Stk4142ii

kinser

Member
2004-01-11 12:21 pm
R'aanana
Hi all,

Panning on starting a new sub amp, and found an STK4142II in an old amp.. thougt it would be good to bridge! BUT... the recomended power supply is 26Vdc+/-.. and all i have is 35Vdc+/-.. the max Vcc on the STK4142II is 39Vdc+/-.. so can I use 35Vdc?

Second thing is that the amp outputs a minimum of 25watts x2 @ 8 ohms.. so at 4 ohms it will be 50watts right? and i wanna bridge it using an 8 ohm driver.. so can i run each amp at a 4 ohm load with 35Vcd? and if i can get hold of a 4 ohm driver can I use it with this amp? Becasue i dont think these amp will handel 2 ohm loads at 35Vdc.. unless i add some extra tansistor 2 the output?

Thanks,
Kinser!
 

metal

Member
2004-01-29 5:25 pm
Hello

If you connect 4 Ohm to the output it will not be 50 watt @ 26+/- cuz there are things that I have no idea about till I started studying electronics, I am talking about my self.

The efficiency is 70 % for class B amplifier when connected to 8 Ohm resistor, and 63 % when connected to 4 Ohm resistor, so don't expect to get more the 30 to 35 watt @ 4 Ohm speaker.

Also the impedance of power output transistors plays a considerable role here, when using 4 Ohm speaker the current increases, meaning that I have larger voltage drop across output transistors, limiting the maximum possible output voltage swing, hence limiting the power output.

Regarding how to bridge amplifiers, you better go to :

http://www.diyaudio.com/forums/showthread.php?s=&threadid=27465&pagenumber=1

and see you there...
 

kinser

Member
2004-01-11 12:21 pm
R'aanana
metal,
Im not using 26vdc... i only have 35vdc.. so the output will be abit higher right?
about bridging.. i know how.. i have done it befor..

i just wanna know how much power i can get using a 8ohm driver, and a 4ohm driver, if possible to bridge into 4 ohms(2 ohms an amp..) and if i add some MJL's to the outputs can i bridge using a 4 ohm driver? i mean i know that adding transistors 2 the output wont increas power.. cuse that dependes on rail voltage.. but the extra transistors will help will driving low loads, right?(please correct me if im wrong)
Sorry for asking so many Q's.. im learing myself to... heheh!

Thanks,
Kinser