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"If one tube in the Chinese SVT is even "slightly" out of match, it won't turn on or operate at all."
That statement is blatantly false.
Look at the comparator circuits and do the math. If you can.
The Chinese SVT uses the comparator system that was introduced in the USA-designed & manufactured SVT-II.
I can testify with absolute certainty from personal experience that the comparator circuit will tolerate a wider range of mismatch in the power tubes than I, or perhaps any reasonable person, would be willing to tolerate in everyday use. Any SVT that isn't well matched will have an unpleasant amount of hum in the output, to the point that the hum would bother anyone wanting to use the amplifier. With proper matching and biasing this hum can be minimized, and with improper matching and biasing the amp WILL operate with what I think is an intolerable amount of hum at idle. To get rid of the hum problem I use the idiot lights on the bias panel to rough-in the bias setting, and I fine tune the bias setting by minimizing hum in the output.
The amp will tolerate what I think is a pretty wide range of mismatch and still go through the power-on test and function like an SVT is supposed to function. I suppose that the amp might go into protection mode and shut down if some idiot tried to load the amp with unsuitable tubes and or he was successful in intentionally getting the bias settings as far off as possible just to prove a point. In my amps I can run through the entire range of the bias control pots and the power-on tests will still allow the amp to function. You must be doing something really, really wrong. Or maybe you're just trying to see how badly matched & biased you can make the amp, in an intentional effort to run the amp in unstable condition that forces it to enter protection mode and shut down.
When the amp does turn off, it turns off because it's entering protection mode, because the difference in cathode currents is large enough that it it exceeds a pre-defined safety threshold. You can choose to ignore that threshold if you want to, and yes you can run the original Ampegs at ridiculously bad levels of mismatch if your intention is to intentionally drive the amplifier into the ground until it bursts into flames.
But any sane person thinks it's better to establish safe operating parameters for the amp, and operate within them, shutting the amp down when a danger condition is sensed.
I believe that the advent of these comparator circuits represents a major step forward in both design concept and amp reliability. It prevents expensive repairs and potential self-destruction when something goes seriously awry. I like the comparator system in my SVTs so much that I wish every other amp that I own had it. I even think that it would be a good idea for someone to market a board that offers this style of protection to amp builders that are willing to start thinking in the 21st Century rather than just rehashing old designs from the 1950s, 60s and 70s.
The comparator circuit senses dangerous operating conditions and shuts the amp down if a dangerous operating condition exists. It's a responsible way to design an amplifier. Sure, you can avoid acting responsibly, and you can be totally reckless if you want to be, but that's not good for an amplifier. If you choose to act with recklessness it's not fair to blame the amp because it was designed to stop you in your tracks. Going into protection mode doesn't mean that the amps are bad or that they are poorly designed. It some respects, it means that the designer of the circuit is smarter than the guy who is complaining about it.
I think that you're pontificating all of this BS just because you resent the level of complexity that's involved in a modern design. Personally, I embrace the implementation of what I think are very forward-looking ideas.
That statement is blatantly false.
Look at the comparator circuits and do the math. If you can.The Chinese SVT uses the comparator system that was introduced in the USA-designed & manufactured SVT-II.
I can testify with absolute certainty from personal experience that the comparator circuit will tolerate a wider range of mismatch in the power tubes than I, or perhaps any reasonable person, would be willing to tolerate in everyday use. Any SVT that isn't well matched will have an unpleasant amount of hum in the output, to the point that the hum would bother anyone wanting to use the amplifier. With proper matching and biasing this hum can be minimized, and with improper matching and biasing the amp WILL operate with what I think is an intolerable amount of hum at idle. To get rid of the hum problem I use the idiot lights on the bias panel to rough-in the bias setting, and I fine tune the bias setting by minimizing hum in the output.
The amp will tolerate what I think is a pretty wide range of mismatch and still go through the power-on test and function like an SVT is supposed to function. I suppose that the amp might go into protection mode and shut down if some idiot tried to load the amp with unsuitable tubes and or he was successful in intentionally getting the bias settings as far off as possible just to prove a point. In my amps I can run through the entire range of the bias control pots and the power-on tests will still allow the amp to function. You must be doing something really, really wrong. Or maybe you're just trying to see how badly matched & biased you can make the amp, in an intentional effort to run the amp in unstable condition that forces it to enter protection mode and shut down.
When the amp does turn off, it turns off because it's entering protection mode, because the difference in cathode currents is large enough that it it exceeds a pre-defined safety threshold. You can choose to ignore that threshold if you want to, and yes you can run the original Ampegs at ridiculously bad levels of mismatch if your intention is to intentionally drive the amplifier into the ground until it bursts into flames.
But any sane person thinks it's better to establish safe operating parameters for the amp, and operate within them, shutting the amp down when a danger condition is sensed. I believe that the advent of these comparator circuits represents a major step forward in both design concept and amp reliability. It prevents expensive repairs and potential self-destruction when something goes seriously awry. I like the comparator system in my SVTs so much that I wish every other amp that I own had it. I even think that it would be a good idea for someone to market a board that offers this style of protection to amp builders that are willing to start thinking in the 21st Century rather than just rehashing old designs from the 1950s, 60s and 70s.
The comparator circuit senses dangerous operating conditions and shuts the amp down if a dangerous operating condition exists. It's a responsible way to design an amplifier. Sure, you can avoid acting responsibly, and you can be totally reckless if you want to be, but that's not good for an amplifier. If you choose to act with recklessness it's not fair to blame the amp because it was designed to stop you in your tracks. Going into protection mode doesn't mean that the amps are bad or that they are poorly designed. It some respects, it means that the designer of the circuit is smarter than the guy who is complaining about it.
I think that you're pontificating all of this BS just because you resent the level of complexity that's involved in a modern design. Personally, I embrace the implementation of what I think are very forward-looking ideas.
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