Here's the circuit of the self-balancing push-pull amplifier using 1j24b and 2x 1j29b.
The 180pF capacitors across the transformer primary are to suppress residual HF spikes from the AC filament heating. As mentioned, there's a neutralisation circuit which injects ripple of appropriate amplitude and phase into g2's, but I found that the ripple disappeared (apart from spikes) with the trimpot just about at its central position - which says something for the constructional symmetry of the rod pentodes.
The O/P transformer is sectionally wound (secondary and closely-coupled bifilar feedback tertiary) split in half, each side of the primary.
Frequency response is also shown into a resistive load.
It's no doubt not quite up to Jez standards, but it has drawn favourable comments from a former hi-fi retailer.
The 180pF capacitors across the transformer primary are to suppress residual HF spikes from the AC filament heating. As mentioned, there's a neutralisation circuit which injects ripple of appropriate amplitude and phase into g2's, but I found that the ripple disappeared (apart from spikes) with the trimpot just about at its central position - which says something for the constructional symmetry of the rod pentodes.
The O/P transformer is sectionally wound (secondary and closely-coupled bifilar feedback tertiary) split in half, each side of the primary.
Frequency response is also shown into a resistive load.
It's no doubt not quite up to Jez standards, but it has drawn favourable comments from a former hi-fi retailer.
