For 500W/4R you need 45vac RMS on amp out, that will be 127Vpp at cliping level + 10V for compensation voltage drops on outputs. Limiter start at +/-15 under rail voltage, that is for reserve to don't have hard cliping at full power. 127+10+30 that is 167V rail to rail, +/-83,5V rail voltage 2x59vac on transformer secundar. Efficiency of AB class is about 70%, for 1000W (2x500W) at output you need 1430W from PSU (transformer).
Regards
Regards
sir i completely agree with ur pSu calculation ...... but what about current requirement ????? if i use 60-0-60V trafo current requirement by 4E will be as it will generate only about 45V on the output so current required per channel is I = V/R
so,
I= 45/4 = 11.25A per channel
that is the transformer spec for 2 channel will be ->60-0-60 @23A i.e 2760VA
Am i getting it wrong again may be so kindly correct me where am i doing it wrong ...........
regards
sekhar
so,
I= 45/4 = 11.25A per channel
that is the transformer spec for 2 channel will be ->60-0-60 @23A i.e 2760VA
Am i getting it wrong again may be so kindly correct me where am i doing it wrong ...........
regards
sekhar
2nd channel prob...
apex...
sir,...
today i powered up my b5oo second channel...
output transistor were fine...so were the drivers...
no hum on speakers...
no dc on output...
touching input produces hum on speaker...
problem is,...
as i plug in my rca with the computer playing...
i noticed there was no audio output...
touching input makes output produce dc up to 5v...
it seems like dc voltages is amplified upon touching input...
i uploaded a video on youtube showing the case...
here's the link...
YouTube - b5oo second channel
please help...
tnx...
apex...
sir,...
today i powered up my b5oo second channel...
output transistor were fine...so were the drivers...
no hum on speakers...
no dc on output...
touching input produces hum on speaker...
problem is,...
as i plug in my rca with the computer playing...
i noticed there was no audio output...
touching input makes output produce dc up to 5v...
it seems like dc voltages is amplified upon touching input...
i uploaded a video on youtube showing the case...
here's the link...
YouTube - b5oo second channel
please help...
tnx...
Attachments
![APEXaudio B500 PCBMON 220X52.5 [640x480].jpg](/community/data/attachments/169/169632-b78854e56946e4a64e50c63f6919e84e.jpg)
i took wire in the bottom away so everything in the pcb could be seen...
i connected the wire when i was testing it...
the transformer only passes current/charge to the amplifier PSU when the mains AC voltage is high enough to allow the secondary voltage to exceed the smoothing capacitor voltage.
This happens only for about 5% to 10% duty cycle.
For the remainder 90% to 95% of the mains cycle the transformer is effectively switched off. It takes no part in meeting any of the amplifier current demands.
The transient current demand of the amplifier is mostly met by the decoupling capacitors on the amplifier PCB. The main low frequency current demand is mostly met by the PSU smoothing capacitors.
The transformer VA is simply chosen to top up the smoothing capacitors without overheating.
a 500W into 4ohm amplifier can be powered successfully from a 500VA to a 1000VA transformer.
A pair of 500W amplifiers can be powered successfully from a 500VA transformer to a 2000VA transformer.
1430VA or 1500VA is just about ideal (in terms of value for money) in that VA~1.5times{total maximum output power}
A pair of 500W amplifiers can be powered successfully from a 500VA transformer to a 2000VA transformer.
1430VA or 1500VA is just about ideal (in terms of value for money) in that VA~1.5times{total maximum output power}
sir,
touching with finger makes speaker hum, but also makes dc output increase...i was wondering why audio signal is not amplified...
i have 0v dc on output but when touch by finger increases dc...
please help...
i dont use torroidal xformers...i dont know where to buy them..nagpapagawah lng akoh ng EI transformers...
I can't help you without any informations and pictures, and you must use my suggestion about first powered amp. If you have friend with more expirience in DIY ask him for help.
Regards
Video and pictures are not clear. DC offset you can only measure without signal on input (input short to GND). When you touch input with finger you put ac signal to input, and only way to know what you have on amp out is oscilloscope.
Regards
sir.,,
this second channel doesnt behave like the first one...yes dc offset is zero without signal...i used my fon to produce audio signal but output sound was very distorted...LED clip indicator lights on when i touch the input...its my first time to face this kind of problem...