There have been a few threads on Radford's unique design but not much about what the Radford amps actually sound like.
I've been playing with my own version with LTspice, using 6SL7 for input, 6AU6+6SL7 as LTP splitter with cascoded BJTs CCS in the tail, 6SN cf drivers and EL34s in full pentode AB1 PP outputs. GNFB is present at about 20dB, with the usual corrections for LF and HF peaking.
This is, admittedly, a long way from what Radford produced, but it seems to work really well and the FFT analysis shows extremely low distortion.
I realize that a sim doesn't really provide a definitive answer on distortion and there's nothing like the real thing, so I was wondering if anyone has heard a real Radford style amp? Are there any pitfalls that my sim doesn't reveal?
I've been playing with my own version with LTspice, using 6SL7 for input, 6AU6+6SL7 as LTP splitter with cascoded BJTs CCS in the tail, 6SN cf drivers and EL34s in full pentode AB1 PP outputs. GNFB is present at about 20dB, with the usual corrections for LF and HF peaking.
This is, admittedly, a long way from what Radford produced, but it seems to work really well and the FFT analysis shows extremely low distortion.
I realize that a sim doesn't really provide a definitive answer on distortion and there's nothing like the real thing, so I was wondering if anyone has heard a real Radford style amp? Are there any pitfalls that my sim doesn't reveal?