Reduce signal generator to 5mV?

[Axtman]

I am working on a Fender FM 212R amp. The schematic calls for an input signal of 5mV AC. The lowest my BK signal generator will go is about 52mV. How can I reduce the signal to 5mV?

[Helmholtz]

Use a voltage divider.

100k/10k will divide your signal by 11.

[Chuck H]

That sure seems like a weird test parameter for a guitar amp!?! But whatever, right? Just make a voltage divider with a pot and run the signal generator through that. Probably 100k to 500k to avoid loading the signal generator which I suppose could cause distortions.

[Helmholtz]

That sure seems like a weird test parameter for a guitar amp!?!

Why weird?
The low level just shows that the amp has lots of gain with vol. fully up.
It makes sense that test levels are low enough to avoid distortion in the signal chain, as many meters don't read distorted signals correctly.

[g1]

Depending on what kind of parts you have around, it may be easier to just put a pot across the BK output terminals.

[J M Fahey]

It´s hard to adjust a pot with precision below 10%, while resistors are known value and can make ANY ratio you want.
And *stay* there, while even brushing a pot knob will change setting.

100k to 500k to avoid loading the signal generator

On the contrary, most generators can drive 600ohm safely, I suggest 100k/1k only because high attenuation is desired, but any general they can easily drive 10k/1k

[Helmholtz]

For best resolution I use a 10k multiturn pot in an aluminum box (BNC from generator: In - jack plug: Out).

[J M Fahey]

To calm OCD?
Maybe, if the goal is to get 5.000000000mV, not 5.000000001 or 4.9999999999

That said, value will still depend on stability of *real* generator feeding the attenuator.

Me?

I am quite certain Fender suggestion admits some tolerance, and in any case, like Enzo says, this is s Guitar Amp, not NASA.

[Helmholtz]

Funny, wasn't it JMF who introduced the precision criterion?

Sometimes I want precision/high resolution (as well as good shielding) - other times like here, +/- 10% doesn't matter.

[The Dude]

IMO, both ideas have merit. If you just want a quick divider to work on ONE unit, Juan's idea is good. If you're want better adjustment for working on MULTIPLE units with different input level specs, the pot might be a better and more permanent solution for a "fine adjust" sort of thing. I don't see anything wrong with either idea. Either will get you similar results.

[Helmholtz]

IMO, both ideas have merit.

Sure, see post 2.

A pot is just a variable voltage divider, so it's used where you need variable.
When using a pot it should have linear taper.
Precision can be greatly increased by wiring a larger resistor in series with a lower value pot (e.g. 10k resistor feeding a 1k pot.).