Amp & Speaker matching

Depending on the design - if you don't mind a slight reduction in power, using the output taps lower than the impedance of your speakers can be beneficial in some cases. Presently I prefer the 4 ohm tap over the 8 in my system where the spkrs impedance ranges from 8-10 ohm. The difference is easily heard. I've heard it go both ways w/several different tube amps w/my speakers.

In the case of my current amp, Roger Modjeski/Music Reference, the designer in his own words, "Although higher idling current will reduce distortion, it can also be reduced by light loading. Basically, light loading reduces the output current demand on the output tubes, allowing them to be more linear. It also reduces noise, raises damping factor, and allows for more peak current when needed. The only loss is about 20% of the power rating or 1 dB."

The only loss is about 20% of the power rating or 1 dB

Hi Pehare,

That may be true for some of Roger's amps, but it is by no means true as a general rule. As I indicated earlier, the amount of power loss is dependent on the output impedance of the amplifier, on the degree of light loading (i.e., the relation between the impedance of the speaker and the load impedance that the output tap is optimized for), and on other amplifier-dependent variables.

On a percentage basis, the power reduction resulting from light-loading an amplifier having an output impedance of 1 or 2 or 3 ohms or so, such as the Mahi, is likely to be much greater than it would be, for example, with some SET amps that may have output impedances of perhaps 4 to 8 ohms or more.

Best regards,
-- Al

Hi Al,
I agree that the "light loading" principle is likely to yield varied results and is amp dependent. For example my amplifier has an 8 and 16 ohm speaker tap. My speaker is 14 ohm nominal load and 10 ohm minimum. Without question the sound is better at the 16 ohm tap rather than the 8 ohm. Simply put all music reproduction parameters are just better.I understand that the Music Reference amplifiers could be a different situation and thus benefit from the light load appraoch.If there`s loss of power it unnoticeable, the sound is actually more transparent/open, dynamic,with increase scale, fluidity and flow.
Regards,