how much power my amplifier out ?!

[Astro Power]

Hii All.

i build this 2 of this amp...


i build 2... to make a bridge...

i change the original output transistors......to->

2sc5200\2sa1943 X8 ->to one amp.
2sc5200\2sa1943 X16 -> in total....

and the amplifier work great !
on 2 subwoofers (2 ohm load in bridge)

but... how much power the amplifier out?

in AC VOLTMETR it is see 42VAC...(in 60HZ high volume).

the powersupply is 37.5V+\- 1000VA

if i change to 37.5V+\- 1500VA....

the amp will out a 50V of AC ?

becouse i want more power.... so i put a 1500VA of powersupply.

what do u thinks??

and if u want i will put a photos of the amp...


thanks
tamir

[AndrewT]

Hi,
your power output is V * V / R = 42 * 42 / 2 = 882 watts
Some designers recommend a transformer between 600va (not good for bass) and 2000va (very stiff) for this amount of power.
you will get a small increase ( about 0.2 to 0.5db) by changing to 1500va.
A big increase will only be had by increasing the voltage at the supply rails. 40v will give about +1.2db (1156w) not worth the effort or expense.
By the way your LTP is not balanced, tail current about 3ma and collector current 1.2ma. The tail current will change with supply voltage changes and cause further unbalance. Try using a constant current source.
regards Andrew T.

[Astro Power]

thanks U !.

tamir

[darkfenriz]

ac voltmeter cheats if the signal is overdriven

[Jan Dupont]

AndrewT:

You can't use the measurred 42 Volt to calculate the output....
The output will NEVER go higher than the rail supply (37.5 VDC)

And then it's not normally possible to drive the output to full rail voltage....

The formel you used (2*supply / load + load) is ok, as it gives a hint of the possible output wattage. In this case you are right by only dividing by one time load, as the amp is bridged.

My guess of the actual output would be: 35*35/2 = 612 Watts with lots of distortion >10%

[UrSv]

Originally posted by ACD
AndrewT:

You can't use the measurred 42 Volt to calculate the output....
The output will NEVER go higher than the rail supply (37.5 VDC)

And then it's not normally possible to drive the output to full rail voltage....

The formel you used (2*supply / load + load) is ok, as it gives a hint of the possible output wattage. In this case you are right by only dividing by one time load, as the amp is bridged.

My guess of the actual output would be: 35*35/2 = 612 Watts with lots of distortion >10%

Are you perhaps forgetting that the amp is bridged?

[Jan Dupont]

By UrSv:

Are you perhaps forgetting that the amp is bridged?

By me:

The formel you used (2*supply / load + load) is ok, as it gives a hint of the possible output wattage. In this case you are right by only dividing by one time load, as the amp is bridged

Non-bridged = 306 Watts
Bridged = 612 Watts

[AndrewT]

Hi,
ACD can you check your figures?
I have rechecked mine & I still think that 21Vac comes from each half of the bridge amp. With opposite polarity that gives 42Vac across the load?
regards Andrew T.

[Astro Power]

whay it is can out 42VAC ?! it is in bridge....!.

in peak i get 51VAC to 8 ohm load..!

http://www.anidian.com/audio/construct/p3a_1.shtml

i can out 25VAC in normal
and 50VAC in bridge.
in optimal mode.



it is to weak......... i want to amplifiers ti bridge that can out 60VAC !.

so what amplifier i need to build? and what power supply.

because it car amplifier.....and i have a SPL competition soon...

more 8 days ~~!.

tamir

[Jan Dupont]

I think we have a small misunderstanding here

I was refering to a single amp given max. +/-35V on the output.

35V*35V/4R = 306 Watt (max)

In bridged mode:

35V*35V/2R = 612 Watt (max)

In bridged mode the signal meassured on the speaker terminal can be up to 70V / single amp drive up to 35V