Topic: crossover question

[Audiophiliac]

Got a few question about crossover and it's component

1. If Cap state 22MF +/- 10% at 100 VDC is it the same as 0.22 microfarad at 1200 VDC ?
2. If Capacitor value stated as 475J 100V what is the value in micro Farad ?
3. If Capacitor Value stated as 1.5J 100V what is the value in micro farad ?
4. For the coil waht do we need to consider when we source; is it the larger the better ?

[netken]

from my basic understanding :

1. Its 22.0uf
2. use an online converter http://www.export911.com/convert/convert.htm
3. as the answer above.
4. do u mean the value or the width? i.e. 10awg / 12awg / 14 awg ?

[Audiophiliac]

TQ Dude
1. On the number one I think get the Hovland Music Cap
2 & 3 Open the link already still do know is it 475J/100V then convert to farad or how.
4. The coil got value ? If that so I will look at what is the value listed.
 
Sorry electrical and electronics is just not my field that why need to elarn a lot

[netken]

some say hovland not so good, but that's just me hear - say ....

not too sure about the V, i think its stays the same - 475J i lost my way too .. lol ..

coil's value is in : mHy
http://www.the12volt.com/caraudio/cross4ohm.asp

[Audiophiliac]

I guess I have to bring that crossover to sifu sifu to have a look and give the values..or parameters.

[jinhan]

j is the capacitive reactance of the cap

Capacitive reactance Xc,

Xc = 1/(2*pi*f*C)

Thus,

C = 1/(2*pi*f*Xc)

where
pi=3.142
Xc=cap reactance in j
f=frequency

[carcrazy]

Got a few question about crossover and it's component

1. If Cap state 22MF +/- 10% at 100 VDC is it the same as 0.22 microfarad at 1200 VDC ?
2. If Capacitor value stated as 475J 100V what is the value in micro Farad ?
3. If Capacitor Value stated as 1.5J 100V what is the value in micro farad ?
4. For the coil waht do we need to consider when we source; is it the larger the better ?

Audiophiliac,
1. 22uf/100V or more
2. 4.7uf/100v or more
3. not sure
4. need to measure ur original coil with LCR device, depends on ur speaker cables

[Audiophiliac]

Thanks Sifu dudes, now I know what value of Cap to buy in...can start collecting component for the xover

[Audiophiliac]

Audiophiliac,
1. 22uf/100V or more
2. 4.7uf/100v or more
3. not sure
4. need to measure ur original coil with LCR device, depends on ur speaker cables

Sorry another question arise you mean 4.7uf / 100 vdc or more means I could have 22uF / 1200 VDC ?

[carcrazy]

Sorry another question arise you mean 4.7uf / 100 vdc or more means I could have 22uF / 1200 VDC ?

Your capacitance value is 4.7uf
Your voltage is 100vdc
So ur capacitance value is fixed but your Vdc can be 100 or more.
If you change your capacitance value then the crossover point will shift

[Audiophiliac]

Thank You very much; now I know;
Anyway do you have or sell Mundorf Supreme/Oil 4.7 uf VDC 1200 ?

[netken]

Thank You very much; now I know;
Anyway do you have or sell Mundorf Supreme/Oil 4.7 uf VDC 1200 ?

yes he does!

[calvinhpk]

Your capacitance value is 4.7uf
Your voltage is 100vdc
So ur capacitance value is fixed but your Vdc can be 100 or more.
If you change your capacitance value then the crossover point will shift

the Vdc is the max withstanding voltage, means the max voltage the cap can support

[calvinhpk]

j is the capacitive reactance of the cap

Capacitive reactance Xc,

Xc = 1/(2*pi*f*C)

Thus,

C = 1/(2*pi*f*Xc)

where
pi=3.142
Xc=cap reactance in j
f=frequency

wah...so theory mer....
unfortunately, for this case.... you're wrong.
the 475J here means 4.7uf, and the J means +/- 5% tolerance

[Audiophiliac]

Thanks Calvin Dudes

Therefore 1.5J 100 VDC means 1 Farad 5% Tolerance with 100 vDC or more ??
Pls. confirm..

[built]

Thanks Calvin Dudes

Therefore 1.5J 100 VDC means 1 Farad 5% Tolerance with 100 vDC or more ??
Pls. confirm..

http://www.electronics2000.co.uk/calc/calccap.htm

[calvinhpk]

Thanks Calvin Dudes

Therefore 1.5J 100 VDC means 1 Farad 5% Tolerance with 100 vDC or more ??
Pls. confirm..

i never see 1.5J before, usually those capacitor code is 3 digit, without decimal point,

and I repeat, the Vdc is the max Volt the cap can handle.

[netken]

normally how high VDC do we need?

[built]

i never see 1.5J before, usually those capacitor code is 3 digit, without decimal point,

and I repeat, the Vdc is the max Volt the cap can handle.

using the calcualtor, 1.5J is 100nF +/-5% tolerance.
(100nF is equals to 0.1uF)

normally how high VDC do we need?

probably can be calculated by using ohms law, V=IR.
where V = Voltage (volt), I = Current (amphere) and R = Resistance (ohm)

can anyone confirm?

[calvinhpk]

normally how high VDC do we need?

usually for speaker signal side, 100Vdc is good enough, i don't really goes very high

on general, you can use P = V^2 / R, but not into specific calculation
P = power
V = voltage
R = Resistance/Impedance (speaker)

example your power per channel is 100W, driver is 4ohm, on a full 100W transfering into your 4ohm speaker, you have
100W = V^2 / 4
V = 20V only, which is 100W continuous power, not music power

[built]

more on ohm's law
http://www.the12volt.com/ohm/ohmslaw.asp#pie

and ohm's law calculator...
http://www.the12volt.com/ohm/page2.asp#voltage

[Audiophiliac]

How about if we put all the web link listed in the knowledge based column

[Audiophiliac]

Still struggling in one item for this xover building, how do we decide on the inductance (mH) value for air core ?

[wengweng]

There are many defination. Even with the same frequencies, using different defination also comes out with different value. There are too many variables.

Best is dont bother about the exact value. Roughly get the value build one and try. Then modify from there using your ears. I think it is as difficult as striking lottery to get first time right.

Those highend speaker manufacturer R&D for 30 over times, and with the help of equipments. For us using ears, more difficult to get it perfect.

Let carcrazy to build a pair for you for a start to cut short the process loh.....hahaha

[Audiophiliac]

yup follow your advice then