Any ideas?

If you unsolder the red and black mic wires from the pc board does it still buzz?

 

If you unsolder the red and black mic wires from the pc board does it still buzz?

I'll try that...

 

A Single-Sided PCB is not going to work very well for a Mic Preamp.
At the very least it needs a 2-sided Board with a mostly solid Ground-Plane on the bottom,
and it needs to be in a Metal-Box.
How particular Parts are arranged on the Board can make all the difference.
It's possible to not only get hideous Noise,
but You could actually turn the Circuit into an Oscillator.

Huh, Hadn't noticed it was a single sided circuit. Why would that matter?

I agree it ultimately needs a box, but that's not why it's buzzing. I've breadboarded this circuit before and it worked with little or no noise. Something else is going on.

 

The Circuit You are using, while elegantly simple,
has no convenient means of reducing the High-Frequency-Response of the Op-Amp.
This means that it will quite happily amplify RF-Frequencies, just like Audio-Frequencies.
Therefore, it must be carefully shielded from outside Noise.
It also means that it has the "potential" to become an RF-Frequency-Oscillator,
which You may, or may not, notice,
but it can affect the performance of the Amplifier in many odd and unpredictable ways,
many of which can only be demonstrated on a good Oscilloscope.

The same situation goes for the design of PCBs.
PCB design is as much of an Art as it is a Science.
Many Spec-Sheets will provide PCB-Layout recommendations,
and there can be very significant consequences for not following their advise.

There are also "General-Best-Practices" for designing PCBs,
one of which is providing a "Ground-Plane" for the entire Board.
.
.
.

 

Your red MIC IN wire is an antenna that picks up 50Hz or 60Hz from electricity wires in your walls, floors and ceilings. You must use a shielded audio cable. Maybe your 9V is noisy?
I have made and have had made hundreds of mic preamp circuits on a single sided pcb or stripboard with a gain as high as 200 and they do not produce hum or buzzing.

 

Your red MIC IN wire is an antenna that picks up 50Hz or 60Hz from electricity wires in your walls, floors and ceilings. You must use a shielded audio cable. Maybe your 9V is noisy?

So you’re saying the same thing that @sghioto suggested. I’ll check that.

 

Your red MIC IN wire is an antenna that picks up 50Hz or 60Hz from electricity wires in your walls, floors and ceilings. You must use a shielded audio cable. Maybe your 9V is noisy?

You're right, on both accounts. My OneSpot 9V was significantly worse than my Cioks. But also when I removed the input, it also go better. I've made more progress on another circuit in another thread, I'll post there.