discrete outs

[JaredC79]

I am finishing up a number of amps now and I would like to add discrete output on each channel to allow easy bi-amping/tri-amping/multi-amping of drivers should the need arise. I am guessing LM4562 would bE a good device for this application? 30v total voltage, 15 pos add 15 neg...pos and neg inputs are connected to the opamp with the out being another XLR. Would this work?

 

[JonSnell Electronic]

It won't give you a balanced output and is far too complicated resistor value wise.
https://www.google.co.uk/search?q=b...=U-QSWdefK4eWgAaH_ozwCA#imgrc=7MpNfWR2qsFuAM:
is good enough with an LM4558 or TL072 etc.

 

[JaredC79]

It won't give you a balanced output and is far too complicated resistor value wise.
https://www.google.co.uk/search?q=b...=U-QSWdefK4eWgAaH_ozwCA#imgrc=7MpNfWR2qsFuAM:
is good enough with an LM4558 or TL072 etc.

Thanks - I will look at those schematics more in detail as well as find a good opamp. The Rane schematic is a duel being shown as A and B correct? OPA2134 is supposed to be lower noise however the slew rate is 20v/us. The amps slew rate is 80v/us and would hate to have the amp being held back by the omamp. I can look at low noise, faster ones and figuring out how to make it function correctly - like anyone in this game, I would like a mirror image on both amps. I understand it is impossible with another connection, as close to it is ideal. I attached another schematic that to me, I understand a little more. Basically I want my XLR input to split with + - and gnd going to the amp itself with the other leads going to this circuit. I also have a 4UF input cap that is off board and on the + terminal of the XLR. So that I do not have 8UF when bi amped I should have the circuit jump prior to the input cap I assume correct?

 

[scottjoplin]

OPA2134 is supposed to be lower noise however the slew rate is 20v/us. The amps slew rate is 80v/us and would hate to have the amp being held back by the omamp.

Different voltages in a power amp than an opamp.....not a problem

 

[JaredC79]

Different voltages in a power amp than an opamp.....not a problem

Thanks, I didn't know if the slew rate of the driver circuit will bottle neck the performance of the amp. What do you feel will be the best performer in this location? Basically I want it to be unity gain with an input of 1 and output of 2? Will the input and output impedances stay the same?

 

[scottjoplin]

Any of the opamps you mentioned will be fine, LM4562 seems to be a favourite with many at the moment. There are a number of different ways to implement balanced drivers/receivers. Input impedance should be high and output impedance should be low, unless I'm not understanding your question

 

[analog_sa]

So, how many opamps make one "discrete out" then?

 

[scottjoplin]

I have no clue what a discrete out is so chose to ignore it

 

[JaredC79]

Any of the opamps you mentioned will be fine, LM4562 seems to be a favourite with many at the moment. There are a number of different ways to implement balanced drivers/receivers. Input impedance should be high and output impedance should be low, unless I'm not understanding your question

Basically I was asking if having a line driver added into the mix changes the input impedance of the second amp. Does it work better if the input impedance matches the input impedance of the amp or if the output impedance matches the input impedance of the amp - noted the input should be higher.

 

[JaredC79]

I have no clue what a discrete out is so chose to ignore it

I assumed that was the standard term for outputs that are unchanged from the input signal - it is a term used in pro-audio DAWs.