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4-ohm setting with 8 ohm speakers

I have the Nightingale CTR.2 open baffle speakers. The manufacturer claims that "the Concentus CTR-02's speakers and crossover are designed and assembled on the acoustic screen following a scheme meant to guarantee that the impedance stays linear as the frequency changes."

However, with every amplifier used with these speakers, a 4-ohm setting sounds more natural and relaxed. Now I am listening them with the Hans Labs KT-88 power amplifier. With the 8-ohm setting, the sound is more tight, bland and stringent, it sounds more like a mid-level SS amplifier. I am wondering how this can be explained from technical point of view?
transl

Showing 2 responses by clio09

clio09
3,341 posts
 
The output tubes or transistors will see less of a load using the 4 ohm tap, perhaps maybe half of what it would using the 8 ohm tap. That is the purpose of output transformers (impedance matching), and autoformers.
Hifihvn (Answers | This Thread)

I agree with this. As I agree with Hifihvn. Another good explanation is offered by Roger Modjeski who recommends trying "light loading"his the RM-10 MkII amps. There is a pretty clear explanation as to why in the owners manual. Lower distortion and longer tube life being a couple benefits, at least where the RM-10 MkII is concerned.
clio09
3,341 posts
 
What Plato describes regarding the bass is the effect I get when light loading my Music Reference RM-10 MkII. The loss of power is minimal as well, roughly 20%, so it runs at around 28 watts versus 35 watts. That's pretty negligible with my speakers since they are fairly efficient with a very smooth impedance curve.

Now my Music Reference EM-7 v12 amps can be configured for 3 ohm or 12 ohm output and I have tried both. Again, the lower output exhibited tighter bass and less distortion. However, with these amps I prefer the higher output.
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