[sdiy] [Slightly OT] Op-amp headroom in synth & audio applications

jays at aracnet.com jays at aracnet.com
Tue Mar 10 19:53:43 CET 2015


Another aspect of having high signal levels is the relative signal to 
noise level gets better. If you have 10 mv of noise in a system and the 
signals are +/- 5V you have a much better S/N ratio than if you have +/- 
1V signals.

Jay S.

On 2015-03-10 11:43, Donald Tillman wrote:
> On Mar 10, 2015, at 11:21 AM, Justin Owen <juzowen at gmail.com> wrote:
> 
> I understand that there's a margin for staying away from the rails and 
> for the tolerances of parts like VRegs and what not and maybe part of 
> it is a hangover from the days of less efficient amps - but considering 
> that a good op-amp like the OPA134 will (according to the data sheet) 
> operate down to +/-2.5V and work-horse amps like the TL072 aren't far 
> behind that - why so much headroom?
> 
> 1. Headroom good.
> 
> 2. Why constrain the choice of opamp?
> 
> 3. Discrete circuitry appreciates the wiggle room.
> 
> 4. Originally ARP, but now MOTM and many other synths run audio at
> high levels to match the range of control voltages.  So it's less
> "headroom" and more a high reference audio level.
> 
> -- Don
> 
> --
> Don Tillman
> Palo Alto, California
> don at till.com
> http://www.till.com
> 
> 
> 
> 
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