Current amp vs Voltage amp


Two different topologies with different intent. There are arguments for and against both technologies. Not having a electronics background I'm tying to get a clearer understanding.

Speaker matching including impedance and power requirements: how does one match 1:1 :: amps:speakers? General rule of Higher sensitivity benign/high impedance to tubes, and, low medium/sensitivty variable impedance to SS (considering they can be of higher power rating)?

This is not to see which is best, but to better understand the process of matching components.
deadlyvj
If we put aside the issue of damping for the moment, and so long as such a ss amplifier has the required output power, such a ss amplifier would almost always be able to provide more linear output regardless of whether they are ESL's or dynamic speakers, and that would hold true whether or not the impedance swings were wide or not. Whether or not thus would always be audible is of course another issue.:-)
Hi Unsound,

Yes, "such a ss amplifier would almost always be able to provide more linear output regardless of whether they are ESL's or dynamic speakers, and that would hold true whether or not the impedance swings were wide or not." (Assuming that by "linear" you are referring to flat frequency response).

However, as I indicated that is not what matters. What matters, with respect to this issue, is the frequency response flatness of the output of the SPEAKER, as judged against the INPUT to the AMPLIFIER. Which in turn depends on how suitable the match is between amplifier output impedance and the design of the particular speaker.

Frequency response flatness at the amplifier output/speaker input has no direct relevance. Speakers whose impedance varies significantly as a function of frequency, and that match most optimally with tube amps, can be presumed to require a non-flat frequency response at their input terminals to produce an acoustic output whose frequency response is flat. If such a speaker is mated with a solid state amplifier having near zero output impedance, frequency response flatness will have been optimized at the output of the amplifier, but it will be wrong at the output of the speaker.

Best regards,
-- Al
Please forgive me, as I don't seem to understand.
I would think that if the speakers impedance varies, and as such it's sensitivity varies, I would think that unless the amplifier can adapt its power output appropriately, the speakers frequency output response will deviate from linearity.
@ Almarg, Hi, I was currious of your statement above, amps operate in a current mode and voltage mode?,, This is quite confussing to me,, My Krell 700cx clearly on all the technical papers, says this amp solely operates only in the current domain!, Krell is very famous for doing that!,, If you can study up on these technical papers for me, that would be cool!How can Krell make such a statement?,, thanks Almarg!,, cheers!
Unsound,

If the output impedance of the amplifier is a good match for the particular speaker, the output of the amplifier WILL adapt appropriately.

Think of the amplifier as an amplifier having zero output impedance in series with a resistor whose value corresponds to the actual output impedance. If the impedance of the speaker varies significantly as a function of frequency, and if the amplifier's output impedance is significantly greater than zero (e.g., 1 or 2 or 3 ohms or so, as in the case of most tube amps), the voltage divider effect resulting from the interaction of that output impedance (corresponding to Z1 in the first figure of the reference) and the impedance of the speaker (corresponding to Z2 in the first figure of the reference) will result in the voltage at the amplifier output/speaker input varying as a function of frequency. If the amplifier's output impedance is a good match for the design of the particular speaker, that variation in amplifier output will result in minimal variation of the output of the speaker, as a function of frequency.

Audiolabyrinth,

I didn't say that amps operate in a current mode and a voltage mode. Actually, I don't know what that would mean, if anything. What I said is that amplifiers amplify both current and voltage. In other words, the voltage at their output is greater than the voltage at their input, and the current supplied by their output is greater than the current going into their input.

You are probably referring to Krell's CAST concept, as described here. Note the statement in the first paragraph that "A Krell system connected in CAST transfers the signal in the current domain, throughout the signal path to the amplifier output stage where only one current to voltage conversion (I-to-V) takes place."

Following that current to voltage conversion, at the output of the amplifier, both voltage and current would certainly be greater than at the input of the amplifier, or it wouldn't be able to drive the speakers to anything approaching reasonable volume.

I see in the manual for the 700CX that its gain is spec'd at 26.4 db. That corresponds to an increase in voltage of about 20 times. And its 700 watt capability into 8 ohms certainly represents vastly more output current (actually, about 9.4 amperes, when the full 700 watts is being delivered into 8 ohms) than any preamp could ever supply to the amplifier's input.

Best regards,
-- Al