I found the stats for the FOUR ohm model, I then plugged those (DC resistance 3 Ohms, Voice coil inductance [H] 0.00045) into the Zoebel circuit calculator (http://www.carstereo.com/help/Articles.cfm?id=55#second) , and I get a design using a 3.75 ohm resistor and a 50mF capacitor! I can't even find 50mF capacitors on speaker city. They only go up to 20!


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13th January 2005, 06:48 PM	#4
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	That's the correct way to wire it. I take issue with the attenuation resistors. No degree of attenuation results in those values. Also, since this is a textbook crossover which cannot take into account the response curves of the drivers, it will only approximate correctness. A zobel across the woofer will help.

13th January 2005, 10:16 PM	#6
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	Sorry, my mistake. The 2 resistor values are correct but they are reversed. As to the parameters on the woofer, see: http://www.d-s-t.com/vifa/data/mg14sk09-08d.htm

14th January 2005, 03:05 AM	#9
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	They have it. You're looking for an electrolytic. It's $1.75.

14th January 2005, 03:52 AM	#10
tdemont diyAudio Member Join Date: Jan 2005 Location: Arizona	you guys know how to make a noobie feel welcome You could almost charge for it... thanks again.

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