Hi,
another idea that came to my mind while reading this:
www.thatraymond.com/downloads/solidstate_guitar_amplifiers_teemu_kyttala_v1.0.pdf
(see page 112)
Is the possibility to have a floating ground tube power amp working in class A amp plus a class B/C/whatever with high efficiency and high power. The secondary of the tube amp (and the iron as well I would say) has to be able to supply the needed current for the full swing of voltage of the D class amp + the A class tube amp.
The C/D/whatever amp, together with the preamp, will be grounded, while the PA & OT will not, but will use the floating ground controllet by the C/D/blabla.
Does anyone see any reason why this could not work as planned?
another idea that came to my mind while reading this:
www.thatraymond.com/downloads/solidstate_guitar_amplifiers_teemu_kyttala_v1.0.pdf
(see page 112)
Is the possibility to have a floating ground tube power amp working in class A amp plus a class B/C/whatever with high efficiency and high power. The secondary of the tube amp (and the iron as well I would say) has to be able to supply the needed current for the full swing of voltage of the D class amp + the A class tube amp.
The C/D/whatever amp, together with the preamp, will be grounded, while the PA & OT will not, but will use the floating ground controllet by the C/D/blabla.
Does anyone see any reason why this could not work as planned?
What you are suggesting is a tracking B+ for a class A tube amplifier to improve the efficiency of class A. Usually this is considered (mainly in SS designs) for the purpose of avoiding crossover distortion (via a "floating" class A part), and avoiding the high power dissipation of pure class A (using class D or G or H tracking rail Voltage, or B+ voltage, class B won't buy you anything here with only one rail for tubes B+).
There is only one B+ rail to make tracking for a tube amp, so no need for floating power supplies or a floating ground. It could readily be done, a direct B+ rail tracking approach. (Tubelab has built one version) One wants a high PSRR class A tube amp to avoid intrusion of the tracking B+ effects (ie, class D, G or H) from spilling over into the output signal. So pentodes would be the suggested implementation for the class A part.
Another related approach is like the "tube booster" diagram below. The SS (class AB or class D etc) amplifier provides most of the power, the small (low power class A) tube amplifier adds on the final voltage layer using a low power class A amplifier, with a very low Zout OT and pentode tubes. (the OT secondary must supply high current, but low voltage and low power) The class A tube amplifier has the final say about the output V via its N FDBK monitoring of the summed amplifier voltages.
Looks like a tube veneer add-on, but actually the whole thing is equivalent to a class G or H composite amplifier (ie, two Voltage amplifiers in series). (The SS amp effectively feeds the tracking B+ variation backwards thru the OT to the pentodes). This design best fits using existing equipment.
Then there is the parallel I and V amplifiers, or composite V/I amplifier, approach. A large efficient SS amplifier (class AB or D etc) with high Zout (a current mode output amplifier) is paralleled with a low Zout Tube Voltage amplifier of low power class A operation. A current sensing resistor in the ground return of the V amplifier is used as N FDBK for the large current amplifier. The large amplifier tries to always minimize the current drawn from the V amplifier. But the V amplifier always sets the actual output voltage due to its low Zout. The V amplifier always see a high Z load impedance due to the unloading effects of the current amplifier. This makes for low distortion from the class A Voltage amplifier.
Probably more ways too.
There is only one B+ rail to make tracking for a tube amp, so no need for floating power supplies or a floating ground. It could readily be done, a direct B+ rail tracking approach. (Tubelab has built one version) One wants a high PSRR class A tube amp to avoid intrusion of the tracking B+ effects (ie, class D, G or H) from spilling over into the output signal. So pentodes would be the suggested implementation for the class A part.
Another related approach is like the "tube booster" diagram below. The SS (class AB or class D etc) amplifier provides most of the power, the small (low power class A) tube amplifier adds on the final voltage layer using a low power class A amplifier, with a very low Zout OT and pentode tubes. (the OT secondary must supply high current, but low voltage and low power) The class A tube amplifier has the final say about the output V via its N FDBK monitoring of the summed amplifier voltages.
Looks like a tube veneer add-on, but actually the whole thing is equivalent to a class G or H composite amplifier (ie, two Voltage amplifiers in series). (The SS amp effectively feeds the tracking B+ variation backwards thru the OT to the pentodes). This design best fits using existing equipment.
Then there is the parallel I and V amplifiers, or composite V/I amplifier, approach. A large efficient SS amplifier (class AB or D etc) with high Zout (a current mode output amplifier) is paralleled with a low Zout Tube Voltage amplifier of low power class A operation. A current sensing resistor in the ground return of the V amplifier is used as N FDBK for the large current amplifier. The large amplifier tries to always minimize the current drawn from the V amplifier. But the V amplifier always sets the actual output voltage due to its low Zout. The V amplifier always see a high Z load impedance due to the unloading effects of the current amplifier. This makes for low distortion from the class A Voltage amplifier.
Probably more ways too.
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Thank you alot, smoking-amp.
My purpose in not to build an efficient A class amp, but to be able to build a power scaling working on the opposite side: be able to have a good sounding tube amp with the capability to increase its volume to how much is needed through the SS amplifier.
My purpose in not to build an efficient A class amp, but to be able to build a power scaling working on the opposite side: be able to have a good sounding tube amp with the capability to increase its volume to how much is needed through the SS amplifier.
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