I don't think that kind of accuracy is too important in this case. There's such a broad range of input levels from guitars, that going from 100mV to 300mV is perfectly reasonable. It's probably worth testing the input level before it gets amplified to see what the actual levels are, regardless of what the signal generator says, and maybe compare that to a couple guitars on hand. In some cases, testing levels is required anyway, like the Tenma unit on my list (since there's no display to determine any amplitude claims). That said, while the Tenma unit is acceptable, the Siglent units I have allow for much finer tuning. The inbuilt AWG in my scope allows you to go as low as 4mVpp. That's well below any useful voltage for a guitar amp. It even allows setting amplitude to 100ths of a mV, not that I would in this case, but it's cool: This inbuilt AWG is less robust than their standalone unit I have (SDG2042X)...but it's more than I generally need, so the SDG2042X usually sits in the box. Ha! That reminds me, I have another one that works well too. A UNI-T UTG932E. The UTG932E goes down to 2mVpp, but can't do any decimal places in the mV range, though it does go in increments of 1mV.TriodeLuvr wrote: ↑Thu 04/29/21 2:00 pmYou know, a more basic issue about all this has to do with the generator itself. I've seen a lot of generators that don't have a suitable attenuator for working at these levels (musical instrument input). Ideally, the output of the signal or function generator would be variable down to 1mV or less. Many are only useful if the work is essentially line level, and the output is only easily adjustable in the range of maybe 100mV to several volts. Also, most generators are rated with a 50 ohm or 600 ohm output impedance. Attaching them into the input of a typical musical instrument amp, which is nearly an open circuit, causes the generator's output level to increase even more. Some generators have an internal load that can be switched in, but some don't. The latter type need to be terminated externally, and that means you can't use a simple adapter. What's needed is a box with an input jack, an output jack and a switch for 600 ohm and 50 ohm terminations. It might also need to have a switched divider network (attenuator) to make the generator's output useable. If output level accuracy isn't important (or if it will always be checked with a scope when testing), a 100K linear pot can replace the divider.
Jack
You're absolutely right for more sensitive equipment, but why be concerned with something as variable as guitar stuff? Test some vintage strat pickups and compare them to some modern high-output ceramic humbuckers and see what kind of range you get.
Thanks,
Josh