Current - Class A vs Class A/B, various wattages

Is there a difference in current between two various amps outputting 30 or 100 watts each, or if one is Class A and one is Class A/B, so long as the wattage is the same?

If there is, is there a way or spec to look at to judge one that is "high current"?
To the fist question, if both amps are making the same power into the same load the current will be the same as well.

The higher powered amp will be capable of more current at higher power levels.

'High current' amps are usually those that can drive 4 ohm loads with double the power that they make into 8 ohms. This characteristic is also known as 'constant voltage', i.e. the amp is regarded as a voltage source. What this means is it can make the same voltage regardless of the load. So if the voltage is the same into 4 ohms, the current will increase such that the power is double that of the 8 ohm load, given that both loads see the same voltage.

Now if you are still with me, the real question is, 'is that important for musical reproduction??' The answer is a qualified 'No'. IOW its important for some speakers, and other speakers sound worse if the amp has that power doubling (high current, constant voltage) characteristic. You have to look at the intention of the designer of the speaker to sort that out.

If the designer uses tube amps, its likely that a SS amp that can double power will not exhibit flat frequency response on that speaker. OTOH if the designer did use a SS amp with his speaker, then 'high current' might be useful.

Hi Ralph, looks like you have a life mission to educate us so-called audiophiles about Rule 1 of Hi-Fi: amop/speaker matching. Mesaboogie, Ralph (Atmasphere), Al (Almarg) and I have communicated about this issue a "ba-zillion" times by now.

It's a difficult issue to get one's arms around, but it's critical to get it right, or at least not get it wrong, if you plan to dump big bucks into a rig. If you follow my threads over the last 6 months, you'll see that I've been on my own personal mission to understand this concept. I think I may have finally figured out why my amp and speaker combo seems to work well, even though on paper it shouldn't.

Too complicated to explain here, but Ralph is 100% right that if one is interested in buying speakers or an amp, the first Q to get out of the way is whether the combo you have in mind is compatible. This may require separate calls to the amp and speaker manufacturers, as Ralph suggested. Otherwise, after dropping a lot of time and money into buying components, you may have a bad day when you bring it all home and set it up. The gear may not sound like it did at the dealer.

Btw, right now there is a thread running now about a chap who is having major aggravation getting his Music Fidelity amp to work on his PSB speakers. A lot of folks have dropped posts trying to help the member out. It may turn out the problem is a bad amp and speaker match. Jury's still out.



P.S. I have another great article for lay folks like me that does a great job of explaining what is meant by a tube friendly speaker. I'll post it later today or over the weekend.
I would toss in that the current capability is more about the speaker load.
"High Current" delivery amps can drive low impedance speakers better.
The lower the speaker impedance, the more current the amp needs to be able to have available. (in general)
Halving the impedance, means wanting to double the current.. which 'high current' amps can do. many other amps cannot manage it.
well my friend who got me into moving passed a high end consumer system was using some Gallo speakers. and I have really liked them so I ended up buying a pair of 3.1s. he was using a class D amp and I had intended to go tube from the start...but now all I read is how the load varies in then and 200 watt solid state is about the only option for not losing the bass. which means I might end up with very expensive pair of mono blocks that I wasn't ready for. $5k or so was what I was hoping be stay around, but 200 watt tube is more like $10k entry fee....and those don't do the power doubling even then.
Would anyone know if the Gallo 3.1 be considered a "voltage driven" speaker based on Ralphs link?
Mesaboogie: Call the factory and ask what type of amp they recommend. I would also ask the factory a reality check Q about the type of amp the designers had in mind when they voiced the speaker.

I would also search the web to see if Stereophile or HT published any bench test results on the Gallos. If the impedance curves are all over the place and there are low frequency negative (capacitive) phase angles, I would surmise that the Gallos are NOT tube friendly.

Here's the other article I mentioned above about tube friendly amps:
Elizabeth, Isn't that what Ralph said?