correction
ALT!! i realised that i told i ******** telling that my cable has and impedance of 2 Ohm. Now i explain better.
the resistance of a cylindrical conductor is equal to R=p*L/A
-p is the electrical resistivity in ohm*m;
-L is the lenght of the cable in m;
-A area cable in m^2.
with p=1.68*10^-8 , L=4 and A=5*10^-6 (because i use a cable with 5 mm^2) it results R=0.01344 Ohm.
Now the DF seen by the subs is DF=8/(Zout+R)=8/(0.008+0.01344)=373 .....So in the end the subs doesn't see a DF of 1000 but about 1/3 of this value.
The choise of the cable is really very important not for the real power lost but for the real DF seen by the subs.
I will check my result by testing my cable with a TESTER and i will tell you if my count were right.
ALT!! i realised that i told i ******** telling that my cable has and impedance of 2 Ohm. Now i explain better.
the resistance of a cylindrical conductor is equal to R=p*L/A
-p is the electrical resistivity in ohm*m;
-L is the lenght of the cable in m;
-A area cable in m^2.
with p=1.68*10^-8 , L=4 and A=5*10^-6 (because i use a cable with 5 mm^2) it results R=0.01344 Ohm.
Now the DF seen by the subs is DF=8/(Zout+R)=8/(0.008+0.01344)=373 .....So in the end the subs doesn't see a DF of 1000 but about 1/3 of this value.
The choise of the cable is really very important not for the real power lost but for the real DF seen by the subs.
I will check my result by testing my cable with a TESTER and i will tell you if my count were right.
Thought I'd pull this up.
Would seriously recommend AGAINST doing this. More caps means less ripple, means less time for the transformer to charge them. The transformer has to pass more current in less time, so your R*I^2 losses go up, transformer gets hotter, and shortens the life of any nearby components, assuming the transformer itself can handle it.
I'd trust the engineers that built the amp to have got the balance between transformer, rectifier and capacitor storage right.
Chris
I think here djk is referring to small (100-470uF) caps to decouple the power feed inductance. In some of these newer amps where the whole power supply is on the PCB with the output transistors it won't make much difference. In an old-school amp with the separate power supply, control PCB, and output transistor bank it can clean things up a lot for the output transistor bank to have its own local decoupling.
Sorry Chriss, but are you talking about caps? caps means capacitors? I have speaking of CABLE.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.