Radford’s missing monoblock amplifier

DOES THE LITTLE SEEN MA25 BRIDGE THE GAP BETWEEN THE BRAND’S STA15 AND STA25? HFN READER FINDS OUT BY BUILDING HIS OWN

David Lord

I think it’s fair to say that the Radford STA15 is one of the most highly regarded vintage British valve amplifiers. I have never owned an original, but a few years ago I built one from scratch using transformers and other essentials purchased from Radford Revival. This certainly impressed me with its excellent sound, but the main drawback I found was the limited power available to drive the sort of low-sensitivity loudspeakers that I typically prefer. As Radford groupies will know, the STA25 is the same amp as the STA15 but with more watts squeezed from the output EL34 valves by running them with fixed rather than auto bias, and through increasing the HT rail voltage by changing to solid-state rectification and avoiding the voltage drop across the valve rectifier…

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Hi Fi News (Digital) - 1 Issue, April 2025

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