S/N in opamp how low do i need?

[Tubis]

I dont understand how the gyros make up for most of the noise?
They are there to manipulate the feedback in the amp L4A,right?.
Shouldnt L4A be the biggest contributer of noise?

In comparesen mith the MXR 10band eq the Boss is much noisier. Disspate that ihas an 18V addapter so the gain kan realy be pumpt upp high but with very low noise. I dont have the scematics or that one.

Is the Boss circuit a bad one?
If any have the mxr 10band schematic, wat makes it so quiet?

As Steven says, "anything you put in front of a high-gain amp will increase the noise level to some extent".

Thats wy i started my quest to understand and try to minimize the noise as far as possible in any circuit, not just in this one, this one was just an example.

What about if you had a bunch of only cutting gyrators and then have a makeup gain opamp at the end? Would that in anyway make the circuit les noisy, the same, or worse?

Finaly, can anyone share a schematic how to do a multiband eq for minimum of noise and minimum frequensy interaktion.
The Boss and the gyrators are good in that sense that the notches just go up an down without interaktion with the other bands.

[Mike Sulzer]

I dont understand how the gyros make up for most of the noise?

The outputs of the six 022s feed into the amp above; so the question is how much noise is on their outputs.

Each 022 is a follower with positive feedback. The positive feedback increases with frequency, so we expect an increase in high frequency noise. How much?

A simple analysis shows that a noise voltage source in series with the positive input is amplified at the output by a factor of approximately Zi/Zf when Zi is large compared to Zf, that is, almost 300 times at high frequencies.

So you can see the need for the pre-emphasis/de-emphasis.

[Robert M. Martinelli]

You mean "lower magnitude of impedance as we move away from the resonance", right?

Hi Mike
I was referring to the R/Z ratio, sorry I didn' t state it explicitly.
Regards
Bob