[quote name='discreet' timestamp='1428355816' post='2740593']
I believe the reason for the perception of 'heft' in valve power amp transformers is due to 'sag'. As I understand it, 'sag' refers to the reduction of the power supply voltage in response to large transient signals which lends an important dynamic 'feel' to the amp that is not found in solid state amps... I could be wrong of course, as I'm no techie. But I do know the most 'heft' I've ever experienced in 40 years of playing bass has been from all-valve amps.
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Early all-valve guitar amps used valve rectifiers, such as EZ80, EZ81 and GZ34. These were very good at 'heft'. This has got me thinking that one way forward might be a simple 3-watt amp with valve rectifier driving a DI transformer.