500W PA amplifier with Limiter
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 15th November 2011, 10:36 AM #1791 AndrewT   R.I.P.   Join Date: Jul 2004 Location: Scottish Borders post1786 shows how to calculate Vpk from load and power specification. __________________ regards Andrew T.
JOHN BALI
diyAudio Member

Join Date: Jun 2010
Location: Near the Mountain
Quote:
 Originally Posted by AndrewT post1786 shows how to calculate Vpk from load and power specification.
Thanks you Andrew T
Ok, now for 500W into 4R load
Vpk = sqrt(500 * 4 * 2)
= sqrt(4000)
Vpk = 63.2
Now I know to get 500W into 4R load we need 63.2 Vpk but
how I know the ideal rail voltage to get this 63.2 Vpk?
If the rail voltage says +80/-80V DC is this enough?
I know to get 63.2 Vpk we need higher rail but don't know how much high

also the Vac from trafo says 57Vac = 80VDC
in real life maybe not 80VDC, it's will drop anyway... bad caps or something else

I'm sorry if I miss the formula to calculate this rail voltage, if there was posted

Regards

irvynejay
diyAudio Member

Join Date: Nov 2010
Location: Philippines;Mindanao,Butuan
Quote:
 Originally Posted by JOHN BALI Hi everyone, Hi jacobsetti, have you built it one? Mr Mile will be answer you if you built one of this good amp Maybe 60 - 0 - 60 volt DC will give you 300w to 4R see this one 100W Ultimate Fidelity Amplifier AX20 I made it, my B500 already on the heatsink & hope not too small But: 1. Why offset just to high as recommended 20mV or less, my B500 is -466mV & -123mV & the voltage on 100ohm resistor is little below 0,5V on base emitter KSE340(bias) is little below 2V 2. use 2 x transformer 50Vac but DC after rectifier is 61VDC, should be 65-66VDC (Vac is drop to 46Vac because test is at night) Maybe bad caps or something? Anyone please help, where do I start to check it out? Regards
Have you found the problem?
__________________
Knowing GOD is not being good,Knowing GOD is just knowing him as my friend

JOHN BALI
diyAudio Member

Join Date: Jun 2010
Location: Near the Mountain
Quote:
 Originally Posted by JOHN BALI This is my new pcb design, change of 43k with 10k + 33k another one is on page 500W PA amplifier with Limiter enjoy
I'm sorry there was a mistake to my design...
pin of IC is split
pin 1 & pin 3
now there is two jumper on the back side of my PCB
that was make the amp not working...
I feel so sorry if there was anybody made it too

Now this couple amp I made has 8mV & 9mV offset
I will post picture soon

Regards

JOHN BALI
diyAudio Member

Join Date: Jun 2010
Location: Near the Mountain
Quote:
 Originally Posted by irvynejay Have you found the problem?
Yes I have...
Now it's working, but when the volume just a little the sound is distort
Maybe some bias adjust will fix this,
but I will experience with this
I want to otak atik

irvynejay
diyAudio Member

Join Date: Nov 2010
Location: Philippines;Mindanao,Butuan
try to separate S ground and main ground
on your PCB main and s ground is joined it should be separated

mark red should be on separate wire going to ground of psu
Attached Images
 APEXaudio B500 PCBMON.jpg (460.5 KB, 1187 views)
__________________
Knowing GOD is not being good,Knowing GOD is just knowing him as my friend

AndrewT
R.I.P.

Join Date: Jul 2004
Location: Scottish Borders
Quote:
 Originally Posted by JOHN BALI but how I know the ideal rail voltage to get this 63.2 Vpk? If the rail voltage says +80/-80V DC is this enough? I know to get 63.2 Vpk we need higher rail but don't know how much high also the Vac from trafo says 57Vac = 80VDC in real life maybe not 80VDC, it's will drop anyway...
expect the quiescent voltage of a ClassAB amplifier to be ~1V below the Vpk at the smoothing capacitors.
This will result in ~83V-1Vdc on the supply rail when the mains is at nominal voltage and the amplifier is biased to it's design settings.
Expect this 82Vdc rail voltage to vary by ~+-6% for mains supply variations. That will give you supply rail voltage range when delivering zero power of ~78Vdc to ~88Vdc.

Now to delivering maximum power.
Are you a manufacturer that is guaranteeing the maximum power at the output for the full range of possible mains voltages? Or a manufacturer looking to impress gullible customers where the guaranteed maximum power can only be delivered when mains supply is at maximum voltage tolerance?
Or a DIYer who wants Maximum Power when mains is at nominal supply voltage? Or do you want to design the output stage to survive the rare operational condition of maximum output power being delivered when mains supply voltage is at maximum tolerance?
__________________
regards Andrew T.

JOHN BALI
diyAudio Member

Join Date: Jun 2010
Location: Near the Mountain
Quote:
 Originally Posted by AndrewT Now to delivering maximum power. Are you a manufacturer that is guaranteeing the maximum power at the output for the full range of possible mains voltages? Or a manufacturer looking to impress gullible customers where the guaranteed maximum power can only be delivered when mains supply is at maximum voltage tolerance? Or a DIYer who wants Maximum Power when mains is at nominal supply voltage? Or do you want to design the output stage to survive the rare operational condition of maximum output power being delivered when mains supply voltage is at maximum tolerance?
I don't wanna be a manufacturer looking to impress gullible customers
like that (like the picture bellow)
I don't want to lie or lying costumers like that
I have take a look what inside, there is one tafo 23,5Vac ct 23,5Vac (150VA maybe)
amplifier circuit using 1 pair TIP2955/3055 per channel
so the rail says +/-32 VDC
power output = ... I don't know how to calculate?
maybe only 50 to 60 watt, to get 50W need 28.2Vpk?

I am a DIYer who wants maximum power when my mains voltage allow to do maximum.
right here the ac main voltage not so good regulation
when at evening - night the voltage drop to 180V - 200V ac
normally its 220V ac

I don't have measuring equipment such as oscilloscope, but multitester only
So to get 500W to 4 R load = ... V DC? Please the formula or an example

Regards
Attached Images
 SANKEN SMM3000.JPG (190.0 KB, 1029 views)

JOHN BALI
diyAudio Member

Join Date: Jun 2010
Location: Near the Mountain
Quote:
 Originally Posted by irvynejay try to separate S ground and main ground on your PCB main and s ground is joined it should be separated mark red should be on separate wire going to ground of psu
Yes mam...
It's just for testing amp...
The PCB track is separate

Few days ago I saw this Apexaudio Vertex Amp 2 Step - SOLFEGIO | www.solfegio.com
that is on Indonesian forum
Its really you (I don't think so) or someone else try to surprise the forum
I'm sorry if all of this make you mad

Thanks
Attached Images
 correctting pin 1 to 3 copy.jpg (255.4 KB, 951 views)

Last edited by JOHN BALI; 16th November 2011 at 05:30 AM.

 16th November 2011, 08:14 AM #1800 irvynejay   diyAudio Member     Join Date: Nov 2010 Location: Philippines;Mindanao,Butuan yes your correct that's my post on your forum no im not mad why do i have too? __________________ Knowing GOD is not being good,Knowing GOD is just knowing him as my friend

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