Inherent offset voltage in the op-amp inputs, amplified by the circuit configuration, will result in a heavy DC current in the transformer primary, saturating the transformer core and possibly overloading the op-amp. You show an op-amp driving a transformer directly. They made simple errors in keying that anybody could make, but because they had no experiince of working things out by hand, they did not recognise the answer as impossibly high, and they accepted what they got.īut just as a calculator is indespensible in adult life, SPICE is a valuable tool for electronic engineers who know from experience what they are doing. Many ended up doing things like 24 x 31 and getting 7464 instead on 744.
Newbies using SPICE is much like 1980's primary school kids who were allowed to use a 4-function calculator. Not only is this just as quick to do, you'll rapidly come to understand how circuits really work. Learn to do simple algrebra calculations with sensible approximations. Learn to read datasheets - undertand the impact of EVERY thing they list.Ģ. May I respectfully suggest you follow this advice I give to all newbies:-ġ. Cone resonance can vary +,- 10% or more, leading to poor control over resonance. Series operation requires driver matching. For 2 x 6C33C, about 200 ohms would be right, ie 4 times Philips 800 ohm drivers in parallel, or 7 x 32 ohm drivers in series. Totem pole and SRPP tube amplifiers require high impedance loudspeakers. The maximum power into 8 ohms is thus 0.63 Watts not 16W. This allows a maximum signal of 0.28 A RMS. Therefore with your HT voltage the maximum allowable standing current is 0.4 Amp. The maximum dissipation allowed in a 6C33C is 60W per tube.
Main question is how stable it is, wrapping GNFB around such "inter-stage transformer".Īttaching the asc and inc (changed to txt) file, i am hoping someone with better skills in LTSpice could simulate a more real-life condition and check the stability. The toroid model is also still too perfect, with no winding resistance, inter-winding capacitance and leakage inductance. You can, however, use the more ubiquitous LM1875 or TDA2030 family since the chipamp itself is making more than 24dB gain. Maybe it's the 6C33C model i'm using but some say at Vg=0 and Vak=150v, 6C33C might give 2.5A current, which translates to 25W to 8 ohm.Ĭhipamp shown is OPA541 which is unity gain stable. It gives you 16W output while dissipating about 220W for single channel. Want to spend more on your electric bills? Need a way to make a chipamp have much worse efficiency and lower output power? Attached schematic might help you achieve those goalsīasically a chipamp fed to a dual primary toroid transformer (24V to 110V+110V, 24v secondary as input from chipamp) driving totem-pole 6C33C output stage, wrapped in super-triode connected GNFB.
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