Philips had some innovations in this area in the 1970's with their MFB speakers ...
Review MFB
Motional Feedback
Motional Feedback (MFB) is an active high fidelity loudspeaker system ... The loudspeakers have built-in amplifiers and feature a feedback sensor on the woofer. The sensor measures the output signal of the woofer and compares it to the amplifier input signal. This results in a very low distortion and furthermore a more extended low frequency response in a relatively small enclosure. Any distortion induced by the enclosure or the woofer itself is immediately corrected by the feedback loop. To a degree, the sensor-feedback system also compensates for non-optimal room acoustics.
Review MFB
Motional Feedback
Motional Feedback (MFB) is an active high fidelity loudspeaker system ... The loudspeakers have built-in amplifiers and feature a feedback sensor on the woofer. The sensor measures the output signal of the woofer and compares it to the amplifier input signal. This results in a very low distortion and furthermore a more extended low frequency response in a relatively small enclosure. Any distortion induced by the enclosure or the woofer itself is immediately corrected by the feedback loop. To a degree, the sensor-feedback system also compensates for non-optimal room acoustics.
Thanks @smoking-amp and @jhstewart9 for the further studies on this circuit.
What I've seen on LTP is that with a DF of 228 we have -2 dB at 20 kHz, but if we reduce the pot from 44.5% to 35%, we have -3 dB at 28 kHz and a Zout of 1.14 so DF of 7.
What I've seen on LTP is that with a DF of 228 we have -2 dB at 20 kHz, but if we reduce the pot from 44.5% to 35%, we have -3 dB at 28 kHz and a Zout of 1.14 so DF of 7.
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Posts on another topic have been moved here starting at post #200https://www.diyaudio.com/community/threads/single-ended-the-pentode-retaliation.373257/post-7049242