Single-ended triode

This requires inserting a gap in the transformer core to prevent core saturation by DC current; adding a gap decreases primary inductance and limits bass response; the inductance and bass response can be restored by using a larger transformer than if the DC were not present.

An alternative schematic, parafeed amplifier, solves bandwidth problem by blocking direct current from output transformer (which does not need to be gapped, thus improving its bass response).

Power supply is reconfigured into a constant current source, usually with a massive, high-inductance anode choke (gapped inductor), so there is little, if any, gain in cost and weight of magnetic components.

A stereo class A single-ended design with KT88 kinkless tetrodes which produces 15W of output power per channel, and 5W when triode-connected, is the Antique Sound Lab MG-SI15DT.

This perceived high sonic quality is mainly attributed to the simplicity and minimalistic approach of the circuits involved and the triode amplifying tubes that are typically used.

[citation needed] On the other hand, the legitimacy of branding single-ended triode amplifiers as adequate for Hi-Fi purposes is debated, as from a technical standpoint, SET amplifiers are considered to be generally far inferior to subsequent (and more common) push-pull tube designs or solid-state amplifiers:[3] SET designs require output transformers which are able to cope with a strong DC component in the signal, which causes them to have worse performance in regard to frequency response, distortion and efficiency (although the latter is not generally a priority for most SET enthusiasts, or audiophiles in general).

Grid currents can place extreme demands on the driving circuitry, sometimes requiring as much as 8 watts input for larger tubes such as the 211.