Originally Posted by pandaemonium

I would like to make a CCS (Constant Current Source) for testing loudspeakers.
I've used the constant voltage and voltage divider methods but I don't know what the requirements are for a CCS for this application.
Can someone give me some info or maybe a pointer to a schematic?

Perhaps you should explain more what you are trying to do?, it doesn't make much sense to me?.

Originally Posted by pandaemonium

I want to measure the Thiele/Small (and other) parameters of speakers. There will be a sine wave generator at the input of the CCS and the speaker at the output of the CCS. The voltage of the CCS will change according to changes in the impedance of the speaker, I will measure this at various stages to calculate the speaker parameters.

A constant current source is generally DC, but a simple way to do it for this is to use a high power (and thus high voltage!) amplifier to drive it. You can then feed the speaker through a highish value resistor, and as this effectively swamps the impedance of the speaker it produces a fairly good constant current.

This is a VERY! old technique for giving a constant current!, probably older than Audioguru? :twisted:

This circuit puts 2mA DC into the speaker, but since the level is low, it should not affect the measurment. The AC component can be 2 ma peak max.

I just feed the speaker through a 100 ohm resistor directly from the output of my sinewave generator.