1.2kw amp schematic to check

[djk]

"Does this amp have short circuit protection (that it will survive if the outputs are shorted for longer period of time at max output)?"

T10, T11 are the current limiter transistors.

"How to add balancd input to this amp? anyone..?"

Just wire an op-amp up as a buffer and feed the output to the base of T4. Use the same R1, R2 ,C1(C111,C112), C2 on the input to the buffer as what you are using at the input of T3.

Alternately, just get one of these:
http://www.analog.com/productSelection/pdf/ssm2141.pdf
or wire up an op-amp this way, and feed it into the amplifier input. The resistors have to be selected to 0.1% to have a CMRR of 60dB.

 

[skaara]

djk: You mean I must connect output of opamp to base of t4, and on the input of the opamp i must use everything that is used on base of t3? Where do I connect what is already connected to base of t4, to negative input of opamp?

 

[skaara]

Output of opamp to base of t4, - input from xlr (with R1, R2 ,C1(C111,C112), C2) to - input of opamp and output of this amp thru 22k resistor to + input of opamp - is that ok?

 

[The Saint]

This amplifier has a differential input already. You don't have to add an opamp to get balanced input. It just adds more noise to the output of this amplifier.

 

[skaara]

Anthony: I thought this too when I looked at your AV800.. Would you be and tell me what do I have to do?
thank you

 

[skaara]

Saint come here and enlighten me

 

[audio_pip]

hI skaara,

are you saccesfull with this amp construction?
is it posible to send me the rest of the paperes from the amp, I think i miss there some informations...

thx Sebastian

 

[kimberlator]

yeah I did notice it later on, That would cause the gain to half as you mentioned above. I would recommend the removal of the 27k resistor and replacement with a 1k resistor.

It should improve the dynamic range quite a bit as well I would have thought.

Anthony

In your 1kw design you have the C11 to C20 reversed.
Cheers.