Can u acheive lower output impedence by paralleling op-amps?

[strangeandbouncy]

Greetings One And All . . . . .

I am just a novice to Electronics, but use All kinds of Analog gear everyday. I have lots of gear that runs on 24Vd.c. and would like to start experimenting with building more gear. One thing interests me, which might help to integrate my intended projects with my existing (Coutant) Power supplies, which are probably big enough to weld with.

. . . . . I Ponder This . . . . .

My Neve and Audix mic/eq's achieve extra headroom beyond the operating voltage of +24Vd.c. by using a 300/600 ohm output tx to step up output. Can I do the same by paralleling two op-amps say 5534s/5532/op275 and a 1:2 step-up tx? what about discrete op-amps like Forsells? or the bag of Helios line-amp cards I have?

If so, will i have to change any resistor/capacitor values? Does input impedence of op-amps halve? Would this matter in practice? Have I lost the plot ?

Ho Hum . . . . .


Thanks in advance.


AndyP

 

[NewYorkDave]

You can't directly parallel the outputs. You can run opamps in parallel with current-limiting resistors to achieve greater current capability than with a single opamp. The general concept is outlined in this Burr-Brown paper
http://www.nalanda.nitc.ac.in/industry/AppNotes/BurrBrown/appnotes/AB-051.pdf

But for higher output voltage, a better use of two amps is in push-pull, either with a floating load, or via an output transformer.

 

[strangeandbouncy]

NewYorkDave,

Many thanks, v v useful and interesting info.


I shall ponder on!

Thanks,

AndyP

 

[rafafredd]

Any papers on PushPull opamp output stages?

 

[BradAvenson]

Check out these links:
http://www.dself.dsl.pipex.com/ampins/webbop/opamp.htm
http://www.dself.dsl.pipex.com/ampins/webbop/opamp.htm
http://www.rane.com/note124.html

They all have some relevance to the topic. Either parrallelling opamps for more current or output stages that use a push-pull topology.

 

[SonsOfThunder]

And here's another link to Douglas Self's site that should be of interest here: http://www.dself.dsl.pipex.com/ampins/balanced/balanced.htm
Peace!
Charlie