There is nothing particularly special about the design of the Dual Rec's power section. It is pretty much like 90% of other amps except for the feature of disconnecting the NFB in modern mode ( the amp does have an NFB that is engaged for the other modes ), which does still leave some components in the PI circuit. Not having messed with one enough to know how it acts, I can't or won't say why it does what you say it does. Obviously, not 100% of amps will react the same way, depending mostly on their topology. The Mesa DR does have stuff left in the PI circuit, so that could be a factor as to why it does what it does?
If you read what I said about how the feedback loop works, you will see I said exactly what you have. I did err in saying low pass filter, where what I meant was Hi-pass filter to allow the highs into the PI. I did iterate the function correctly with the exception of that. That was an oopsie.
The FM curves can cause the perception of an amps sound to be different at different volumes, but would work in the opposite direction to what most would complain about an amp. I would argue that most people with a 50 to 100-watt amp complain that at bedroom levels, it sounds thin, bright, and anemic. The " loudness " button that comes on 99% of consumer electronics is an FM curve eq implementation that boosts the highs and the lows to create an equal perception of sound at lower volumes. The DJ smile if you will. So if your amps is too bright at bedroom levels, then it is because the amp is that bright, or you could say that it has very little low-frequency energy. Another consideration to make for the FM curves is that the fundamental frequencies for the guitar are just about equal to the higher frequencies of the guitar's harmonics. Meaning that if the amplifier was fairly linear, you would perceive the highs and lows about equal at bedroom levels. The equal loudness contours show us how much actual SPL at X frequency is required to hear them equally at X target SPL. This seems to support my theory that the feedback loop in guitar amps is there because, without it, they would sound less pleasant. Negative feedback loops are used in audio amplifiers for the purpose of making the power amp more linear. It helps even out the frequency response. Since the feedback loop requires forward gain to work effectively, it explains why at bedroom levels ( where you are dissipating 10ths of a watt perhaps ) the feedback loop is not as effective.
I do agree that the cabinet does have an effect on the whole of things, but that is a completely different subject. The reason I wouldn't clump it into tube amp myths is because it is a fixed variable. If you only have one cabinet and 5 amps, that cabinet is going to react the way it does regardless of which amp you plug into it. I feel that cone breakup occurs later than most people think it does. Of course, only a scientific test would weed that out. Despite the result, you can't really change that outcome. If you operate the amp loud enough to start creating PI distortion, Power tube distortion, and speaker distortion, then all you can truly say is that you have a LOT of distortion. If that is the sound you are going for, then how you got there is irrelevant.
If you read what I said about how the feedback loop works, you will see I said exactly what you have. I did err in saying low pass filter, where what I meant was Hi-pass filter to allow the highs into the PI. I did iterate the function correctly with the exception of that. That was an oopsie.
The FM curves can cause the perception of an amps sound to be different at different volumes, but would work in the opposite direction to what most would complain about an amp. I would argue that most people with a 50 to 100-watt amp complain that at bedroom levels, it sounds thin, bright, and anemic. The " loudness " button that comes on 99% of consumer electronics is an FM curve eq implementation that boosts the highs and the lows to create an equal perception of sound at lower volumes. The DJ smile if you will. So if your amps is too bright at bedroom levels, then it is because the amp is that bright, or you could say that it has very little low-frequency energy. Another consideration to make for the FM curves is that the fundamental frequencies for the guitar are just about equal to the higher frequencies of the guitar's harmonics. Meaning that if the amplifier was fairly linear, you would perceive the highs and lows about equal at bedroom levels. The equal loudness contours show us how much actual SPL at X frequency is required to hear them equally at X target SPL. This seems to support my theory that the feedback loop in guitar amps is there because, without it, they would sound less pleasant. Negative feedback loops are used in audio amplifiers for the purpose of making the power amp more linear. It helps even out the frequency response. Since the feedback loop requires forward gain to work effectively, it explains why at bedroom levels ( where you are dissipating 10ths of a watt perhaps ) the feedback loop is not as effective.
I do agree that the cabinet does have an effect on the whole of things, but that is a completely different subject. The reason I wouldn't clump it into tube amp myths is because it is a fixed variable. If you only have one cabinet and 5 amps, that cabinet is going to react the way it does regardless of which amp you plug into it. I feel that cone breakup occurs later than most people think it does. Of course, only a scientific test would weed that out. Despite the result, you can't really change that outcome. If you operate the amp loud enough to start creating PI distortion, Power tube distortion, and speaker distortion, then all you can truly say is that you have a LOT of distortion. If that is the sound you are going for, then how you got there is irrelevant.
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