It can't have been, it uses an opto-coupler (relatively expensive back in the 60s), whereas the bias tremolo is directly coupled to the main circuit electrically. I'm not sure why the opto trem was chosen - possibly because bias trem tends to 'thump' a bit at high depth settings. But opto trem has some problems too - the neon discharge often causes the audio circuit to 'tick' (well known in Fenders), and the opto unit has a limited life expectancy - the LDR part tends to stop working eventually, I've been seeing a lot more dead ones in BF and early SF amps now than I did 20 years ago when I started repairing amps.jps wrote:It has been said that CLF like the later BF tremolo better, probably due to it being cheaper to implement!
I prefer the tone of the bias trem too by the way, it's more organic and rich... the opto trem can be a bit bland.
