In his paper on Current Source amps NP talks about how he started off playing with such an amplifier when driving ribbon tweeters.
Then in the F2 manual he says this;
“A current source amplifier delivers a precise current to the voice coil of the loudspeaker driver, ignoring the series impedance elements in the circuit, including the wire, connectors, the inductance of the voice coil, the resistance of the voice coil versus temperature – all that stuff.”
So I have a question. In an active speaker set up would an F2(J) be capable of driving a long ribbon tweeter (think Apogee) that has an impedance of 2 ohms? The quote above seems to say that a current source amp is not fazed (see what I did there 😎) by the impedance demands of a driver, but I haven’t totally got my head around this so I may have misunderstood. Can someone elucidate further for me?
Then in the F2 manual he says this;
“A current source amplifier delivers a precise current to the voice coil of the loudspeaker driver, ignoring the series impedance elements in the circuit, including the wire, connectors, the inductance of the voice coil, the resistance of the voice coil versus temperature – all that stuff.”
So I have a question. In an active speaker set up would an F2(J) be capable of driving a long ribbon tweeter (think Apogee) that has an impedance of 2 ohms? The quote above seems to say that a current source amp is not fazed (see what I did there 😎) by the impedance demands of a driver, but I haven’t totally got my head around this so I may have misunderstood. Can someone elucidate further for me?
A nice little article, just the right stuff before bedtime. Strongly recommended because it draws a parallel between different types of amps vs different types of speaker drivers
http://www.atma-sphere.com/en/resources-paradigms-in-amplifier-design.html
The first two paragraphs are most likely the closest match (answer) to your question (look here: https://forum.audiogon.com/discussions/voltage-source-vs-current-source-amplifiers):
"First, a voltage source is an amplifier that can make constant voltage regardless of load. No amp can actually do this, but they can come pretty close. This is the phenomena where the power is doubled as the load (speaker) impedance is halved.
A current source amp is an amplifier whose output impedance is significantly higher than that of the load and so makes constant current regardless of load. This is not a tube or solid-state amp in particular; to achieve this, the amp must employ current feedback, which is a bit different from voltage (traditional) feedback."
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Thanks for that. So if I’ve got this right, if the ribbon has a relatively flat impedance curve then a current source amp would work well and the question would be, does the F2J have enough power to drive the ribbon to reasonable SPLs.
That is highly subjective and dependent on the room size and acoustics as well, not to mention that with the inclusion of the passive crossover (large inductance and capacitance values depending on the required frequency/slope), the correlation between a current source amplifier and a flat impedance tweeter (in isolation)... falls apart somewhat. Using an electronic active crossover, together with a current source amp... may have some merit. This might be worth a try... but only you'll know if the achieved sound pressure (and sound quality) in combination with F2J, is to your liking.