1000W Simple PA Amplifier

[apexaudio]

hi apex sir,
in my hand the 8.2k resistor not available, now i checked with 7.5k resistor, bias is ok,
92vdc power supply.
i feed 50hz sinewave and it clips 52v ac on output,
my 4ohm dummy load 250pcs x 1k x 5watts.

output transistors getting hot over 90degrees at 40v ac on out..

Amp must be cased air must flow with two fans thru heatsink.

 

[wattaniya]

is it fans push and pull?
is it 12vdc fan ok?
what is the size?

 

[apexaudio]

is it fans push and pull?
is it 12vdc fan ok?
what is the size?

I prefer 48vdc 120x120mm fans. In BA2400 fans is push and pull 24vdc per side (left right), but 12vdc can be use with 15vdc regulated suply.

 

[apexaudio]

my psu is smps 90vdc.

Schematic?

 

[wattaniya]

its detex 1.2kw,
only 2etd49 core used.

hi apex sir, what will happen if i change emitter resistor 10 ohm instead 1 ohm?

 

[apexaudio]

its detex 1.2kw,
only 2etd49 core used.

hi apex sir, what will happen if i change emitter resistor 10 ohm instead 1 ohm?

Is T2:A and T2:C reverted on schematic?
1 ohm is maximum value for emitter resistor you can use only value under 1 ohm but 0,47 ohm minimum.

 

[wattaniya]

sorry for the wrong image,
here is the right one.

 

[apexaudio]

BA1000 diy work

 

[wattaniya]

hi apex sir,
what is the maximum temperature on output transistor to cut off?
if i give 95v dc power supply? is it clips at 80vac?
then how many watts for the 80vac out?

 

[wattaniya]

hi apex sir,
i try with bd139,
same heat on outputs when 40vac on out. over 90 degree celcious.
it clips n 40vac.

 

[apexaudio]

hi apex sir,
what is the maximum temperature on output transistor to cut off?
if i give 95v dc power supply? is it clips at 80vac?
then how many watts for the 80vac out?

With +/-95V dc rail amp clip at about 60v ac or 900w/4R load.

 

[apexaudio]

hi apex sir,
i try with bd139,
same heat on outputs when 40vac on out. over 90 degree celcious.
it clips n 40vac.

3k3 must be replaced with 2k2 in bias circuit. Test amp with audio signal, sine way is only for short test.

 

[wattaniya]

ok sir i try.

 

[wattaniya]

i feed audio signal and checked, but it clips at 39vac,

 

[apexaudio]

i feed audio signal and checked, but it clips at 39vac,

and what is rail voltage drop at clip?

 

[wattaniya]

88vdc

 

[sajti]

88vdc

Please check the clipping voltage, with different conditions:

1, No load,
2, 8ohms
3, 4ohms

Sajti

 

[wattaniya]

ok, i will check sajti,
is it ok to feed 50hz sinewave?

 

[sajti]

ok, i will check sajti,
is it ok to feed 50hz sinewave?

Yes, 50Hz will be OK.

Sajti

 

[RipX]

Hello guys !

I'm going to make this 1000w amp.

I have find on this thread the amp board, the dc protect board, the input display board and the psu board.

Something is missing for my build ? A soft start or something like this ?

And, for the PSU, it's two transformers 38V-0V-38V in serie for an output of +110V/GND/-110V ... it's right ?
And if it's good, what is the rated VA for one of the two 38V transformers ?

Thanks a lot and sorry for my english