2 preamps in Series causing overloading

[walters]

When hooking up 2 preamps in series it causes overloading

How do i measure the output gain of preamp#1?
with a oscilloscope or do i need a AC volts meter for this?

When i put my AC volt meter on the output jack of the preamp what should i be looking for? there is different scales which one should i use?

How do i measure the gain of a preamp? do i measure the gain from a AC volt meter and how do i do this please?

 

[akg]

When hooking up 2 preamps in series it causes overloading

How do i measure the output gain of preamp#1?
with a oscilloscope or do i need a AC volts meter for this?

When i put my AC volt meter on the output jack of the preamp what should i be looking for? there is different scales which one should i use?

How do i measure the gain of a preamp? do i measure the gain from a AC volt meter and how do i do this please?

to measure the gain of a preamp ..it's better to use an oscilloscope
and why shld u put two preamps in series??

 

[audioguru]

Suppose that you have preamps each with a gain of 500. But their noise level is 1/500th so the output of the 2nd one is overloaded with noise!

1) You can measure the gain of a preamp with an AC voltmeter if it is calibrated for the frequency you are using. "Ordinary" multimeters measure 50Hz or 60Hz mains frequencies accurately but are very poor at other frequencies. The AC voltmeter also must have a scale that is sensitive enough to measure the low input level and a scale for the high output level.
2) You should also have a 'scope connected to the output so you can see if noise or clipping is ruining the measurement.
3) The preamp should be driving its rated load resistance.
4) Duh! Then the gain of the preamp is simply calculated as the output level divided by the input level.

 

[bloki]

Of course to the input of the preamplifier you must connect signal generator which signal must correspond to the preamplifier nominal level and frequency.

 

[Russlk]

The input to the preamp will no doubt be too small to measure. Set the signal generator output to a level than can be measured, then feed it thru a potentiometer to attenuate the signal to the preamp. Adjust the pot such that the preamp output is equal to the signal generator, then measure the pot resistance to calculate the preamp gain.

 

[bloki]

But it is still unknown what kind of preamplifier we have in mind. Is it phono or line preamplifier.

 

[audioguru]

But it is still unknown what kind of preamplifier we have in mind. Is it phono or line preamplifier.

Does anybody still have a phono? I do, but haven't used it for about 20 years. It uses probably the last and best Shure cartridge that was made.

What would a line preamp do? Have a gain of 1 like a piece of wire?

I think it is a microphone preamp with a lot of gain and barely audible hiss. With two in series then the output is a roaring waterfall! :lol:

 

[bloki]

It could be a guitar preamplifier allso, I guess.

 

[audioguru]

It could be a guitar preamplifier allso, I guess.

How would you stop the sustain if you used two preamps in series? Turn off the thing?

 

[jimbob jones]

You can measure the gain of a preamp byidentifying first the type of amplifiers used in the preamp.Get the gain formula for these and apply.