Thanks Al ... the problem is my misuse of terminology.
Perhaps a better way for me to think about my amp's performance window is that it does not appear to choke when asked to deliver power. Perhaps that is because I am not really tasking the amp all that much during "normal" operations.
In my layman's way of thinking, what I think of as "headroom" is my perception that if the amp is making say 25 to 50 watts of power during "normal" operations, a transient peak that pushes the amp out to 100+ watts is well within its rated power capability. Not headroom in the technical sense, but headroom insofar as the amp can produce a lot of power at reasonably low distortion numbers and remain stable.
Another fine point from the Atkinson report is that my amp will produce rated power in those cases where the load impedance matches the nominal tap value, i.e., an 8 ohm load plugged into the 8 ohm tap; or a 4 ohm load plugged into the 4 ohm tap. However, the amp will not produce rated power where there is an impedance mismatch between load and nominal tap value.
That said, in my case, my speakers have a 4 to 6 ohm saddle in a good part of the low frequency range, say 70 to 500 Hz. Impedance goes vertical past 700 Hz.
I surmise that most of the power demands placed on my amp fall within those goal posts. Given the foregoing, the 4 ohm taps make the most sense from a impedance and power matching perspective. And as an aside ... my rig sounds the best to my ears off the 4 ohm taps too.
Perhaps a better way for me to think about my amp's performance window is that it does not appear to choke when asked to deliver power. Perhaps that is because I am not really tasking the amp all that much during "normal" operations.
In my layman's way of thinking, what I think of as "headroom" is my perception that if the amp is making say 25 to 50 watts of power during "normal" operations, a transient peak that pushes the amp out to 100+ watts is well within its rated power capability. Not headroom in the technical sense, but headroom insofar as the amp can produce a lot of power at reasonably low distortion numbers and remain stable.
Another fine point from the Atkinson report is that my amp will produce rated power in those cases where the load impedance matches the nominal tap value, i.e., an 8 ohm load plugged into the 8 ohm tap; or a 4 ohm load plugged into the 4 ohm tap. However, the amp will not produce rated power where there is an impedance mismatch between load and nominal tap value.
That said, in my case, my speakers have a 4 to 6 ohm saddle in a good part of the low frequency range, say 70 to 500 Hz. Impedance goes vertical past 700 Hz.
I surmise that most of the power demands placed on my amp fall within those goal posts. Given the foregoing, the 4 ohm taps make the most sense from a impedance and power matching perspective. And as an aside ... my rig sounds the best to my ears off the 4 ohm taps too.
