Questions about 400W mono amplfier

[DANIEL SPASOVSKI]

Hi to all friends

I want to build two pcb of these to have 2x400W amplifier

http://postimage.org/image/fwsb20b93/

What do you think , how much power can i expect on 4 ohm load and how much on 8 ohm load ?? And how much THD can i expect on 4 ohm and how much on 8 ohm

I expect real answers , cheers

 

[Tekko]

As that circuit is class B and looks like from the ampletos website, i'd say 0.5-5% THD.

And only four sets of 2SC5200 and 2SA1943 is not quiite enough for 400 watts into 4 ohms at the rail voltages specified, 6 pairs will be better and 8 pairs will be even better, at 10 pairs you'll have a reliable amp.

 

[Dave Zan]

That is a very mediocre circuit. Read Bob Cordell's book and learn why.
The schematic is not really complete, you can do better with another amp.

Best wishes
David

 

[DANIEL SPASOVSKI]

Then please give me schematic for one mono amplifier that gives 400W RMS on 4 ohm load

 

[djk]

A TIP 42 won't work very well at ±75V, nor will the D718/B688.

 

[TonyTecson]

agree with djk on the Vceo issue......

we are given half of the amp, with the rail shown drop further with load? i am not aware of any convention when showing rail voltages on a schematic, is that the unloaded rail of fully loaded rail?

 

[Tajzmaj]

Check this out.
http://www.diyaudio.com/forums/solid-state/164208-500w-pa-amplifier-limiter.html
http://www.diyaudio.com/forums/solid-state/162408-900w-h-class-pa-amp-limiter.html
Cheers

 

[TonyTecson]

too small can't see very well...

 

[AndrewT]

Attach your pics and make them at least double the pixel width, preferably near 800 by 600. 180 by 129 just does not work for me.

 

[DANIEL SPASOVSKI]

I upload the pictures again I think that this time they are okey
Now , i want to know how much RMS power gives each separately , and which has smallest THD . Im gonna aprecciate your answers

400W Amplfier Circuit - View image: 400 W Amplfier circuit

Antoher 400W Amplfiier Circuit - View image: Another 400 W Amplfier circuit

350W Amplfier Circuit - View image: 350 W Amplifier circuit

600W Amplifier Circuit - View image: 600 W Amplfier circuit

200W Amplifier Circuit - View image: 200 W Amplfiier circuit

 

[djk]

A base resistor of about 470Ω on the CCS for the Vas that has a common reference voltage with the diff input CCS will improve the performance under heavy load.

 

[DANIEL SPASOVSKI]

I upload the pictures again I think that this time they are okey
Now , i want to know how much RMS power gives each separately , and which has smallest THD . Im gonna aprecciate your answers

400W Amplfier Circuit - View image: 400 W Amplfier circuit

Antoher 400W Amplfiier Circuit - View image: Another 400 W Amplfier circuit

350W Amplfier Circuit - View image: 350 W Amplifier circuit

600W Amplifier Circuit - View image: 600 W Amplfier circuit

200W Amplifier Circuit - View image: 200 W Amplfiier circuit

And something to say about this schematics ??

Now , i want to know how much RMS power gives each separately , and which has smallest THD . Im gonna aprecciate your answers

 

[djk]

THD and power?

Who cares?

THD is a function of feedback, add another opamp around the whole amplifier and it will reduce the THD to vanishing levels.

Will it then sound better?

Of course not.

Power is a function of your supply quality.

Can you hear 3dB?

Just barely.

±3dB would be 250W~1000W. Now you could probably tell the difference between 250W and 1000W, but not always. In a PA situation I have heard an amplifier rated at 200W/8Ω pound harder in the base than another that could produce 750W/8Ω.