PacoCasanovasOld
Fractal Fanatic
Dear friends, Dear FAS
This was the first hint from FAS what's coming next..... IMO
Many of you might ask - why does 12.04b sound different? Is it just 3D magic? Why FAS now put full attention to various power tubes in the new firmware when it's just about various damping factors which could be simulated by flatten- or de-flatten the impedance curve by in- or decreasing LF Res and HF Res parameters - why FAS would add all specific tube data and the dynamic damping parameter which had different default values for each tube? I tried to explain this a bit more in detail, without getting too much into details and also to keep it as simple as possible (if some of you want to add or correct my words, feel free - I would love to get your insights on this!)
Sad part - there is no magic in electronics...there is the reality on one hand and the perfect world on the other, where a loadline in the plate characteristics would stay linear - the line from the maximum plate voltage at the perfect Class B operation point to the plate current maximum when the control grid negative voltage is zero.
this is done for the usual calculations regarding operational points, reading max plate current, plate voltages and to calculate the max. excursion of the signal in relation with plate characteristics and correct adaption for the transformer between tubes output- and primary transformer winding impedance (mostly refered to a measurement frequeny 800 - 1000Hz which is far away from a typical guitar signal).
If this is would be the reality, the dynamic resistance (ra = delta V/delta I) of a power tube circuit will remain the same over the whole frequency range. So the various ratio on various tube types between the output impedance and the impedance curve of your loadspeaker would be only tied to the theoretical assumption of the output impedance.
False.....
This is not reality....the primary winding of the output transformer is another inductance, not a linear resistance - which means, their impedance rise when the signal frequency gets higher or fall if the frequency lowers. There is now also a phase drift between voltage and current because of the inductance - this makes the loadline look more of an ellipse and has a substantial effect on all operational parameter - so the damping factor is not only tied to the interaction between the impedance curve or how good the amp „can see“ the load, it is also frequency-dependent and the amount of influence varies on different tube types and their different characteristics (now added to the power amp modeling in 12.04b)
The damping factor influences the power amp clipping, the effect most of us known as tube compression - punch when turning up the MV - and now this is not just related to the impedance curve of the load only, it is frequency dependent (and a bit more, which would makes this too theoretical here) too....so the high frequency top end clipping which make it sound more 3-D is not magic.......
I assume, this is a very complex implementation in the digital domain, and causes hard hard work! Well done FAS!
Cheers
Paco
There's a little more to it as the output transformer plays a role as well and 6L6 power amps typically have a slightly higher impedance ratio. There's also different operating voltages and bias points but I'm trying to keep this simple.
This was the first hint from FAS what's coming next..... IMO
Many of you might ask - why does 12.04b sound different? Is it just 3D magic? Why FAS now put full attention to various power tubes in the new firmware when it's just about various damping factors which could be simulated by flatten- or de-flatten the impedance curve by in- or decreasing LF Res and HF Res parameters - why FAS would add all specific tube data and the dynamic damping parameter which had different default values for each tube? I tried to explain this a bit more in detail, without getting too much into details and also to keep it as simple as possible (if some of you want to add or correct my words, feel free - I would love to get your insights on this!)
Sad part - there is no magic in electronics...there is the reality on one hand and the perfect world on the other, where a loadline in the plate characteristics would stay linear - the line from the maximum plate voltage at the perfect Class B operation point to the plate current maximum when the control grid negative voltage is zero.
this is done for the usual calculations regarding operational points, reading max plate current, plate voltages and to calculate the max. excursion of the signal in relation with plate characteristics and correct adaption for the transformer between tubes output- and primary transformer winding impedance (mostly refered to a measurement frequeny 800 - 1000Hz which is far away from a typical guitar signal).
If this is would be the reality, the dynamic resistance (ra = delta V/delta I) of a power tube circuit will remain the same over the whole frequency range. So the various ratio on various tube types between the output impedance and the impedance curve of your loadspeaker would be only tied to the theoretical assumption of the output impedance.
False.....
This is not reality....the primary winding of the output transformer is another inductance, not a linear resistance - which means, their impedance rise when the signal frequency gets higher or fall if the frequency lowers. There is now also a phase drift between voltage and current because of the inductance - this makes the loadline look more of an ellipse and has a substantial effect on all operational parameter - so the damping factor is not only tied to the interaction between the impedance curve or how good the amp „can see“ the load, it is also frequency-dependent and the amount of influence varies on different tube types and their different characteristics (now added to the power amp modeling in 12.04b)
The damping factor influences the power amp clipping, the effect most of us known as tube compression - punch when turning up the MV - and now this is not just related to the impedance curve of the load only, it is frequency dependent (and a bit more, which would makes this too theoretical here) too....so the high frequency top end clipping which make it sound more 3-D is not magic.......
I assume, this is a very complex implementation in the digital domain, and causes hard hard work! Well done FAS!
Cheers
Paco