I would distinguish between label and content.
The simple exercise here: replace your BD139/BD140 with, for example, BD441, BD442. These are audio transistors;-)
... and please do the same here: do it yourself, audite! then answer.
The simple exercise here: replace your BD139/BD140 with, for example, BD441, BD442. These are audio transistors;-)
... and please do the same here: do it yourself, audite! then answer.
That would be a total failure, BD441/442 are 3MHz devices that were used as final devices for low power amps,
generaly in car radios, anyway thank you for confirming that you know nothing about what is a power stage driver.
Eventualy BD789-791/790-792 can be used as drivers since they have a 40MHz Ft.
generaly in car radios, anyway thank you for confirming that you know nothing about what is a power stage driver.
Eventualy BD789-791/790-792 can be used as drivers since they have a 40MHz Ft.
Last edited:
😉
Are engineers engineers if they do not engineer what they claim to engineer;-)
It's really hard to recognize what we're not doing;-)
Are engineers engineers if they do not engineer what they claim to engineer;-)
It's really hard to recognize what we're not doing;-)
Unfortunately, these are not technical data at all, but descriptions of an individual perception of sound.
You have already built several amplifiers, so you have knowledge of the components used, and therefore also of correlations.
Now just list the readable (manufacturer-specific) data.
You know very well that I would like a concrete, complete example from you.
;-)
You have already built several amplifiers, so you have knowledge of the components used, and therefore also of correlations.
Now just list the readable (manufacturer-specific) data.
You know very well that I would like a concrete, complete example from you.
;-)
I remind you, to do your homework, an audio beginner exercise: connect channel-separated power supplies and listen;-)
I like to know a bit more about this. What is the part number and do they also have the complimentary?
What do they know anyway: Moto and Philips are just lousy semiconductor manufacturers, they spit out devices without a clue, and assign them a role. Their opinion on their own products is completely spurious and irrelevant, and should certainly not be taken into account; they are just incompetent amateurs, unlike some clever DIYaudio members
TTC011/TTA006. TO-126 versions of their (discontinued) C4793/A1837. They never were as rugged as some of their old TO-220 types. I’ve seen high end equipment using two in parallel in the driver stages to get around this. They were comparable to most TO-126 types, which, for 50 watt-ish (what they call a 100W AVR) applications, are fine. And it’s 99% of the market….
They never do any listening tests in their lab. All they have is 50 million dollars worth of test equipment.
243/253 is relatively known T0-126 used as a driver but would only be tolerated if you needed higher voltage tolerance
which is closer to 100 volts compared to 80 volts.
If criteria is based on Transition Frequency and assumed moving from amplifier with gain to actuator blah blah.
Its just a amplifier with emitter follower = no gain. At low voltages the BD139/140 will be "faster" and Safe operating Area
is hardly even a concern in a 18 +/_ or 36 volt headphone amplifier
Short answer absolutely use BD139/140
Excellent, Thank you Ic =50ma Vce 5 volts
Audio amplifier assuming Emitter follower with DC bias likely place differently than lab test.
Not debating much. Lab test be under different methods.
I have 3 spice Models, lets all start arguing = Dont care. Observe list for obvious reasons
1) BD139 from TinaTI library
2) BD139G from OnSemi/Modpex Model dated 2004 for current production
3) MJE243G from OnSemi/Modpex Model dated 2003 for current production
All examples tested under SAME CONDITIONS in model = 0dB gain ( emitter follower) Vce 5 volts Ic 50ma with DC bias
Frequency will be marked -3 dB ( frequency scale listed in 243 only = sorry, all graphs scaled the same)
1) BD139 from TinaTI library = 143 MHz
2) BD139G OnSemi current production Modpex Model = 74 MHz
MJE243G OnSemi current production Modpex Model = 18 MHz
Toshiba’s NPN/PNP matching tends to be pretty good. Better enough to hear? Hell I don’t know. Better enough to measure? Maybe, but it might depend more on other factors that you may or may not be controlling well. It’s a headphone amp, right? If so the low quasi-saturation of the lower voltage parts may not be that important as your output levels are probably pretty low. But if I were trying to eke out every millivolt possible out of an 18V supply my bets would be on the BDs. Or maybe I’d try Toshiba’s version next time I get a Mouser order together, and see for myself if hfe holds up at 1 volt. I have a ton of Fairchild and ST BD139’s.
And no, (not mentioning names), the BD441 is not in the same league. It’s on the same process as the TIP31. It’s a step above, but only a step. It has a 2N equivalent (and ON sells both).
Is it good enough for an emitter follower at 3-4 MHz? Yes. But it will have excess phase that the faster parts do not, and closed loop stability margin will be reduced if global NFB is employed. It seems counter intuitive but often faster parts have less problems with oscillation, depending on the nature of said oscillation.
Is it good enough for an emitter follower at 3-4 MHz? Yes. But it will have excess phase that the faster parts do not, and closed loop stability margin will be reduced if global NFB is employed. It seems counter intuitive but often faster parts have less problems with oscillation, depending on the nature of said oscillation.
- Status
- Not open for further replies.