Current Source Amps

[zenmasterbrian]

This topic applies to all audio applications. But I think it most likely to be of used with subwoofers.

The best theoretical loudspeaker book I've ever found:
High performance loudspeakers / Martin Colloms , 1991, is where I first learned of this idea. Colloms is convinced it will make for better sound.

Any thoughts, opinions, experience? Anyone built such? Anyone have a schematic? Any commerical products on the market?

A standard amp is a voltage source, and approximates zero ohms output impedance. A current source approximates infinite impedance.

[forr]

With a high impedance source, the Qe of the driver disappears and the unit resonance is only damped by its Qm which Qt equals now.
High impedance idea may be a valid idea far above the main resonance. Its advantages as well as the restoration of the damping of the main resonance by motion feedback has been dealt by Hawksford :
http://www.essex.ac.uk/ese/research/...e%20patent.pdf
and Greiner-Travis :
http://www.aes.org/e-lib/browse.cfm?elib=11756

[zenmasterbrian]

Thank you. I'm reviewing your links now. I know this is complex, and I am aware of the damping issue.

Colloms seems to think it is good. Thats why I'm putting it out.
It came up in another thread as a way to run a subwoofer below fs. What do you think about it in that context?

[forr]

Hi zenmasterbrian,

I have Colloms's book. He refers to Hawksford who says that current driven speakers exhibit lower distorsion. He shows some examples just as Greiner-Travis.

---It came up in another thread as a way to run a subwoofer below fs.---
Have you the reference ? I think of a misconception here.

[zenmasterbrian]

forr, see Giant Subwoofer?

You have Colloms, fantastic. The idea of Current Source has been with me for a long time. Mostly from Colloms. It was only on this forum that I thought about it as being a good way, maybe, to go below fs.

[richie00boy]

There has been a lot of talk about current source amps on here, have a search. Quite a good discussion IIRC.

[ttan98]

I may know the whole story about Colloms' idea about being convinced that current amplifier is the way to go, however I am confident that with his networking ability he knows many competent amplifier designers, I am confident that he could convince one of them to design one unit for him to test out.

Did this happen? I don't know. If it did what is the outcome.

[zenmasterbrian]

Colloms just thought that it was one of the next boundaries to be crossed. He didn't say he was interested in doing it.

Any one find any threads about such?

Any one have any ideas about current amplifiers being good for going below fs

[Christer]

Time for something I have always been thinking every time this topic has been up for discussion.

What about headphones? Would they also have similar problems with being current driven, or could it be a more interesting option there?

[richie00boy]

If anything they would be more amenable to current drive since the headphone socket on 99% of amps is simply taken from the normal power output stage via a resistor of some 'significant' ohmage.

Nice module appearing on my website soon that can be used for current or voltage drive of headphones or line inputs