Hey everyone, I've been working on an 1x12" amp design and learning a LOT in the process. My "reference" amp is a Fender Hotrod Deluxe which I do like. I'm not trying to emulate it with solid state circuits, but it has been a good reference point so far.
One thing that's baffling me is the "presence" control. On the Hotrod I always have it cranked... I find things sound terrible otherwise. I've plotted the curve of the Fender power amp with the presence control cranked and have been trying to get something similar in my power amp. I know that the presence is part of the current feedback circuit, reducing the feedback at the higher frequencies. I'm having trouble though when it comes to knowing how much feedback I should be using in my own circuit.
With respect to current-mode feedback, I have implemented it around my amp using a 0.25R resistance in series with the 8ohm speaker. I have buffers and such set up to amplify the recovered signal from the shunt and mix it back into the signal feeding my amp. I use a dummy load that is switchable to 8, 12 or 24 ohms and I've been using this to see how the load affects the output signal from the amp. When I change from 8 to 24 ohms the amp output changes by about 3-4dB based on my configuration. But I have no idea what is the "normal" amount of feedback to apply, and how much my load should affect the output voltage of the amplifier.
Can anyone explain what is the normal amount of feedback and how much it should affect the output of the circuit? So far I haven't come across any hard and fast numbers based on practical implementations. Thanks!
One thing that's baffling me is the "presence" control. On the Hotrod I always have it cranked... I find things sound terrible otherwise. I've plotted the curve of the Fender power amp with the presence control cranked and have been trying to get something similar in my power amp. I know that the presence is part of the current feedback circuit, reducing the feedback at the higher frequencies. I'm having trouble though when it comes to knowing how much feedback I should be using in my own circuit.
With respect to current-mode feedback, I have implemented it around my amp using a 0.25R resistance in series with the 8ohm speaker. I have buffers and such set up to amplify the recovered signal from the shunt and mix it back into the signal feeding my amp. I use a dummy load that is switchable to 8, 12 or 24 ohms and I've been using this to see how the load affects the output signal from the amp. When I change from 8 to 24 ohms the amp output changes by about 3-4dB based on my configuration. But I have no idea what is the "normal" amount of feedback to apply, and how much my load should affect the output voltage of the amplifier.
Can anyone explain what is the normal amount of feedback and how much it should affect the output of the circuit? So far I haven't come across any hard and fast numbers based on practical implementations. Thanks!