Why are You trying to use a TL081, ( or any Op-Amp in that family ), and running it on ~9-Volts ???

If You have any concern at all about Clipping,
and Your Pre-Amp is not being used as a "Distortion-Effect",
You should be using a modern Rail-to-Rail-Op-Amp, or an ~18-Volt-Supply, or both.
Then Clipping is not even a consideration,
except in the Input-Circuitry of the poor unfortunate equipment that follows this Pre-Amp,
and, at that point You would be running at Voltage-Levels that are far above "Line-Level".

All Guitar-Distortion-Effects are intentionally Asymmetrical, always.

Here's a good place for Effects ............
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That's good to know, but you threw me off about the output level being above line level input limits.

 

A Rail-to-Rail-Op-Amp with an 18-Volt supply can deliver very close to Plus & Minus ~9-Volts.

Consumer-Grade-"Line-Level" is roughly Plus & Minus ~1-Volt, usually less.

Consumer-Grade-"Mic-Level", and "Instrument-Level" is roughly Plus & Minus ~0.5-Volt, usually less.

Most "Consumer-Grade" Equipment-Inputs will start to Clip when driven in excess of the above numbers.

Most "Professional" Balanced-Line-Inputs are designed to withstand much higher Voltages without Input-Clipping.

The Input to a Musical-Instrument-Tube-Amp
is the only Input purposefully designed to accept higher levels than those listed above.
They are designed to generate Distortion by purposefully over-driving actual Tubes.

Other Devices may generate Distortion by way of Internal-Amplification, ( with a "Gain" Knob ),
NOT by having their Input Over-Driven.

There are occasional exceptions to the above rules, but don't push your luck,
or You could have weird problems that defy analysis.
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I've heard the old standard of .775 volts into a 600 ohm load, producing 1 mW of power. Did they mean .775 volts RMS or Peak to Peak ?
1 mW RMS or 1mW Peak to Peak ?

 

I've heard the old standard of .775 volts into a 600 ohm load, producing 1 mW of power. Did they mean .775 volts RMS or Peak to Peak ?
1 mW RMS or 1mW Peak to Peak ?

You can't have peak-to-peak power, nor RMS. It's just power. And from that you can deduce that for an AC signal the voltage is 775mV, which must be RMS because it is an AC signal defined by how much power it produces in a known load.

 

Thank you. That helps.

 

Don't go by "old" standards.
No modern "Consumer-Grade" equipment has an Input-Load of 600-Ohms,
so the Input-Impedance is largely irrelevant.

Effects-Boxes should not change the overall Gain between its Input and Output when
the "Volume" Pot is at ~12-o'Clock,
and any "Gain" type Knob is turned to either "zero" or ~12-o'Clock,
and any Buttons not punched.

On a Pedal-Board with let's say ~10 Pedals, is first set-up,
every "Volume-Knob" should be set to ~12-o'Clock,
and then only the very last "Volume-Knob" in the "Chain"
should be adjusted, and only if absolutely necessary, and it should almost-never be necessary.

This type of set-up should maintain the Output from
every Box on the Pedal-Board at roughly "Instrument-Level-Voltage",
or the Voltage-Level generated by the Instrument being used.
This is, of course, with all Buttons in "Bypass-Mode".
This is the Voltage that the "usual-Main-Tube-Amp" expects to see coming into it's Input.
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Got it.

 

Dirty potentiometers can be problematic. Crackling volume control on a home stereo comes to mind.

I WAS NOT suggesting the use of such "volume control" type variable resistors, but rather the type we use in serious electronics, which are much smaller physically, and enclosed, so that they avoid contamination. The good ones are not found inside "consumer-grade" electronics. So many folks have never seen them. Cheap, unsealed controls and adjustments should stay inside consumer-grade stuff, those components have no place in equipment where reliability matters.

And how did this discussion suddenly veer off into the field of guitar effects pedals??? We were discussing ways to utilize the maximum used range of an amplifier IC, and I pointed out that normal tolerance variations make it wise to allow some space at the ends.

 

You're right, a sealed variable resistor would allow for precise setting of bias voltage.