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In the Forum: Audio Discussions
In the Thread: Devid Berning amplifiers: the anti-trnsformers frenzy?
Post Subject: Underdamped bass on SETsPosted by morricab on: 10/2/2007
"Indeed for classical work I often find a slightly under damped bass response to be emotionally evocative and of benefit to the illusion of the acoustic"
Have you looked at the primary cause of this issue with most SET amps? I can tell you that the number one reason for it is output transformer saturation. Another is an inadequate driver stage. Get these two things right and you will not have sloppy underdamped bass. Take the KR audio amplifiers as a good example. Their latest generation hybrid amps (yes the input and driver stages are SS) show almost no distortion increases at bass frequencies. Other SETs regularly show >1% in the bass even at almost no power! OTLs have the problem of dynamic bias drift when asked to deliver a lot of current (ie. in the bass). You can see this quite clearly when you watch a DC offset meter as it pulls to one side or another with big bass signals. This always means a big increase in distortion and therefore sloppy bass. IF you get the output transformer right you will have transparency and good control in the bass frequencies and a high damping factor, requiring a lot of signal destroying negative feedback, is not necessary. Prevention of transformer saturation is sadly neglected by most SET manufaturers and perpetuates the myth that these amps can't have good bass control.Rerurn to Romy the Cat's Site